Comments on: Passive House Air Sealing – Lessons Learned

By: Larry Rose

Larry Rose — Sat, 11 Dec 2010 14:46:07 +0000

bernini,
I retrofit my house and payed a lot of attention to air sealing, but I never tested it. We tore our house down to the studs on the outside, and back filled with polyurethane foam in the wall’s, joist cavities, and eves. Double studs ware caulked. Rigid XPS over the shell, all taped. New windows throughout, and lots of additional foam. All attic headers have been foamed over too.

The only real ventalation the house has is a 80 CFM bath room fan, that is also triggered by the furnace running. We also have a barometric damper for fresh air.

I monitor indoor humidity, and I found that in the heating season, I no longer needed a humidifier! The indoor R.H. never goes lower than 50%, all winter long.

Before the remodel, air inflltration was leading to local condensation, and a hidden colonly of mildew would start. This lead to our family having a low level cold the entire winter. Since the retrofit, these symptoms have disappeared.

By: Cliff Kornegay

Cliff Kornegay — Fri, 15 Jan 2010 19:33:32 +0000

Great post, but I have some questions about sealing against the existing party/common wall. I couldn’t see how you attached the barrier to the existing wall. Could you provide some details? Was the surface uneven, if so, did you do something to mitigate pockets of air? Do you have any thoughts about attaching a barrier to an uneven common wall?

By: bernini

bernini — Mon, 16 Nov 2009 12:13:12 +0000

what happens to the dew point in these uber tight passive houses?

By: Drew Abussell

Drew Abussell — Fri, 13 Nov 2009 09:46:58 +0000

There are also companies that offer liquid EPDM rubber coating which aids the roof during water immersions. The best thing about liquid rubber coatings is that it can be applied repeatedly and when rubber coatings are done multiple times, it will create a stronger protection compared to the usual elastomeric coatings. The liquid EPDM rubber coating can be applied on concrete and even on rusty roofs without using primer.

By: chad

chad — Fri, 30 Oct 2009 13:34:59 +0000

Todd – I’d imagine an EPDM gasket of this variety would last nearly forever once packed in a wall and completely shielded from the elements. Most gaskets of this type are put on car doors that are opening and closing multiple times a day, attached to metal and exposed to wild temp and humidity fluctuations…

We haven’t used any of these gaskets or methods to date, so we will try to provide more pics during the next project. We’ve been thinking about including more labeled pics in our construction docs as well.

By: ken levenson

ken levenson — Fri, 30 Oct 2009 12:56:38 +0000

Chad,
Thank you for sharing the results and all this great information with your perspective. It is very sobering and useful.

By: Todd Oskin

Todd Oskin — Thu, 29 Oct 2009 22:05:17 +0000

I don’t really know anything about building gaskets and the sealing tapes..but do you have any idea how long they are suppose to last?

I would guess that rubber gasket’s would were relatively quickly..compared to the rest of the building… although they say on the website that “They’re made from cellular (foam) EPDM, a synthetic rubber with extraordinary aging properties”…. just wonder how long ‘extraordinary aging’ equates to.

More pictures would be helpful to ‘see’ and visualize all these details you are talking about. Don’t know how frequently you are on site to take pictures…but the more the better, IMO.

A time-lapse slide show would be cool too. Not sure how to implement that..but…its an idea.

By: Building Gaskets and Air Sealing Tape | 100K House Blog

Building Gaskets and Air Sealing Tape | 100K House Blog — Thu, 29 Oct 2009 15:08:40 +0000

[...] we looked at some lessons learned from our aggressive air sealing goals on the Passive Project. In doing so we mentioned that we will [...]