ᐅ Opening for exhaust hood

Created on: 2 Apr 2019 13:22
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chrisw81
Dear forum members,

Our walls are currently being built, and the masons could create a core drill hole for us so that the exhaust air can be routed through it later.

Additionally, a wall vent box will need to be installed. My question is, when is the wall vent box installed (after attaching the insulation or already now?) and how is the insulation protected from condensation? With expanding foam?

Maybe some of you have already dealt with this.

Thank you very much for your input.
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pffreestyler
2 Apr 2019 15:13
You can have the core drilling done later when the box is installed, or temporarily seal the hole with a foil.

After all, the window openings also remain as just holes for a long time until the windows are installed.
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chrisw81
3 Apr 2019 09:23
Yesterday we visited our fireplace installer, and once again he advised against using an exhaust hood—for several reasons we've already discussed multiple times, which aren’t necessarily related to the fireplace itself (removal of warm air, negative pressure, interference with controlled ventilation systems, thermal bridge).

Now we are seriously reconsidering.
I could live with the usual issues—negative pressure monitors or occasionally opening a window wouldn’t be a problem.
The thermal bridge, however, is definitely a concern. Who would properly install the wall box to ensure no thermal bridging occurs and no condensation gets into the insulation?
My masons only create the opening; I have to take care of everything else.
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guckuck2
3 Apr 2019 09:52
The bricklayer is not the right person for this. The core drilling is done at the end, when the wall is completely finished, including insulation, plaster, etc.

It’s much easier than making a hole now and having all trades work around it. Just drill straight through once and that’s it. Plumbers, ventilation installers, and electricians all have core drills.

There are insulated duct boxes and others that only open when the extractor hood is switched on. Better let the kitchen fitter install that.
Yaso2.03 Apr 2019 12:57
In our existing property, the core drilling was done afterward, so I can’t really comment on that.

However, the Weibel wall box was recommended to us. It costs a bit more, but I can recommend it 100%! We have been very satisfied for almost 4 years!
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chrisw81
4 Apr 2019 15:21
Thank you for your answers.
I will have the core drilling done later, once the interior plaster and insulation are in place.
I believe there is a trade that can handle this alongside their work. I need to check with the kitchen studio regarding the installation.
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chrisw81
10 May 2019 09:35
One more question... the opening for the wall box will be about 150mm (6 inches) in diameter—do you need a lintel for that, or can you just drill it directly into the exterior wall?