ᐅ Windows set slightly outside the wall – how to properly seal them from the outside?
Created on: 17 Jul 2013 06:01
W
warriorHello everyone,
I am building a plastered house with a 17.5 cm (7 inches) exterior wall, plus 16 cm (6 inches) external insulation, and plaster.
At the moment, I have the following problem:
My windows are installed recessed to the outside, so only about 1 cm (0.4 inches) is inside the wall, and the rest (about 6 cm (2.4 inches)) is outside. During the window installation, the windows were sealed from the inside only with a tape. The external insulation is now installed as well. However, the worker who installed the insulation glued the insulation boards very close to the windows. There is now almost no gap left to foam around the windows.
I spoke with the window installer, and he said there should be a gap of 1.5–2 cm (0.6–0.8 inches) between the insulation boards and the windows, which can be filled with foam. His recommendation was to cut back the insulation around the windows and then foam the spaces.
The person who installed the insulation said that if he does this, first, the insulation will not be as effective in the area where it is cut back, and second, he would not know how to properly plaster the area afterwards, because the plaster layer at that spot would be too thick, and he is not sure if he could get the edge or corner straight.
To make things easier, he suggested not cutting the insulation at all, but foaming the windows through the insulation instead: first, he would finish the reveals/corners/edges around the windows, and then from the outside he would pierce the insulation around the window frame every 10–15 cm (4–6 inches) with a foam gun nozzle and inject foam. The foam would then fill all the cavities.
What do you think about this? What do you consider the proper approach here? I couldn’t find a clear answer online. I also read that some use an external seal tape against driving rain that is also vapor-permeable. What are your thoughts on that?
Thanks in advance for your answers!
I am building a plastered house with a 17.5 cm (7 inches) exterior wall, plus 16 cm (6 inches) external insulation, and plaster.
At the moment, I have the following problem:
My windows are installed recessed to the outside, so only about 1 cm (0.4 inches) is inside the wall, and the rest (about 6 cm (2.4 inches)) is outside. During the window installation, the windows were sealed from the inside only with a tape. The external insulation is now installed as well. However, the worker who installed the insulation glued the insulation boards very close to the windows. There is now almost no gap left to foam around the windows.
I spoke with the window installer, and he said there should be a gap of 1.5–2 cm (0.6–0.8 inches) between the insulation boards and the windows, which can be filled with foam. His recommendation was to cut back the insulation around the windows and then foam the spaces.
The person who installed the insulation said that if he does this, first, the insulation will not be as effective in the area where it is cut back, and second, he would not know how to properly plaster the area afterwards, because the plaster layer at that spot would be too thick, and he is not sure if he could get the edge or corner straight.
To make things easier, he suggested not cutting the insulation at all, but foaming the windows through the insulation instead: first, he would finish the reveals/corners/edges around the windows, and then from the outside he would pierce the insulation around the window frame every 10–15 cm (4–6 inches) with a foam gun nozzle and inject foam. The foam would then fill all the cavities.
What do you think about this? What do you consider the proper approach here? I couldn’t find a clear answer online. I also read that some use an external seal tape against driving rain that is also vapor-permeable. What are your thoughts on that?
Thanks in advance for your answers!