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Build & Remodel


My wife and I are renovating our modular home. The exterior walls are 2x6 construction. The house is very poorly insulated. We are looking at the option of spray foam insulation. So I have several questions. If we use spray foam should we fill the entire void? If we do not fill the entire void with foam, due to cost, should we fill the remainder with fiber glass? In either case is a poly vapor barrier needed when using spray foam?

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Posted 2013-03-25T21:23:35+0000  by quadjt14 quadjt14


Hi Quadjt14,


Spray in foam insulation is the ideal solution; however this is typically not a cost effective do-it-yourself project.


Spray foam insulation requires specialized equipment and specific safety gear. A contractor who specializes in spray in foam insulation should be consulted and the cost can be quite high.


The most cost effective solution would be blown in cellulose insulation. This is a project you can do yourself.


Home Depot offers free use of the machine with a minimum purchase of the insulation. The wall cavities can be filled completely and there is no odor or residual gas.


You will have to drill holes in the interior walls to reach the cavities, and on most walls two holes will be required to fill the entire cavity, one top and one mid wall.  


This is to get around natural barriers such as fire blocks, plumbing etc. These holes can be plugged or filled in and the walls refinished.


The insulation can also be blown in from the exterior if that proves to be an easier method, however the same top and mid wall holes will be required, as well as the repair work.


If you still want to use spray in foam it has been suggested that the attic be treated with the foam and other less expensive product used in the walls.


According to industry sources, foam attic insulation alone will reduce your energy costs more than cellulose insulation thought the entire home, walls ceiling and attic.


The roof area of a house should be the first area sprayed as it is the largest energy consumer of the envelope. The floor or crawl space should be next.


Sources advise not trying to re-insulate walls with spray foam as the payback on an 18% loss would be cost prohibitive and not practical.



Posted 2013-03-25T22:41:40+0000  by Mike_HD_OC
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