Adding basement entrance in stone wall
I am interested in adding a basement entrance from the outside. I would plan on hiring a contractor familiar with this work. Is it possible to do this on a house built on a stone foundation? I’ve seen the large saws they use to cut through concrete walls. Is the process the same?
I plan on having the entrance put exactly where a 36″ wide window well is now – so the way I figure it the outside wall isn’t bearing on anything now b/c of the window well – so it won’t make any difference in that respect.
I’m just curious how they would go about cutting a wall made of small stones without disrupting them. One thought I had would be to create a concrete wall on both sides (a sandwich basically) and then cut through it.
TIA, PJ
Replies
You have to disturb the stone wall further back than the width of the new entry, then fill back in to the CMU.
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as Piffin said, you must disturb the stone wall.
here are the basic steps:
1. determine if location is acceptable (ie, buried cables, utilities, check grade to be sure the property doesn't slope to this location, etc.)
2. determine width of opening for layout. ( the fact that you have a window helps, but often the width is determined by the stock size of the Bilco door resting on top of the wall.)
3. excavate the area. if you go with a size C Bilco, that gives you an outside wall width of about 55" or 4'7". if you use 10" concrete block for your walls, then you deduct 19" from that to get your inside wall width of 36". because you have stone walls, you will need a significant overdig in width because you don't know how much stone will fall out when you start removing it. the width of the excavation on a stone wall will probably be in the neighborhood of 7' for a size C.
4. consider shoring the stone wall now that it is excavated. (to provide the lateral support that is now missing)
5. remove the wall stone in the area where the opening will go
6. form and pour concrete footing
7. concrete block walls to construct the stair opening
8. repair stone wall with stone and concrete block
9. parge and foundation coat masonry walls in affected area
10. pour concrete floor
11 backfill
12. install Bilco unit with proper flashing
13. build stairs
14. install exterior door at bottom of opening
well, something like this. don't let anyone tell you that you can hang a precast concrete stair unit on your stone walls. see the link below for more info.
http://www.bilco.com/foundations/store/shopdetail.asp?product=1BD%2DS%2D1
depending on the site, $10,000 would be a ballpark.
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