Homasote

[leonmon]

I built my roadbed with 1/2" homasote on top of 1/2" plywood and cork road bed on the homasote.
I've noticed that during the winter months when the humidity is low the track seems to buckle.
In the summer months when the humidity is higher rail gaps open up.
Has anybody using homasote had the same problem?
Is there a fix for this?
Would it be better to mount the cork roadbed and track directly to the plywood and eliminate the homasote?

[wp8thsub]

This subject came up in previous threads, so you may want to search the archives for more information. As I see it, based on 20 years experience on my own layouts using Homasote, and the experience of others whose layouts I've worked on and operated, the Homasote likely isn't the problem.

The wood in the benchwork and subroadbed will move a LOT more than the pieces of Homasote on top of them. Eliminate the Homasote and all the wood still expands and contracts. Soak same sized pieces of Homasote, plywood and/or other benchwork materials and measure them before and after to see which changed size most. Some people on another internet list I'm on did just that and were finding the Homasote was changing the least. Someone will probably come along and completely disagree with me on this.[:D]

My last layout (with Homabed brand roadbed) didn't give me expansion problems at all, so here's how I built it...

All of the benchwork was a "studwall" of 1X3 lumber with crossmembers on 16" centers, assembled with drywall screws. Along the walls I attached the benchwork to every other stud (at most). Roadbed, whether plywood or hardboard spline, was attached to risers at every crosspiece. Plywood roadbed had small gaps at the joints (as you would install wall or roof sheathing) to allow for movement. The layout was also built in a finished room without great fluctuations in temperature, but I had no humidity control.

I'm no fan of L-girder, since the portions of the previous layout I built with it moved around much more than the open grid studwall sections. The L-girder concept was hatched in a era before good power tools were so prevalent and was intended to allow the builder to assemble everything without having the more precise joints you get with open grid members cut with a power miter saw. I don't know if you're using L-girder or not, but I throw that in because it's a possible issue and I wonder if others have noticed the same thing.

[Anonymous]

Buy an humidifier and a de-humidifier. If the humidity problem is that bad your furniture, house, and health will thank you too. FRED

[willy6]

never had a problem

[dknelson]

homasote is made from old newspapers and does wick up moisture more than wood. Following advice Jim Hediger gave years ago in Model Railroader, I painted my homasote with shellac to seal it (the edges too) front and back. I drilled a whole, and hung it up to dry from the ceiling of my garage (newspapers underneath). I had not used shellac since I was cub scout and had forgotten that that is a smell you might not want in your house.
This makes the homasote harder by the way, and little more difficult to drive in a spike or a nail but not impossible.
Dave Nelson