paullmullen
Senior Member
- Location
- Wisconsin
- Occupation
- Electrical Engineer & Master Electrician
I am working on a project for a home built on Passive House principles. This means there is a lot of external insulation and all of the penetrations have to be sealed. At the same time there is a need to be resilient for changes that will be needed for future wall penetrations (Future proofing-ish) that are hard to implement while maintaining the sealed building envelope. Note that sealing these penetrations has to happen at the air barrier which is between the exterior insulation and the framed wall.
Just putting in a piece of 2" PVC and sealing around it with a gasket and sealing within it with spray foam doesn't quite do the trick because the spray foam doesn't come out easily when someone has to fish a new wire.
I've come up with an approach (see drawing) that I think accomplishes the task. Essentially it is to put a weather-tight box on the outside of the building (and a distant twin on the inside of the exterior wall). The PVC penetration is sealed at the air barrier. The weather-tight box provides a way to keep that conduit closed without spray foam. Individual new wires could be sealed as they enter the box, while leaving the conduit open for fishing new wires in the future.
The solution would probably work, but it also feels a bit complex. There has to be a simpler way. What have others done?
Just putting in a piece of 2" PVC and sealing around it with a gasket and sealing within it with spray foam doesn't quite do the trick because the spray foam doesn't come out easily when someone has to fish a new wire.
I've come up with an approach (see drawing) that I think accomplishes the task. Essentially it is to put a weather-tight box on the outside of the building (and a distant twin on the inside of the exterior wall). The PVC penetration is sealed at the air barrier. The weather-tight box provides a way to keep that conduit closed without spray foam. Individual new wires could be sealed as they enter the box, while leaving the conduit open for fishing new wires in the future.
The solution would probably work, but it also feels a bit complex. There has to be a simpler way. What have others done?
