Blown-in vs. expanding foam insulation?


Old 10-26-05, 04:11 PM
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Join Date: Oct 2005
Posts: 19
Question Blown-in vs. expanding foam insulation?

I live in a 12 year old high-rise condo building in the northeast. I lose heat in each room only through the weather-facing wall which has no insulation. (The other three walls, as well as the floor and ceiling ajoin other heated condos). The exterior is brick, the walls have metal studs, and the ceilings and floors are thick concrete.
Sooo, where's my heat loss? My outside walls; and also my large, double-hung, double-paned--but leaky-- aluminum picture windows in each of those cold walls.
My question: I've read below that i could blow in cellulose insulation. I even found a Rent-All type store that can rent me a large blower with a hopper that I can fill with bags of the insulation they also provide....
BUT....I also read under your "Bloopers" category that a poster mis-used a can of expandable foam insulation, a product he said "expands ten times it's original size".

Will it work in my walls?? I only need to fill the three outer walls, and must only insulate about 175 sq. ft. of wall cavity (subtracting the area of the windows). Is expandable foam viable for treating this space? If I can avoid drilling the LARGER upper and lower holes that I would need for blown-in application, and instead require only a straw sized holes, it would make the post-insulation clean up, touch-up, etc, so much easier.
What do you think?

(Secondly, I DO lose a lot of heat with the windows but I treat them all with plastic, 'heat-shrink' insulation as a further thermal barrier. (it does help a lot).
Short of replacing the windows I'd appreciating any further thoughts.

Thanks in advance for your time and replies.
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Old 10-27-05, 10:26 AM
Join Date: Mar 2005
Location: USA
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Blown-in vs. expanding foam insulation?

How do you know you have no insulation in the exterior wall?

If you have no insulation and feel you should insulate, use the cellulose instaed of the foam. It is intended for walls and won't blow your wall out. You can patch the holes in the sheet rock. There are a number of tricks to make the patching easier.

Before insulating, invest in a stud finder (not expensive), so you can map out the wall and figure out where the studs are, including any blocking. This will allow you to plan where you should put the holes.

Old 10-30-05, 06:57 PM
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Join Date: Oct 2005
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Thanks for replying Dick.
I presume there is no insulation. I based that on the frigid temperature of the exterior wall on any cold day. The feel of the wall (temperature) matches the feel I had in my previous 2 uninsulated homes. If it met code qnd even had a 3 1/2 inch bat it would not be nearly as cold.
Thanks for your suggestion on the blown-in cellulose as the best way to go.
Can you guide me a bit more with regard to application?

Will I ikely need only one hole at the top and bottom of each wall cavity?

Will I wind up with a mess of cellulose fibers traveling throughout the house--as one poster advised elsewhere--much like spackling and sanding of wallboard installation can cover your home with dust if not properly sealed off?

Finally, how do you avoid condensation problems w/ blown-in? There is no way to install a vapor barrier.

Old 11-03-05, 11:39 AM
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Blown-in vs. expanding foam insulation?

There are low-expansion formulations of expanding foam designed for exactly this situation-- made to fill already covered wall cavities without generating blow-out pressures. They don't suffer from the over-time R value loss that cellulose (compaction and settling) can and they form their own vapor barrier (something like 1.2 perm for 2 inch thick foam) so they don't have the wind/air related R-deterioration either.
Do a search for "Polystyrene insulation spray" and you'll get a bunch of relevant hits..
Old 11-03-05, 01:14 PM
Join Date: Mar 2005
Location: USA
Posts: 6,126
Blown-in vs. expanding foam insulation?

There is a wide range of long term installed properties of foam insulation.

The components are factory produced, but are blended on site. Time, temperature and humidity all are varieables that must be compensated for on-site.

The application can vary from crew to crew. The moisture content of the wall materials will effect the curing rate and foam properties.

One of the problems of foam, in the effort to maintain controlled expansion, is the long term shrinkage. If the foam shrinks and pulls away from the wall materials, air spaces are created and the insulation acts as a "baffle" in the wall. The baffle effect reduces the insulation value and increases infiltration.

Since this is a site and crew specific installation look for contractors with a good history, factory training and follow up. Avoid new contractors with claims of superiority over other types of systems (nobody has invented "the worlds greatest insulation" yet).

Here is a test - If they claim a R20 wall with R20 foam, they are not being accurate - it is not possible.

Old 11-03-05, 08:47 PM
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Location: central Iowa
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We've only done blown in on homes we're siding so the holes dont matter. I've always drilled a hole at wall mid point for the first batch of cellulose and then another hole at the very top under the sill plate to fill the top half of the wall, this helps with maximum compaction and good wall fill since often if you only drill at the top of the wall the cellulose will crreate a "dam" so to speak and often the insulation will only fill the top half of the wall leaving the bottom of the wall empty.

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