Need to fix unlevel foundation walls
grinnin
| Posted in Construction Techniques on
Looking for ideas how to correct out of level concrete foundation walls before attaching sills. The top surface is very uneven with a couple high bulges, and out of level by a bit over an inch.
Wondering if using mortar or a rich pea gravel concrete mix on top would be sturdy enough. It would be a cinch to clamp 2x’s on both sides as forms and fill in with mortar. The anchor bolts are plenty long enough for this.
Good idea? Bad idea? altenatives?
Thanks
Edited 8/22/2006 10:17 am ET by grinnin
Replies
I just dealt with a simualr situation. But I caught it before they stripped it so I held off on the strip, and used a high strengh concrete with a bonding agent.
if you have areas that slope to level the then avoid the agregate.
Simple enough, thanks.
To level sills, grind high spots with angle grinder with stone wheel for concrete if you can. Otherwise or in addition, shim sill level with steel shims and fill gap with non shrink grout. Steel columns are grouted to fill gap when erecting steel on multi-story buildings, so I believe it should work for a foundation.
what you describe is standard building practice. But with the last foundation I had to deal with there was maybe about 1' (literally) that was level to the level strip.
The conctractor had trouble finding someone to do the pour as it was a small one, so he got his guy to do it.
the ammount of shimming would have been ridiculous. So I opted to relevel before it got stripped, and was glad I did.
sounds to me like grinnin may have a similar situation that I had, with too much shimming.
was just rereading your post; it sounds like you're a commercial construction guy. while what you describe is standard. one would not typically mortar a mudsill.
while I have worked almost exclusively on residential, I have worked on plenty of homes with structural steel, so I am famililar with mortaring and the steel shims as you described.
typically, one would shim a mudsill under the joist layout and all bearing points. But I can't fathom trying to mortar the whole thing like that. if he was to mortar the whole thing, then makes sense for him to do it before the sill goes on, with his form boards up.
Non shrink grout is different from motar and is generally speced at 3,4, or 5K psi , and I've seen it high as 10K. Comes in 25 and 40 lb. bags and is not cheap. No fine aggregate (sand) is needed, just mix with clean water and/or water and an addmix that comes with some types.
Be kind of pricey to do a whole foundation wall with it, but it would work. The only places he need shim are the points neccessary to keep the sill plate level. The grout would be strong enough for all other bearing points.
Dave
sorry I was using mortar as a generic term which was incorrect.
thanks for the correction, my bad.
You can set your mudsills on mortar to level them, but you don't need any formwork or anything like that.
Cut your pieces of mudsill and have them ready to go, drilled for the anchor bolts. Buy mason's mix (for setting brick and block). Mix the mortar and use a trowel to lay out a nice bed of mortar on top of the stemwall under the first piece of mudsill. Use plenty of mortar. Put the mudsill on, put the nuts and washers on the anchor bolts, and start tightening. As you tighten the mortar will squeeze out. Use a long level, a stringline, a laser, or something else to help you get the mudsill exactly level and flat. A rotary laser is by far the best tool for this.
When you've got the first piece of sill in, go to the next. Mix more mortar, add the mudsill, cinch it down, check for humps between the bolts, tap it with a hammer, check your laser. Repeat until done. It goes without saying that you need to know what elevation you are shooting for. It might be best to start at the high spot and work to the low spots, where more mortar will be needed to get the same elevation.
That sounds easier still. Any admixtures or bonding agent recommended?
Nope, just mix with water and go. It had far more than enough compressive strength for this application, as long as it's not too thick. I've built up as much as 3/4" under a 2x6 mudsill and it's not a problem. I certainly would not go several inches or anything like that.
sounds a little more touch and go for me. But worth giving a try, I'd try a section and see how it worked, may be a little more skill involved then simply working off a level strip.
but for someone who's got the right touch and feel could be the way to go.
If there are anchor bolts sticking out of the stemwall then it's a piece of cake. Lay the mortar down, stick the mudsill on there, add the washers and nuts, then tighten the nuts until you've pulled the sill down to the elevation you want. The mortar will squeeze out nicely under the pressure. Then use a long level or straightedge to check for high spots between bolts.
It's 2024. I don't know who you are and where you are in the world but guys like you make the world a better place. You have just saved me thousands of dollars and a week of headache trying to brainstorm how to correct this same issue on a foundation. Thank you brother!!!!
You could totally use mortar or a pea gravel mix to level out those walls before attaching the sills. Just make sure you clamp some 2x’s as forms to keep it all in place while it sets.
It sounds like a solid plan, especially since your anchor bolts are long enough for this. As for alternatives, maybe look into self-leveling compounds or even foam leveling if the walls aren't too out of whack.
At this point, it is history rather than a plan.
Using mortar or a pea gravel mix could work, especially with the clamps and long anchor bolts for support. Another option could be using a self-leveling compound, which might be easier to work with and could give you a smoother finish. Just make sure whatever you choose is strong enough to support the sills and will hold up over time.