Inuslation Foam top vs Plywood

I have 1" thick blue foam on 1/4" ply and my track screws are long enough to reach the ply. This may defeat some of the sound deadening qualities of the foam, but it is very light and my layout is portable. There is no reason to use the foil backed foam The dense blue and pink are available at the big box stores.

For a permanent layout, I would actually consider the L girder construction the HO and scale guys use if I were going for realism. 

Also, I forgot to add- foam glues very well with adhesives available for foam. These are in the caulk gun tubes- just check the labels. Also available at BBS.

I guess I'm old-school, I wouldn't use just foam.  My new layout is using 1/2" multi-ply birch, that's topped with 1/2" Homasote.

Alan, I used Elmer's glue to attach the foam to framework. If you cut the foam you will want to find blades to fit your sabre saw, you will want the ones without teeth, they are like knife blades. They do cut clean but you need to cut carefully where you want to join sheets together. If you are patient you can use the same Elmer's glue to join them, otherwise I am sure there may be a water base contact cement that would work, the solvent base glue will eat the foam. I used low temp hot glue to attach my track to the foam with a dual temp glue gun set to the low temp, the high temp will melt the foam. How do I know?

Ray

I tried that. RealTrax on 1” rigid foam with open L-girder underneath and no plywood base is going to be noisy. I’m not sure how much a plywood base would help, but foam is not the sound deadening material people think it is. Yes, it may help reduce noise traveling through walls, etc., but when you put trains on it, the sound actually increases, especially beneath the decking. It’s mostly for sculpting landscape features and I only used it to save weight on a Christmas layout that had to be moved/stored. I added batting under the tracks and added a skirt around the layout. That helped, but it was still hard to carry on a conversation with trains running. And this was in a 3-car garage with the doors open. YMMV

I used a foam base for lightness and portability.  There is no sound deadening.  The dense foam actually acts like a drum magnifying the sound.  With that beautiful base I would follow GRG's method of plywood and homasote.  You can use the foam for building terrain but not supporting the track.

Chris

Like others have said, I think you are better off using a thin (3/8" - 1/2") plywood top before installing a rigid foam base (3/4" or 1") from a big box store w/o a foil backing.

 The foam does not dramatically reduce noise, but it does seem quieter than plain plywood. In addition, it provides a nice medium for simply gluing and pressing in scenics like telephone poles and trees on your layout rather than having to drill through plywood.

I have always used a construction tube adhesive (like Liquid N**ls) to adhere the foam to the plywood and placed heavy items (books, tools, etc.) on top to weigh it down overnight. I use a utility knife and a very sharp 10" commercial chef's knife to cut and trim the foam. I also tape any seams with duct tape which seems to hold up very well. You could also use a flexible joint compound or similar product to fill in the seams, but I haven't found it necessary.

Depending on what you are looking for, I typically paint the foam with an earth brown latex paint in sections and sprinkle with green and yellow fine turf while still wet to hold the turf in place and, when dry, brush very lightly with a dry utility paint brush to spread the turf around and remove any blotchiness and then spray with a high hold hair spray to keep the turf in place.

Pic of latest project attached.

gunrunnerjohn posted:

I guess I'm old-school, I wouldn't use just foam.  My new layout is using 1/2" multi-ply birch, that's topped with 1/2" Homasote.

I am in Alabama and cannot find homasote. Where did you find it?

Warrenville's base is 5/8" plywood, no foam or homosote.

I LIKE the sound of multiple Postwar trains running, e-unit buzzes, and bicycle type horn and air whistle sounds, better than digital train sounds. But this is me, different tastes in this hobby are what makes our small worlds go around (pun intended).

I enjoy seeing what you guys are doing and look forward to updates of your progress

It's readily available up here in PA, don't know about Alabama.

dogdoc posted:

I am in Alabama and cannot find homasote. Where did you find it?

http://www.homasote.com/wheret...p;State=AL&City=

The drop down state options shows cities where retail stores in Alabama stock it or will order it.

Sooner or later, you will need to on the train table. Will the open grid with foam support your weight?

In testament to those who have said foam is noisy.  I agree completely.  Here’s 2” blue foam over a 1“x6” wood grid on the xmas layout.

I am in the camp using plywood topped with Homasote for tabletop and track base on a permanent layout.  I use foam for scenery only on a permanent layout.  I have a 2" thick foam base for the Christmas layout for portability, and it is noisy like Ted's.

Poorly supported foam will eventually sag. Don't ask me how I know this...  I recommend supporting it with 3/8" plywood or better.  Not certain how well it works as a sound deadener, but having it under your track allows you to cut it out and have things immediately next to the track below grade.

Chris

LVHR

I went all out (my layout is not in the running phase, so I don't know about the sound or lack thereof), I have 4" of foam over 3/8" plywood, which in turn is on a ladder-style base with cross pieces on 16" centers. While I don't plan on going on the layout, the plywood alone did hold my weight at one point.  I decided to experiment with foam because I was too chicken with my first layout in decades to do open grid, by using the 4" I can easily do sub track level features like ponds, rivers (and an 'abandoned' rail line). The foam seems pretty strong. With sound, I'll likely use roadbed under the track (if I ever get that far, don't ask me whether track planning is my favorite thing, it #((($! isn't. 

Thanks for the helpful responses!

After reading through your posts, I'm leaning towards plywood topped with 1/2" foam. I have a 3/4"x 3 'x 6' green painted sheet of good ply from my last layout.  Going to rip it to support the track and leave some open areas for scenery above and below grade.

Always wanted to try Homasote, but the BBS don't carry it on the west coast. 

Here's my track plan, simple and using track I already have.  Very much a test layout where I can revive my Legacy and DCS gear and test locomotives.  Lower track will be MTH RealTrax and upper loop O-27.

We're off to the coast for a night - have a good weekend everyone.

Alan

PL 300 for your foam board adhesive. It works. I've used it to adhere extruded foam to plywood on two other layouts. I am using an exclusively foam base, but I am using vented elastic resin shelving to adhere them to. I agree with others who recommend thin plywood base in the case of L-girder construction.

Make frames out of 1" x 3" strips of wood and 1" x 4" strips of wood screwed together. 

All you need is 1/4" thick plywood that is sealed by painting it with colored latex paint primer.

You can drill holes for wiring before painting.

Screw the plywood to the frames. Seal everything with a coat of colored latex or acrylic primer paint.

Then put layers of 1" to 3" thick sheets of Extruded Polystyrene foam on top of the framed plywood sheet.

Andrew