Lots of insultation question...

This looks like the best place to get answers on a few subtle questions that I haven't seen addressed elsewhere:
I've purchased a 10'X12' pre-fab shed as a reptile room. It's a white pine 2X4 (mostly) frame with aluminum siding and pressure treated floor (plywood over 2X6's).
I live in south Florida, so it's far more important to keep heat out during the summer than in during the winter. I will be puting in a small window air conditioner. I will be shooting for somewhere around 75-80 degrees F during the summer.
I will have 3 1/2" of space I can insulate in the walls and more in the ceiling. Is 3 1/2" fiberglass insulation (R-13) the best I can do here? I think I gather that using thicker insulation and packing it in will be worse rather than better, but is there a better insulation I can use? Everything else I've looked at seems to have a lower R value for the same thickness.
Given that the siding is aluminum, would it make any difference to put that reflective foil between the siding and the insulation, our would that only help with a wood surface? How about between the insulation and the wood panneling on the inside?
The shed is on blocks rather than a slab (maybe 6-8 inches above ground). Would I gain anything by insulating under the floor or would I be better off letting heat from inside radiate to the ground below, which will be cooler than the air outside? Will it just be unworkable to have fiberglass exposed undernieth holding in moisture (entirely aside from the issue of animals nesting in it)? Would I gain more by putting some sort of skirt around the perrimeter to keep hot air from blowing under the floor?
I got the shed in all white to minimize heat absorbtion. Would it matter much if I painted the roof with reflective silver roofing paint?
Anything else I haven't thought of?
Yes, I realize I may be going overboard, but anythything that reduces the load on the AC and gives me more time before the room becomes an oven if the power or the AC fails during the summer is probably worth doing.
Also, any suggestions on how I could treat the white pine frame, in place, to keep termites and such out that would not be toxic to reptiles? Yes, I know the second part is pretty far afield for this group, but I thought I'd ask...
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Look into foamboard the foil faced is R 7. per inch vs apx R 3.5 per inch for fiberglass batts. I thought reptiles liked it hot.
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yup
Polyisocyanurate.foam
not cheap but are to beat for R per inch
cheers Bob
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how are you insulating the roof?
can you consider an "umbrella roof" another lightweight roof over the actual roof to keep the sun off the actual roof? with an airspace in between?
heat gain from the sun is much more than any other factor...
Mark
.
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Fiberglass batting unless someone else has a better idea. I now see that Owens-Corning makes a rigid fiberglass board that is slightly better (R-15 vs R-13 for 3 1/2") but it's way more expensive and I don't know enough about the subject to know whether that's a significnt difference. I think I've worked with the foam board that m Ransley mentioned and found by experiment that it burns like a sparkler if you get it started.

I thought of that, but it cost me almost $600 (counting a survey) and took 5 trips to the building department just to get a permit to drop a prefabricated shed in the yard. I don't even want to think about trying to get a permit to structurally modify it myself.

That much I was pretty sure about...
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rockwool batts (eg: Roxul) have about R15 for 3 1/2", and usually don't cost any more than fiberglass. A lot easier/nicer to install too.


An "umbrella" roof could be literally that - tent structure - not structural.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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On Sat, 10 Dec 2005 06:04:30 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

But is it actually for sale anywhere?
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Foam board and spray in foam go in 2 basic R values R 5- 5.5 per inch and R 7.2 per inch, R 7 spray in is an outgassing type that needs time to release harmfull chemicals. Actualy Foamboard even foilfaced exposed to suns heat as in a roof deck theoreticly will cook and outgas. For sensitive animals " people too" a Non Fordmaldehide Fiberglass is available, usualy white and labeled. Rock wool might be better but who knows, and im not sure on the R value being higher than fiberglass. Also the double roof or tent is interesting. Vermiculite is non toxic, I think, out gassing is an issue not fully apreciated like smoking but can and does harm people every day in new construction.
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Certainly. Less than 5 miles from here. But that might not do you any good ;-)
Try the Roxul web site. They list distributors/retailers in the US too.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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Rockwool is R 4 per " compared to fiberglass R 3.5"
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Yes, they like it hot relative to us, but it can be 95 in the shade here in summer which is about the upper limit. In a closed room it can get much hotter than that and snakes have no way to cool off (they don't sweat).
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Larry Fishel wrote: ...

No. Likely the best you can do without adding thickness to the walls is to use a foamed in place foam. Call around and find a contractor. The stuff is not all that cheap, but it should not be too expensive for your application and it will add quite a bit over what you have planed.
You may also want to consider adding a layer of rigid foam under the outside or inside siding if this is possible with your construction. An added inch or even less of high R value material will make a big difference overall. This could be in addition to the foam in the wall cavity.
--
Joseph Meehan

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I would think of it simply like a home.
I wonder if a ceiling and some sort of ventilation in the mini attic would be the way to go. It would provide a thermal barrier between the roof and the living structure. Insulate the ceiling and you would have a similar construction to a house.
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