Outside Lights on Foamie Question?

[Shirestone]

A quick question. I seem to have a lot. LOL
What is the best method to mount outside lights and reflectors on the Foamie.
I have 2 inch thick XPS pink with canvas glued on the outside. The canvas is then primed and painted. I now want to add some outside lighting etc.
I was thinking I would either:
1) silicon them to the outside of the canvas and poke a hole to the inside for wiring...making sure the hole was covered well in silicon as well to make it water tight. I am worried that this may not work completely and the canvas would pull off the foam if the light ever got knocked around.
2) second method I was thinking was to poke holes in the canvas and foam for the mounting bolts..those holes would be surrounded in silicon. Then on the inside glue a thin 1/8" sheet of wood where the holes are and tighten the nuts down onto the wood to allow the spreading of surface area on the foam.

Let me know if any of you have done this or point me to a link.
Thanks for your help as always.

Cheers.

[TimC]

Sink blocks of plywood or solid wood into the interior wall and use them to anchor the lights with screws long enough to reach the wood. Your idea to use a thin sheet of ply would work but will be less sturdy than burying a block in the wall. The blocks can be foamed in with great stuff or gorilla glue. Then spackle will hide the block.

Personally I wouldn't use silicone to seal the lights. Butyl tape is more commonly used for sealing this type of thing.

If you want to make a "dry" gasket with silicone caulk I describe the process in the second post on this page...
http://www.tnttt.com/viewtopic.php?f=50&t=63575&start=120

Using the gasket once trimmed and anchored behind the light allows you to change easily should something bad happen to the light.

[pchast]

I just scanned through my pictures! So many were overlooked that could
have helped...

I planned my light locations and, before canvas, I inserted wood blocks.
Those blocks were larger than the planned light and shaped like an
inverted bowl to be glued into the foam. The hollow provides solid support
for the canvas and light yet leaves enough room for the connections.

I hope this helped.

[ScottE]

I've attached a photo that shows the mounting blocks inserted into my foam walls prior to canvassing (you could also cut these reliefs for mounting//gluing blocks after canvassing.) You can see the mounting for my tail lights as well as rear clearance lights. Good Luck!

[ghcoe]

I put a shallow 1 gang electrical box on the inside of where the light will be. Then I screw the light in from the outside through the foam into the back of the electrical box. This will sandwich the foam between the light and the electrical box. This will make the outside skin look uniform and allows a place for the electrical connections that are easy to get to on the inside. Cover it with blank electrical cover to keep everything tidy.

[Shirestone]

Thanks for all the input from everyone.
I think I will take George's suggestion. I would like to keep the outside look as clean a possible and my canvas is already installed.

Thanks again for all the replies. Really finding this website useful for all the little details.

[ghcoe]

Thanks for all the input from everyone.
I think I will take George's suggestion.

These are the boxes I use.

1 gang box

1 Gang Box.png (141.9 KiB) Viewed 736 times

I can usually find them at Lowes for under $2.00. I use a soldering gun as a hot wire to cut out the foam for the box. I glue them into place with Dap Latex Caulk.