Bending rigid insulation

[CheshyreKatt]

I wouldn't recommend heating and bending....not good on the foam (some foams, I've seen it "melt" away under the heat.

Many folk have used saw cuts...but that is going to depend on the severity of the bend. Most curves you can get away with cuts ~1-1.5 inches apart about 3/4 of the way through (please check with others, they may have better statistics). I've seen a few posts and some of the other members builds where they've done this.

Another alternative is to put in layers of flex foam rather than rigid foam. Not sure of the performance value though. Or spray in foam...becomes rigid when it cures.

[goldcoop]

Powder-

I used the ridgid 1.5 on straight shots, on the curves of my roof I used 2 layers of R TECH by InsulFoam.

At just under 3/4" thick per layer it fills out the 1.5 perfectly.

It is white popcorn styrofaom sheet insulation, has a clear film on one side, a blue film on the other and is sold in sheets AND is extremely FLEXIBLE.

I bent it around my 22" Radius on the front with NO prob.

Oh yea, bought it at Lowes...

Hope this helps!

Cheers,

Coop

[goldcoop]

Powder-

Just found this thread that may help:

http://tnttt.com/viewto ... highlight=

Cheers,

Coop

[Arne]

If you have to use rigid, make slots across it.. it wil crack, but the slots should be placed so they will close up when you bend it...

[asianflava]

I did the same as Coop. The rigid foam on the sides, the stiff yellowish stuff, and the Rtech on the top, a soft white styrofoam (like packing foam). I also used the stiff stuff for my shelving and bulkheads.

Heres a tip, when cutting the foam for the top bays, cut them slightly large. Then they will have to bow in the bay rather than lay flat.

[toypusher]

I used rigid insulation from Home Depot. It is white with thin plastic film on one side and foil on the other. Just used 3/4" first and then 1/2" over that. My roof spars are approx 12" apart and I had no problems with either thickness bending around the radius. Just my experience!

[TomS]

My roof is 1 1/4" think. I used 2 layers of insulation 1 layer 3/4 " thick and the second 1/2" thick. I kerfed my insulation with a table saw to get it to bend around the curve. After I did this and posted the photos, someone suggested that I should've place the kerfed side on the inside of the curve to eliminate the gaps caused by the kerfing.

[madjack]

Tom, just think of those gaps as "dead air space"...the almost perfect insulation(under vacum)
madjack

[TomS]

Tom, just think of those gaps as "dead air space"...the almost perfect insulation(under vacum)
madjack

Oh, Kinda like the space between my ears?

[madjack]

Tom, just think of those gaps as "dead air space"...the almost perfect insulation(under vacum)
madjack

Oh, Kinda like the space between my ears?

...hey I didn't say that ...you did...but............
madjack

[TomS]

Hey, I've got to be able to laugh at myself from time to time. Otherwise, I'd be a pompos miserable S.O.B.

[madjack]

...hey, if we can't laugh at ourselves then we've no right to laugh at others(or something like that)
madjack

[Steve Frederick]

I kerfed two layers of 3/4" pink board. Glued to the headliner, and each other. Works great!


The spacing shown is about 1", this will go around the tightest curve nicely.

[Steve Frederick]

Thats great guys
How many kerfs and how deep would I need to do 2" high density foam for a 16" radius?

Dunno!!
But, I came up with my system by taking a sample piece of stock and whittling on it with the circ/saw. When I got the results I needed, I worked on the actual stock for the roof.
BTW, The kerf is through all but about 1/4" of stock.
If your foam has a foil skin on it, go deeper with a wider cut. I'll bet the foil will hold the sheet together 'till you get it glued in place!

[Denny Unfried]

I had an inch and a half thickness to fill so used three layers of ½" thick sheets of polystyrene from Lowe's. The stuff bends like rubber and easily conforms to the countour. In the sun at 100°+ heat the headliner doesn't seem to have any heat build-up to the touch.

Denny