family cabin

markert2523 · March 29, 2012, 05:17:45 PM

Hello Folks,

I've decided to build a cabin near a pretty creek in Oklahoma. I'm planning to build it with another family that I've known for many years. As it stands we're planning to have a shared kitchen and central area with each family having two bedrooms and a private bath on each end of the cabin. I found a duplex plan that I think would work rather well if we just built it without the center wall.

I have a hand drawn new floor plan but I don't have a good program for mac to do fancy floor plans.

Here is the site.

The site is at a fairly good slope. Planning to have a contractor pour footings, build a block wall and install engineered floor joists/decking. After that I plan to frame it up, install roof trusses and dry it in as much on my own as possible. I estimate the block footing will be 16 inches high on the uphill side and about 8 feet on the downhill side.

This is a private club with about 25 other old, mostly modest cabins. Nobody actually owns the land the cabins sit on but most families are in cabins handed down over many decades. The club was started about a hundred years ago.

As far as the design, I'm working on changing the front porch into a 20' deep elevated deck running 48' along the front. Part of this will be a sleeping porch, and part an open deck with roof. Not real sure for now how to run the roof over the deck as a plain shed roof would have to have a pretty low slope to still have some height at the edge, even if I use 10' walls. Also I don't like the way the shed roof in the stock duplex pic comes off part of the way up the main roof. I've always thought it looks better when it comes off where the roof meets the walls. But I guess you gain some height that way.

Any ideas?

Bob S. · March 29, 2012, 05:30:25 PM

Have you considered John's Solar Salt box plan?

March 29, 2012, 05:32:28 PM

Alright, a cheesy model but I'm just trying to wrap my brain around this long shed roof thing.

Would make it easier to design if we just would put a 10' deep covered deck on front and a 10' sleeping porch on the back, but the other family likes the idea of having the sleeping porch along the front. You would walk through the sleeping porch out to the deck.

markert2523 · March 29, 2012, 05:36:23 PM

Thanks, Bob. I've wanted it to be one story as I really don't care for multi-story dwelling.

markert2523 · March 29, 2012, 05:44:49 PM

By the way, I've never built anything this big but I did build this:

http://countryplans.com/smf/index.php?topic=7077.0

I keep telling myself that it's just a really big shed!

March 30, 2012, 10:51:10 AM

Put a gabled roof in front and it looks much more proportional to me. Could have the front as a large covered deck and move the sleeping porch back to the rear.

Not exactly sure how to support the front deck/roof since it will be 8 feet off the slope. Would you have the roof structure go all the way to ground or do you build a beefy deck and support the roof on it? Or both? I'm sure this part I would contract but just want to have an idea of what I want before I talk to him.

Thanks

Eric

alex trent · March 30, 2012, 09:53:55 PM

I think you might try sticking with the shed roof in front. Just from a construction perspective it seems a lot simpler. But I also think it could look great. I do not think your models do it justice on how it could look. Plenty of old country houses in the South have that kind of long porch across the front. Of course, yours is deeper so you need to factor that in...but should try some decent sketches. You have anybody that can sketch be good to pay a few bucks and sit with them a while to doodle and noodle it. at this point i don't think you need any fancy floor plans..get the shape you want for the function and then start playing with it.

flyingvan · March 31, 2012, 10:53:28 AM

I'm partial to the gable, but if your preference is having the porch come off the height of the wall there's no reason the wall can't be 2' higher the width of the porch. You could take porch beams from the ridge straight out to the far end of the porch. You'd have a little kick out wall on each side where it meets the main roof

duncanshannon · March 31, 2012, 11:03:06 AM

Cool!

We hope to build in a few years... and are 'selling' some friends on the idea that we should co-own it.

One of their requests is to have two master bedrooms, which I think is reasonable. So, we will take the 1 1/2 Story 20x34 plans and explore options to have to bedrooms with adjoining bathrooms (and call them master bedrooms).

March 31, 2012, 12:35:25 PM

See what this does for a jumping off point;

2' overhangs, I made the main pitch 6/12, the back porch is drawn at 3.5/12, the front gable is 6/12 so 24' wide there. The back porch is 10' deep, I pulled the front gable out 12'

Flyingvan suggested raising the exterior wall up to porch rafter height, this shows the shed roof just lying on the main roof. I like his way better.

If you can run posts uninterrupted it's stronger, otherwise notch the lower post into the floor rims and either hide a plate inside the upper to lower post or strap them together on a face.

alex trent · March 31, 2012, 04:32:47 PM

Why not shed roof front and back...to me the gable roof in back looks odd. Like it is stuck on...does not flow with the house.

Don_P · March 31, 2012, 08:17:40 PM

I think the right wing of this house is what Alex is describing. The porch tie in is what FlyingVan was describing

If memory serves the wing is 24', scissor trussed. The porches are 8' with a 4/12 roof above.
To break up a long expanse of shed roof, you can combine a shed roof with a centered gable... more complex tho.

alex trent · March 31, 2012, 09:09:23 PM

That is a really nice look...and each has their own porch...common one can be in the back.

My experience...some separation of the parties when desired will make life easier over time.

Lots of house to build!

RIjake · April 01, 2012, 09:06:21 AM

My advice to is make sure that party wall extends right up to the underside of the roof. I've seen a couple examples in the city where I work where it wasn't done, and then a small fire that could have been stopped in one unit got going and extended into the attic. Without the party wall extending all the way to the roof it will take a fast response by the FD and aggressive work by the Ladder Company to get that roof opened up to before you lose the whole roof.

It's cheap insurance. Type X drywall on both sides of a 2x4 partition is sufficient. Just make sure the drywall is scribed to the rafters and all penetrations are sealed with a proper sealant. FIRECODE by USG is popular in the northeast.

Good luck with the project!

April 01, 2012, 02:10:19 PM

Thanks much for the replies. I've been up at the prospective cabin site all weekend with no internet access.

Alex---I'm still considering the shed roof on both sides. If one side is gabled, it will be over the front deck.

Flyingvan---I see your idea on raising the front wall but I'm planning on pre-made roof trusses and that would make the custom trusses a little complicated. So the shed roof(s) are likely to come off the existing roof.

Don P---Thanks so much for taking time to sketch that out. It is pretty much what I had envisioned, except I'm thinking of a wider front porch, maybe 30' wide and 20' deep. I think the truss company could make up some 30' trusses with a fairly low slope, maybe 4/12. If my exterior walls are 10', would you take the shed roof off the existing roof or at the top of the exterior wall? Also, I'm not sure I'm understanding your post recommendations.

markert2523 · April 14, 2012, 07:53:51 PM

Hey folks,

I've been moving forward with the cabin planning. The other family and I met and decided to finalize the design with a shed roof porch (veranda) on the front and a shed roof sleeping porch on the back. Building dimensions will be 24'x64'. Sleeping porch 10'x58' and front porch 12'x58'. I apologize for the bad photos but I don't have a way to scan.

I think the front porch will utilize a triple 2x10 beam on top of 6x6 posts using simpson brackets. The posts will be spaced 8' apart. 2x10x12' joists will sit on the beam at 16" OC. I'm still not seeing a good way to support the shed roof posts. If I wanted the posts to run continuous from the ground to the roof, they would need to be at least 22' and I don't have the equipment or manpower to do that. So I need a way to support the porch posts on the deck/lower posts. Don_P had a suggestion above but I'm not understanding it.

Also, I'm wondering if the simpson brackets will be enough to prevent twisting/rolling of the beam. Will any additional bracing be needed to stabilize the beam?

Thanks

alex trent · April 14, 2012, 08:20:51 PM

The Simpson brackets will definitely not be enough to prevent the posts from rolling front to back or side to side...they pretty much keep the post on the footing and prevent uplift. You have a really long moment arm (looks like 12 feet) from the ground to the porch. I guess being anchored to the house helps a lot. I am sure Don P will have some good advice. I am not sure you should not put another row of posts behind the front row. Your bracing between the rows of posts will be most of what holds this from swaying...I guess you can also brace back to the house, but 12 feet is a long way and another set of N to S braces looks needed.

In any case, I would not build the front porch as a "deck", just attached to the house, but tie the porch joists back across the front beam on the house to the beam under the front house wall. I assume the house front is a standard foundation with a wall above it...is that a block or a framed wall? Whatever it is that wall needs special treatment to help hold the porch in place

For the top posts, you could fasten the posts to a sill plate with one of several available Simpson type brackets...or just build a conventional frame for the wall.

markert2523 · April 14, 2012, 09:29:17 PM

Thanks Alex

Your bracing between the rows of posts will be most of what holds this from swaying
Yes. The drawing doesn't show it but I plan to cross brace the posts, both in the plane of the beam and back towards the house.

I am not sure you should not put another row of posts behind the front row

I don't think they are needed from a "sag" standpoint, but I suppose they may help stabilize the whole thing.

For the top posts, you could fasten the posts to a sill plate with one of several available Simpson type brackets...or just build a conventional frame for the wall.
I hadn't thought about that. I suppose a beefy sill plate, like maybe a 2x6 would spread the forces and transfer the load to the bottom posts?

markert2523 · April 15, 2012, 07:26:03 AM

Alex, I've been thinking more about your post...

..is that a block or a framed wall? Whatever it is that wall needs special treatment to help hold the porch in place

The foundation wall will be concrete block with rebar and some cavities filled. The porch deck will not attach to that but rather to the rim joist of the engineered floor joists. I agree that rim connection will need special treatment. I have seen photos of folks using OSB for the rim when using engineered joists, but I would need a solid rim that's connected well to the joist flanges. The ledger would get carriage bolts/washers through the rim and some lag screws through the rim into the joist flanges. Maybe I could add some blocking to the house engineered joists and tie that to the porch deck joists with a simpson lateral load device as below:

Thanks for the input

alex trent · April 15, 2012, 08:55:50 AM

I am not expert and hopefully someone who is will weigh in on this. My experience comes from recently building my small house in Nicaragua (in the owner builder section). I gave building on a slope with tallish posts a LOT of thought...so that is where a lot of this comes from. Some comments on what you just wrote. If you look at that, about half way down the most recent page you will see my front posts...about 6 feet tall, so i can imagine 10 feet being a challenge to keep stable.

1. I'd check out the strength of the concrete wall to the stress of taking the lateral movement from the porch, as that wall looks pretty tall in itself (like 10 feet). You don't want that pushed over. Seems to me a high concrete block wall has poor lateral resistance. Pretty EZ to check that out.

2. I assume from what you wrote the main house beams run left to right. If that is the case, why not rest the joists from the porch right on them with a good overlap and tie them to the beam. Seems to me that beats attaching with a ledger board and to the rim joist...not only stronger connection, but actually looks easier. Since those front beams will be tied to the rest of the beams in the house, you end up with good "bracing" for your porch as any force is resisted by the entire structure, not just connections to the rim joist.

April 15, 2012, 11:18:30 AM

Yes, Alex--I have been tuning in on your very interesting build.

I assume from what you wrote the main house beams run left to right. If that is the case, why not rest the joists from the porch right on them with a good overlap and tie them to the beam. Seems to me that beats attaching with a ledger board and to the rim joist...not only stronger connection, but actually looks easier. Since those front beams will be tied to the rest of the beams in the house, you end up with good "bracing" for your porch as any force is resisted by the entire structure, not just connections to the rim joist.
Actually there likely will be no beams supporting the engineered floor joists. The engineered joists should be able to span the 24' but my contractor is checking with the joist manufacturer to get span info. If it is needed, we will put a single beam halfway through the span. If the ledger connects firmly to the rim/engineered joists, would that not essentially tie the deck laterally to the house floor structure?

I'd check out the strength of the concrete wall to the stress of taking the lateral movement from the porch, as that wall looks pretty tall in itself (like 10 feet). You don't want that pushed over. Seems to me a high concrete block wall has poor lateral resistance.
I agree that I need to have an engineer look at this wall. The block wall will have a sill plate that the house engineered floor joists will sit on and be connected to. Besides the internal rebar in the wall, it seems the floor joists would help prevent lateral movement of the wall. Or am I thinking wrongly?

Thanks

MountainDon · April 15, 2012, 11:20:49 AM

Quote from: markert2523 on April 14, 2012, 07:53:51 PM
Hey folks,

Wow that's a high porch! There are no prescriptive methods for that, none I know of. A thirty inch height is usually the cutoff point between "go ahead and do it" and "you need a permit, an engineer and an inspection". Any advise I would have to offer would be a guess as I'm not an engineer, but I do believe that porch/deck does require a special look.

Also, note that if there were permits, inspections and so on involved here a deck/porch usually has a greater sq ft load requirement than the closed in structure. Open spaces like decks/porches are gathering places for people. As such plan for 60 psf rather than the indoor main floor load of 40 psf.

alex trent · April 15, 2012, 11:54:16 AM

I agree, it is quite structure because of the height. I have to say, until I got started on mine, I was pretty cavalier about that. On the other hand, it likely can be done if you do your homework...and likely make some adjustments in how you do things. You certainly need an engineer to look at it. There are lots of buildings that have these characteristics.

But here are my "non-engineeer" comments.

1. The wall...I have looked a bit for info and most of it is on retaining walls, not ones "hollow inside"..likely there are some to be found. My thought from experience down here (where everything is concrete and they build for quakes) and what I read is that that will not be the limiting factor if done right.

Right means a good footing, a lot of steel (rebar) in the wall and from the wall into the footing, good morter and maybe poured concrete, not block for the wall. Here we pour a horizontal column every six to eight feet high and every eight feet horizontally. The blocks (usually crappy) fill in. but it is the columns that do the work. In a two story house here, the columns are 8x8 and 12x12 on corners. Have rebar posts of three strands of 3/4' rebar inside, formed into cages. These are generally set 3-4 feet into the soil below the footing pour. so on your wall, you'd have 9 vertical columns and two above the footing...one at 5 feet and one on the top.

There will be tables someplace that give the specs and the loads.

2. If you get a good wall, I'd still consider putting the joists on the wall and tying them in, not fastening them to a ledger board on the outside.

3. Given the height and the other considerations, i think you will need another row of posts behind the first row...not as much for "sag", but lateral support.

One more thought...the front height does not look all tat much greater than the current wall height. If you put a wall in front, you pretty much solve all this and get a room to boot. I know it alters the look, but you could work around that with some nice openings and finish.

markert2523 · April 15, 2012, 07:06:44 PM

Yup, MountainDon, I would hate for it to collapse with a bunch (or a few) people on it.

I was talking to my father-in-law today. Years ago he built a small barn for his tractor. He welded together some brackets to hold a beam on posts. Basically an 'H" outline with some depth to it. Think of it as a really heavy simpson post cap. I'm thinking that would help with the beam rolling/twisting worries. I could probably take a piece of 6x6 post and three 2x10 pieces to a local welding shop and tell them I need something that bolts over the top of the post and holds the triple 2x10 beam in-place. Use fairly heavy steel and have bolt holes drilled for carriage bolts or at least lag screws. Any thoughts on that?

Also I have been contemplating the bracing. The front of the deck would likely need x bracing like on the bottom of this image:

MountainDon · April 15, 2012, 08:34:30 PM

Quote... bolt holes drilled for carriage bolts or at least lag screws. Any thoughts on that?

Machine bolts and nuts. Lag screws depend on proper depth of the screwed in part and the strength of the wood. Carriage bolts are normally threaded full length and that reduces the strength. Machine bolts are not threaded for their length except for the end where the nut attaches, that makes them stronger. All that threading along the length of a carriage bolt not only reduces the effective diameter of the shaft but also provides many points where a fracture can start more easily.

The weak point on much bracing is the connection point. They are frequently too close to the end of the wood brace where stress may cause a split. Splits have no strength at all. I believe steel plates, something like a T-plate make decent connection reinforcements. I'm not an engineer though.

Re: the sloping ground. A danger to the piers is that if the ground slopes a lot the footings for the piers need to be really deep to keep them far enough below all the ground level, including the slope. There's an unofficial 7 foot rule that should be considered on sloping ground. On steep properties, the slope of the ground around the footing could affect the footing's stability. The 7-Foot Rule states that there should be a least 7 feet between the bottom of a footing and daylight. Again, not an engineer, but it sounds reasonable.

Just off hand I don't know if this is an IRC item or if it is just a local rule. Once a pier for a deck/porch gets 30 inches tall above ground, or more than 30 inches deep it requires engineering. And locally those pyramid blocks are not permitted for anything where the deck/porch is more than 30 inches above the ground.