Re: Screw size
Reply #1 –
Here is a quote from a old thread, where we were discussing the coach wall construction. Don (Don & Tys) described his coach:
"This one (wall thickness) I do happen to know for our coach (99' U270), and I would guess is likely the same for all of the Unihome/Unicoach models, even if the layers differ somewhat. On ours, the blue styrofoam is an inch thick and there is some brown foam of a different (stiffer) constitution. My guess is that they found the brown stuff to be easier to adhere to the laid up fiberglass outer skin. From left to right, there is ¼" Luan plywood, .060" FRP or Filon sheet, 1" blue styrofoam, ½" rigid brown foam of unknown composition, approx. 1/16" fiberglass, and finally the gelcoat. This is a plug from my installation of the washer/dryer. It is shiny because I coated it in the epoxy I used to stick the basement skin back on. This was a test to see how the epoxy resin reacted with the styrofoam before I stuck the skin back on. I am not sure if the blue styrofoam would have fared as well with Polyester resin. Also, it makes a nice souvenir to show people how our coaches are made. So the short answer is 1 ⅞".
Photo below of Don's plug, and a photo of the wall on our '93 U280 when the window was removed to install residential fridge. You can see the foam in ours is slightly different from Don's '99 U270, but the basic construction/thickness is the same.
Unless you happen to hit a frame member, the interior wall "skin" is pretty thin. You can use a magnet to check for steel frame members behind the paneling. Use a fastener suitable for "thin" material, and with sufficient grip to hold the anticipated weight.
Topic: Screw size