best way to support exterior wall for foundation rebuild
Danjer
| Posted in Construction Techniques on
Got into a basement remodel and discovered that one of my customer’s CMU foundation walls had buckled and needed to be replaced. The length of wall is 16′ with above floor joists running parallel, then one story of 2×4 wall with roof rafters bearing. So, I need to support the weight of the 2×4 wall and the roof. What is the best way to do this? I was thinking of knocking out a few blocks and running a steel or lvl beam through to the outside. How many beams should I use to support the 16′ of wall and what size should they be? Is there a better way to do this?
Thanks
Replies
There are guys who specialize in this sort of thing. You might want to get someone involved with experience. That way you know it will be done right, plus you get to learn from the experience.
Just two observations:
1) Depends on how heavy and sound the rim joist is.
2) Depends on how long you'll need to support things -- 3 days, 3 weeks, or 3 months?
The joists are sound, but only 2x6. I will need to support things for one week.
Is the wood framing
fully sheathed?
There are two sets of casement windows in the wall, sheathing and vinyl siding.
Two layers of sheathing. 1/2"
Two layers of sheathing. 1/2" plywood over old 3/4" planks.
With that much sheathing
you are not likely to get much settling/sagging at all. I would bolt a 4x12-24' to the outside of the rim joist and start jacking the ends very very slowly with 20-ton screw jacks. Use a laser level and monitor carefully to see if it's going up as a whole or if the middle is sagging. If the middle does sag, you'll need to do some demo and install a perpendicular beam under the main beam to do the additional lifting, and then raise 4 jacks all at once in coordination. Then, the masons will need to leave out a block there until you lower and remove the beams. Make sure to talk to them first about how they can accommodate what you need to do. You really only need to raise it a hair, just enough to slip a credit card in above the top block.
There are other ways to approach the job but this one is fairly easy and you can find out in a couple of hours whether or not you have a viable plan.
Disclaimer: this post is worth less than you paid for it.
I agree with david.. except, didn't he say that the joists were run parralel to the baring wall? (bad practise? yes... unseen? no).. in which case, he'd have to run two 4x12's , right?
Joists parallel to bearing wall
What about a house with a hip roof design? Bearing on all four walls of the house.
Figuring out what's bearing and what's not is outside the purview of this thread, at least so far. I'm intending to describe a method of lifting a rim without getting under it, something that often has to be done to do foundation retrofit or repair work. For all I know he has a three-story building with a structural ridge and a post bearing right in the middle of the 16 foot wall. If that's the case, he's going to need to go to plan B, or maybe C.
I do like the sound of all the sheathing on the wall, though. Pretty good chance of lifting that from the ends without distorting it.
Bolt the 4x12 up under the rafters ,catch as many studs as you can. Set kickers (strongbacked 2x6s)under the beam to the ground at 20 degree angle to the building. Jack the beam up ,drive the kickers in at the bottom. Lift just enough to get weight off th foundation.y The more angled kickers the safer.
Something sounds wrong with this description
Normally when the joists run parallel to this wall and it is only 16', the roof is not bearing on it.
Is this not a gable end wall?
Is there a roof beam bearing on it?
I attached a quick sketch. The floor joists run parallel, however, the roof rafters one story above are bearing. The rim is 2-2x6 and the beam in the middle does catch them both. I am thinking jack post under the beam and under the rim where it comes off the foundation to the interior. Then, poke a temp beam through the foundation between the existing beam and the gable end. Further comments/suggestions much appreciated.
can't seem to view sketch
not sure what the problem is. seems to be on the FHB end
Now we know what "enhancement" they installed over the weekend.