What is the reason for ice and then in turn mold to build up on bedroom walls - lack of insulation?

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Posted by: from Smithers
3/8/2012 at 1:15:49 AM

We moved into our 23yr old home 3 years ago. There is a bedroom above the garage with 3 outside walls. In the winter ( 0c to -30c), the corners of the room get terrible ice/frost build up which on thawing turns to mould. It was so bad one winter that the paint was peeling of the wall. The same happens with an inside wall going up the stairs, that is against a garage wall.

We want to redo the siding outside and also paint the walls. Are we looking at an insulation problem, i.e, not enough insulation was put in, that we have to deal with first before we do siding or paint or at the same time as doing the renos?



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CPC Universal Group in Calgary
Date/Time3/8/2012 at 2:28:43 AM

Greetings to Mrs. Jackie,

My name is Andreas Pirelli, from CPC Universal Group of Calgary, I am Supervisor-Coordinator-Estimator for the Builder's & Renovation Division.

As per your question asked on black mold formation!

Yes indeed the is a problem with the insulation, and possibly as for the air exchange between the interior of your home and the exterior (outside), which humidity is the main.

1-You probably have poor insulation around the window frame

2-Your walls have probably poor insulation

3-Checking the air flow between the interior of your home & the exterior

4-Checking the humidity level of your home (air exchange)

5-Get an estimation for the remedy to your problem,

6-Don't wait to long, because Black Mold infection will cause harm to your health status, (breathing problem etc...)

Yours Truly

Andreas Pirelli

Supervisor-Coordinator-Estimator for

CPC Universal Group

What is the reason for ice and then in turn mold to build up on bedroom walls - lack of insulation?
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Date/Time3/8/2012 at 10:26:24 AM

Hi Jacquie

We found in some occasions that poor air flow in the room can create areas where air is not moving at all and it let the humidity stack on the wall and create mould.

You should check air flow at the corners and add fan(s) in the room to move the air. Air in motion has no time to stop and deposit water.

Try to put a simple humidity meter on the table and check it after 2 days if its over 30 you may want to think of a dehumidifire.

I hope this will help


Harry C.

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Date/Time3/8/2012 at 12:26:09 PM

Hi Jackie,

It looks like we are all on the same page.

Ice forming on the walls and mold growth. The ice forming means water is present and temperatures below 0 degrees celcius. The mold growth is the by product of liquid water being present with a food source.

Paper is a great food for mold, so gypsum wallboard (drywall) or wall paper (although mostly vinyl) will support the growth.

The important thing is, get rid of the water and treat the mold.

The water can be from a number of sources. The first is a exterior roof, soffit, or wall leak. Look for thicker areas of snow on the roof at the eaves in that area. This is called ice damming and is an issue that needs to be addressed but could be a source for the water penetration. Also, if your downspouts are clogged and the eavestroughs cannot drain, the water will pile up like a resevoir in them. This large volume of water is more mass than they are designed for and can lead to the eaves pulling away from the fascia allowing the new raised water level to get under the starter course of shingles and eventually into the home.

The next is humidity levels. Invisible moisture in the air from showers, sweat (even when you don't notice it), breath, etc. is in the air around us all of the time and we keep contributing to it. When the warm moist air comes in contact with a much cooler or cold surface, the water vapour condenses on that surface almost immediately becoming liquid water (and a great environment for mold growth). For it to freeze means that your walls are below zero and that either due to a crazy air conditioner or more than likely a lack of insulation (possibly none).

So there are a number of issues to have a look at. Start by looking up on the roof for evidence of ice damming. Next, light a candle and (SAFELY) slowly move it around the wall in question and look for flickering (I have actually had candles blow out because of drafts), particularly around windows.

If this happens, carefully pull of the casing (trim) around the windows. There should be a gap beside the side of the window and the structure of the house. This should be filled with insulation. If you see pink or white fibreglass insulation tucked in the cracks, take it out and replace it with LOW EXPANSION spray foam. You might want to remove a baseboard on an outside wall and cut the drywall to peek behind it and check for insulation.

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Date/Time3/9/2012 at 12:13:05 PM

Yes, poor ventilation and high humidity can cause these problems as stated by the other contractors. I would also check into the level of insulation in the ceiling above the garage (the bedroom floor). Also is the garage heated (keeping the lower space heated would be a help).

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Date/Time6/3/2012 at 9:33:59 AM

Sounds like its not just an insulation problem. More like a moisture problem.

If you are removing the siding, then remove the building paper. The wood sheathing behind the buildind paper will show you water stains and any rotten wood that has formed.

A heated garage would be nice, but won't solve this problem.

More insulation would be nice, and may help. However you need to fix the problem first. Could be as simple as a bad overlap on the building paper, or no building paper aptly all.

A good airflow is nice to have, but that would only be in the attic, no air flow in the walls unless its a centre block.

Only best option is to remove the siding, remove the building paper, repair the damages to the structure, I'm sure there is. The the water stains will lead you to the problem, if its a window, then repair it.

It this time you could install a rigid insulation, but make sure you install a house wrap or building paper first. Needs to be water tight, need to overlap it like a shingle. The rigid insulation will help alot with turning the ice cold walls into a Luke warm wall. But you should fix the problem before any up grades.


Winnipeg Drywall and Stucco

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