Hello,
my wife would like to have our basement window removed and the resulting opening closed. The window is completely below street level.
Our basement was poured with waterproof concrete, coated with bitumen, then the perimeter insulation was applied, and finally the dimpled membrane.
My questions are:
1. What is the best way to close the opening?
2. Should I use formwork and concrete? If so, all at once? What is the best way to seal the top edge, considering concrete shrinkage?
3. Or should I use masonry?
Thank you in advance.
my wife would like to have our basement window removed and the resulting opening closed. The window is completely below street level.
Our basement was poured with waterproof concrete, coated with bitumen, then the perimeter insulation was applied, and finally the dimpled membrane.
My questions are:
1. What is the best way to close the opening?
2. Should I use formwork and concrete? If so, all at once? What is the best way to seal the top edge, considering concrete shrinkage?
3. Or should I use masonry?
Thank you in advance.
K
KarstenausNRW7 Apr 2023 10:44headroom schrieb:
My question is:
1. What is the best way to close the opening?1. Remove the window and roller shutter box 2. Brick up the opening (using sand-lime bricks) and anchor it securely to the adjacent walls. Suitable metal ties are available for this purpose.
3. Apply waterproofing
4. Plaster the inside, insulate and plaster the outside, and apply sealing slurry (waterproof coating)
Now comes a very interesting question. Will everything be backfilled afterwards? If so, part of the insulation should be removed to allow the waterproofing to connect properly to the outer layer.
Nobody recommends concreting here. You won’t get a qualified answer on that, neither in this forum nor others.
K
KarstenausNRW7 Apr 2023 19:47headroom schrieb:
Thank you for the kind response. After that, the area will be backfilled. Why wouldn’t anyone use concrete? If I have a masonry wall, there are quite a few joints where moisture could potentially penetrate.Why? Because it is a huge effort to convert a former window opening into a waterproof concrete structure (“white tank”):- Reinforcing steel must be installed into the surrounding walls
- Joints need to be properly sealed. How do you achieve a watertight connection to the existing walls?
- How do you pour the concrete? Pouring from above is not possible.
- It’s a custom job, which is extremely expensive
By the way, did you notice that I also mentioned the point “waterproofing”? Masonry basements are very common. And applying waterproofing on top—whether bituminous waterproofing membrane or reactive waterproofing—is standard practice. No water will get through. So no, there aren’t any problematic joints. It is then a straightforward and cost-effective routine task to close an opening with masonry.
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