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Offline SouthernTier

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Soliciting comments on cabin design
« on: January 20, 2013, 12:04:33 PM »
As promised, I am starting this thread to solicit comments on my plans for my cabin, which hopefully will get started in 2014.  Want to finish up the plans this year so I can get the permits.

I have details of where I am building in the thread linked above.  I am in the southern tier of upstate NY.  I started out designing the cabin layout in IMSI floorplan 3D software, but when I got to the details, I switched to TurboCAD.  I probably should have checked out sketchup as I have seen many nice renderings here using that, but too late now. 

The FP3D plans aren't tied into the TurboCAD design, but here is a few FP3D renderings to get an idea what I am attempting:



FP3D is somewhat limiting - the dormer is not really what I have in mind.  But it does give a chance to "look inside" to get an idea.  Here are some renderings using a super-wide-angle view, which makes it look way bigger than it actually is:







One last screenshot from FP3D.  This shows the approximate floorplan and areas:



OK, switching to the TurboCAD renderings, here is an overall view of what I've come up with:



I'll follow up with a next post to go over some of the design decisions.

Offline Alan Gage

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Re: Soliciting comments on cabin design
« Reply #1 on: January 20, 2013, 12:33:09 PM »
Is this just a weekend getaway place? How much time will be spent there by how many people?

Some little things that jumped out at me:

I don't see any closets. Storage is important in small houses.

Stove? Refrigerator?

Do an extra wide counter on your kitchen peninsula so you can have seating on the other side.

You're furniture is arranged the wrong way (at least for my preferences). You've got what I assume is a beautiful view out those big beautiful windows and all the furniture is facing the inside of  the house. Not a big deal but I'd make sure the room layout allowed positioning the couches for an outside view.

Some dimensions would be helpful as well. How big is the house?

Alan


Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #2 on: January 20, 2013, 01:30:13 PM »
To start off, here is the floor plan and some dimensions:



The dimensions probably seem weird, after reading of everyone's plans for 20x32, 24x48 and other round numbers.  There's history behind this.  I originally started out with a 22x22 design.  The 22' distance was based on two things: (1) is it is a multiple of 8" so that it would accommodate a block foundation.  And (2), considering lumber comes in fixed lengths, this width accommodates a 10-on-12 roof pitch with a 16-foot board perfectly.  I know so does a 20-foot wide building with a 12-on-12 pitch, but I'd rather have 2 feet more width and a squatter pitch looks better to me.

So what about the 27' 9-3/4" part?  Well first I extended the back a bit because an 8 x 10 bedroom would just be too small.  So I added 40" (2-and-a-half blocks) to make it 25'-4".  Then I decided to add 2' to the front room, easy enough with 24'-on-center framing.  That made it 27' 4".  But the bathroom was still too narrow, so I extended the back so that the last rafter fell on the inside of the top plate rather than the back, which is a 4" move.  And I had originally cinched down the spacing between the last two rafters from 24" to 22.25" to fit the multiples-of-8" foundation spacing, but since I abandoned that anyway, I stretched another 1.75" and that makes 27' 9-3/4".  As you will see however, this actually makes much sense when laying everything out.

Well, I already started talking about the foundation blocks (or lack thereof), but I am going to go by Mountain Don's advice to design from the roof down to the foundation, so I will start with the upper part of the cabin.



Since I wanted to have a cathedral ceiling, this means I have a ridge beam.  The loft area will have somewhat of a lateral tie, but since I need a ridge beam for the front, the back gets it too.  I did calculations here to come up with a triple 1.75 x 9.25 LVL for the ridge beam.  There is ridge beam support at the gable ends and also one central post, so the spans are 13.5' (back) and 13' (front).

The rafters will have to be 2x 12's to allow enough room for insulation (more on that later).  I plan on notching the ends to they sit on the top of the ridge beam.  Not shown on the drawings are plywood triangular gussets I plan on fastening on either side of each rafter pair at the top to keep them together.  I sized the notch so that the amount of rafter touching the side of the beam corresponds to a simpsom bracket (forget the reference).

Here's the view from the front:



As you can see, I have lots of window space in front.  I plan two 5-foot-wide sliding doors with transom windows, plus a total of four fixed glass windows above.  Note, I have not done any engineering calcs to size those headers (2x10's above the sliding doors and 2x6's above the first pair of fixed windows).  However, this front wall is not load bearing (more on that in a second).  I mainly placed 2x10's above the door/transoms to get sufficient distance to the fixed windows (>24" above moving doors, I believe) to not have to get them tempered.  So I guess that is one thing I would be looking for comments on.

Here are the side elevations:





A few comments on these:

  • I am going with 2x6 studs 24" o.c.
  • I have lined up the rafter to the studs to the extent possible to provide a more direct load path down to the foundation.
  • Yes, I have a strange top plate over the studs.  I have consciously not designed a loft with a knee wall and let-in ledgers as seems popular on CP.  Since I have a ridge beam, the spreading issue is less an issue.  However, aesthetically I am looking for a squatter profile.  And this is truly a cabin - folks don't need to spend lots of time standing around up in the loft - they should be getting outside after a night's rest!  (note, I did check that I have enough space above 5' to meet the minimum habitable area for a room).  That said, I did try to get a few more inches of headroom by lowering where the loft joists sit. 
  • I have extended out the top plates beyond the front and back walls to provide supports for the first and last rafter without lookouts.  I did this on my shed and it works well.  I haven't seen this anywhere else, so maybe there is a reason not to do this.  This seems like a clean alternative to lookouts, but comments on this are welcome.
  • For the above reason, you can see how the front wall is not load bearing.  It actually comes up between the first two sets of rafters.  I plan on extending the balloon framing and the slanted top plate right to the roof sheathing.
  • It looks like I can save money buying windows from stock from either the big blue or big orange box.  But that means that I have to go with a 24" R.O. window size, which screws up a uniform stud spacing.  However, I think the load paths down the overlapping windows are close enough to the rafter locations to keep loads of the windows.  I don't have a jack stud under the header, but I would use one of the clips I've seen to support the header apart from nails from the king stud.  I think this will work, but again solicit comments on whether this would be underbuilt.  I could overbuild but then it would reduce spacing and require trimming of the insulation bats.

And for the back:



The back isn't balloon framed because of the loft.  The windows are stock sized Pella thermastar or American Craftsman windows, smallest size allowing for egress (single hung bottom, casement loft).  The bathroom is squeezed on size so I would frame this with 2x4 (I'll have a separate post on insulation, probably in the general forum).  The gable is also 2x4 framing, but only because it fits "behind" the last rafter, which is sitting on the inside of the top plate.  I will actually have a full 6" of insulation here.

OK, this post is long enough.  More later.  I see I already have one response!  Thanks.
« Last Edit: January 20, 2013, 04:16:28 PM by SouthernTier »

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #3 on: January 20, 2013, 01:43:05 PM »
Thanks Alan for your comments.  Just what I am looking for.  I have thought some about these issues.

Is this just a weekend getaway place? How much time will be spent there by how many people?

weekend get-away place.  Probably just me and my wife (OK, who am I kidding, probably more just me, but I can only hope).  Kids are in (or off to) college (hence why this isn't built yet  ;) ).

Quote
Some little things that jumped out at me:

I don't see any closets. Storage is important in small houses.

Good catch.  I almost left these out.  I have worked some in, but it may not be enough.  In the TurboCAD floor plan layout in my 2nd post, you can see two walls cutting across the bathroom.  One is the front of the shower (I figure to do a built-in custom size one). The other wall is how I pushed in the edge of the bathroom to make closet space.  It's about one hanger-width (+) width.

Also, I plan on using all the space under the stairs as closet space, something I couldn't figure out how to render in FP3D.  I am actually planning on having four separate storage spaces under there:

  • Opposite the kitchen, I plan to have a pocket door opening to about 3 feet of closet space under the highest part of the stairs
  • For the middle part of the stairs, on the bedroom side, I planned on putting in shelves
  • For the living room side of the middle part of the stairs, shelves there also
  • under the stair landing, I figure I have space to  install two clothes drawers.

More storage can be had in the shed and in the basement.

Quote
Stove? Refrigerator?

Fridge, yes.  that's part of the reason for that wall to nowhere.  Not only does it make sort of a mud room at the entry door, but the fridge would go there.  No oven , but I have a 4-burner stove top from a kitchen remodel that I plan to use.

Quote
Do an extra wide counter on your kitchen peninsula so you can have seating on the other side.

That's a great idea.

Quote
You're furniture is arranged the wrong way (at least for my preferences). You've got what I assume is a beautiful view out those big beautiful windows and all the furniture is facing the inside of  the house. Not a big deal but I'd make sure the room layout allowed positioning the couches for an outside view.

I agree.  Still scratching my head how to best to that.  Probably will have to wait until I see the actual space.

Quote
Some dimensions would be helpful as well. How big is the house?

Alan

Got that up at the same time you were typing.  Thanks again for the comments!

Offline rugger8

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Re: Soliciting comments on cabin design
« Reply #4 on: January 22, 2013, 11:30:45 AM »
Southerntier,

It looks good and you have definitely put a lot of thought into her.   :)  I know you said that the dormer was not quite right, so not sure what you plan to do there.  But from my perspective, aesthetically, the one dormer makes the layout lopsided when viewed from the outside.  Have you considered doing 2 matching dormers to be symetrical.  Or a larger shed dormer more centrally located on the roof?  Just some initial thoughts.

i look forward to seeing your progress.

Jeff

Offline waggin

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Re: Soliciting comments on cabin design
« Reply #5 on: January 22, 2013, 01:42:51 PM »
SouthernTier, I like your cabin use philosophy!  A couple of things that stood out to me involved snow.  Your porch roof seems to have a very low pitch, and I would foresee lots of snow building up there.  That combined with a dormer that extends close to that level seems to be asking for trouble during freeze/thaw cycles.  Also, your stairs onto the porch are in-line with where snow may be sliding off the roof.  Granted, this lines up with the entry door, but it might be safer to put the steps to the porch on the gable end or have a 2nd set there for when it may be unsafe.  I've watched deadly amounts of snow come off roofs like that.

I second rugger8's comments on the dormer, and my personal preference is for one large, centered shed dormer.  That would also bring more natural light into your kitchen area.  Didn't see anything on which direction the cabin would be oriented, but that would be a big consideration in window layout for me.  My last house was on a hill facing west, and the solar heat gain from large expanses of glass made it miserable on hot days.

Enjoy your project!

If the women don't find you handsome, they should at least find you handy. (Red Green)

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #6 on: January 22, 2013, 04:50:58 PM »
Thanks for the comments waggin and rugger.  I hadn't thought too much about the outside appearance of the dormer, so I will have to give that some thought.  I am somewhat limited as to where I can move it because it is for the loft, and the loft on that side only goes half way across the building (to the stairs).  I could move it slightly more towards the front, but it would still be in the back half.

The reasoning on the loft was two-fold.  One was to provide a little less claustrophobia in the loft.  Second, the loft would be the guest (or kids') bedroom, and I wanted to put a queen size bed up there.  The dormer is just wide enough to fit one in.  This is another reason for having it more towards the back - a little more privacy for late sleepers rather than sleeping at the edge of the loft.

I could add another dormer to the other side to balance things out.  But as I will discuss in an another thread, I have issues with the required insulation, given the big windows up front.  Opening up another dormer will hurt my UA score in rescheck, and as it stands now, I just barely pass even with lots of insulation.

The cabin does in fact face west, and it will be warm on summer afternoons.  However, I am in a valley and the sun ducks behind the ridge much earlier than true sunset.  And when it is warm, I'll be out on the deck anyway (or on my mountain bike in the nearby trails).

The pitch on the porch roof was also a concern I had myself.  I actually lowered the elevation of the porch floor so I could get that 3 on 12, which is the minimum for a metal roof.  I will look into mounting those porch rafters higher up onto the main rafters.  I didn't do that at first because I thought it would add load to my roof which my ridge beam would ultimately have to bear in part, and also I would risk leaks if I didn't flash the roofing quite right (I am planning on a metal roof).

I also thought about the avalanche danger at the steps.  But I have seen lots of use of snow guards (random google search) on places around here that seem to work well.  I was going to use these over the entrance way and dormer, but otherwise encourage snow to slide off.  With less snow coming off the dormer, there would be less above the entrance way and that combined with the snow guards should keep the avalanche danger manageable. 

But these are all great suggestions and will give them some serious thought, especially since I may have to do some loft/dormer revisions based on yet another code book reading.  Keep them coming!  I'd especially be interested in any comments about the framing plan and any potential structural issues there.  Note, I have not shown blocking between the studs, but I plan on installing them between all studs.

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #7 on: January 22, 2013, 06:21:08 PM »
As Don_P recently said:

Quote
Anyone that says they're fully up on anything past the '90's codes is probably being overly optimistic

This isn't my day job, but I thought I had read the building code inside and out, but found a gotcha yesterday.  As I mentioned, I made sure that the loft had a minimum area of >70 ft2 as required be code, and as defined as ceiling height >5' for sloping roof rooms.  What I didn't do was make sure >50% was more than 7' tall.  I was more like 30% - 40%.  So that means loft modifications.

Doing some geometry, it looks like I still can avoid the knee walls and/or let-in ledgers.  What I have to do is raise the ridge beam by less than a foot (I can still use 16' rafters, I'd go from 10/12 to 10.5/12 pitch) and more importantly, lower the loft floor.

Lower the loft floor? you ask?  How do you do that?  Well, I have an idea, but again solicit opinions.

I had originally planned on using 2x8's 24" oc for the loft joists (just barely to code if I used select).  The rafters would sit along side the joists (more or less) on the top plate.  Like this:



What I plan to do now is switch to 2x6's 12" on center, and basically have the rafters' birds mouths sit on the floor which would be at the same elevation as the top plate.  I was planning on T&G 2x6's for loft flooring, so I would have the top plate run on top of the joists, so that the flooring would be the same elevation as the top plate.

A picture is worth a 1000 words:



You can't see the loft floor in this elevation view because it is hidden behind the top plate.  I would have an intermediate "top plate" below the loft joists as well as shown.

Is this enough headroom under the loft?  I think so.  I would be using full uncut 8' studs in the front of the cabin.  That means under the loft joists (which would be open to below - no ceiling; you'd just see the bottom of the T&G boards), there would be 7'-9 1/2" head room, which should be plenty (and is well within code).

Here's a perspective view:



Note, in this view, I hadn't yet adjusted the beam in the middle of the loft, so you see it sticking out.  That gives you an idea of how much the floor was lowered.

Both these images still have the 10/12 pitch - haven't adjusted that yet until I head what people think.

Of course, with the rafters sitting on top of the floor, I don't get tie-in for spreading resistance.  But since I have a ridge beam, that isn't a problem.

Thoughts?   And speaking of Don_P - I'd love to hear any comments you might have on this or the rest of the upper framing.

Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #8 on: January 23, 2013, 02:43:51 PM »
Sorry, I've been busy,I've had to hang up my bags and am trying to do some design work which like anything new, is taking me more time than it will later.... then we awoke to hard water this morning... happily enough for making coffee  c*.
If you haven't played around with the ridge size options try plugging in a double 11-7/8" ridge as opposed to the triple 9-1/4" one.
http://theownerbuiltcabin.com/calculators/TT/MomentCalculator.htm
The bending resistance in the section modulus equation is very close between them but notice the change in moment of inertia, stifness.

I'm a neanderthal, I use full ground snow load. At some point the full load is going to hang up there.

I prefer not to notch rafters or to not bear on the notch if it is like the one at the peak, I'd want 1/4" clearance between the seat of the notch and the beam. You want the connector taking the load not that re-entrant notch corner, it'll split in a snow or wind event.I'd rather you sit all the way up on the beam with a really minor notch or hang from the face of the beam.

Check the specs on your header clips, I've never used them. Other than that I really haven't taken the time to look too hard, nothing is jumping up and down screaming  :D
« Last Edit: March 26, 2013, 10:07:53 AM by MountainDon »

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #9 on: January 24, 2013, 10:11:52 AM »
Coffee, I can relate.  I told myself I would not get back to you last night until I got a draft proposal done for my day job.  That ended up taking until 3 AM  :o .  So today I need a caffeine IV.

Thanks for getting taking a look. I was starting to think that either I got everything right (unlikely) or everything wrong and you wouldn’t know where to start.

Good advice on the rafters.  I will address that when I redraft the roof to 10.5/12 as I stated above.  I had planned on using Simpson LSU26 slopable hangers for attaching the rafters to the ridge beam as the main point of attachment (not really relying on the notch).  In my redesign, I will go with the mini-notch approach you suggest, especially after pricing those brackets ($9+ a pop!).

Going with the mini-notch will mean a lower elevation for the beam relative to the peak of the roof.   Originally that would have presented a head room problem, but it probably won’t now when I go to the 10.5/12 slope.   However, I probably will not be able to combine that with a deeper LVL and still have enough headroom.  That may be cutting it too close.  Going deeper always provide better performance than going wider, but I’ll have to see if it fits.  I ran the calcs with a full 50 psf snow load and the triple 9-1/4” still qualifies but much closer.  There’s no question there will be more deflection, however.  But I don’t plan on a drywall ceiling, so a little flex shouldn’t hurt.  Besides, I’d never get that full load, right?:

:)

Thanks for taking the quick look.  If you have a chance, these are the few key things that I am not 100% sure about and/or are a little bit different:

  • The use of extended top plates rather than lookouts.  Here's how it turned out (well) with my shed:


    Note, I would enclose the soffits on the cabin.

  • Related: not having a rafter in the plane of the gable wall.  Not needed if overhang rafter is supported by extended top plate.
  • The size of the bathroom.  I can meet all the tolerances given in the code here (toilet 4” from lower left corner, sink next to window - offset from toilet, 24” from shower door, shower minimum 30” in shortest dimension).  I actually have a half bath smaller than this design (minus the shower) at home and it works fine - and this is *just a cabin*.
  • the 2x6 @ 12"oc loft joists.  Yes, these will be flexy, but the strength is to code, and the loft is just a sleeping area.
  • no collar ties.  The triangle gussets I'll add on both sides of the rafters above the beam will provide enough tie-it-together strength
« Last Edit: January 24, 2013, 10:58:29 AM by SouthernTier »

Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #10 on: January 25, 2013, 05:07:33 AM »
Extending the top plates out is never done nowadays in frame construction but it has certainly been done in the past by log and timber builders. It can invite rot and water in if detailed poorly. Yup, that would be poor detailing on the shed. If its out in the weather put a copper rain cap on it, and it'll still fail prematurely. Mr Wright and the Greenes were big fans of this detail, millions (yeah really!) has been spent on their houses repairing it. I can also point to the detail on european timber structures hundreds of years old... keep it dry. Also remember that 2 flatways 2x6's don't make a very good cantilevered beam, under load they can begin to creep and take a deflection set. A bracket attached to the wall was the arts and crafts solution... those brackets are often in distress where they extended the end grain out into the weather for aesthetics. Keep em behind the fascia and protect the end grain. These things are notorious for rotting, detail carefully.

The skewable hangers... I wonder if they actually sell any at that price. I typically mount to the face of the ridgebeam using their 9" L brackets, check loads and allowable shear and it'll probably work ~$3 a pop, narrow leg on the beam wide leg on the rafter, install low, fill all the holes.

The gable end rafter is unneccessary, I often use it for speed of framing with flatways lookouts and to provide an interior ceiling nailer, for 4 that's about $120, my labor comes at a price so it works out there, better framing is the dropped gable wall and upright lookouts. As loads increase and overhangs extend I switch. You are showing some snow :)

2x6 joists, well your eyes are wide open, go for the stiffest species and highest grade you can find, Dougfir or SYP and hand pick for dense and straight grained.

Collar ties are one method of tieing the rafters together across the ridge, the plywood gussets are another, a metal strap over the top nailed to the rafters on either side is also fine. Imagine a sudden inflation of the building in very high wind, a window or door blows out, this keeps the roof from unzipping down the ridge.

Well I had the bill of materials for the house typed up and ready by 12:20 last night and hit send... poof... I love computers  d*



Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #11 on: January 25, 2013, 01:18:09 PM »
dropped gable wall and upright lookouts.
Brilliant!  That's exactly what I'll do.  Thanks.  That will make the gables load bearing, and I may need to beef up the header over the front sliding doors, but that's OK.

Since I will build a cold roof, I take it the vertical lookouts don't have to be the full 2x12 like the rafters, right?  I figure 2x8 or 2x10 lookouts installed a couple of inches below the top of the rafters should provide enough support while still allowing space to put in the baffles for air flow.

So the extended top plates definitely will go.  I knew there must be a reason I haven't seen this around.

What about the beam?  Should that stay all the way inside, too?  Even with the lookouts, it would still be nice to hang the top of those end rafters off the beam.  If nothing else, for ease of building - holding the rafters in place while I nail in the lookouts.

I know of Mr. Wright because he's got a a bunch of buildings here in Buffalo.  But I had to look up the Greenes.  I thought maybe this Buffalo guy was one of them, but no. 

I wonder how much of the millions went to keeping the eaves on this Greene building in shape (courtesy of Wikipedia):


Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #12 on: January 26, 2013, 06:01:28 PM »
If you notch the extended ridgebeam so that it is no deeper than the thickness of the framing then it is there to support the overhang but is enclosed within the soffit and not exposed to the elements, up there is dry as well, as you go down the wall the wind drives water in more.

Usually my lookouts are 2x6, I use 2x6 subfascias and 1x8 fascias most of the time. I install them up to the top of the rafter/underside of the roof sheathing and make 1x5" notches for airflow if its vented.


Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #13 on: January 27, 2013, 02:25:34 PM »
If you notch the extended ridgebeam so that it is no deeper than the thickness of the framing then it is there to support the overhang but is enclosed within the soffit and not exposed to the elements, up there is dry as well, as you go down the wall the wind drives water in more.
Not quite sure I understand what you are describing, but in any event, I have decided not to extend the beams past the walls anyway.  I am going all-in with your advice and switching to a double 11.25" LVL, and will hang the rafters off the side of them with either the slopables or L-brackets.  Since I won't be resting the rafters on top of the beam, then the incentive to do that for the end rafters to help in constructability doesn't apply.
Quote
Usually my lookouts are 2x6, I use 2x6 subfascias and 1x8 fascias most of the time. I install them up to the top of the rafter/underside of the roof sheathing and make 1x5" notches for airflow if its vented.
This just triggered another revelation.  I have 2x12 rafters for insulation space reasons.  There's no need to have such big ones on the overhang!  Maybe this is obvious to everyone else, but it wasn't to me.  I can save money and make it easier to build by putting in 2x6's there, covered by 1x8  fascia.

Thanks again for the advice.  It has been invaluable.

Been working on the revisions in CAD, but we had absolutely perfect skiing conditions all weekend, so couldn't stay inside.  Priorities.

Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #14 on: January 27, 2013, 07:10:56 PM »
I've seen that catch a few folks by suprise. It's just a detail most people have never had a reason to think about. I got the truss drawings this morning and have been doing the roof. this is a typical truss detail but is similar to what we are talking about, the gable end truss over the wall is dropped 3-1/2" for 2x4 lookouts on edge. This is typical for a truss roof, for a stick framed roof you would frame the wall to the same level as the dropped gable truss and pass the lookouts over it like in this pic. This is all in 2x4 subfascias and 1x6 fascia. They are laid out for the top and bottom edges of the plywood sheets to break on them.



I was kind of curious how close sketchup could come to the pro software medeek is using. These are 20', 4/12 raised heel trusses for the local 20psf live load.
« Last Edit: January 27, 2013, 08:26:18 PM by Don_P »

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #15 on: February 12, 2013, 07:12:34 PM »
Haven't gotten the revised framing done yet in CAD, not to mention not posting more moving on down to the floor framing and foundation, but I mentioned in another thread that I would put up an overview of the site layout.

Cartography is an avocation of mine, and as any cartographer will tell you, you use a whole slew of different programs in making maps.  About 10 years ago, I forked out the big bucks for a copy of Esri ArcGIS (although any GIS folk will tell you GIS is about databases, not cartography, but I digress).  I got a new computer recently running windows 7 and my old copy of ArcGIS wouldn't load on it (Esri is as bad as autodesk in making you upgrade every year).  So I started to get more familiar with the open source alternative QGIS.  And what better way than to do up a site plan overview of my lot:



I am not too fond of the labeling capabilities of QGIS, but otherwise it is pretty powerful.

Any way, as I mentioned in the other thread, the creek drives a lot of what I can do.  Unless I want to put the cabin out in the open nearer the road (which I don't), I am forced to put it further to the south of the center of the property, so that I can fit the leach field where indicated, which is why I need to extend the driveway.

Some cartographer I am, I didn't even put a scale on this map (was still learning QGIS).  For scale, the road frontage is 400'  The "spring" such as it is is a tributary draining into the creek so it should be pretty clean.  It is only a surface spring in springtime, but if I dig down I believe I can collect water into a tank.

I am going to work on the driveway extension this coming summer.  Here it is staked out looking downhill on that bend towards where it crosses the creek:

« Last Edit: February 13, 2013, 04:03:30 AM by SouthernTier »

Offline Medeek

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Re: Soliciting comments on cabin design
« Reply #16 on: February 12, 2013, 08:36:09 PM »
Really nice design with your cabin.  I like the way you use lots of windows in combination with the porch roof and decks, the overall effect is really quite nice. 

I like your roof model there Don P, I was wondering why the raised heel on the trusses, is it due to insulation?  Those top chords look heavier than 2x4, I'm assuming that is due to the snow load.
Nathaniel P. Wilkerson, P.E.
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Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #17 on: February 13, 2013, 04:08:17 AM »
Drawing the site is still a big weakness of mine. I've done a little in google earth with their tools and then tried to develop contour lines in sketchup and pull them up right around the building to try to figure initial grades.
Thanks Medeek, I used sketchup's stock painting tools to dress up the drawing. It does lack the crispness of your software. It also started really bogging down as I added the eye candy. I'll save a line drawing to work in next time and use color just for presentation. The truss was designed for 20 lb live load/ 10 psf dead load, so a minimum load. It specced 2x6's for the top chord and the "slider" that raised the heel for insulation. The HAP(roofer talk, "height above plate") over the outer wall at the building line is 1'1-1/2", there is adequate room for insulation and air chutes at the wall line. The wall sheathing is extended up to the underside of the top chords to provide lateral and to help prevent wind washing thru the insulation down low. Bottom chord is 2x4 on this 20' span.

Offline Medeek

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Re: Soliciting comments on cabin design
« Reply #18 on: February 15, 2013, 09:49:41 PM »
I'm assuming there will be either solid blocking or framing between the trusses at the wall line/top plate.  Interesting term for the "slider" I was wondering what they called that part of the truss.  With one of my recent designs I decided to drop the gable truss and have a configuration similar to this example:



Is the lookout stitched onto the gable truss to create the overhang also called "sliders" or is there another term used.  I couldn't seem to find a drawing anywhere that had a particular label for these.

Sketchup has a more architectural feel in my opinion, which isn't at all bad.  If you want to do fancier renderings of sketchup models there is third party software (mostly freeware from what I understand) that will import the sketchup model and apply more realistic shading etc...  I haven't used it a lot recently but a guy I was working with not to long ago was showing me how he rendered some of his stuff with plugins and third party software and it was pretty amazing.

I use Solidworks for all of my 3D stuff, I used to use AutoCAD for 3D but Solidworks is much better in my opinion, the parametric ability of Solidworks makes it very powerful, whereas AutoCAD used to create dumb solids.  I've also used Catia V5 at my previous job and was not overly impressed.  The problem with Solidworks is that once you load up an assembly with hundreds of "parts", like some of my models, it gets very heavy and will bog down even the best PC out there.  Due to this and the fact that AutoCAD is so much more stable when it comes to large "flat drawings" with hundreds or even thousands of lines I've recently begun moving some of my work back onto AutoCAD, especially for cross sectional views and elevations that don't need that isometric or shaded look.

The makers of Solidworks realize that they couldn't beat AutoCAD with their "3D" software, Solidworks.  So they basically came out with an AutoCAD clone called  DraftSight and offered a free version of it.  I've used it some and probably for 90% of AutoCAD users would be and excellent drafting program in lieu of shelling out hundreds of bucks for AutoCad.
Nathaniel P. Wilkerson, P.E.
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Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #19 on: February 17, 2013, 05:41:02 AM »
I might be about to learn something. With a raised heel truss I simply nail the sheathing to the vertical end of the heel to provide lateral resistance. Looking at BCSI B-8 or pg 66 of the BCSI truss manual, the quick answer is that for a 6" or less HAP with <50plf lateral no additional lateral restraint is needed, the heels can handle it. Beyond that... and I'm beyond that, additional restraint is required. 

I'm going by the logic that very often my engineered floor rims' lateral restraint is the wall sheathing. The engineer of record is supposed to design all permanent bracing but it is fairly rare for the truss design to coincide with the building design. In both of our drawings we obviously are ahead of that ball but we still have a problem. Typically for residential the designer is a non engineer, there is no engineer of record on most residential jobs. We are really operating outside of the proper procedure and the codes recognized that by saying that absent competent design, if I've specified my own permanent lateral bracing, it's my responsibility not the truss engineer's. In other words the proper procedure is the overseeing engineer on the job, the engineer of record, co-ordinates with the truss engineer. The truss engineer designs the truss, the engineer of record specifies connection of the individual truss members to his structure and any permanent bracing it may require. I've had an EOR only a handful of times and never on a smaller job.

All of that excusing and explaining later... solid blocking would be worlds better at preventing the tall truss heels from rolling.

 We had a church roof collapse here last year during construction. It consisted of monotrusses (think shed roof) with raised heels on the lower end and a vertical wall about 8' tall at the upper end. These framed over wings on each side of the sanctuary and then scissor trusses were to go over the sanctuary. They failed to sheath or adequately temporarily brace the tall side of the monos and started setting the scissors when the poorly braced monos began to domino. Putting a load on top of something tall, narrow, and poorly unbraced... that mistake can happen at many locations if you think about it, or don't think about it.

"Slider" is what MiTek calls that part... I'll have to get back with you on the tail extension's proper name, I'm glad you made me look, he extended the dropped tail on the gables, that ain't gonna work  d*

Offline PEG688

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Re: Soliciting comments on cabin design
« Reply #20 on: February 17, 2013, 01:11:36 PM »





 Raised heel trusses are becoming pretty common here, mainly to meet the new energy code. We solid block the bays , generally if the soffit is enclosed we bring the blocking to 1 1/2" down from the top of the top cord to allow for ventilation to the ridge vents.  If the soffit is to be left open the solid blocking is bored like a standard bird / anti-rotaion block .

  Blaspheming the Greene brothers!!   Jeesh,  you got nads Don P.  :o  Wright , well I can see that, poor design galore, flat roofs in Illinois, and the such!   But the Greene brothers and by proxy the Hall brothers!!!     Big ones Don , that all I got to say about that  c* 
When in doubt , build it stout with something you know about .

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #21 on: February 20, 2013, 07:41:11 PM »
Thanks guys for keeping the thread alive while I went back to the drawing board.  Took a while.

Where we left off, I was taking Don_P's advice and replacing my 3 x 9-1/4" LVLs with 2 x 11-1/4" LVLs since these also did the trick, but just were taller.  That (taller) became less of an issue when I took the advice to not notch the rafters and have them sit on the beams, but attach them to the face.  Also, I needed to go from a 10/12 to a 10.5/12 pitch in order to get enough headroom to meet code for 50% of floor space > 5' was also > 7'.  This also meant lowering the floor, forcing me to use 2x6 joints @12" oc.  So I get a stiff ridge beam but a flexy (but strong enough) loft.

And finally, the barge rafters would be supported by vertical 2x6 lookouts rather than extended top plates.  And these would just be 2x6's, not 2x12's like the real rafters.

This is what I came up with (just noticed I forgot to trim those top plate extensions - ignore those):



I also increased the slope of the porch rafters up to 4/12 and increased the size to 2x8's.  The dormer will dump onto the porch roof, which is problem discussed starting here.  So I may increase the number of rafters below the dormer from 2 to 3.  Note, the dormer spans from the ridge beam to the wall, so there is no load on the adjacent common rafters.  I haven't shown the dormer sidewall framing here.

Both the ridge beam and the rafters are 11-1/4", so there is some stickup above the beam.  I understand this is better than the other way around because the rafter is in compression rather than tension under load.  That said, it is about the same price to go to a 11-7/8" LVL or to plop a 2x4 on it's side up there.  But I will leave some space to allow the venting out the peak.

Here's the side and back view:





Since we are still working our way from the top down, here is a look at the support for the loft rafters:



Here I have the back wall turned off so you can see.  The bedroom wall has a door in the middle, with a closet on the right, and space for a pocket down on the left (slides out so I can access under the stairs as a closet).  Above this wall, I have a 6x6 that spans from the 6x6 center column holding up the middle of the ridge beam, and a 6x6 column I have embedded in the back wall to hold up the back of the ridge beam.  I don't intend for this 6x6 beam to be bearing the whole loft.  Rather I intend to have the bedroom wall under it to be a bearing wall.  Specifically, either side of the door will be built quite stout, providing support at about the 30% - 40% intervals (not counting on support above the pocket nor the closet door).  I am bringing this up now as it will come into play when I discuss the foundation.

In case you are having trouble visualizing that back view, I learned from this board about homestyler.com and ginned up a model of the first floor.  In plan view it is here:



Still working on the floor arrangement.  I mentioned I am not a fan of corner sinks but I did put my cook top there (no oven in this cabin).  But I also no I am no interior designer.  I did change the kitchen from a "U" to a "L" for more space, but overall, this needs more work.



Comments welcome as usual.
« Last Edit: February 21, 2013, 04:43:33 AM by SouthernTier »

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #22 on: February 26, 2013, 05:11:09 PM »
I guess my redesign of the rafters and loft passed muster, so now to continue working down.  Next layer down is the joists (and floor sheathing).  Cutting to the chase, here is the floor joist layout:



If you recall, the dimensions are roughly 22' x 28'.  So in the front I have close to 14' span, and in the back close to 11' span connecting to a girder.  The 14' span in front required me to go to 2 x 10's @ 16" oc.

In the back, the span tables say I can go to 24" oc, but decided with a couple of exceptions to be conservative and go 19.2" oc.

Exception #1: I left a full 24" spacing just past the midline of the cabin.  I did this because throughout this design, I am designing not just to be functional and hopefully not too ugly (I guess I failed on that with the dormer, though) but also to minimize waste.  So I wanted to minimize wasted floor sheathing, so I came up with this arrangement which uses 96% of the advantec flooring I would need to buy:

 

Those first cross-wise joists are 16' from the front of the cabin, hence the ~24" spacing after the front 14' section.  Now on the right hand side, that's where my stairs will be so not much need for extra support there anyway (just lightweight storage under the stairs, and the stairs supported by their perimeter), but I may throw another joist in the left since that will be in the kitchen.

Exception #2: The back 12' aren't an even multiple of 19.2" so I needed to place two joists closer together somewhere.  I decided to align them under where walls (non load bearing) were going:



So that's the thinking.

Let me know what y'all think, and if it looks OK, then we will move on down to the foundation.  As you can suspect, I will be supporting that midline through the cabin by having a full (walkout or semi-walkout) basement in the front, and a crawl space in the back (sloping lot).  And the girder in the back, if you recall, is below load-bearing wall holding up the loft joists, so I didn't even bother sizing it as a clear span - it will require intermediate supports.  But that is all for the next post.

Offline Don_P

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Re: Soliciting comments on cabin design
« Reply #23 on: February 27, 2013, 04:57:44 AM »
On the ugly, well I'm still smarting on that front this morning, I believe the term I heard yesterday over the phone regarding something I had drawn was "that looks like some butt ugly adirondack trail shelter" ;D. So... to be pc, the aesthetic of the dormer does not speak to me. Gable dormer? The hallway on the main floor is wasted space in a small house. Try to get rid of hallways whenever possible.

To the floor, the sheet layout and orientation doesn't work. The long axis of the floor sheathing needs to be perpendicular to the joists. Joints need to be offset between rows. remember you're not just covering joists, you're weaving together a strong diaphragm. The waste floor sheathing is my stair subtreads and landing.

Offline SouthernTier

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Re: Soliciting comments on cabin design
« Reply #24 on: February 27, 2013, 07:14:54 PM »
More good advice, as usual.

This arrangement uses the same number of 4x8 sheets (20 of them) and I think it meets the overlap criterion best I could considering my joists switch direction halfway through:



To make this work, though, I had to go to a straight 19.2" joist spacing all the way through the back half, which should not be a problem.  Still have a joist under my stairway wall, and only the short, non-bearing hallway wall lies between joists.

Note, I was wondering why nobody brought up the hallway before, for the reasons you mention.  The reason for that hallway is two-fold.

First, it is to provide a wall against to put the fridge and kitchen counters/upper cabinets.  Second, it is to provide a small mud room space upon entering.  A place with hooks to hang up jackets, and not have blasts of cold air go into the main areas.  Also, for the corner unit of the kitchen corner, I plan on installing under-counter access (shelves) from the *hall* side to store wet boots, hats/gloves, etc.  makes good use of under counter space that is usually not well used, at least I think so.  I suppose I could do all that without a wall, although there would still be the kitchen counter there, since I switched from a U-kitchen to an L-kitchen.  I suppose I could move the fridge to the other end of the counter.  I'll give that a try in homestyler.com and see what it looks like.

The dormer is ugly simply to make it easier to build.  The purpose there is to provide a little more headroom for an upstairs bed.  Also more building material conservation.  I plan on a metal roof, which comes in 3-ft wide sections.  The dormer starts 3 feet from the back gable, and is 6 feet wide on top (not going to have much overhang on the side eaves).  So not much metal cutting nor waste.  But the consensus is that it is ugly so I will think about it some more.