Using Great Stuff as glue for foam board insulation?

[Vanderbus]

So, I've got my foam board insulation, and I've got my Great Stuff. From reading here and talking a while back with JackConrad, I think that I can use the Great Stuff to hold my panels in place (on the walls and the ceilings). My question is this: Am I going to have to rig a bunch of supports to hold the panels long enough for the Great Stuff to cure (or at least harden enough to hold)? Or can I just spray it and let go? Should I just glue the panels in place and then spray the stuff over that?

My main concern is that the panels will fall down or straighten where they need to make a slight curve to stay against the ceiling.

Also, while I have your attention, how much space do you reckon I need to leave between the edges of my panels and the bus frame members? I was thinking 1/4" or so on all sides.

Thanks in advance,
Joe

[Dallas]

Cut your insulation panels so that they fit in the spaces as tightly as possible without glue or anything else.
When they are installed, use the greatstuff foam to fill any open spaces between the foam and the metal.
You are trying for a complete dead air space, and any space between the panels and the support structure defeats the purpose.
When you have all of that done, install a furring strip all along the structure supports and cover with Reflectix, sealing the seams with aluminum tape.
Good luck with your endeavour!

[DaveG]

Great Stuff will not work as an instant stick adhesive...you'll need lots of rigging.

[JackConrad]

    Cut the panels and put them in place using a little polyurethane construction adhesive, then fill the gaps with expanding foam. As the foam expands it will lock the panels in place and fill any gaps that would allow heat transfer.  Jack

[belfert]

I am pretty sure they make an adhesive caulk just for foam.  I only used foam in the sidewalls where I had skinned over windows.  The foam fit so tight I didn't need any adhesive.  The ceiling has spray foam direct from the factory so I didn't use any foam up there.

[JohnEd]

I called the Mfr rep about that canned foam.  She said that if I sprayed it in a closed cavity, like a 2X2 tubing that it would NEVER cure.  That stuff needs to evap to set up.  Like keeping the cap on glue....it stays soft.  The 2 part spray on cures within itself, so to speak.  Ace had pics of his bus and the foam he put in was so precisely cut that it had to be carefully pressed into the area.  I am sure he used some sort of cement to hold it but that stuff also would need a long time to cure.  His install looked to be almost a perfect seal and he must have worked at it.  The less "stuff" you need to fill gaps the better.

The spray in foam serves to deaden the sound.  If you fit foam board it will serve to dean the sound also but not as well.  I think you can enhance the deadening performance by making sure the board is tightly fixed to the bus skin by using a cement under the foam board.  The tight fit is what would hold the foam in place till the cement set up.

To relieve the tension on the board where it attaches to a curved surface you should score the board with a table saw till you can lay it in place and it doesn't push back much.  Make the scores on the side that will close up when you press it in place.  Close fit like Ace and it will stay there till the cement underneath dries.

2 cents,

John

[RTS/Daytona]

does your foam have paper or foil on each side

If so - just open all windows - put a fan at the front door and use contact cement

just use a cheap brush - brush the foam and brush the ceiling - push together - tap with a rubber hammer and a piece of board

You'll only get one shot at each piece

I will stick instanly - won't come down - you'll have to pick it apart to remove it

[Vanderbus]

Thanks, everyone, for the ideas and the advice. I'm going to study on it a little more today, and hopefully get a good chunk of it done over the weekend. If you're interested, I'll post the results and how I ended up going about it.

Thanks again,
Joe

[viento1]

Dont do it.... I used a product similar to great stuff and it ate half way through the foam. I only noticed when I needed to remove a section for repair. Use PL 300 (maybe 700)

[fraser8]

What ever you use get it tight, I drove an ambulance that had a loose piece of styro in the wall and the squeak got to you after a while. ( I didn't want to say drove me crazy)

[Lee Bradley]

If the foam board is expanded polystyrene, 3M makes an adhesive just for that.

Polystyrene Foam Insulation 78 Spray Adhesive

[JackConrad]

If you are using spray foam in a can, I remember several years ago reading about a person that sealed the OEM AC ducts with spray faom and a few hours later turned on the AC blower.  KABOOM!!! The wxplosion swelled the sided of the bus and I think ruptured 1 or both eardrums.  Seems the gas that was used as a propellant was flammable and heavier than air.  It laaid in the ducts until a spark from the blower motor ignited it.  This was several years ago and I do not know if this same propellant is used today.  Might want to read the label before using.  Jack