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PoleCat 09-30-2013 05:25 PM

Shake & Rake or Blown in???
I have a 144sqft addition that used to have a flat roof over it. A 5:12 pitch roof has been built over this area now but the original cavities between the joists are empty. The old decking is still in place so I need to get insulation in there the hard way. Can the blown in fiberglass bales be used like the shake and rake material? i.e. I don't want to rent the blower for just 60 cu. ft. of material.:huh:

oh'mike 09-30-2013 06:47 PM

I've used the blown in cellulose and the machine rental was free----

I've never used the fiberglass---however in that awkward space--the blower would sure be the ticket-----That machine easily tosses the product 12 to 15 feet---

PoleCat 09-30-2013 07:06 PM

The machine appears to be a two man act. I am flying solo. My thoughts were along the lines of cramming it through the cavity with a ram rod like they used to do wadding in the old cannons.

oh'mike 09-30-2013 08:31 PM

You are right--you need a feed and a spreader---so the shake and rake method sounds like the best option----yucky job------

Gary in WA 10-01-2013 03:17 PM

You probably will have condensation problems because of the old roofing (if still present) acting as a vapor barrier, limiting drying to only the interior....


Wet fiberglass lose 60-70% of R-value;

If asphalt sheet roofing, figure a Class 1 vapor barrier on the wrong side of roof cavity for your climate;

Need to insulate your "closed" roof system correctly; with foamboard under/over the decking then fiber below to move the dew-point to prevent condensation per location/climate zone- chart;



PoleCat 10-02-2013 06:32 AM

The old roofing has been removed. The 1X8 decking is still there but has 1/4 to 1/2" gaps between boards and various other openings here and there. Of course the outside edges had to be cut back to accommodate the new rafters. It should vent OK. I found me a hillbilly insulation blower in the back yard yesterday - our old Eureka upright vacuum. I'll post a video if it works.

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