20x34 Universal Foundation Questions

Started by GulfCoastCowboy, December 08, 2016, 07:30:10 PM

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GulfCoastCowboy

The wife and i have been looking through your website for a few years now. Finally bought a lot and the set of plans and are in the planing stage.

(1) looking at the pier and beam crawlspace option i noticed that there is no requirement for a extra piers or a girder. In the stemwall option this is present. What is the reasoning and are the 2x12's gonna be enough to span and carry that load?
(2) the stem wall plan calls for  vents and a crawlspace door. The detail looks as if the interior of the footing has been dug out and then back filled on the exterior. if so and only 8 inches are above grade how does the crawspace door get accessed and no water in it. Can the footer be dug below grade and the poured with the stemwall at the same time, stemwall 24" above grade. would it be safe.
(3) if a monopour slab is done can the plumbing for the kitchen waste be poured in the footer to come up the wall.
We are from texas, and the location is about 50 miles outside of houston. soil is catilla sandy fine loam. dont think frost is even a concern down here. any recomendations on slab on grade vs stemwall or pier and beam.
thanks for your help.

John Raabe

If most people in your area are doing the slab on grade foundation I would suggest the same. Be sure to have the plumbing layout done by a pro since you will be burying that.

If you  do a stem wall foundation you will need to block out for the crawlspace access door. How that works will depend on the height of your stem wall above the grade and below the grade. When you  use a concrete perimeter foundation you will want to use either two by tens or 2 x 8s with a centerline bearing beam (check with your supplier for joists sizing), or the full span I-joists shown elsewhere on the plans.
None of us are as smart as all of us.


GulfCoastCowboy

Thank you for the quick response. Homes in the neighborhood have both slab and pier and beam foundations. That is why i was asking about the pier and beam foundation first. This would be the cheaper option of the 3. My only question about the pier and beam foundation is about the piers only being on the 34ft side except for the 2 in the center of the 20 ft. I was asking weather or not the full spane I joists or the 2x12's called for in the print are enough to carry the load of the two posts to the second floor where the stairs go up. the crawlspace stem wall requires a girder and the slab on grade requires extra footings. I just wanted to be sure that the pier and beam foundation did not require this. there was no note about it. Only the exterior piers and 2 beams none in the interior space.

John Raabe

#3
Now I have the plans in front of me and may be able to better explain this.

For the Beam and Pier foundation (see sheet 9) there are 5 piers on each of the long sides supporting glulam beams. That supports full span (20') engineered floor joists on top. There are two additional piers supporting doubled joists at midspan in the 20' end walls. These are to provide additional bearing for porches and possible future additions. For the upper floor see Framing Plan Floors on the next sheet where you use the the same I-joists as the first floor. An opening needs to be framed for the stair (see left hand floor plan sheet 10). It doubles the joists for the stair and does not need interior posts for support.

If you don't want to use engineered joists you can frame both floors with the 2x8 joists and interior beams shown on the right hand side of sheet 10. There would be beams and two interior support posts that carry both those floor loads down to a footer or pier under the beams. See the Crawlspace plan sheet 7 - that plan works for pier and beam as well as crawlspace foundations. Note, try to get the built up beam to have splices over those posts or within 4' or less.

If I were building the post and pier foundation, I would raise the floor up higher to say 3' or so that you have plenty of  room for cross bracing those foundation posts against high winds and earthquake forces.

Does the above make sense now? I added a lot of options to this universal plan and have made it more complex than if it had only one way to do it. Sorry about that.
None of us are as smart as all of us.