Cutting a hole in my cinder block basement

[CopperNick]

By any chance does your local vocation high school or college have a construction course listed on the curriculum? If so it might be worth a call or visit to find out if they do on the job training or small scale projects as part of the teaching syllabus.

One thing that does occur to me is that when you cut away those blocks and create your rough opening you are going to have to acquire some 1/4 inch flat plate, about 6 inches wide and make an upper sill for each opening that spans the width of the hole plus about half a block more on each side. To install them you will first have to cut away the mortar very carefully, creating a block-wide slot into which they will index, wipe them with fresh mortar and carefully and gently ? hammer them in to the slots. The why for this is that widening your window openings as you have described gets you your correct sized opening but also results in the loss of previously present support structure from the basement wall in the form of those additional blocks which, in turn, could weaken the wall and possibly cause the upper floor to want to droop or sag. The use of the plates replaces the missing materials and returns strength and structure to the wall to allow it to correctly support the house wall above it.

 

[81cutlass]

don't they concrete fill cinder blocks used for foundation walls,,,,,

From what I've seen in my place no. Part of my water issues stemmed from water getting between the old concrete steps and the basement wall. Basically there is brick fascade everywhere but right under the front door and the top of the bricks were open and when it rained water would land on the steps and run back to the house and then down the steps into the wall. I foam filled the top and covered with concrete.

 

[81cutlass]

By any chance does your local vocation high school or college have a construction course listed on the curriculum? If so it might be worth a call or visit to find out if they do on the job training or small scale projects as part of the teaching syllabus.

One thing that does occur to me is that when you cut away those blocks and create your rough opening you are going to have to acquire some 1/4 inch flat plate, about 6 inches wide and make an upper sill for each opening that spans the width of the hole plus about half a block more on each side. To install them you will first have to cut away the mortar very carefully, creating a block-wide slot into which they will index, wipe them with fresh mortar and carefully and gently ? hammer them in to the slots. The why for this is that widening your window openings as you have described gets you your correct sized opening but also results in the loss of previously present support structure from the basement wall in the form of those additional blocks which, in turn, could weaken the wall and possibly cause the upper floor to want to droop or sag. The use of the plates replaces the missing materials and returns strength and structure to the wall to allow it to correctly support the house wall above it.

That's good info, thanks!

A good friend of mine's brother installs egress windows professionally and originally I was going to hire him to cut the holes, but he has backed out.

The steel upper sills make a lot of sense. I have done some reading and I hadn't seen that. I was planning to put a 3 wide layer header of 2x6 up top, and then run the vertical posts down to a sill to create the rough opening, but the steel is a great idea.

I'll have to look into the tech college idea. Great suggestion!

 

[81cutlass]

You could also do it the redneck way. Use a chisel to go around the lines you mark where you want the hole to score the blocks. Then simply hammer the hole out. Blocks should be parged anyways so it will be covered up afterwards... Or do as said above. Gas saws really are simple. Don't overthink it. Just do it.

The redneck farm boy in me just wants to do it.

The wife is afraid the house is going to fall in if I screw up and wants to hire it out so I have some convincing to do 🙂

 

[Streetbu]

The redneck farm boy in me just wants to do it.

The wife is afraid the house is going to fall in if I screw up and wants to hire it out so I have some convincing to do 🙂

Always remember, it's easier to ask forgiveness, than it is permission 😉

 

[pontiacgp]

use a few of these to support the floor in the area of the cut

Tiger Brand 6 ft. 6 in. to 6 ft. 10 in. Adjustable Steel Building Support Column 3 in. O.D. 3A-66610 - The Home Depot

Find the Tiger Brand Jack Post 6 ft. 10 in. Adjustable Building-Support Column 3A-66610, for primary support under wood or steel beams, adjustable, easily installed, for new-home construction from The

www.homedepot.com

 

[CopperNick]

Eyed up the picture of that Tiger Brand support column and thought back to the basement of a relative now long deceased. Gotta wonder if the demo support was put in the right way cause the ones I remember had the screw at the ceiling not the floor. The other thing with those is point load and for posts, code usually asks for a footer so wide by so large by so thick of poured concrete with maybe rebar in it for insurance that will transfer the load from the upper floor to the ground without damaging the basement floor or kicking out of position.

The other thing is that.even with that upper plate in position, you still are going to need room to install the rough in frame in that window pocket so you will have to make allowances for the 2x6's or whatever you rough frame the opening with. Figure at least one upper plate, one lower plate, and two side plates for each side. I am saying 2 by 6 because you mentioned that your blocks were 6 inch.

Nick

 

[Max Headroom]

I own this T-Shirt. Before you do anything, find out what the building code four you local area is. It keeps you from making a costly mistake and it tells you about 80% of what you need to know about doing the work. As one of the posts above mention, you will need a plate several inches wider than the whole to support the wall above. That is in the building code where I live and if you get a permit and the work inspected, not having it will fail the inspection. I advise against using a regular circular saw if you are cutting more than a few inches of concrete (block or otherwise) concrete saws usually run at a different rpm than regular saws and several feet of concrete dust can get into the guts of the saw and in some cases ruin it. Cutting from both sides of the wall is tricky and it is easy to make a mismatched cut. Another thing, what kind of window will you install that will let you exit the basement in an emergency? How does the window actually open, how big is the window, what sized hole will you need to install it? Do you have to have a certain amount of open space outside the window to allow for an escape? (code should tell you this)

This is an excellent opportunity to get in over your head before you know it. I'd have a cup of coffee (not a six pack of beers) and think about this before doing anything. Hope it works out for you. (It's a really crappy T-Shirt)