newbie question on insulation

[mike c]

Hi all, any thoughts on fiberglass insulation in walls and ceiling?
I thought of taking 3 1/2" and peeling it apart for 1 1/2" walls and ceiling.




Thanks for any and all opinions


mike c

[Mary K]

Hi all, any thoughts on fiberglass insulation in walls and ceiling?
I thought of taking 3 1/2" and peeling it apart for 1 1/2" walls and ceiling.




Thanks for any and all opinions


mike c

I am sure there have been lots of thought on this, but why deal with the itchy stuff when you can use the R-Tech board insulation? http://tinyurl.com/3yjz3d



It is real easy to work with.

[Miriam C.]

I used rigid foam because it was rigid. I am not sure you would get much benefit from a thin fiberglass sheet. You might check on water heater blankets to see the rating of the thin.

[mikeschn]

Mary,

I notice you didn't go the full thickness on the r-tech. It makes it real nice for securing the insulation, but do you have any regrets not going to the full thickness?

Mike...

[mike c]

Aunti m i was thinking this because that i have quite a pile of fiberglass i'm not sure what the R-value is when you peel it in half? I was more concernd with it getting wet from condensation and such


mike c

[Juneaudave]

Well..you will lose some R value...but I'm not so sure that is necessarily an issue in one of these trailers. It may be more of an issue in soundproofing, constructability, or something else. My guess is...if you keep the moisture out...no problems with a fiberglass bat.

R-Value Table - Material R/ Value Per Inch Thickness

Fiberglass Batt 3.14-4.30
Fiberglass Blown (attic) 2.20-4.30
Fiberglass Blown (wall) 3.70-4.30
Rock Wool Batt 3.14-4.00
Rock Wool Blown (attic) 3.10-4.00
Rock Wool Blown (wall) 3.10-4.00
Cellulose Blown (attic) 3.13
Cellulose Blown (wall) 3.70
Vermiculite 2.13
Autoclaved Aerated Concrete 1.05
Urea Terpolymer Foam 4.48
Rigid Fiberglass (> 4lb/ft3) 4.00
Expanded Polystyrene (beadboard) 4.00
Extruded Polystyrene 5.00
Polyurethane (foamed-in-place) 6.25
Polyisocyanurate (foil-faced) 7.20

[mikeschn]

Now there's an interesting point...

Does pink fiberglass, which gets moldy when damp, get damp and moldy when inside the walls and roof of a teardrop???

Which fiberglass insulation would be less susceptible to mold?

Mike...

if you keep the moisture out...no problems with a fiberglass bat.

[starleen2]

If you are using Styrofoam insulation, then vapors should not be able to pass through. It is the water vapor that passes through the fiberglass medium and condense on the other side that gives so many problems. Since Styrofoam is not easily penetrated by water vapor, then you should have no problem. I would use aluminum tape to seal around the joints and seams to keep the air transfer between sides to a minimum. Tried the pink stuff first – a sure headache for us. By the time I got the first panel insulated, the stuff was so compressed, that it bowed the paneling – Stopped there and ripped out the wall and went with the closed cell stuff.

[Mary K]

Mary,

I notice you didn't go the full thickness on the r-tech. It makes it real nice for securing the insulation, but do you have any regrets not going to the full thickness?

Mike...

I didn't know any better Mike. I thought that was the way to do it. They only had one thickness at lowes to get and I surly did not want to fight putting another layer on top of that one.

The TD stays cool if it is in the shade and does stay somewhat warm on a cool night. Also, it is pretty soundproof. So I am happy, but maybe ignorance is bliss huh?

Mk

[Andrew Herrick]

RV insulation happens to be a pet subject of mine (nerd alert, I know!)

So here's the thing to keep in mind: R-value is NOT a CONSTANT! It fluctuates depending on the temperature, installation, age of material, etc. And just because your insulation material has an R-value of, say, 3.0, doesn't mean your whole wall will! With fiberglass batts, for instance, it's not the glass itself that has an R-value: it's the glass + all the air its supposed to contain.

Rigid foam (XPS, EPS, Polyiso) has MANY advantages over fiberglass batts. They repeal water, add structural rigidity, maintain their shape, avoid mildew, and have superior R-value/inch. Honestly, in this day and age, only the cheapest RV manufacturers still use fiberglass - and I've seen lots of pictures of RV owners opening up their walls to discover that the "fluffy" fiberglass had flattened out and sunk to the bottom because of the road vibrations. Not to mention that once fiberglass gets wet, it starts to mold and loses much of its R-value.

Will fiberglass get wet inside a teardrop??? Depends. If you have a moisture barrier on the exterior, I doubt it. But if you designed your wall to dry towards the inside (aka, if you have an aluminum skin), then I suspect it might get damp eventually ... ... probably not a deal-breaker, but there are other reasons, I think, to avoid it ...

That's the long way of saying that, appealing as it sounds to stuff fiberglass willy-nilly into every crevice and not have to worry about cutting rigid foam to size, it's probably not a good solution. You'll be much better off using rigid foam or expanding spray foam. Just my $0.02!