What do you think caused this

So enough water is coming right through the vapour/barrier to wet the drywall…he said it was fairly dry!!!

Understand the conditions that allow/encourage mould to grow!!

Don’t be talking in circles, Marcel. ;-):twisted::shock:

The first problem was a “humidity problem” so the sentence then reads “could be a humidity problem from a humidity problem”

Joe Lstiburek has been promoting this for over a decade now. There is no vapour barrier* on the interior behind the drywall and the drywall has to be the airtight barrier.

Just wait until you try and get this one by the local code officials!!! It’s not in their code books nor their heads yet…the new building science*, like the new math a lot cannot understand!!

** NEW SCIENCE…just read something today that a Canadian 31 year old physics wiz has been working on…being able to measure characteristics of sub-microscopic particles that past physics experts said could not be done as the light photons/other particles used for measurement would actually change the motions of same size/smaller particles that they were trying to measure!!

Your reasoning??

In terms of “healthy housing”, why would you want to paint TAR on the inside of your home??

[quote=“dandersen, post:13, topic:60267”]

Mold spores can’t dig through plastic can they?
Air sealed wall will not have mold if it can’t get in.
Mould spores are everywhere…airsealed wall will have spores sealed in it unless constructed in a “clean room”!!!

With more information, we can now move up to #2. (Thermal Bypass)

(Still don’t have all the info needed however).

A little more info and we can move to #3. (Thermal Bridging)
Bottom plate and framing conducting heat away at the floor and corners.
You’re thinking like an engineer now and not a building scientist with HVAC experience!!

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Yeah but the thermal bridging is in every wall above grade that experiences more “cold” without the mould growth. The lower wall in the basement does not see the Delta T that the above ground wall does…By the above theory, we should be seeing more mould growth in upstairs corners experiencing colder outdoor temps…if all indoors RH’s are similar.

Didn’t we just “cover” this last week. NO vapor barrier below ground. :slight_smile:

OK ,OK,so you just proved you were paying attention.Big Deal…:slight_smile:

Now riddle me this.
In the present situation when you are not sure…who do you call? (what type of contractor)?

You call someone like a certified energy auditor with** lots of field** (not book) **experience **in house retrofit, IAQ, HVAC.

Bonjour Patrick, (and all):slight_smile:

In an ideal situation I would prefer foam insulation as it sticks to cement and seals.
But since it is not a perfect situation, Grading & French drains I would investigate and of course, I would also try to determine weather the heating baseboard is actually being used or if is it only used as a decoration!

Marc-Andre
BMAinspection.com

Any concensus developing yet??

Well, since we are just giving opinions on what the problem may be after all the information supplied, why don’t you the GodFather of all HI’s tell us exactly what caused the problem, then we will all know.
I think you are the one talking circles here.
I have seen exactly what happens in the field when a vapor barrier is installed on the inside. I have taken some apart due to the same problem.
Extruded foam is the answer when the foundation walls don’t leak.
And do we all know if that is the case here.
No, Might it be humidity, maybe.
In anycase, we are all speculating except you of course.

Marcel is the greatest He saw through Brian M instantly .
Thanks Marcel … Roy

So do we have a leaking concrete wall, blocked drainage tiles, poor grading at the exterior, lack of air space behind the batts and the foundation wall causing this? From the info supplied so far, I don’t think so!

I have seen this problem over and over as a carpenter doing reno’s and as an HI. The problem is the tar paper that is put up on the interior of the wall. If a concrete wall cannot breath then when they sweat the moisture has no where to go. The proper way to do this is: 6 mil poly to grade and swept under the interior 2x4 or 2x6 frost wall. If you put it all the way up the vapor from sweating will have no where to go. then you install the insulation and then the vapor barrier. Drywall follows.

Forgot to mention the required 1" air space so that air can move around behind the wall to help keep it dry.

Greg:

Yes, the tarpaper is the wrong material to place in that wall system but not because it will not “breathe” (I hate that word) but because it is a permeable paper…it will let soil moisture (if poor or deteriorated exterior dampproofing) or leaking water behind it at the concrete to diffuse inward into the insulated wall system…not a good situation.

The 6 mil poly moisture barrier at the concrete as you described is a system that has a chance of working but excellent detailing/airsealing must be carried out. The framing being put into this “plastic bag with an open top” must be dry!!!

From “Keeping the Heat In” from the Canadian Government"
“Use dry lumber for the framing. If not, allow the framing to dry for at least two weeks before adding insulation and covering the wall with the air and vapour barrier. Some temporary bracing may be tacked on to keep the wet studs from twisting as they dry.”

Don’t shoot your self in the foot anymore!! What document from a recognized agency or expert says there must be an air space?

From “Keeping the Heat In”:

Framing a New Wall
The next step is to install a wood-frame wall in the basement. There are two approaches. You can install the new wall flush to the old wall using 38 mm x 89 mm (2 x 4) lumber. Alternatively, you can use 38 mm x 64 mm or 38 mm x 89 mm (2 x 3 or 2 x 4) lumber built out from the wall by 64 mm (2 1/2 in.). The second method takes up more room, but does provide more insulation, less thermal bridging through the studs and better moisture protection.
**
Insulating
Insulation is installed in two layers (for the thicker spaced-out wall system) . The first is a horizontal layer between the studs and the wall.** It is important that the insulation is tight against the foundation wall.** Next, install a vertical layer and make sure it fits snugly between the studs. There should be no gaps or air spaces where convection currents could help heat to bypass the insulation. Insulation should be wide enough to match the stud spacing and be cut to fill the full height of the wall.

You wish…

Many couldn’t see the answer when it was right in front of them in post #3.

In post #4, Patrick saw and recognized the correct answer:
“It makes sense, how can we control that?”

but others chimed in and it moved backwards from there!!!

Don’t get too NACHI-fied, Patrick…others from outside have knowledge also!

did not know I was speaking to the guru of framing. I guess my 24 years as a framer was for nothing. You always leave an air space between the concrete and the wall. If not thermal bridging can occur and the concrete wall will begin to sweat.