our company is remodeling and adding an addition to a kitchen. we gutted 2 exterior walls and have done all framing with 1/2″ cdx on exterior walls. we installed tyvex paper with taped seams on the sheathing in october. the owner deceided to wait until spring to complete the project and is heating the room with nat. gas space heater. now there is moisture and mold on the inside of sheathing at bottom and all studs. any thought on what caused this. is the tyvex waterproof from rain. i would appreciate all legitimate responses thanks tim
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Gas flame produces gallons of moisture. Hopefully he has it vented enough to keep from killing himself with CO fumes.
Anyways, if the insulation and vapour bar or vapour stop are not integral yet, the damp air is getting to the dew point and coindensing to feed the growth of the miro-organisms.
If the owner is the ccause of the delay in ompletion, th fault is not yours.
thanks for the input. he has a rinnai ventless heater. also if we lift up the tyvex on the outside and the sheathing is dry will this be a confirmation of your analysis. hope to hear from you. thanks tc
Yep, heating with an unvented gas space heater will do that.
Another bad application for Tyvek.
Nothing wrong with Tyvek, in a properly constructed wall of a properly heated structure. These walls weren't properly constructed, and the structure was not properly heated.
Likely would have seen the same symptoms with felt.
The Tyvek should be 'waterproof from rain'. That's it's fundamental job ... prevent bulk moisture from coming through, but allow vapor to pass through readily.
This doesn't mean that it may not be part of the problem. Tend to agree, if gas space heater used and the place isn't well ventilated, the moisture will condense on the cold surface (the inner part of the sheathing).
Absolutely, the moisture will be coming from burning gas and no venting outside. That said, I wasn't aware Rinnai made a vent free gas unit. We've got three Rinnai units with small, thru-the-wall vents (combustion air comes from outside, combustion byproducts vented to the outside) and I couldn't be happier with them.
thanks for the input. i talked to the client and i guess these are older vent free units that are no longer on the market. i assume its because of the problems we are having.
>>thanks for the input. i talked to the client and i guess these are older vent free units that are no longer on the market. i assume its because of the problems we are having.
The age of the units is immaterial - physics and chemistry haven't changed.
Burn a carbon based fuel and there will be a lot of water in the flue gases.
Keep the flue gases in the house, and have a cold surface, and you'll have condensation.
QED
Absolutely, the moisture will be coming from burning gas and no venting outside. That said, I wasn't aware Rinnai made a vent free gas unit. We've got three Rinnai units with small, thru-the-wall vents (combustion air comes from outside, combustion byproducts vented to the outside) and I couldn't be happier with them.
Surely the warm, moist interior air is condensing on the cold sheathing. Seems that a bit of insulation and VB might be in order?