Got a call to look at a job today. Nice size deck with some extra work involved. The people said a few people looked at it and never called back. Went to look and I think I know why. The deck is huge and the back yard is a big hill, however thats not the problem. The problem is that they want to cut out six feet of the foundation wall in the basement which is only four feet high and the rest is wood framed to make room for a patio door so they can have a little private patio under the deck. Now my landscaper is ready to go with the retaining wall and pavers if I do the job but the whole cutiing the foundation wall scares me a lot. Not the cutting but the preventing the cave in after I’m done. My thinking is I cut out a section of the foundation for the door now i have a week point so that the soil on each side could cause enough pressure to knock the wall over. Is this line of thought correct. I am planning on going back with a structual engineer to give his opinion on this case but iI figured I would throw this out here and see if anyone has done this and had any problems with it.
Thanks to all.
Replies
I think your headed in the right direction to enlist a structural engineer. let him make up the demo/construction plan. all the liability will be his.
dirty... you don't list your location...
in frost area you will have to pour a new footing below the door down to code frost depthMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
I second what Mike said. It will need to have some support tying the two walls together again.
Structural engineer.
Will Rogers
couldn't he cut out for the door but leave the existing footing below grade intact?View Image bakersfieldremodel.com
I think it depends on the size of the footing and the forces on the walls.
One of the reasons concrete basement walls are so strong is because of their height and that they are continuos.
Once you interrupt that wall with an opening I could see how the footing could be overloaded.
On some of these basement wall systems the footing is more of a bond beam than a footing. It's job is more to keep thing aligned than to support large loads.
I can't remember the name of the basement wall system that sits on gravel. the walls links together are what ties it all together.
Or I've seen where there is just a small footer to set the forms on. The footer is just to have something to set the forms on.
"There are three kinds of men: The one that learns by reading, the few who learn by observation and the rest of them have to pee on the electric fence for themselves."Will Rogers
if it was a full basement , then the original footing was say...7' below finish grade... now to make a walk-out ... you lower the grade and the footing is only say...1' below finish grade...
here the footing has to be 40" below finish gradeMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
After the excavation and footings for the retaining walls are poured, then the new retaining walls are toothed into the basement wall. This strengthens the cutout portion. Your engineer or architect will advise you better.You can brace the wall from the inside temporarily if you think it's needed. Probably not needed if the excavation is large enough.
mike
here we have to have 4' of coverage over the footings however i have seen foundations with a walkout where the foundation guys put stryrafoam under the footing where the walkout was going in
It must of been code as they were all inspected by the bi
"stryrafoam under the footing where the walkout was going in"Do a search on Frost Protected Shallow Foundation (FPSF). It works. The concept is based on the foam (XPS) having a thermal conductivity so low that a couple of inches of it is worth a couple of feet or more of soil. The conductivity of the ground under the foam has no problem keeping the temperature at the footing from freezing. You'd want to slope the foam to shed water away from the foundation. Gravel and other surfacing can go over the foam to protect it.I would think that the foam would have to run up the sides of the excavation also. Either that or the excavation could be a bit extra in width initially to let the foam go laterally wider than the final width of the space under the deck.