Acceptable Number of Wall Penetrations
bongo30
| Posted in Green Building Techniques on
We are building a new home in Zone 4a (2,800 sq ft) and are currently working through air sealing our penetrations, which got me thinking how many penetrations, on average, would Pretty Good House have? We currently have –
(2) ERV Supply 6”
(2) ERV Exhaust 6”
(1) Basement Bathroom fan 6”
(1) Kitchen Exhaust 8”
(1) Kitchen Make-Up Air 8”
(1) direct-vent gas fireplace 8”
We have 2 Panasonic Intelli-Balance 100 ERVs (one for each floor), hence, 4 ERV vents. We also re-routed 2 of our bathroom fans through soffits, otherwise we would have 2 more penetrations.
So how many is too many? How many do you have?
Thank you,
Lana
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Replies
I don't think there is a "too many", provided you NEED all the ones you have. You'll have to take the usual precautions to seal things and use dampers, but aside from that, if your equipment requires outside air, you don't really have any choice but to poke a hole through the building envelope somewhere to get that outside air connection you need.
Bill
Ideally a PGH would be small enough and designed to need single ERV intake and exhaust penetrations, range hood exhaust and makeup, and that's it (other than plumbing and radon vents through the roof). But there are always compromises.
Walls by their nature are going to have multiple penetrations, both of the type you listed, and also windows and doors. Having a good plan on how to detail these penetrations is critical since they are unavoidable.
I like to try to run my penetrations out either the box joists or the gable. However, some houses do not have box joists (ICF foundations with a ledger floor system) or a gable (hip roofs). Houses with neither a rim joist nor gable can be challenging to find space to terminate ducting etc.
Penetrations out of the box joists can be sealed in with spray foam, and anything going out the gable will need to be sealed where it penetrates the ceiling. There are many good details for ceiling penetrations, including EPDM gaskets or constructing an air tight box that houses your fixture (light, fan etc), the box then gets tied into your air barrier,