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helgymatt 02-22-2011 05:06 PM

Venting and insulating 1 1/2 story
 
I have a 1922 1 1/2 story home with finished attic space. It has knee walls on each side of the attic as well as a mini-attic above the finished area. Currently, the knee walls, knee wall floor, and knee wall roof area are all insulated with batts. The attic ceiling has blown in insulation. NO venting anywhere, except one small box vent on one of the knee walls. I have no soffit vents or ridge vents. Old houses like this never had any venting. The attic space gets very hot in the summer. This winter when poking around the knee walls I discovered frost in between the sheathing and batts and lots of white mold.

I know I need to correct the venting issue, but don't know the best and economical way to do so. I have some contractors coming to see what they think.

Obviously I cannot just install soffit and ridge vents because they will do no good with the attic ceiling full of blown in cellulose. I do know I need to remove the insulation from the knee wall ceilings and then fix the mold problem.

Here are a few things I'm considering - least work to most work
1. add gable vents on each end the knee walls. Remove insulation on roof sheating and insulate the floor (walls are already done). Will this do much of anything to correct the moisture problem? Possibly use powered gable vents?

2. try to remove insulation from attic ceiling, install soffit venting (something like this...http://www.cor-a-vent.com/in-vent.cfm), add ridge vent. How would I then reinsulate the attic ceiling? The rafters are only 2x4's. After installing baffle there it would only leave about 1" for insulation.

3. Add a new "sleeper" roof deck with ridgid foam inulation. Keep everything else the same except add more blown in insulation to knee wall floor. How much would this cost? I will need new shingles anyway. Home sq. footage is about 1,100. Like this - http://advice.thisoldhouse.com/showthread.php?t=6934 I will need a new roof soon anyway. So the extra cost would be the new sheathing and foam board.

4. Pump spray foam into the attic ceiling and knee wall ceiling and forget venting. I would have to remove the blown in cellulose in the attic ceiling first. Would cost me about $3,000 or more I estimate.

Please help with what my best options are. I don't expect to live in this house for more than 5 years, but I need to fix the mold issue and I would also like to use the attic space for an office or my wife's hobbies or quest bed.

helgymatt 02-22-2011 07:58 PM

Using SmartVent as an exhaust seems to be a promising way to vent my knee-walls. I would probably still keep the blown-in insulation in my attic ceiling - so no venting there - unless someone can suggest
an easy way to do that (only 2x4 rafters).

http://www.dciproducts.com/html/shedroof.htm

Anyone done this before?

Also, can someone suggest a good product to kill the mold and remove stains in my attic? I saw Bora-care/Mold-care and was wondering if that would be any good.


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