How to open a concrete wall to fit a window?

Question

I live in a semi detache ex concil house from 1955. It is built of concrete blocks. We have split one of the bedoom in two leavng one of the new room without a window.

I want to make an opening for a small window but not sure what is the way to do it with concrete houses. With brick i think you need a lintel, but do you need it on a concrete house ?

Any detail will be appreciated.

Thank you in advance,

Answer 1

With blocks, you need a lintel. (You don't have the option of a brick arch.)  Because blocks tend to crumble, it's usually best to lay bricks at the tops of the window sides and lay the lintel on them.

Answer 2

It depends if the blocks have been sold filled or not etc

There is a lot more to this that meets the eye. I would use a galv angle iron to support the blocks  as a lintell etc There are other issues like water proofing etc flashing systems etc.

and permits etc. it needs to look like you have  always had tis window etc

Answer 3

ok this is for the width,  measure the window....add 1 inch for the rough opening..then add 3 inches for the supporting jacks.... for the height, measure the window, add 14 inches....

lay out the window and remove the block...be easy with the last course near the top.....

build a box header the width of the block width, 2 x10 with a 2 x 8 on the top and bottom....this makes a box.....used all treated lumber...install a sill  , 2 x 8, then the header with 2 x 8 jacks on each side cut tight....use cut nails to install the jacks and the sill along with construction caulk........

install the window...sq it up....plumb it in.....add insulation on the sides and top.....and trim out the outside and inside and ur there.....

lic. gen. contractor

Answer 4

Yes you will need a lintel for concrete block walls as well as brick walls.

I would recommend using 4" x 4" galvanized steel angle Iron you can pick this up from a builders yard.

I will be back in a mo.

Start by marking where you want the window on the out side of the house, in each corner drill a whole right through to the inside of the house.

On the inside and out:

Join the holes up with a pencil line.

Chop of the plaster in this area.

If your house has a cavity you have a choice of steel, either one with a cavity built in or 2 separate ell shaped angle irons. Which ever you get add 6 inches on each side. So if the opening is 3 feet wide you will need a steel 4-1/2 feet long.

Start chopping out the row of concrete blocks to the head of the window below the top pencil line, extend this 6 inches on each side to allow you to fit the steel. Do this for the inside and out. (You may need temp supports here)

Fit steel/s in place and support this temp.

Remove blocks to window area.

Test fit window, once you’re happy.

Bed brick support on each side inside to support steels.

Fir window and seal around window.

You can also use a disk cutter to open up the window this will give you straight lines to work to, but it does kick up the dust, not recommended for the inside of the house.