Foam insulation board & foam underlay combo

[BobDM]

Thanks to somebody on this forum, sorry I can't remember who, I watched Laurie Calvert's series of videos on YouTube where he made layouts using foam insulation board with Guagemaster foam underlay stuck on.

Now as somebody is utterly useless at any practical work, the idea that I could make a layout quickly and without risking expensive turnouts by using traditional ballasting techniques really appealed.

Has anybody here tried this combination? I would be interested in any comments.

Two things I thought of were:
1 Is the rumpled foil finish you seem to get on some foam insulation going to cause problems given that the baseboard is not smooth?

2 How do you join two pieces of foam together to make an extended run?

[Mountain]

I'm afraid I've not tried it myself. I know the boards feel sturdy as we had offcuts when we had to have a new roof due to a tornado. Be aware that though they are supposed to be fire retardent they burn pretty well, so take care with using hot items. They do seem very sturdy. My only thoughts in regards to the foil are will things stick to it? It is interesting to see the solutions to the possible issues. One can make a wood surround which can be used to fasten two boards together.
In houses boards don't really need to be joined as they are simply cut to size and one board is placed next to the other. I assume they use nails to hold them in position?