I had my pine, plywood, homasote, and masonite (backdrop) in the basement for at least a year before I started doing anything with it. Some of it has now been down there for several seasons. I store it flat so it does not develop a built in warp. I also seal the homasote with shellac (which has no water in it) which however does take away some of its sound deadening properties and also makes it harder to drive spikes or brads into it.
It seems like the first set of seasonal changes is the worst.
Dave Nelson
On advice that I once read on a forum, I primed my pre-assembled wood for my bench work. This included both sides of the plywood before it was attached to the bench work. I have not had a hint of movement in several years. My layout is in a basement that does get damp in the summer (which necessitates a dehumidifier), but is not quite the extreme that ‘Selector' has.
Most of my track joints (mostly flex track) are soldered. I also model in N-scale, so even small expansion issues can get very serious.
I'm convinced that completely sealing the bench work makes a huge difference in preventing expansion issues.
I don't really enjoy soldering...let's say I am indifferent to it. I wouldn't think, however of doing anything less than soldering every feeder, and I often solder one join on a curve for stability. Other than that, I am a firm believer in letting things move a bit, so I rely on metal joiners and good ballasting techniques to help keep things from squirming too much.
In fairness, I also run a dehumidifier for about 10-12 hours a day, turning the machine off only at night. My layout is in a basement with poorly sealed jumble block (cinder block) and an unsealed cement pad surrounded by very deep sand soil that is wet for much of the winter. I really have no rational choice other than to paint all the wood to seal it, or to dehumidify the entire basement for the good of all else that therein dwells.
Note that I have MDF spline roadbed, and have not noticed any problems during periods when the dehumidifier could not run...such as during extended power outages inside of a given week.
My advice: solder feeders to the rail sides or bottoms, use joiners that are new and not allowed to bend upon insertion, and keep the joiners free of anything except for an initial weathering. Use the odd track nail, particularly on curves, and then let the rest of it float as best it can within solidly glued ballast. When you make your joins, try to leave about 1/32-1/16" gap at the end of every three foot secton of flextrack for cheap insurance. Finally, spring for a $200 dehumidifier.
I also have a non-climate-controlled layout room - a Mojave Desert garage where temperatures might kiss freezing on a midwinter morning and WILL top 120 F at three PM in August.
My personal solution is not to solder ANY rail joiners. I only lay track with hard-butted joints when the temperature is 100+. At 80 I leave a 1/2mm gap, which widens 1/2mm for each 20 degrees of temperature drop. My track is laid in latex caulk on foam, which doesn't hold track nails vertically.
To assure bulletproof electricals I solder a jumper around EVERY uninsulated rail joint. The jumpers are bent, so they don't inhibit rail movement.
I have seen others suggest that rail joiners at turnouts should never be soldered, presumably to make it possible to change out a malfunctioning (fill in brand name here) pre-built. I hand-lay my specialwork in place, so to me this is a non-issue.
Note that I haven't mentioned humidity. Here in the Dessicated Desert humidity in the double digits is considered high. Wood products will sometimes (usually!) assume strange shapes as they lose moisture, so my major benchwork material is steel in the form of steel studs.
Chuck (modeling Central Japan in 1964)
Here's my experience. My layouts in a 20'x20' out building with no climate control in Tennessee.2"x4" bench work with particle board top. (the kind they make cheap furniture out of) Temperature ranges from 30F in the winter to 115F in the summer. I soldered all my joints except for turnouts. BIG MISTAKE! I had to go through and cut gaps in all my curves.I think the expansion/contraction comes more from the bench work than anything. It's OK to solder many of your joints but definitely leave some expansion gaps about every 6'. Solder in feeder wires for your power.(about every 6') Don't rely on the rail joiners to conduct the power.
If your in a basement and can keep things between about 60F and 90F I don't think you'll have much trouble, but better safe than sorry. Run your dehumidifier. I would recommend holding off on your ballast for about a year till you see what the seasonal change will do to your track work.
PS-I used about 1/32" gaps when it was hot. Now they've opened up to about 1/16+ with the cooler weather.
Looking at the posts for gluing problems led me to search archives for expansion and contraction of layout frame problems. Darn, I never thought of this! Wish I had used foam board, but I needed something terribly smooth to sit on a carpet and move around later.....so I used Medite (MDF)....that stuff from Sierrapine corp.
Now I have moved the layout to a new home and into a basement where I went ahead and started to enlarge it. I can control heat and humidity to a fair extent, but it still might swing a bit.
Questions: 1. Has anyone else used MDF for a layout board and what is your experience with expansion and contraction? I think it should be less than that of regular plywood and softwood stringers.
2. I see two kinds of recommendations, I think.....(a) spiking down the flextrack every couple of inches and soldering all joints, or (b) leaving some sliding rail joiners and some expansion gaps in the track. Have I got that right? Which is the best method and what sort of gap are we talking about here?
I still have time to change the method of track laying, but the medite layout board and cork roadbed are all in place.