cellulose in Walls?


Old 03-06-03, 05:46 PM
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Question cellulose in Walls?

I am about to insulate my new home in Houston. High humidity and hot outside in the summers. The insulation contractor suggests using blown in cellulose. Says it will give me a better insulation factor because it does not discriminate for the shape of the wall it inhibits. Well my question is. Is this stuff worth going to? They tell me they blow it in wet and has boric acid and water. And I need to give it a few days to dry before sheetrock. Anyways. This upgrade costs and Additional $532 is it worth it? Same R value as the batts. I am also worried about settling. I have three very large walls that are 20 foot high and have a hard time believing its not going to fall inside the wall after time. Any suggestions or recommendations? I am going to schedule my insulation ASAP. Thanks for all your help! Luis in Houston
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Old 03-07-03, 08:41 AM
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http://www.eere.energy.gov/consumeri...riefs/bd4.html This is Dept. of Energy brief on Vapor Diffuser Retarders (VDR) or what is commonly known as vapor barriers and on Air Barriers.

The reason I'm suggesting you read this site is because it discusses one of the major concerns with insulating in warm humid climates, especially the "AIR BARRIER".

Cellulose has a higher absorbancy to moisture than fiberglass. One might think that in warm climates that fiberglass would be better. In reality, the cellulose is better. This is because insulation does not stop heat flow, it slows it down. And all heat has moisture in it. Since fiberglass has such a low absorption rate towards moisture, the probability with condensation is higher with it than cellulose in warm humid climates.

The brief also discusses vapor barriers in warm climates. It implies in other sections of the brief that because of fiberglass low absorbancy rate towards moisture, a vapor barrier must be applied. Yet in the discussion concerning warm humid climates they discuss not applying vapor barriers in those areas. The real concern and they discuss it well, is air infiltration. This is what usually causes moisture damage in structures in warm climates.

Here cellulose clearly outperforms fiberglass insulation. Cellulose by application and purpose prohibits air movement. Fiberglass attempts to accomplish the same but just looking at the application, you can see that it cannot outperform cellulose and you don't need the physics to figure it out.

Now I know you're wondering about cellulose holding moisture, besides borate other chemicals are mixed with cellulose, such as amonimum sulfate. These chemicals are added to cellulose to make them flame retardent, moisture, ordor and fungi resistent. The chemicals used can be found in the ingredients of a bar of soap. Though cellulose can hold more moisture than fiberglass can, cellulose is superior in warm climates because it takes considerably longer for materials to expel moisture than heat.

The rule with condensation is that heat condenses on cooler surfaces. This fact plays a major role concerning moisture problem with insulation in warm humid climates. All insulation retains heat that posesses a percentage of humidity and it does this deliberately in any climate and/or season. At night when the temperature outside begins to drop the heat with a percentage of humidity held inside the insulation also begins to drop temperature. With fiberglass because it has a low moisture absorption rate, it will lose temperature faster than it will expel the moisture. Under certain circumstances, condensation could occur. With cellulose because of its ability to absorb moisture, will actually absorb the moisture in the heat. And allow for enough time for the humidity to be absorbed elsewhere later. This does not mean that condensation cannot occur in cellulose, what it does mean that fiberglass insulation has a higher probability for condensation than cellulose in warm humid climates.

So the key differences between the two when it comes to condensation inside insulation in warm humid climates are air movement and ability to absorb moisture and release that moisture at a slower rate. Remember, materials lose heat considerably faster than it does moisture.

As far as installing it wet. This is not really an issue for you, rather it is an issue for the general contractor scheduling work. If he's/she's worth his/hers salt, it's not really a big issue. You see I am politicaly correct, BABY. Talk about issues, don't get me started.

I like you to do me a favor. At the bottom of this message you can Email this message to a friend. Please Email this to your insulation contractor. He/She should have explained this to you.
Old 03-07-03, 08:55 AM
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Thanks... that helped me alot. As far as being politically correct*L* She just happens to be female! Dang you are good*L*

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