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-   -   Wrap insulating board around soldiers? (http://www.fornobravo.com/forum/f28/wrap-insulating-board-around-soldiers-8140.html)

kebwi 10-05-2009 11:56 PM

Wrap insulating board around soldiers?
 
First of all, my soldier course will be laid flat, cut into wedges, piled three (or was it four?) bricks high. I like this design because it mitigates the thick mortar gaps that occur in nontapered vertical soldiers.

So, the outside of my solider course will be pure brick with no mortar gap and relatively long straight walls: either 9" or 4.5" long on the outside (I haven't decided if I will cut the bricks in half for those lower levels or not).

All of that said...I'm thinking about standing insulating board (Insblock 19) on end, flat up against the outer face of the soldiers, either 1" or 2" thick depending on which Insblock I buy.

I haven't seen anyone do anything like this on FB yet, so I'm a little weary, but Insblock is much cheaper if you buy it by the box and I will have quite a bit left after I insulating the floor (but not enough to do the floor twice).

What do you think?

I am also tempted by the prospect of using the Insblock 19 to eventually make a door, but other threads have kind of scared me against such an approach for reasons of toxicity. I might be able to seal it behind a steel sheet, but only if I can figure out how to cut, shape, and otherwise work with sheet metal, which seems like a dim prospect.

Thanks.

Breven 10-06-2009 09:13 AM

Re: Wrap insulating board around soldiers?
 
Keith-

Any insulation you put around your dome, whether your talking about the soldier course or the dome itself, is a good thing. You can't have too much in my opinion. And you only get one shot at it. Once it's done, you can't easily go back an add aditional insulation. However, that being said, the FB Insulation blanket might be large enough to wrap your dome twice...which is more than adequate.

kebwi 10-06-2009 09:29 AM

Re: Wrap insulating board around soldiers?
 
I'm not using the FB blanket. I have 50 lbs of bulk InsWool HP packaged in two 25lbs 24"x20"x18" boxes (so 10 cubic feet at 5 lbs / cubic foot). If my oven where spherical and 36" on the inside, then it would have an outer surface area of about 22 square feet ((PI*45^2)/2). Since it's lower than its horizontal diameter, the surface area is actually less than that estimate, call it 20 square feet for a round number. 10 cubic feet would cover 20 square feet 6 inches deep, but I also need to put some insulation over the arch and around the vent (not up the chimney I don't think!!!), plus, the guy I bought it from told me it can easily be compacted and that doing so would actually increase its insulating effectiveness. He suggested intentionally wetting it down and packing it fairly hard, so if I do something like that it will end up considerably less than six inches deep.

Any thoughts on this approach? In particular, w.r.t. soaking and packing it instead of fluffing it on lightly? Both approaches seem to have a twisted logic in their favor and I don't know which is more representative of "thermal truth". :) Logic one: less dense implies more air, thus better insulation for the same reason a fluffy sleeping bag is warm. Logic two: more dense implies more material to impede the transmission of heat...which I find relatively illogical but everyone keeps swearing to me that denser insulation is better (e.g., 8# board is better than 6# board).

So, whatever, I'm not using the FB blanket is all I was really responding to.

dmun 10-06-2009 09:48 AM

Re: Wrap insulating board around soldiers?
 
Quote:

I am also tempted by the prospect of using the Insblock 19 to eventually make a door, but other threads have kind of scared me against such an approach for reasons of toxicity. I might be able to seal it behind a steel sheet, but only if I can figure out how to cut, shape, and otherwise work with sheet metal, which seems like a dim prospect.
I saved a sheet of insblock 19 for just this purpose. Copper flashing, although pricey, is much easier to form than other sheet metals, particularly steel. All you need to do is envelope the insulation: I was planning to bend up flaps and tack them to a wood backing board. You can get crisp bends in sheet metal by clamping the metal between two wood boards, then first pushing then tapping the flap up.

kebwi 10-06-2009 09:58 AM

Re: Wrap insulating board around soldiers?
 
dmun, do you have any pictures of your door? How thick is the copper?

Also, you haven't had trouble with the metal scorching the wood through direct contact?


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