Basement Wall Custom Home
Basement Wall Custom Home
(OP)
I do alot of basements for custom homes and the ceilings that they want are usually 10' with 24" deep trusses. The restraint force per foot of wall is easily in the 1,200-1,600plf range.
I don't see how the assumption that the floor diaphragm will take the load works. I run numbers and those are huge forces. The other issue is stair openings. No floor framing to restrain it, even if it is in the middle of the floor, there is not a continuous compression member/diaphragm to resist the force and restrain the wall.
Typically when I get loads that are just too high for my comfort level I design the walls as cantilevered and require the contractor to backfill before placing the floor framing and then having a 1/4" gap at the ends of joists/trusses so that the wall can rotate.
Of course this is more costly because the footings are much larger and the wall can be as well so contractors don't like it. I always get the "I've been doing this for 30 years and I never have had to do this!" Of course 30 years ago the basements were 8' ceilings with 2x12 floor framing that was all above grade making it 5-6 feet of retaining, now we have 11-12' retaining! What are your thoughts
I don't see how the assumption that the floor diaphragm will take the load works. I run numbers and those are huge forces. The other issue is stair openings. No floor framing to restrain it, even if it is in the middle of the floor, there is not a continuous compression member/diaphragm to resist the force and restrain the wall.
Typically when I get loads that are just too high for my comfort level I design the walls as cantilevered and require the contractor to backfill before placing the floor framing and then having a 1/4" gap at the ends of joists/trusses so that the wall can rotate.
Of course this is more costly because the footings are much larger and the wall can be as well so contractors don't like it. I always get the "I've been doing this for 30 years and I never have had to do this!" Of course 30 years ago the basements were 8' ceilings with 2x12 floor framing that was all above grade making it 5-6 feet of retaining, now we have 11-12' retaining! What are your thoughts





RE: Basement Wall Custom Home
Glad to hear I'm not alone.
RE: Basement Wall Custom Home
OR, I can also assume the wall is pinned on 3 sides and put "standard footing" but then I will use a lot of reinforcement in the wall (almost like 1 away slab).
What do you guys think? Do you think my approach is correct? Typically the basement wall I design are 10" thick with 12" thick footing that is about 2-3' wide. Especially with the 55-65 psf lateral load that the geotech has been giving me. I dont get a lot of complaints about the footing width though.
RE: Basement Wall Custom Home
RE: Basement Wall Custom Home
Everything to do with concrete is an approximation, but it works because the stiffness of the reinforcement tends to make it behave the way you have designed it.
regards
csd
RE: Basement Wall Custom Home
RE: Basement Wall Custom Home
LG
RE: Basement Wall Custom Home