Changes to the 14'x24' Little House

Started by pericles, April 05, 2008, 12:43:58 PM

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pericles

After a huge amount of really great advice from the group on the Owner-Builder project, I wanted submit my changes to the little house plan here to make sure that the group, but especially John, would sign off on them as not completely wrong-headed.

From the stock Little House (14'x24') plan, my wife and I want to make the following changes:

(1)  Instead of using the post-and-pier technique described in the plans, we want to set the simpson brackets into the concrete and load the foundation beams directly into the brackets.  We may run into problems with getting everything precisely level, in which case we'd switch back to posts, but a number of the projects on the forum cut the posts out.

(2)  Without posts there would be no braces, so we'd move the piers to the outside of the frame, directly underneath the loadbearing walls.

(3)  This would increase the distance between piers, so we would increase the width of the floor joists to 2x8 (should use use 2x10 instead?)  We'd probably have to do so regardless, because there are areas of the floor over which we'd like to install ceramic tile, which might break if the 2x6 joists called for in the materials' list were to deform too much.

(4)  We'd also like to increase the wall height by either one or two feet.  Instead of resting the loft joists on the wall plates, we would increase the studs to 2x6x104" and make the 2" ledger let-in that PEG recommends.  (MountainDon has pushed me toward that as well.)  Loft joists would be secured to the ledger with hanging brackets.  Based on the layout we're projecting, there would be a wall underneath the loft as well that would provide some support, although no third foundation beam would support that wall.

(5)  For the moment we're planning on throwing up T1-11 siding, no Tyvek, no siding.  In the future we'd like to wrap the T1-11 and add boards and batons, but speed of assembly is going to be key for us in order to get the project done over the summer and sealed for winter's snow.

That's it!  I'd really appreciate it if you'd point out whether anything we suggested will cause the cabin to collapse, or if there's a cheaper/easier way to accomplish our goals.  Thanks also to the whole group who made a lot of the suggestions that went into our changes, especially MountainDon who has been a real help and motivation.

Jack Larkin
jlarkin1@law.villanova.edu
Jack Larkin
jlarkin1@law.villanova.edu

MountainDon

To touch on number (5) first...

If I was going to put the final exterior covering on at a later date, I would sheath the structure with OSB over the studs, then wrap it in good old #30 building paper (roofing felt). I'd be sure to get the seams nailed down well enough to keep the wind from getting a hold, maybe cover the seams with battens that could later be reused.

My reasons: OSB is much cheaper than T1-11 (around here) and the "tar paper" will keep the drafts out and the water away from the OSB and the insulation in the walls, etc.. It'll also allow you to properly flash the doors and windows.

Or if sheathing grade plywood was reasonably priced I'd use that in place of the OSB.

You should also check to see if you can obtain 4 x 9 or 10 ft sheets in your area. If it's available it could be used to advantage. Placing the sheets vertically you could avoid and horizontal seams and have the sheet cover from the top plate down overlapping the rim joists. Makes for a nice tight rigid wall. The sheets cost a bit more per sq. ft. but make the work nicer.

Just my thoughts. OMMV
Just because something has been done and has not failed, doesn't mean it is good design.


MountainDon

Number (4)
QuoteLoft joists would be secured to the ledger with hanging brackets.

It could be simpler to place the ends of the ceiling/loft floor joists on top of the ledger board, and nailed into the wall studs. That eliminates the hanger cost. Either would work.
Just because something has been done and has not failed, doesn't mean it is good design.

MountainDon

Number (3) Beams further apart, under the exterior wall line.

Even the best 2x6 at 16" OC would not do for that span.
Doug Fir Select 2x8 would be pushing the limit, lesser grades a no-no.
Doug Fir 2x10, even #2, would work.

The 2x6's probably wouldn't break, but the floor would be springy and at the very least the grout lines crack.
Just because something has been done and has not failed, doesn't mean it is good design.

MountainDon

Number (1) & (2)

Along with floor joists sizing changes this should be okay. Previously we discussed changing from 4 ft pier spacing with 4x8 beams to 8 foot pier spacing with built up 6x12 beams, or 6 foot spacing with built up 6x10 beams. John will likely have some input on that.

One thing to keep in mind is that your building code official may want the beam material to be PT wood, unless the lower edge of the beam material is at least 12 inches above grade. Similarly for the joists with an 18 inch minimum clearance above grade. Run that by them.


++ John, when you drop in what would you recommend for ceiling/loft floor joists?
Just because something has been done and has not failed, doesn't mean it is good design.


Redoverfarm

Jack if I may inject my $.02 worth

(1)  There shouldn't be any problem with the levelness of poured or blocked filled piers providing you have a builders level(transit). Followed by scrap material the same demension of the beams you are using attached to the Simpson an rested on the top of the block for the right elevation.  The main problem you will have is setting the brackets for squareness.  Use of High batterboards should take car of this.
(3)  For a floor I would not go any less than a 2X10. Less bounce especially with tile.
(4)  I put 4X8 beams for a loft floor in my cabin.  I used blocks sized the same as my wall studs(2X6) nailed into the studs at the same elevation to place my beams onto and then screwed the beams to the studs.  Although you are not using that heavy of floor/ceiling joist you could just nail. This would probably mean you would have to add cross block at the bottom of your floor  joist between the studs to attach dry wall but normally there are extra blocks from cut offs that will be available for this from other aspects of your project.
(5)  Years ago I learned of a technique on Board & Batten and it really changes the appearance IMO to the better.  On your batten strips take a hand/electric planner and bevel the edges.  It makes the batten strips blend alot better. I used a Makita 3-1/2" planner which had a V-groove in the bottom plate. Ended up with a slight uniform bevel on each side. 

John Raabe

Good advice from Mtn. Don and Redoverfarm.

Since you aren't getting the continuous span effect with the 2x6 floor joists (support beams stepped inside the walls) use the 2x10 joists as suggested. Your loft will now be usable living space so I would size the joists for a 30psf live load. That would best be carried by 2x8 @ 16" (DF or SP #2 or Btr.) If you expect to load that floor as heavily as the main (tile in the bath?) then do the same as the main floor. If there is no plumbing sticking down you could do a beam and decking system. 4x10 @ 48" with 2x6 T&G would be about right.

You are putting more load on the floor beams and pier foundations. Without trying to replace the local engineer who knows all the local loads and soil specs, I would suggest being generous with pier placement (or the depth of the beam) and the size of the footings. You have an interesting design that is really a narrower version of the 1 1/2 story 20' wide.

Post some pics when it gets done, it should be neat! :D

None of us are as smart as all of us.

pericles

Thank you ALL for your advice; it's prompted some changes in my plans, and will make a big difference both to approval and helping my building not fall down!

Jack Larkin
jlarkin1@law.villanova.edu
Jack Larkin
jlarkin1@law.villanova.edu

considerations

For John Raabe

At what height does headroom or other considerations cause an indoor area to be considered part of the square footage? 





MountainDon

Just because something has been done and has not failed, doesn't mean it is good design.

John Raabe

Thanks, Don's right on as usual.

Most other codes have similar readings on this. Below 5' is considered storage rather than habitable space.
None of us are as smart as all of us.

mvk

Anybody

Does this apply to property taxes? on my old house a cape we have a lot of square footage that has a ceiling height under 5'?

Mike

MountainDon

For tax purposes they usually go by the exterior measurements, at least here. But I'm not sure how they factor in an upper floor with sloped walls in places.  ???  I've never owned anything taller than a single floor. And the answer could vary by tax district. The best answer would probably come from the tax office. Of course finding someone who really knows might be a challenge.
Just because something has been done and has not failed, doesn't mean it is good design.

Redoverfarm

And to convince them otherwise would be an even bigger challange.



considerations

Thank you gentlemen for the guidance, the link will be most helpful as well.