Water (condensation) behind cementious fibreboard siding

[David Scott]

Inspected a 3 years old home with Hardie board siding that was very well sealed up. Below the Hardie board siding was a 6" trim board made of composite materials that was heavily blistered, cracked, soft, decayed around all sides of the house. At the bottom edgeof the compostite board was evidence of water or condensation running out from behind the Hardie board, with fuzzy brown mold growth. The homeowner had recently installed an electrical recptacle through the lower exterior, advising me that the house was wrapped with Tyvek over OSB siding. (Hardie board was attached to the siding) A cutout sample of the OSB was saturated with moisture, and water stains to the Hardie board cutout. There was no way to check the insualtion for a vapor barrier in the exterior wall, and homeowner could not confirm. No evidence of moisture getting to the foundation wall, as it was an unfinished basement. Advised client to remove a section or 2 of drywall to check for a vapor barrier. Would appreciate any additional comments or thoughts of what is causing the excessive amount of condenation or moisture running down the exterior wall.

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[Scott Patterson]

Inspected a 3 years old home with Hardie board siding that was very well sealed up. Below the Hardie board siding was a 6" trim board made of composite materials that was heavily blistered, cracked, soft, decayed around all sides of the house. At the bottom edgeof the compostite board was evidence of water or condensation running out from behind the Hardie board, with fuzzy brown mold growth. The homeowner had recently installed an electrical recptacle through the lower exterior, advising me that the house was wrapped with Tyvek over OSB siding. (Hardie board was attached to the siding) A cutout sample of the OSB was saturated with moisture, and water stains to the Hardie board cutout. There was no way to check the insualtion for a vapor barrier in the exterior wall, and homeowner could not confirm. No evidence of moisture getting to the foundation wall, as it was an unfinished basement. Advised client to remove a section or 2 of drywall to check for a vapor barrier. Would appreciate any additional comments or thoughts of what is causing the excessive amount of condenation or moisture running down the exterior wall.

David, I think you are on the right track. By removing a section or two of drywall you can then see the insulation and whatever else might be present. But, you will not be able to see the house wrap (Tyvek) as it is on the exterior side of the OSB.

Was the water problem all around the home or just in a few areas?

[David Scott]

I actually saw, what I think was Tyvek wrap, through a 2 x2 inch decayed hole in the exterior board. It was a white wrap with blue lettering. As I stuck my fingers in the hole ( I know what you are thinking), all was wet, the exterior Aftco board, the OSB behind the Tyvek was extremely moist and decayed. No rain for 6 days prior to the inspection. There was even an aluminum Z flashing at the base of the Hardie board. My thoughts are that the drying prosess of the house was through the siding, but I can't prove the vapor barrier. Ventilation was adequate in soffits and roof.

[Roger Hankey]

I would definitely recommend further investigation by a qualified building scientist.

I suspect that there IS a vapor barrier, probably class I non-permeable and that there are multiple sources of moisture including condensation on the inside of the wall at the interior surface since I assume the house has central AC and that Prospect is Prospect, IL.

Your discovery of water damage at the base of the wall is consistent with condensation dripping to the bottom of the wall cavity. I would suggest the investigation start with removal the exterior lower trim board rather than cut into the interior gypsum wallboard. If the wall is moldy, and it probably is, investigations are best done without disturbing the interior.

Keep us posted on the progress of this case please.

[Bill Wieczorek]

David I saw a similiar situation with hardie siding 4 weeks ago. The home was 6 years old, an area of upscale homes, many with hardie siding. None of the others had the same problems.

The siding on the one I saw had cracked paint which has pretty much been determined to have come from the way the siding was handled when installed. If you read the hardie site they tell you it must not be carried over the shoulder where it can bounce up and down as its carried. The stuff I saw wasn't sealed between pieces or at the bottom where it met the flashing. Many of the sheets had peeling paint espectially those over windows and doors, don't have any idea why. The home owner was in touch with hardie, she was going to let me know what they determine the problem is. There were also 3 areas where the siding was soft and crumbling.
I've had Certainteed cement siding on my sum room and garage for 3 years and it looks like new.
Most of the guys responding to my post thought it was the way the siding was installed, just my 2 cents.

[David Scott]

Bill: The problem was in the trim board below the Hardie board siding at the top of the foundation. The Hardie board was not affected. I have been told it is a product by Aftco, since I posted the thread, which is going to be reviewed by the manufacturer, and is under a class action lawsuit. Sounds like homeowner is making progress. Appreciate any input.