28'x40' Maine 1.75 story house

Started by Greenwood, February 12, 2011, 08:01:44 PM

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Greenwood

I have been lurking on the site for sometime now and finally decided to make a post with our current plans (we've changed them so many times I've lost count).  I'm not entirely sure if this is the correct spot to post but I'll go with it. 

We recently purchased 160 acres in Maine, all of the land is covered in trees except a few acres of fields and logging trails(about 20 years old now).  We are planning on building a vacation home (skiing and hunting).  The current plans are for a 28'x40' with an 8' wrap around porch on 2 sides; one side being a screened in porch.  I'm going to attempt to attach some photos of our initial plans (designed ourselves; my wife and I are engineers but electrical).  I would be a newcomer to designing and building myself but I had done 6 summers of contracting work when I was in HS and college, so I know how to do some stuff.  Everything was drawn in Google Sketchup

Anycase here goes, the first picture is of the foundation work, post and pier with about 6" of the pier sticking out of the ground(depending on homesite slope of course).  The frost level is approximately 38", I plan to dig down to 54" or until rock and pour a 12" thich pad about 18" per side.  Then a 12" sono tube with rebar connecting the two.  Followed by a 6"x6"x2' PT post with bracket.  Spacing is 6'6" and 13'4"

With the ground drawn in

There are going to be three beams of built up 3-2"x12"PT and 2-1/2" pieces of ripped plywood. 

I'm not entirely sure about how to brace the beams but I have done some 6"x6"PT on an angle at every post and 2"x6"PT to make it look nice.  Also,  added some 2"x6" the other direction to tie the posts together.

The remaining pics are of the general framing (only load bearing walls are shown) and finished look.  The wife did the layout on paper still haven't found a free software tool that I liked for that part.






MaineRhino

 w*

Very nice job on the scetch!  Nice to see another Mainer here!


Redoverfarm

  w* Greenwood.  Just curious as to why you do not just extend the sono-tubes the additional 2' and eliminate the pressure treated post and secure your beams to the top of the sono-tubes.  There are connectors for this application.   Would lessen the hinge points and IMO make for a more sturdy foundation.  In addition if your frost/freeze depth is 36" then you would only have to have the bottom of your footing at that level or a little more for extra measure.  I would imagine that 40"-42" would be ample. When do you anticipate starting?  

Southern Steve

Wow....looks like a 2.5 storey to me.    :)

Don_P

I agree with Redover, I'd eliminate the hinge caused by the transition of materials in the posts. Depth does equate to resistance to tipping, it helps brace the posts. You are only braced in one direction, the posts should be braced both ways. The girder on top of the posts should be braced to prevent it from rolling, one way is to hanger the joists in between the girders, Simpson also makes a strap that can wrap under a beam and up to the joists sitting on top of it.

I'm seeing a wraparound deck on 2 sides with a porch, a roofed deck, on one side.

I'm assuming the tall walls are balloon framed with blocking at 8', these need engineering at that height. The tall gable wall full of glass definitely needs engineering. I'm using 5"x 20' steel plates in a narrower but similar gable I'm working on to help stiffen the tall walls.

The ties on the rafters need to be in the lower third of roof height. You've drawn some form of kingpost truss with long legs that is not really up to the task. A truss might be worth investigating there or a structural ridgebeam with a central post at the loft edge... which will require a large footing under it and a better load path at the tall gable. Heavy timber trusses, spaced over the pier locations with purlins connecting them might be another option.

I just hit you pretty hard for a first post, sorry about that and not meaning to flame you or your design. Just trying to put down what I see at first blush, this is tall, wide, not on much and not strongly reinforced internally in the open area. Structurally this has a number of areas that need to have someone qualified check on what you are proposing, I'd strongly suggest a SE.


MushCreek

By layout software, do you mean for you floor plan? SketchUp works well for that if you select 'Plan View'. You can download all sorts of objects, such as furniture into your drawings, too. I'm slowly figuring out how to use SketchUP and all it can do. For some reason, though, it won't run on my lap-top, so I do all my drawing at work.
Jay

I'm not poor- I'm financially underpowered.

Greenwood

Redoverfarm,
   I did the 6"x6" post in order for me to make up for the possible slope/terrain and my ineptitude for leveling the sonotubes.  I figured that having the post would allow me to use a water level or laser level and get things much closer to level.  As for the frost level, I couldn't find any useful info, the town next door one direction was 36" and the other was 40".  I wasn't sure how far below I should go, but I'll use your numbers and save my back some.  I don't expect this is going to be a several year ordeal and the digging is one things I can do for cheap, most likely start that next spring 2012.  This year I'll spend clearing some trees.

Southern Steve,
  I didn't know what to call it  :)

Don_P,
  The 2"x6" that I have going over the post and girder on both sides wouldn't prevent rolling?  The post is connected to the pier with a simpson post bracket.  I also have the 6"x6" on the angles which are then covered with 2"x6" that go over the post and girder as well.  I then have 2"x6" that go from post to post across the different rows (third and fourth image).  What direction am I missing?

I hadn't finished the screened in porch in the drawing yet.  But it will be there.

The tall walls are exactly that 15' tall walls.  I'm not using the tall wall for supporting the 2nd floor, the walls there are 8' with 2"x10" for floor joists and then a smaller 6' wall to even the second floor with the other walls.  I'll have to have one my engineering friends take alook at the gable with all the windows and tell me what to do there.

I'm definitely going to have a truss designed and installed by a local company.  I just drew what the wife liked for shape and size.  I'll le thte truss designer figure out whats best to accomplish it.

No problems with the comments/suggestions.  I want to hear them now before I start anything rather then later when I would have to back pedal to overcome the potential problems.  How much does a structural engineer usually charge for this type of job?

MushCreek,
  Yes I meant for florr planning.  I'll have to explore sketchup's plan view.  I like using sketchup, I've drawn out all the components in theimages by hand, except the plywood I grabbed that from the wharehouse.

thanks all!

Redoverfarm

Use the same principle for leveling the sono-tubes as you would the wooden post.  Either a laser level or water will work by either marking the tubes, cutting off or raise or lower to the elevation. Just secure the tubes w/ 2X material and deck screws to keep proper plumb and alignment  As far as the alignment you will need to use a batter board and string line but you will have to use that anyway so just construct the batter boards for long term to do many functions.  I have even used them for elevation from pier to pier but other methods are more accurate. The intermediate middle  boards will only have to be perpendicular to the piers whereas the corners use two legs in different directions.  Take your time in making the batter boards to get them accurate and they will proove invaluable.  Good Luck.

Don_P

QuoteDon_P,
  The 2"x6" that I have going over the post and girder on both sides wouldn't prevent rolling?  The post is connected to the pier with a simpson post bracket.  I also have the 6"x6" on the angles which are then covered with 2"x6" that go over the post and girder as well.  I then have 2"x6" that go from post to post across the different rows (third and fourth image).  What direction am I missing?

I hadn't finished the screened in porch in the drawing yet.  But it will be there.

The tall walls are exactly that 15' tall walls.  I'm not using the tall wall for supporting the 2nd floor, the walls there are 8' with 2"x10" for floor joists and then a smaller 6' wall to even the second floor with the other walls.  I'll have to have one my engineering friends take alook at the gable with all the windows and tell me what to do there.

I'm definitely going to have a truss designed and installed by a local company.  I just drew what the wife liked for shape and size.  I'll le thte truss designer figure out whats best to accomplish it.

No problems with the comments/suggestions.  I want to hear them now before I start anything rather then later when I would have to back pedal to overcome the potential problems.  How much does a structural engineer usually charge for this type of job?

Thanks for taking all that well Greenwood, it felt like a laundry list, and I see part of it was my not understanding all of it;
Yes, 2x6's plating over the posts and girders will do a good job of preventing the girder from rolling. The level 2x6's going from row to row will do very little to prevent tipping in that direction, angle braces in that direction as well. Make triangles to brace things.

The 15' tall walls are supporting half the roof width+ overhang so about 16' of width, this is beyond the prescriptive tables in the code for a wall of that height so an engineer is required by code... and this is a case where I do agree with having one look at it. The porch roof diaphragm is a good brace on the one side. My same concern on the tall gable.

I'm guessing a scissor truss will be the simplest solution for manufactured trusses, this will change the interior pitch and the upper windows in the tall gable end. The interior pitch is usually at least 3/12 below the exterior pitch.

Engineers fees are really dependent on how much they have to do/take liability for. A consult with a friend is usually a few beverages and a dinner, a simple problem a few hundred and a full house review is thousands. I try to keep it in the range of the first two and keep as much of the plan as prescriptive (by the codebook tables) as possible.


Greenwood

Don_P
So for row to row bracing I'm thinking something like this:
But I am concerned on how to attach at the bottom side?  I can face nail at the top to the plating and toenail to the beam but I am unsure what the best approach would be at the bottom side? 

I crisscrossed assuming that is better bracing, I am also thinking to put a 6"x6" where the 2 2"x6"s cross and attach with staggered lag bolts.

Can you attach the code section you are refering to for the wall height to supporting roof width, that will be handy?

I thought that a scissor truss was going to be the choice, the roof pitch is 8:12 so the inside scissor would be 5:12.  I can draw that in and redesign the gable wall's windows for that.

I need to look through my contacts and find a structural engineer for some help.  I also try to stick to the tables as much as I can, in some cases I didn't know there was a table; for instance the wall height to roof width.

Don_P

Sure, I happened to be open to that section from MD's post on loft floors. table R602.3.1... 2 pages beyond the ledger pic he was referring to in that thread. pay attention to footnote b, just about makes it a worthless table.

This is a link to my online codebook, I'm in chapter 6;
https://www2.iccsafe.org/states/Virginia/Residential/Res-Frameset.html

that is a much better brace row to row. braces really work in compression. I'd be happy with a heavy framing angle there or a short piece of angle iron attached to both. if you have a welder you can fab a longer bracket to run up onto the brace well. I'd think about tying the top end to the joists up near the diaphragm of the subfloor. Carry your girder sideplates on it there and nail them to joists, blocks, down from the subfloor, etc. Now look at the labor and costs of that. It is still the weakest foundation going. It's non code. Is it that much cheaper and easier than a crawlspace or at least wall sections at the corners to pick up much better lateral bracing. When the wind hits that big sail above something real needs to transfer that load to the ground without toppling, reliably, every time, for a very long time.

MountainDon

Given the size of the structure and the extensive bracing it does make me wonder too if individual piers is the best way to go on this...



...above from Raised Floor Living
Just because something has been done and has not failed, doesn't mean it is good design.

hpinson

That "Raised Floor Living" website is quite interesting.

Greenwood

Don_P,
Now I might be reading the table incorrectly but based on R602.3.1 with a 2"x6" stud, 16" OC I can support roof only with up to a 18' wall.  With my walls being at approx 15' wouldn't that be fine ????

Framing angle would be the easiest for the bottom bracing, didn't think of using it there d*.  I see your point about extending up above the girder but then each lateral brace would be unique depending on floor joist location above.

You have a very good point about not being much cheaper and definitely more labor but the thing is in my situation where this is going to be done in phases over a long length of time; I have the time to do it myself.  I don't even plan to begin digging holes until 2012 and even then by the time winter begins only having up to the floor joists done (all PT of course).  So I have time.  And to add to it the wife really likes the open pier look which means that is what I'll do b/c I won't be able to do it another way :).

MountainDon,
With the raised floor system and a frost depth of 40", does the footing come all the way to the ground surface as shown in the blown up picture? Or can it end below grade with the concrete block piers coming the rest of the way up?  I still would need three rows of 8 piers, And the concrete pier spacing would be the same as I have now(6'6" by 13'4").  My next question is how far above grade can I go with the concrete piers? I would like to be able to get under the house when needed (say about 3-4').  I assume that I could for go the 6x6 sill bam and still use the triple 2x12 beam with joists on top.?

Digging a trench for the footing would be a lot easier then digging for the piers.

Thanks guys, I like options!


Don_P

Hi Greenwood,
You forgot to read footnote b. The table is for light snow loads on 12' wide or narrower rooms.

We got into it a little bit last night on another thread, I'll continue a little more here. A stud is often subjected to what is called a combined load, or some engineers call it a beam-column. There is the load from the roof above  (snow)where it acts as a column and there is a wind load from the side where it has to act as a beam. There is a formula to check the interaction of the two forces. To illustrate what is going on, imagine placing a thin stick between thumb and forefinger. Squeeze until it begins to buckle and note the force required, this is the column aspect. Without squeezing push on the center until the stick bends, this is the beam action, again note the force. Now do both, squeeze from the ends and push in on the middle, it buckles alot easier from the combined load doesn't it?

Maine has a broad range of pretty heavy snow loads, I don't know yours, it looks like it ranges from 60-100 psf. Wind looks like it ranges from 90-100 mph or call it about 20 psf design load. I quickly ran a scenario based on worst case and blew out by around 50%... that's why I think an engineer is warranted. I'd be happy to be wrong. I'd hate to be right and have agreed with you that it'd be fine.

Greenwood

You are right I didn't read footnote b, which kind of makes the entire useless unless building a very tall shed! 

I am very aware of forces and how to calculate them, but I must admit I hated taking statics/dynamics class.

I was unsure to the snow load in my area when setting forth.  I had asked the town office but they have no useful information as they don't have any codes for building. I didn't think about googling for a snow load map which I just did, incase it comes up later the building will be in Greenwood, ME (fitting name I thought:)) which is in oxford county.
Here is what I found for Snow load 90PSF  @700' (we'll be at 800' so close) and wind 90 MPH.

I think that my best option is to stick to one of John's plans (20'x30') most likely and lengthen it.  I'll have to ask John some questions before I buy though.  Thanks for all your help.

Don & Ginger Lundgren

Did you ask the town how they are handling the new building code for the state of Maine? Only reason I ask is it did come up for me but given that we had started and mostly completed work well before the latest change we do not have to deal with it. Here is a link to what Maine.gov has to say about it.

http://www.maine.gov/dps/bbcs/

Effective December 1, 2010, the State of Maine has adopted a statewide Uniform Building Code. Any building codes that municipalities had in place are null and void. Municipalities over 2,000 in population are required to enforce the new code if they had a building code in place by August 2008. Municipalities under 2,000 are not required to enforce it unless they wish to, however, must still build to the new code.

Now the code change and it implementation has been the source of a lot of confusion and fear for a lot of people as it is a major change from what has or has not been in place. Time will tell as to what really happens.

Greenwood

Don & Ginger,
  Thanks for that information. I hadn't spoken with the town office since November.  It will be something that I will definitely need to do now.  Most likely they will be one of the towns that does not inforce the law but I still will follow the new laws. 

Previously it was "build what you want".

MaineRhino

The problem with the new codes here in Maine is enforcement.  Many towns will have voluntary building code compliance, with no actual inspections.....
The larger cities have the $$$ for code enforcement officers, but most don't.

As with many things, it all depends on location!  d*

Greenwood

I'm over in greenwood, oxford county.  they are going to be too busy with the casino to bother me.  our town is so small tha we share the town positions with 5 other towns, we each get one day a week.