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I am adding a small mudroom with a full basement. I want to create a doorway to the existing basement through 10″ block and insulated stud wall. So far I have only put in the footing for the addition so I plan to work from the outside inward. Should I saw or hammer and chisel? Any suggestions would be appreciated.
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Mauri, This is an easy project. I suggest you rent a saw with a diamond blade to do the cutting. Do some calculations to determine what size opening would fit your situation and then lay it out on the block so that you avoid cutting through the solid web of the blocks. You probably will not have to remove the block all the way to the top unless you have quite a load from the joists bearing on top of your cutout. In that case you should temporarily support the joists and add a header of the proper size. In many cases, you can add joist hangars to the rim joist and double it up to support the existing floor joists over the opening. If there is a very small load, the blocks can usually just stay intact over the door opening. With your wall thickness, I would suggest you use 3/4" plywood as a "jamb" and extend it to cover the entire block cut as well as the existing wood wall. You would glue it with a good construction adhesive directly to the block and brace it until it sets up. The only problem you may run into is if the cores of the block have been filled with concrete and re-bar. This usually does not occur in every core , so you usually have only one or two to deal with at most.
*I'm gonna disagree with G LaLonde on a couple of points...Masonry-cutting saws are not for the timid. My masonry guys both are about 6'2" and 250 lb and they have lots of experience, so they make this work look easy.IF you hit some rebar, look for a healthy up-charge on that blade rental. New diamond masonry blades go for over $200, I believe.Since your jambs must be of treated material, I'd anchor 2x12's and shim out from there.If you're not thoroughly familiar with building construction, and don't fully understand terms like "bearing" and "point load", you would be well-advised to consult an architect or engineer before opening up that wall.You don't give the height of the clock wall, but I'll presume you have the opportunity to insert the necessary steel or pre-stressed lintel.Prepare for a dusty mess...Advisedly, Steve
*Steve, We use 7" diamond blades in worm drive saws and cut holes like this all the time. One pass from each side and you're done. All you have to do is knock on the cores and you can tell if it's filled or not. I agree, it is dirty. There is really no reason to use treated wood in a situation like this. It's an inside wall and will not rot any more than the stud walls that are standing a few inches away. We do use treated plates on the floor at the bottom of the walls and where walls contact outside walls. A good bead of construction adhesive isolates the wood from the block anyway. I do agree that he should seek advice from someone if he's not familiar with supporting floor loads etc. I am saying that the job of cutting the actual hole is really a very easy (but dirty) procedure.
*Psst...andrew...you out there?
*I agree with the above posted sugestions. I have taken down my fair share of block walls. The only problem you may run into is if a row of vertical cells are filled then it gets ugly. Is your mud room heated? Which way does the joists run. Most block walls I have run into the top row of blocks are filled and a row of two 15m rebar are used. If they are filled this should be suffice for a header.
*Cut out entire wall section with purchased mason's diamond blade (Use it on your circle saw.)...Have window fans running to help with dust...Wear dust mask....Fill in with pressure treated wood and use proper header of wood also...Piece a cake job....As far rebar, etc,...I usually take a sledge hammer and knock some "look whats inside the blocks" holes in the area of blocks to be removed...It's your practice run too, at doing the one time edge of hole cuts, with confidence....near the "swiftly flowing cause it ain't never gonna stop raining," stream,ajThe world sure is green though this year...So this is what Seattle's like....
*Actually, AJ, there was an article in the paper a couple of days ago that said that Seattle, "the emerald city", isn't really very green (or emerald) at all. They have eliminated so many trees in the central core that there is less tree cover than in Phoenix and some other desert cities they named... Portland, OR, on the other hand has managed to keep quite a few of the trees in downtown through some rather severe laws regulating the removal of same.