Gaps in Foam Insulation

Model Railroader Layouts and layout building
1

I’m in the final stages of building my benchwork. I have a butt-joint base of 1x4 with 1" plywood on top and am about to start putting 2" foam insualtion on top (I’m building a terminal switching railroad and won’t have roadbed as I don’t want the track raised above the ground around it so I’m using the extra thick insulation to deaden noise) of the ply wood.

I know it will be nearly impossible to have the faom match up perfectly (I know my limitations as a carpenter, so I can’t imagine I will be any better here!) so what can I use to fill thegaps in the insulation where pieces come together? I was figuring on caulk, but if someone has a better idea I’d love to know.

Many thanks.

~rb

2

As you line up the butt joints, shove a skewer in at an angle to hold the two pieces even. One from each side should do the trick. You can then shim from underneith if it is off very much. I then fill the gaps with ground goop when I do scenery.

3

Sprayfoam in a can.

4

wouldn’t lightweight spackling compound work too?

5

I stagger cut my foam so that it overlaps, as you can see in the picture below. I’m not concerned with the lower levels since they will be covered by the fascia.

6

Caulk or structolyte. Spackling often works but sometimes cracks.

7

All great ideas. Many thanks for all of the informed replies!

Best,

~rb

8

Hi. I get the foam joint “close” with a Sureform, then use fiberglass mesh drywall tape and drywall mud to close the joint.

Works for me.

Terry