Track laid on Foam

[larak]

Wood expands and contracts relatively much with changes in humidity. Homasote too probably more so.

Cork is esentially a wood product. Guess how it keeps the wine in the bottle? Yep! it expands when wet.

Rail expands and contracts a tiny bit with temperature changes, but this is a minor effect unless you have extremely long straight runs. A few gaps should handle that aspect.

I glued foam to 3/8 plywood (with foam compatable construction adhesive) and used black foam roadbed. Roadbed glued to foam with adhesive caulk, track to roadbed with the same. No signs of track movement from 0 degrees F to 91 degrees F. Still have to see what happens at 100 degrees in August.

I haven't used cork since the 1980's so I can't say with certaincy, but I presume that much of its expansion will be in width.

Take Zephyr's advice about the noisy layout thread too.

[Texas Zepher]

QUOTE: Originally posted by mikehachey
In other words, was this expansion due to the plywood alone or do the rails also expand and contract?

Wood (and especially homosote) will expand and contract due to humidy. The track rail expands and contracts with temperature. Since you indicated you had wide variations of both, it is difficult to guess which was the culprit.

Don't lay the track directly on the foam though. If you want to know why read the thread called "Noisy Layout".
http://www.trains.com/community/forum/topic.asp?TOPIC_ID=66913

[conrail92]

im assuming it was only the plywood i never had expiernce with track contracting and expanding. and track is plastic and metal so humidity wont bother it as much and if its nickel it wont rust do to humidity and wetness. im not entirly sure about the cork....well cork is essentialy used to keep liquids in such as wine and cidar. But over all plywood can be very vulnerable to humidty and moisture as is any type of wood. if your layout is in the house try using a dehumidifier in the room on the humid days.

[mikehachey]

I'm laying Atlas track on cork roadbed on 2" pink foam. I wonder if anyone has had any experience with track expansion and contraction using this method? My layout room is subject to wide variances in temperature and humidity. The past method I used was track on cork on plywood. The track would kink during differant times of the year. I assume the foam won't expand like the plywood.

In other words, was this expansion due to the plywood alone or do the rails also expand and contract?