Spray Insulation Usage

[Classic Finn]

I was wondering if foam spray insulation that expands when setting is good to use or is this a negative idea?

I know it can most likely be more expensive purchasing it in spray cans than that of styrofoam sheets but it seems a good way to get everything sealed.

If I remember correctly someone here on the forum used this, and did the entire roof before skinning but I cant remember who.

I was wondering what the outcome was on this.

Classic Finn

[TPMcGinty]

I was wondering if spray insulation that expands when setting is good to use or is this a negative idea?

Iknow it most likely be more expensive purchasing it in spray cans than that of styrofoam but it seems a good way to get everything sealed.

If I remember correctly someone here on the forum used this, but I cant remember who.

I was wondering what the outcome was on this.

Classic Finn

I used it on my tear. So far so good.

[Classic Finn]

I was wondering if spray insulation that expands when setting is good to use or is this a negative idea?

Iknow it most likely be more expensive purchasing it in spray cans than that of styrofoam but it seems a good way to get everything sealed.

If I remember correctly someone here on the forum used this, but I cant remember who.

I was wondering what the outcome was on this.

Classic Finn

I used it on my tear. So far so good.

Hi Tim

How many cans did you go through. Did you have to do a lot of cutting and sanding to get it level?

Classic Finn

[Mark McD]

Finn,
Check out your nearest marine supply. The expanding poly foam can be purchased in larger sized pressurized containers, I've used it in a 20 pound can much like a propane cylinder. It comes with the can,hose,and spray gun.It may be cheaper than individual cans and it definetely gives you more control-thus less waste and voids. And if I remember correctly the can/hose/gun can be returned for credit.

The one thing I can tell you for certain is this: get all of your wiring,blocking,etc in place befoe foaming, pulling wire through a foam core is no picnic.

[mallymal]

Picking up on the wiring idea, how about fixing some plastic conduit in place first, then spraying the foam. It would hold the conduit in place, but mean you could easily replace or add to the wiring in fufure.

Hey Heiki, here's a UK suppliers. Smallest foam kit costs £180, plus you need a spray gun at £78, so in total about £258.

http://www.spray-insulation.co.uk/product%20range.htm

I haven't used this, but was looking at it as well, so thought I'd post the information.

As a cheaper solution, could you make up a side panel, lay it flat, then just pour in a small amount of 2 part expanding foam?

Maybe you could use the "silver bublle foil" for the roof.

[Mark McD]

Mally,
Yeah that's pricey. Last time I used it the economy was still strong and my wallet was a little fatter. If I've learned anything over the years it's that anything that has the word "marine" in front of it will cost twice as much.

Placing conduit is a great idea as it allows for adding wires at a later time if needed.
Here's an easy way to pull wire through conduit:
take a piece of string,stuff an inch or two into the same end you're pulling from.
Take a shop vac and hold it over the conduit opening at the other end and turn it on. The vac will suck the string through the conduit and out the other end. Then just tie your wire to the string and pull it through.

[Rock]

How about a hybrid:



Extruded Polystyrene sheets locked in place/gaps filled with expanding foam in a can.

Eric

[TPMcGinty]

Hi Tim

How many cans did you go through. Did you have to do a lot of cutting and sanding to get it level?

Classic Finn

I used about 15 cans if I remember correctly. Menards had them on sale for $2 a can. I didn't do any sanding. I just trimmed the extra off with a hack saw blade.

[kennyrayandersen]

I was thinking of doing the curved parts that myself, but the cans were running $5-6/can. The places that normally do it for houses wanted a lot and the kit to do it yourself over the internet was also quite expensive to do expanded-foam as well. I think $2/can seems like a pretty good price.

Also, I was wondering if the adhesion and strength of the foam is as good as the pink/blue foam as in my concept the foam carries shear loads and is actually part of the structure. Does the expanding stuff seem as robust as the EPS sheet?

[brian_bp]

Spray-on foam is routinely used here as additional insulation under the floor of trailers which are used in winter conditions. It is a pain in the neck for maintenance and repair, but allows a continuous insulation layer. It is normally applied by professional services - even the RV dealers don't do it themselves, they subcontract to specialists. Of course, they're using vastly larger amounts than a teardrop would need.

This stuff seems pretty soft to me, and I would not consider it a useful structural component, but I suppose there probably several types on spray-on foam.

The foam in cans which is normally used to fill gaps in houses comes in two levels of expansion. If injecting it into a closed space, the high-expansion stuff can cause problems by distorting the structure.

[TPMcGinty]

I was thinking of doing the curved parts that myself, but the cans were running $5-6/can. The places that normally do it for houses wanted a lot and the kit to do it yourself over the internet was also quite expensive to do expanded-foam as well. I think $2/can seems like a pretty good price.

Also, I was wondering if the adhesion and strength of the foam is as good as the pink/blue foam as in my concept the foam carries shear loads and is actually part of the structure. Does the expanding stuff seem as robust as the EPS sheet?

I must just be lucky. The spray foam I used is normally $2.50 a can and it's now on sale for 99 cents after rebate. It sticked to the wood very well and is fairly firm when set up. I sprayed it on before putting on the outer skin and after putting on the inner skin. I then trimmed it down with a hacksaw blade so the outer skin would fit correctly. I wouldn't say it's part of the structure. The spars and skin give more than enough structure even without insulation. If you have a question on whether or not it is stiff enough, buy a can and spray some out and see how it firms up.

[Esteban]

Here's a picture of the spray foam Duane King used in his ceiling...to encase the fiber optics to his star field.

[kennyrayandersen]

can that stuff be hot-wired?

[mallymal]

UK builders....

here's an example of the 2 part "pouring" system.

http://www.ecfibreglasssupplies.co.uk/s ... -1187.html

Maybe with practice, a quick pour, then squeegee it out with a piece of scrap plywood.... probably rise to about 1" thick, avoiding the need for too much trimming.