G’day all,
Son and I dug the hole for the window well and I’m very close to the point of cutting the opening for the window.
Here’s the deal; the wall is 8″ poured concrete and the window is kinda big; 4′ tall by 4’6″ wide. I’ve already got a handle on what the header needs to be, and know that I need to support the joists above. I’ll be removing the wall all the way up to the sill plate.
A few questions then, if you don’t mind; what is the best way of cutting the opening – leaving a fairly smooth side, and reducing the section to manageable chunks? Also, will one 2X8 on each side of the opening – fastened to the opening, be sufficient to support the header?
Thanks for your input….
Dan
Replies
I like to do everything myself and almost never hire other people to do home construction or major remodeling. With that said....
I have added windows or doors in the basement in my last couple of houses and I have determined that there is only one way to cut an opening in an 8" poured concrete wall.
Hire a concrete cutting company. They charge by the linear foot.
They have the saws to get the job done. If you don't mind a little bit of overcut they can use a circular saw for the entire job. If you don't want any overcuts then they have to use a chain saw on the corners. This is a lot more expensive.
As far as your header goes, unless you are a structural engineer, hire a licensed structural engineer. I am an engineering but still hire someone to do anything that could cause my house to fall down.
You can most likely use 2 X 6s on the side and some steel on the top and it will not fall down on a sunny day. But.... depending on what is above it you may have a wall crack or a window not work right. Or, in a heavy wind or on a day with a lot of snow on the roof you may end up with a problem.
This is one of the simplest project I have done in my house because I hired someone to determine the loading and I hired someone to cut the hole. I then just had to install and flash the window. I use tap cons to secure 2X6s to each side and the top and then screwed my windows to them. flashed the outside with aluminum and a caulk that was supplied by the window distributor.
Hope this helps.
Tom
hi Dan, you could hire a concrete cutter, but if you really want to demolish something, why not do it yourself. Rent the largest handheld concrete cutting saw you can find, and a rotohammer with a few 3/8 or 1/2 diameter bits, and a wide spade chiseling bit.
build a temporary wall inside the basement to support the joists that land on the section of foundation you're going to pulverize. a top plate, a bottom plate, and one stud for each joist should do it. make it tight. I'm assuming this isn't the basement for a 10 story building, so that should do it.
draw the hole for your window on the inside. remember to make it big enough for window plus framing, plus a little more, for example on this window I would make the opening about 60 1/2" wide. in answer to your second question, no, one 2x8 on each side will not be enough, use two on each side. leave enough room on the bottom for a 2x and also for a finished sill, if you're gonna put an applied sill on your window just leave room for a 2x. you say you got the sizing for the header covered, so, you're ready to rumble.
drill out the corners of your cut line from the inside. it's possible you didn't dig the outside hole deep enough (you'll need enough room on the bottom for your saw, too), you'll find out at this point. Now that you have the corners located draw the cut line on the outside with a level. The outside face of the concrete probably will blow out a little like the exit of a bullet, so stick something through the hole to accurately locate your corner. It's very important to make the cut as precise as possible.
go to work with the saw. make many passes at increasing depth until you bottom the saw out on every cut line. depending on the blade you may have to water the cut, ask the guy at the rental yard. cut the bottom line first.
saw out the sill plate and get rid of it. if your saw cut deep enough and your cut lines were accurate, you now have a very large block of unsupported concrete. at this point let your son bust it out.
just kidding, you may have to make a few more vertical cuts from inside and outside, depending on how tough the concrete is, not all concrete is the same. more likely than not it will be very hard work to break it out but you can do it.
if your saw did not cut all the way through (that is, 4 " or more from each face), you'll have to drill a lot of holes near the cut line to weaken the block. this will take a long time, and be somewhat tiring.
this is really fun work, that's why I typed this all out, I don't want to hog the fun,
good luck, GO
Why would you need vertical 2x8's to support a header over the opening when you have a perfectly good poured concrete wall on both sides of the saw cut opening to support the ends of the header?
Since you are needing to support joists I can only assume that you already have a band joist to the outboard side of the wall. This can be doubled or even tripled with the added header material sitting on the concrete and the floor joists cut back just enough to fit metal joist hangers.
As for the saw cut, if you want to do it yourself, be prepared for the biggest cloud of dust you have ever seen, or provide a fine water spray as you cut. The gas powered saw has a 14" blade (usually) and can be the abrasive type or diamond. You will need several of the abrasive type blades, as they wear down rapidly, or just one of the diamond blades. See if the rental saw could come with the diamond blade - so much better for ease of cutting and full depth cuts.
Cut one side first, marking the corners, and finish from the other. Be aware that there may be some rebar in the way. Cuts that don't quite make it to the corner can be cleaned up first with a chisel and then with an angle grinder. (Or just an angle grinder).
Just in case you manage to cut all the way through, start with the horizontal bottom cut. You don't want that to be the last cut because it could pinch your blade.
A few saw cuts through the meet of the slab will make it easier to break up with a sledge or, better yet, something like the Bosch SDS Max, which can also be rented.
Have fun. We'd like to know how you made out.
As someone who has a real hard time letting anyone else work on my house, I have to say - hire this job out!
If you gotta hog all the fun - buy the diamond blade. You will end up paying up the rental company by the thousandth of an inch of wear, and an 17 feet of 8" deep handheld cut will definately put some serious wear on the blade. I've been told by my rental company that they fairly regularly end up charging more than a new blade to someone ($200-$300) who thought they were just paying $45 per hour.
Enjoy! Nothing like bustin concrete!
Hire it out, I had one done in the basement 4x4 in 8 inch concrete, can't remember the cost but it was very reasonable like $250. They do the dirty work I framed in the window done.
> Why would you need vertical 2x8's to support a header over the opening when you have a perfectly good poured concrete wall on both sides ...
First thought is that for a window rough opening, you'd want wood on the sides to nail into for the final installation. Even if that weren't a consideration, it might well be easier than making the more complex and precise cuts in the concrete to notch out for the header.
-- J.S.
if the area above the window is concrete, why would you need a header. concrete is stronger than a 2x8
He said he's not leaving any concrete above the window, it's going all the way up to the plate and joists as high as he can get it.
-- J.S.
There are two kinds of concrete. Concrete that is cracked and concrete that has'nt cracked yet. I would'nt rely on it for a header
if the area above the window is concrete, why would you need a header. concrete is stronger than a 2x8.
'depends what you mean by "stronger". Concrete has far more compressive strength than wood. Unfortunately, it has also no tension strength.
A header is a horizontal beam that experiences, in different areas, compression, tension, and shear. If you use concrete for a header, it better have rebar in the right places; e.g., the bottom.
I fall in the same category as the rest. I 'do it all ' myself, Mr "how hard could it be", and was going to cut out a 7' x 3' of 8" concrete for an addition I just reciently completed on my house, and realized it was futile. Hire it done, or at least see what it costs. They came, cut, took away all the concrete, mopped up the mess and were gone in a few hours. The cuts were dead plumb and silky smooth.
Ditto here. You know how much difference it makes to have the right tools. You'll pay at least half the cost of the job to rent a big gas-powered saw plus the cost of the diamond blade. These companies cut miles and miles of concrete and your window will be a piece of cake for them. Call and get a few quotes. I think you'll be surprised at the relatively low cost for this type of job.
Billy
Well, now that the forum is running again............
Many thanks to all who replied. All points well taken - sounds like this one is best done by someone with the tools and know how.
Regards, Dan
hire it out, i wouldnt even attempt it myself and i've been in business for 22 years
sure rent a saw, pay for some blades, ever handled a gas powered BIG skillsaw?
every car in your block will need a carwash when you're done, can you work in that kind of dust? safely?
in my opinion, dont even attempt it, get a pro
Hi DanH1,
Hire a concrete sawing company. When it comes to a labor of love, romance is one thing, and it ain't cutting concrete.
R
well as the vote goes,hire the hole cut, around here it's about 300. and they are in and out in a hour with a perfect hole cut. now the next problem when they get done you have this slab of cement that weighs 1500-2000 lbs. when you dig the hole over dig it out from the house and about 1 ft deeper. then just tilt the slab out ,let it fall in the hole and cover it with dirt or gravel. the first one of these i did we hooked a wrecker to and was going to pull it up out of the hole. it stood that wrecker straight up in the air!!! thats when i learned about leaving down in the bottom of the hole and forgeting about it. have fun larry
dan.... we do it ourselves every once in awhile... everytime , i regret it...
we hire Cut-Rite... $400 minimum... let the contractor overcut... and have him slice & dice into about 2 sf. pieces so you can manhandle them out of the hole... or overdig your hole and lay them in the bottom on undisturbed earth .. or you can overdig the hole and lay the whole piece in the bottom... place some scrfeened pea-stone for a bed..
conc. weighs about 150# / cf so getting rid of it is always a consideration
Mike Smith Rhode Island : Design / Build / Repair / Restore
And if you are concerned about the overcuts reducing the strength of the wall just where it will be bearing a load, the cuts can be filled with epoxy made for the purpose. It's easy.
Ron
Excellent discussion gentlemen, thanks for all the feedback.
As to the header - yes, it's my understanding that concrete has great compressive strength but is rather limp-wristed in torsion unless specifically engineered for that purpose. Besides, the building inspector dude told me I had to have a dbl 2X12 header.
I did get a quote of 450.00 for the cut (first Q I got was 700.00!). This does not include removal, natch. While the window well hole is big, I'm not sure it's quite big enough to accommodate the slab without breaking it up first. It's certainly deep enough, though, so I can probably just jack hammer it a bit and then cover it with pea stone.
I'll try to snap some pics of this hole (bawhahaha) mess for anyone interested.
Dan
I WOULD DEFFINETLY GO WITH TOMS APPROACH !! CANT SAVE EVERYHWERE . DO YOU HAVE A CONCRETE SAW TO CUT THAT DEEP ? ARE YOU GOING TO RENT ONE ?? PICK IT UP BRING IT BACK & SO ON GO WITH TOMS IDES ABOUT THE CONCRETE CUTTING COMPANY