Is there a way to stop all expansion and contraction issues? I’m building a large HO scale layout. It’s a regular L-girder benchwork. My subroadbed is masonite splines. The roadbed is cork. Today when I looked at the track I saw gaps between the rails, around 2 mm in some places. There was absolutely no gaps between the rails when I glued the track in place with latex caulk many month ago. The track is not ballasted. Can someone please tell me what the biggest problem is here? Is it my benchwork, my subroadbed, my cork roadbed, my lack of ballasting or something else? Should I solder the rail joints only at the curves? If I use 20 mm thick birch plywood as my subroadbed, will that solve my problems? I mean, masonite may expand and contract more then 20 mm birch plywood or am I wrong? I need all information I can get on this subject. Let’s start a discussion about this. I want to learn a method that is 100% bullet proof.
I am sorry, but I don´t have good news for you. Unless you have a way of keeping temperature and humidity at a constant level all the time in your train room, you will have to put up with tracks showing gaps due to contraction/expansion caused by variations in temperature.
Soldering all joints of your track will improve conductivity, but not help with those gaps. Real railroads even have special joints in their welded rails to allow for the expansion in summer time.
I guess other than carefully laying your track and “repairing” any excessive gaps, there is nothing you can do to fight the laws of physics.
Use materials that are less affected by temperature/humidty swings such as plywood instead of dimensional lumber to reduce the problem. Or steel studs etc. Also, for wood and wood like products you could paint or coat them. Try to keep the layout room at fairly constant temperature/humidity - this can get expensive if taken too far.
In the end, just like real railroads, you’ll need to do some maintenance.
Enjoy
Paul
I wish I had an answer for you but I’ve run into the opposite problem. The plywood subroadbed under my main passenger depot, which has been in place for about five years, for some reason expanded more than normal this summer and I ended up with a hump yard where I didn’t want a hump yard. My solution is to trim the ends with a spiral saw and then put new screws in to flatten it down. Fortunately, there is no scenery in place yet.
Good luck with finding a solution.
Keep a fairly consistant humidity in the railroad room. Store the building materials in the railroad room for several weeks to let the expansion and contraction occur before the material is in the layout. Paint slows the change but doesn’t stop it.
The ONLY way to deal with those issues is a controlled, constant environment. I ran into this with my first layout; which I built in my garage in Phoenix. I could only work on it in the middle of the night; when temps “dropped” to 99°. My current layout is in my basement, which stays warm in the winter and cool in the summer.
Addressing temperature and humidity swings is obviously a big step in trying to address the issue (which is NOT the same as stopping all expansion and contraction).
A couple more thoughts. Maybe this just worked for me but I had most of my lumber, plywood, and homasote in the house for at least one full seasonal cycle before it was used, as opposed to a “buy as you go” routine. So I was not constantly importing new (“wet”) stuff into the house. That seemed to help.
Also I use the David Barrow domino benchwork method for the most part. As some critics point out, that system uses more lumber than the minimum because each 2’x4’ piece of benchwork is stand-alone if need be. But it has the benefit that I can loosen or tighten up the bolts that hold the pieces together if seasonal changes dictate. By the way my bolts are actually pure threaded rod which I buy in 2 foot lengths and then cut to length, and then have wing nuts on both ends - with washers to protect the wood itself – and that way I can tighten up or loosen the wing nuts by hand by reaching underneath, without having to get out wrenches and pliers and such.
Dave Nelson
Wooden benchwork shrinks and swells with changes in humidity. Long term, wood shrinks across the grain and stays shrunk. Shrinkage along the grain is a good deal less than it is across the grain. The wood movement is the real culprit, thermal expansion/contraction of metal rail is negligible compared to shrinkage and swelling of wood and wood products.
Masonite is a fairly stable material, shrinkage wise. I don’t think 20mm (3/4"?) plywood will be much better. Ballast has nothing to do with it.
Your best bet is the distribute the wood movement all along the track. Which means I don’t solder rail joiners. Leave each rail joint free to move. The movement of three feet of benchwork is not great, whereas the movement of a room length bench might be 3/8 inch or worse. With most rail joints soldered, all the wood movement over the entire length of the layout comes out in the one or two unsoldered joints. Which means a really horrible gap or buckled track, depending one whether the benchwork shrinks or swells. Whereas if all the rail joints are free to move, the movement of each three foot piece will be small.
Paint will slow down (or perhaps stop) absorption of moisture. You might give all the benchwork a coat of paint, or varnish top and bottom. Won’t hurt and it might help.
Some areas of the country are worse than others I have built basement railroads in Pennsylvania, Ohio, Michigan and Illinois and never sealed the wood and never had a problem. MR had problems on one of their project railroads years ago in Milwaukee so go figure. Every material has a coefficient of thermal expansion and nearly all organic materials will absorb or emit moisture. A railroad should be able to handle a swing of twenty degrees with no problems so moisture control is probably the critical element. No reason why you shouldn’t be able to seal the entire bottom of the layout and with the railroad on top it may already be sealed. Just make sure to seal the seams of joints real well. You have nothing to lose at this point trying to seal the bottom.
You might also consider the type of lighting you are using too.If you are using incandescent spot lights you might be getting a LOT of heat on the layout surface. Ian Rice pointed that out in one of his books or articles. BILL
I live in Michigan in the USA, where we have extremes in temperature and humidity in my 24’x24’ garage loft layout. I assume that you laid your track in the summer time,and had massive contraction during the Winter months. I built my layout with 2"x4" studs and 5/8" pine plywood surface. I installed a floor model heater/dehumidifier ,(with a drain through the wall to a downspout). As i recall, I laid my 270yds. of track with cork roadbed, 110 turnouts., six reverse loops and three wyes ,(in the Fall of the year, some 5 years ago). No problems, so far! I would suggest using plywood for the underlayment… Bob Hahn
A fellow on model railroad forums who sure sounded like he had a good handle on the subject, a materials engineer, pointed out that Code 100 nickel silver rails expands to the tune of about 1/4" (6 mm) if it is a continuous length [IOW, no gaps!] when the temperature swings by as much as 30 degrees. What he found, though, was that you needed a whopping 100’ of this continuous length to get that degree of expansion!!! Six millimeters over a length of 30.5 meters of the stuff!! He was attempting to put to rest the probability that temperature, even as a major contributor, was the likely culprit in rail ‘expansion’ problems.
Instead, as others have suggested above, it is the underlying support materials, the organic stuff such as woods, that swell and shrink with substantial increases and reductions of the ambient humidity.
I can use my basement, where my layout is, without any mechanical ‘treatment’ all but two months of the year. Starting in August, and ending about now, I have to run a dehumidifier pretty much constantly on automatic, and empty its 8 liter reservoir about once every two days, maybe three.
To underscore my agreement with the rail expansion myth, I also heat my basement with a wood stove, using the furnace fan and ducting to bring the warmed air to the rest of the house. Both I, at the computer, and my layout are within 6’ of the wood stove. Lemme tell ya…it gets mighty warm down here come mid-December. I have to have it hot in order for the heat transfer to work in the broad space above my head and beyond. I see no ill effects from the substantial temperature disparity between the 15 degrees Celsius the basement and layout would otherwise be and the heated 30 degreees Celsius that I have to maintain in order for the house to benefit from the operation of the stove and furnace fan.
I think that if you leave a
I’ve found that “air flow”, not just air treatment (heating and cooling), has a lot to do with it as well…it can be hot as the devil in the room, but as long as you have some sort of air movement and a way to vent it, you encounter far fewer problems.
In answer to the question, no, I don’t think that you can stop it totally, but you can slow it down.
I too, use spline construction with homasote roadbed.
After years of living in Pa. with extreme moisture changes I found that using a sealer like Thompson’s Water Seal, brushed on all surfaces prior to track laying, has minimized the affects of contraction/expansion, and beleive that it has contributed to the lack of any track problems related to moisture.
I now live in Texas and am in the process of construction of my home layout- it’s 47ft x 54ft on the second floor of my home and has climate control year round but I’m still going to seal moisture-absorbing materials with the Water Seal as a barrier against the moisture from the ballast cementing process.
I’d recommend making the necessary repairs to what you have now and then using a Water Seal product like Thompson’s to protect against future issues.
BTW; Yes, I’ve actually treated over laid track and there seems to be no problem with any reaction from the sealant with plastic ties.
Hope this helps.
Rick
I have to agree with air flow.
My first real layout was in my attic (3rd floor) of my then 90 yr old house, no heat except in the summer & no cold except the winter.
The benchwork was all sectional, the largest section being 4’ x 4’ the rest being no longer than 30" x 3’.
Using 1x4 for the benchwork using plywood for the sub road bed.
Everything was put together using screws, no nails & all the sections were bolted together using 3/8" bolts, washers & nuts.
There were 2 windows, opposite each other & I kept them open in the summer as I had little chance of rain coming in as they were right under the peak of the roof. Not once did i have to modify anything on the layout in the 6 yrs it was together.
Gordon
Well if you use all composite materials like carbon fiber, fiberglass, plastic, concrete, cement, PVC, I don’t see any expansion problems. Of course, then you would have to convert every engine into a self powered unit, carbon fiber is way too expensive and although fiberglass isn’t too bad it takes for ever to make yourself and takes a while to prep it to a reasonable level, concrete and cement are way to heavy, and, well, who would want a layout benchwork complelelty made of PVC tubes. I don’t even know if PVC comes in sheets. As for the rest of the plastics you have to watch. Some would be strong enough but a little more expensive than just using wood and…can I stop now I’m starting to bore and discourage myself [%-)]
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Maintain constant temperature and humidity in the train room.
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Store (age) wood in the room for a year before using it.
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In the meantime, visit/operate other model railroads, read about your favorite railroads, build a mini-module to practice scenery skills, keep on fiddling with your track plan, and build structures for the future layout, making sure track plan and structures are compatible.
I had the same problem with my layout which was in a heated basement that was finished, what I found was that the humidity was the culpurt as the wood absorbed moisture expanded and caused the rail toopen up at the joints.
I purchased a dehumidifier and set it in the train room running constantly and in just a day you would not beleave the water it had pulled from the air and this is worse in the winter time.
After about a week and the gaps in my track had closed compleatly.
My layout fills a 15ft. X 30 ft. room and I purchased the dehumidifier from one of the big home improvement stores for about $100.00 and was sized for that room plus 20% this was one of the best things that I have found for keeping the layout from changing next to haveing it in a heated and air conditioned finished basement.
Also I keep the door of the train room closed when I am not working on the layout.
I hope that this helps with your problem.
I will be starting my second layout soon and had some questions about this issue. I haven’t researched all the threads and archives on this topic yet but I was wondering…
what about laying the track on the blue foam board (glued at the edges as necessary) and having this somehow “float” on the wood frame. If one were to make sure the wiring was out of the way of being pinched by frame underneath as it moved with temp and humidity, couldnt the foam just rest up there as the frame shifted?
Or would the sound be too loud if the foam board was left like that?
I can tell you from first-hand experience that the plastic ballasted uni and EZ-track stuff found in kits is quite noisy on straight foam. If you separate the tracks from the foam with either a bit of acrylic latex caulking or with a layer of cork/foam roadbed, you will find it much more quiet.
The foam is stable over temperature ranges, and is of course unaffected by humidity. So if you can find a way to keep the foam put and let if effectively float on underlying wooden structure(s), I would expect it to be fine.
-Crandell