Comments on: Two Rules for Preventing Humidity Damage

By: michelle

michelle — Sun, 29 Dec 2019 22:41:22 +0000

if we are doing a remodeling
if we are doing a remodeling project where windows / doors have been added, moved, replaced (so the stucco has been disturbed and outside air is accessing the framing), we are not yet living there an have no hvac system in place keeping the interior heated, and now winter is here – rain, temperatures at night in the 40s, 50s during the day, have I completely ruined this otherwise mold free home?! should I wait to patch stucco until summer heat comes thru?! so worried and wondering the best course of action now.

in addition, we have added recessed lighting throughout the house at the urging of the designer / architect / electrician – I think they are ugly but am now most concerned with mold issues!

we also removed the hvac system which was in attic, and were planning to replace – should this be put in the crawlspace instead?!

oh dear I’m so worried after finding this site.

By: John Friedberg

John Friedberg — Mon, 12 Feb 2018 05:19:44 +0000

My 1952 concrete platformed
My 1952 concrete platformed ranch house sits in the middle of a valley hill. My master bedroom probably has a concrete floor sitting on dirt. The master bedroom (22' by 17') has asbestos tile cemented to the concrete pad. There is some mildew in the room's walk in closet. The house is used only during the summer. During the winter, only the main room is heated to 53 degrees. All the rooms off it have their doors open about two inches. There is no formaldehyde anyplace. I want to put wall to wall synthetic padding and carpet over the master bedroom asbestos tile. But need you to advise about putting a vapor barrier between the asbestos tile and the carpet padding. What type vapor barrier material (if any) should I use? I do not want to remove the asbestos tile-for the expense and toxicity issues. But if there is no way to avoid moisture problems, I could try to find competent contractor to remove the tile and level the concrete pad-but only if putting down any material over the tile would make moisture worse. Right now natural rubber sits and a cotton beat up wall to wall carpet sits on the tile. By the way, the house is clad in pine siding. Insulation, if any, is cellulose.

By: Grant Dorris

Grant Dorris — Mon, 22 Jan 2018 15:38:57 +0000

Referencing Rule #1, I am
Referencing Rule #1, I am also finding that in houses under construction (the crawlspace is open – no HVAC unit set, no crawlspace door, no insulation, no vapor barrier – and extremely cold weather), interior work is ongoing and the house is being heated with propane heaters.

The result is any moisture in the framing is being driven toward the outside. The crawlspace side of the subfloor is forced below dew point and condensation pours down throughout the day and re-freezes at night.

By: Stephen Cook

Stephen Cook — Sat, 20 Jan 2018 15:20:55 +0000

Rule 2 violations seem to
Rule 2 violations seem to happen on a regular basis.

What we don’t seem to fully understand, or provide direction on, is the point when it becomes an enclosure problem.

For example a set of mean temperatures for zone 4 (dec/jan/feb) 36/37/41. A “standard” wall (cladding,tyvek,osb,2×4/6,gypsum) would have the OSB below the dew point for those months for most (Ok > 50%) of the time. Yet thats been a standard wall and is still allowed by the codes. The 2012 code updates made the OSB even cooler.

If there were/are large scale failures of this wall system why would the codes a) still allow it and b) make the situation worse in recent updates (r13 now r20 discounting of course the +R5 option). If the codes are focused more on energy than durability, its a horrible mistake.

By: j

Wed, 17 Jan 2018 21:34:31 +0000

In reply to Charles Leahy. Dead air is fine, as long as
Dead air is fine, as long as it’s the same temperature as the inside of the building.

By: Mac Sheldon

Mac Sheldon — Wed, 17 Jan 2018 19:13:06 +0000

We say water vapor flows from
We say water vapor flows from higher vapor pressure to lower (higher absolute humidity to lower) and we often say that’s from warm to cool temperature, but there’s one noteworthy exception to the rule about water vapor flowing from warm to cool.

Crawl spaces lacking a robust vapor barrier can be cooler than the space above during winter months in mixed or colder climates yet have a higher vapor pressure than the living space. Code requires a vapor barrier on the floor of a crawl space and if water doesn’t bypass it in either liquid or vapor form, the vapor pressure should always be low enough to not cause problems. A trashed vapor barrier or flooded crawlspace can cause a weak but continuous vapor drive into the home or building, and we’ve seen chronic mold, mildew and algae problems as a result.

Build to code and pay attention to the quality of installation of the vapor barrier (Class-I vapor retarder) and you should be golden.

By: Dave Keefe

Dave Keefe — Wed, 17 Jan 2018 18:10:17 +0000

I sometimes encourage folks
I sometimes encourage folks who live in cold places and are mostly concerned with winter condensation to think of your two rules this way:

If it’s going to be cold, don’t let the indoor air touch it.
If the indoor air is going to touch it, don’t let it be cold.

By: RJ

RJ — Wed, 17 Jan 2018 14:52:58 +0000

The problem with so many
The problem with so many options in foam type, placement and geographical zone differences is that conclusions are rarely offered as to what is best for a given part of the country. The latest issue of Fine Homebuilding also addresses foam types and their pros and cons but still concludes with too many options. As a result, most specifiers stay with housewrap over osb and fibrous insulation. A recommendation by zone groups might be helpful even though there will always be debate, cost issues and advertisers who may not be happy.

By: Charles Leahy

Charles Leahy — Wed, 17 Jan 2018 13:35:24 +0000

What is the cost per wall
What is the cost per wall square foot of that double stud/spray foamed wall? That looks like a whole lot of work. It also looks like open cell foam. Is it?

I cringe when I see spray foam insulation contractors not fill the entire cavity and many builders simply trust them when they say – “oh a couple of inches is enough”. You never want “dead air” in a building envelope, as your opening photo implies. Bad things can happen.