# How to handle insulation on Cape Style House



## ksuclipse (Jun 5, 2011)

I have attached a schematic for better explanation but my problem is this:

i have a cape style house with crawl spaces on the front and rear of the the house with and attic space above that also has a whole house fan. currently i have about an R-3 everywhere and want to do blown-in insulation. since the venting of the house is just soffit vents and ridge vents, how do i get the correct airflow from the crawlspace to the attic space after i blow in a bunch of insulation?????? also do i have to do anything special around the whole house fan? should i be adding ventilation for the crawl space areas and attic space?


Thanks!!!!


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## CoconutPete (Jan 22, 2010)

ksuclipse said:


> how do i get the correct airflow from the crawlspace to the attic space after i blow in a bunch of insulation??????


Use those baffles that leave an inch or 1.5 inches of clearance between the plywood and the insulation.


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## Gary in WA (Mar 11, 2009)

You want to air-seal first. Add partitions in the floor cavities under the knee walls, housewrap on the attic side of the kneewalls, duct the WHF to the exterior, add the baffles CP mentioned with draft-stops 12" higher than the proposed blow-in and at crawl/attic joint; (one piece); http://www.bergerbuildingproducts.com/productsAccuvent.html

Gary


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## ksuclipse (Jun 5, 2011)

Could you explain that a little more? Whatdo you mean by air seal and partition. Also what is the benefit of exhausting that WHF outside?


Thanks!!!


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## Gary in WA (Mar 11, 2009)

The WHF should be exhausting the moist warmed house air to the outdoors, not to your attic to grow mold.

Air seal the holes to prevent conditioned air from below reaching the attic: http://www.familyhandyman.com/DIY-P...ency/how-to-seal-attic-air-leaks/Step-By-Step

http://www.finehomebuilding.com/PDF/Free/021105092.pdf

http://www.google.com/url?sa=t&source=web&cd=20&ved=0CDcQFjAJOAo&url=http%3A%2F%2Fwww.buildingscience.com%2Fdocuments%2Fguides-and-manuals%2Fgm-attic-air-sealing-guide%2Fat_download%2Ffile&rct=j&q=attic%20air%20flows&ei=2pPNTOjIFYOBlAe22uzuCA&usg=AFQjCNEV_sFpJPB8DwLjAd-t6PJoO842EQ&cad=rja

Partition the attic from the ceiling of the living space through the open bays under the knee wall:

http://www.simplesavings.coop/simplesavings/SIMPLESAVINGS knee walls.pdf

Gary


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## msaeger (Mar 1, 2011)

In the family handyman article they talk about taking rolls of insulation and stuffing them below the knee wall. I have insulation in the ceiling of the first floor so to do that I would have to cut it at the knee wall. 

I am thinking I should cut it at the knee wall and pull out the insulation in the floor of the knee wall area and replace it with some blown in stuff. There is so much crap in that area like wires and plumbing that the fiberglass in there now isn't placed very good.


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## Gary in WA (Mar 11, 2009)

I don't know if you are commenting on the original 3 month old post or asking for guidance......

The last link at "simplesavings" above covers it. Foamboard between joist bays, and air-seal it. Run the board up to cover the edge of f.g. batt in ceiling/wall joint at knee wall to prevent wind-washing. Leave room for your continuous baffles installed with 1" end gap as per manufacturer. No insulation under attic room unless garage/cold area below. Cover foamboard per local code possibly with 2" f.g.

Stuffing rolls of f.g would compress it (lose R-value) and still let the air through, which you want to stop...... or f.g. in a garbage bag and canned foam the gaps. Be sure to air seal around those wire/plumbing holes.

Gary


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## msaeger (Mar 1, 2011)

I was just searching the forum and reading this thread made me have a question. 

I keep seeing that I should seal the joist bays below the knee wall but I have insulation between the joists all the way across because when the house was built I wasn't finishing the upper level at the time. So I am asking should I cut the insulation at the knee wall so I can seal the joist bays below the knee wall?


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## Windows on Wash (Aug 30, 2011)

msaeger said:


> I was just searching the forum and reading this thread made me have a question.
> 
> I keep seeing that I should seal the joist bays below the knee wall but I have insulation between the joists all the way across because when the house was built I wasn't finishing the upper level at the time. So I am asking should I cut the insulation at the knee wall so I can seal the joist bays below the knee wall?


Yes. Cut it flush will the framing with the knee wall and install a rigid foam blocker. Caulk/foam seal the blocker to the joist bay.

Pull the insulation back flush to the foam blocker.


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