After cutting concrete block...

TipsyMcStagger · 12-01-2011, 07:16 PM

I have a 36" window in a concrete block wall I'm planning to eliminate and replace with a 36" exterior door. I'll have to cut and remove the block between the slab and the sill of the existing window to enlarge the opening for the door.

My question is how to address the voids that remain in the block after making the cuts? Obviously, I'll have to frame a rough opening for the door using PT lumber, but I'll need solid concrete to properly secure the rough-in.

Any help is appreciated.

TIA.

Tipsy

joecaption · 12-01-2011, 07:21 PM

To do it right your going to have to cut along a vertical morter joint and cut out all of the 1/2 blocks and replace with new 1/2 blocks so there soild on the exposed ends. A whole lot of work. Also is the a lantal over that window and will it come out to the corret height to reuse it. If not then one has to be added to support the block above it.

jomama45 · 12-01-2011, 07:22 PM

Of course it's nicer all around to have the jambs flush, but they don't necessarily need to be. You should be able to either:

A) Fasten into the insed webs of the block with long anchors at lest every other course, or

B) Fasten directly into the 1.25" to 1.5" edge/face of the block with shorter anchors.

TipsyMcStagger · 12-01-2011, 07:40 PM

Quote:

Originally Posted by joecaption

To do it right your going to have to cut along a vertical morter joint and cut out all of the 1/2 blocks and replace with new 1/2 blocks so there soild on the exposed ends. A whole lot of work. Also is the a lantal over that window and will it come out to the corret height to reuse it. If not then one has to be added to support the block above it.

I belive there is a concrete lentil above the window and my rough measurements indicate it will be high enough to allow for the door. Doing as you suggest might be difficult because the window is near a corner. While I'm sure it's possible to do, it might be beyond my capabilities. Is there a way to fill the voids vs. cutting the block out and replacing it with the closed end of a half block?

Quote:

Originally Posted by jomama45

Of course it's nicer all around to have the jambs flush, but they don't necessarily need to be. You should be able to either:

A) Fasten into the insed webs of the block with long anchors at lest every other course, or

B) Fasten directly into the 1.25" to 1.5" edge/face of the block with shorter anchors.

When you say the jambs don't have to be flush, do you mean the PT rough-in (I apologize if I'm using incorrect terms) doesn't need to be flush against solid concrete? In other words, it would be okay if every-other block were hollow behind the PT?

Thanks.

Tipsy

jomama45 · 12-01-2011, 07:56 PM

Quote:

Originally Posted by TipsyMcStagger

In other words, it would be okay if every-other block were hollow behind the PT?

Thanks.

Tipsy

Absolutely, unless it's an extremely heavy door or something. If it can be sawed straight enough, you can simply use an adhesive (like PL 400 or the like) to glue it on and add your fasteners.

TipsyMcStagger · 12-01-2011, 08:03 PM

Quote:

Originally Posted by jomama45

Absolutely, unless it's an extremely heavy door or something. If it can be sawed straight enough, you can simply use an adhesive (like PL 400 or the like) to glue it on and add your fasteners.

I wasn't aware of that. This will simplify things greatly. The sill is only 18" or so from the slab, so it's probably fewer than three courses of block that are affected.

Thanks very much.

Tipsy

joecaption · 12-01-2011, 08:11 PM

Very poor way to do it. There's going to be a ton of ways for water and wind to get in that way.
Also you do not need to use pressure treated wood.
If you did ever fastner you use would have to be ACQ approved. The whole thing will be under trim when your done so none of it will be exposed.

TipsyMcStagger · 12-01-2011, 08:16 PM

Quote:

Originally Posted by joecaption

Very poor way to do it. There's going to be a ton of ways for water and wind to get in that way.
Also you do not need to use pressure treated wood.
If you did ever fastner you use would have to be ACQ approved. The whole thing will be under trim when your done so none of it will be exposed.

Okay...I thought PT was always supposed to be used against concrete.

Although this door leads to an outside space, it will bear virtually no wind load and is under roof, so it will not get wet. It will lead to a small atrium space that is enclosed on three sides. The door will be opposite the open side of the space.

Tipsy

jomama45 · 12-01-2011, 08:28 PM

Quote:

Originally Posted by joecaption

Very poor way to do it. There's going to be a ton of ways for water and wind to get in that way.

And how "stout" & water-tight do you think a DIY "toothing" of the block would be, considering every other bed joint will be merely tuckpointed????

Also you do not need to use pressure treated wood.

Any would that's in direct contact with concrete or masonrly here needs to be treated, not to mention it's also good practice.

If you did ever fastner you use would have to be ACQ approved. The whole thing will be under trim when your done so none of it will be exposed.

Plenty of fasteners available that are approved........