Humidity and track laying

Discussion in 'FAQs' started by Gary Pfeil, Jul 3, 2001.

  1. Gary Pfeil

    Gary Pfeil Active Member

    I thought I'd pass along a lesson I have learned the hard way. My layout is in my basement, which has fairly high humidity in the summer and is very dry during the heating season. Last February I noticed kinks developing in several areas and eventually realized that what was happening is this: The track had been laid in the summer, when the wood subroadbed was somewhat swollen due to humidity. As it dried out, the wood shrunk a little, bringing the track nails closer together, causing the kinks. The solution (or the one I used) was to pull the track nails, use a cut off disc in a Dremel to remove some rail (in some cases, the width of the disc was sufficient, others were as much as 1/8")and solder new leads as required. Luckily, I had not yet ballasted. Track which I laid in the winter has given me no problem. By the way, I had painted the roadbed and subroadbed with latex paint prior to laying track, thinking it would prevent a problem like this, it didn't. Hope this saves someone some aggravation.
    Regards, Gary
  2. George

    George Member

    Hello Gary et all! [​IMG]

    I'm really glad you brought this problem up for the gallery. This will save beginners and people with "Oldtimers Disease" alike, the heartbreak and frustration 6 months after commending themselves on a job thought well done.

    I would like to add that when laying flex-track in the winter, don't forget to leave some gaps in the rail for expansion in the summer months. This is critical to avoid the opposite of what Gary experienced.

    It's also prudent not to be in any kind of hurry to permanently glue everything down and ballast until you're trackwork has gone through one complete seasonal cycle. This will enable you to make sure that problems such as these don't waste more valuable time, and money in construction materials. Not only that, but you may find other mistakes you may have overlooked, like clearances. You just may even change your mind about what you want, when you transform a theoretical plan from your head into something you can run a train over.

    It's lousy to change your mind after the mountain is dried and finished! [​IMG]

    This is also a priceless advantage of working with Homasote, if you live where you can get it. Mistakes and mother nature are easily put in place with minor adjustments.

    Even after desired results are achieved, constant proper climate control is necessary to avoid warping of materials, and even rust in mechanisms.


    [This message has been edited by George (edited 07-03-2001).]

    [This message has been edited by George (edited 07-03-2001).]
  3. Gary Pfeil

    Gary Pfeil Active Member

    Billk, The materials used were 3/4 plywood supported by L girder benchwork. Most of the affected area was hidden staging and so had no roadbed. I still had the same problem to a lesser extent on the visible portions of the layout which are on homasote laminated to the 3/4" plywood. And to prove that I'm a slow learner, last summer I handlaid the throat of a yard thinking that since there would be no track nails thru ties connected to each other such as in the flex track, I would have no problem. I did in fact have a problem, tho minor. In two places I had to use the Dremel cutoff disc to shorten the diverging rail of a turnout, because the extra length prevented the turnout from throwing. This really surprised me. Since I am building a rather large railroad, I have now established a pattern of sorts. In the summer, I build any benchwork and roadbed I need for the next section to be built. I wait till winter to lay the track. Since the benchwork doesn't require all summer (tho time available for the hobby is reduced in the summer anyway) I have time to build models and scenery. I really can't answer the question about gaps with any authority. I have not yet had any problems. I believe that the only type of expansion which can cause problems (at least in a basement) is expansion of wood due to humidity. Rails expanding due to heat may be a problem in an attic. I haven't paid any attention to the gaps between rails. I solder all rail joints on curves, and solder a lead to every other rail joiner on all track. Where I cut gaps (for turnouts, etc.) I usually use CA to glue a bit of styrene which I then file to the shape of the railhead. This is to ensure the gap doesn't close and cause a short. Hope this helps
  4. billk

    billk Active Member

    Here's the Vulcan (logical) analysis, assuming the largest contributors would be the expansion/contraction of wood (and to a lesser extent, Homasote?) materials due to humidity changes.

    1) Expansion is apparently not as big a problem, so you could limit your "construction window" to dry times only.

    2) Prepare the wood and Homasote is that it not so subject to changing with humidity. Apparently latex paint doesn't cut it, but maybe something more specifically designed as a sealer would.

    3) Use materials that don't expand/contract with humidity. A light metal grid, foam panels, etc.?

    4) Secure the roadbed and track so that even if expansion/contraction does happen, it doesn't cause such a major problem. Some sort of flexible adhesive, maybe Liquid Nails or the like?

    Also, re filling the gaps you had to cut - unless they can compress without getting squished out so that they cause derailments, won't you still have problems when everything contracts?

    I'm NOT speaking from experience on this, just theorizing (my layout's pretty theoretical too!), so will certainly defer to anyone's real life experiences.
  5. Shay2

    Shay2 Member

    Hey Gary!

    I was fortunate I guess. I read several posts
    about using different materials for track roadbed before I started my layout. The best info I found specified using 1" pink foam sheets glued to 5/8" plywood.
    I applied this concept and laid the track over the foam, securing with glue only. (plain old Elmers wood glue) The results are a stable layout. The wood grows and shrinks with humidity. The foam remains constant as it will not absorb moisture!
    I know this is a little late for you, but maybe someone starting out could benefit.

    My 2¢


    Rush Run River Logging Co.
  6. billk

    billk Active Member

    Gary - Thanks for the tip. Couple of questions: What were all the materials used (track on cork on plywood, for example) and how was it all fastened together? Also, do you think there will be a problem if (when) the gaps expand?
  7. Woodie

    Woodie Active Member


    Attics and basements are a novelty to me. Don't have them in OZ. I notice just about everyone that has built there layout in "the basement" is having these sorts of problems. Cheeky resolution? Don't build the layout in the basement! [​IMG] Conditions must get pretty extreme for you to have these problems. Suppose we are lucky here. Conditions do not get that extreme, so we don't have the problem. Plus timber (pine etc) you buy here has been "cured" to stop warping etc. I'm sure if I left my layout in the rain, and then the sun, then the rain, it would eventually warp and split, however conditions in a basement can't be that bad........ Can they?????

  8. roryglasgow

    roryglasgow Active Member


    You don't have attics on Australia? Or does "OZ" refer to just part of Australia?

    We don't have basements in Texas (well, most of Texas, anyway). I've always been told that the water table is generally too high. That was pretty true of where I grew up. You could dig down about 6 inches most times of the year and hit the water table. There was a swamp within walking distance of my house (and yes, there were alligators there). My grandparents, who live in Missouri, have a basement in their house. It was kind of a novelty to me...

    But with the except of mobile homes and apartments, I've never lived in a house that didn't have an attic! Granted, some have been small...

  9. George

    George Member

    Where I live the water table is high, but it seems just in the past 25 years, contractor's just don't seem to be able to build a basement that doesn't leak. My house is built on a slab with drains around the foundation. It's nice having windows with the layout, but keep the drapes closed to avoid fading......There's always some issue.

    Several years ago I was shopping for a basement for a layout in Connecticut. I looked at over 80 homes in what I thought were decent neighbourhoods. Every house had a sump-pump, a tell-tale water line along the basement wall, and every house had been broken into! Now it's getting harder and harder to find a basement that hasn't been finished off with a pesky sauna.

    Attic layouts are the pits. They get too hot, hard on the back bending over all the time if the roof isn't high enough, and watch your head, OUCH!

    Putting a layout in a bedroom has it's plus and minuses. Minus- It's never large enough for what you envision. Plus- The look on your mother-in-laws face when you announce that the guest room is becoming your train room!! [​IMG] Having a window is fantastic. Ventilation in a trainroom is a privilige, not to mention the advantage of having central air. The last layout was in a 2nd bedroom in a large condo on the 5th floor. The view outside the window was a large active passenger yard. Can't beat that!

    George. [​IMG]
  10. Woodie

    Woodie Active Member

    Nope. No attics, and no basements. If anything, you might have a 2' X 2' manhole to get into the roof to fix the hotwater service. (old ones only). New hotwater systems are mains pressure and usually outside against a wall. Roof slant is not excessive in design and construcion here, so no room up there anyway. Two storeys is the exception rather than the rule, (no stairs) and the garage or garden shed is usually used for junk (or layouts!) Why dig a hole for a basement, when you can put a shed down the back? It's not a problem with the water table or anything. Just not part of the standard house culture.
    I thought basements where to hide in from axe murderers!! hehehehe (Watching too many movies, I think!)
  11. George

    George Member

    Hi Woodie!

    You guys are lucky you don't have "Crawl Spaces". Sheer wasteless space that's hell to get into. That's where the axe murders stash the bodies in bags!

    Woodie, if you put an addition on your house in the United States, the municipality in most cases jacks up your taxes to the moon. Do you live in a free country where they don't do that? I'M ON MY WAY!!!

    The single story home is ideal, especially in a society with an aging population. Most seniors who bought into these marina condos with the 2nd floor balcony for the view are freaking as they hit 80+ and are getting rid of them in favour of the ground floor to avoid stairs.

    Where I live, the old single story sprawling ranch homes built in the 50's & 60's are being torn down and replaced by large 2 story "McMansions". Ugly, cookie cutter stamped structures that cost an arm and a leg. Don't even know if they have a basement....Seems Woodie that most people like the basement so the railroad is away from everything else in a secure place.

  12. billk

    billk Active Member

    How did we get off on this tangent? Anyway, basements are cool in the summertime and usually have some cheap "real estate" for RR'ing. I'm in mine now!
    Back to the original problem - does anyone know if using Liquid Nails or something similar to secure one or more layers (plywood to homasote or foam, for example, or roadbed to whatever's under it) would help. I'm thinking of the stuff they use to glue panelling onto studs. Anything made to glue materials of dissimilar expansion rates would have to provide some "give", wouldn't it?
  13. Woodie

    Woodie Active Member

    The probs with basements cold/hot/humidity etc must be a real problem for you guys. How much warping expansion/contraction do you get? Does it pull the rails away from the ties? It must get extraordinarily damp. What about mould? and all those grizzly things that go with damp conditons? My house is quite old (1870's) and has problems with rising damp in the walls, yet the layout is not affected. I've poured water all over it (plaster mix/ scenic material glue, water based glue for the roadbed) and still no probs with warping or expansion/contraction. Conditions in basements must get pretty severe!!!

    George, no real probs with extensions etc here. My municipality taxes are about $300 US per year. This covers roads (local), rubbish, libraries, sewer, street cleaning, parklands, aged services, (ie home help) drop-in centres, etc. That type of stuff. There are no other "household" taxes. (except lecky and phone bills!)

  14. George

    George Member

    Hello BillK!

    Plywood to Homasote - Simple - Full strength Elmers Carpenter glue, the yellow stuff. That's what most of the articles on it have said in the past. Liquid Nails would probably work out as well. Myself, I just screwed it down and have had absolutely no problem with it at all for three years now.

    Woodie, I'll e-mail you my taxes. Make sure you're sitting when you open it.

    The humidity here swings erratically from a delightful 64% to a wretched 100%. July and August in the NE is almost like a steaming jungle in New Guinea if it's hot, and eastern Canada gets like an oven sometimes with not quite the same high humidity. Mold spores are a problem, and I have heard of people having occasional trouble with mildew on scenery. The only solution is to run a dehumidifier, as these spores like to grow in the dark, and basements are great for trains and mushrooms! [​IMG]

    When I was a teenager, I spent several days stringing black thread on and around the insulators of Atlas telephone poles on a run of 30 feet. When I was finished, I was thrilled with the appearance. That was in the winter. Summer rolled around and the humidity made the thread sag almost to the roadway, and not drooping like wire, but erratic like a stock chart. Sooooo, instead of finding nylon or something else better suited to the task (as has been extensively covered in another thread here) I re-strung the thread and in the winter dryness, some of the poles were pulled to a 30 degree angle. I gave up that folly. [​IMG]

  15. billk

    billk Active Member

    George - I would bet that the problem probably isn't due to just how humid it gets, but what the overall difference between the maximum and minimum. I know several people (not MRRs) around here (eastern IA)that use humidifiers in the winter time because with forced-air heating everything just dries up.
    The 36% humidity swing you have might not be all that extreme.

    Also, temperature changes and how long the various conditions last would probably effect the level of moisture in the wood or whatever.

    My suggestion re Liquid Nails was to use something that would absorb the expansions/contractions in one layer without passing it along to the next. How about rubber cement?

  16. kf4jqd

    kf4jqd Active Member

    Hello All:

    I started to lay my track late last summer into early fall. Didn't have that problem. And the basement here is very humid! However, keep your locomotives out of it. Humidity will corrode the electrical contacts. I have the locos that I don't use much on display in my bedroom.

  17. yellowlynn

    yellowlynn Member

    I've just found this board today so I may as well jump in with both feet. I don't know how long ago it was that you were a teenager, but if you wnt electric lines, there's a way without humidity screwing things up. Use a tiny elastic thread with just a touch of stretch and even humidity shouldn't make them sag. Luck

  18. George

    George Member

    Greetings Lynn, and Welcome Aboard!

    We hashed out the thread/expansion isue in a thread about telegraph lines and seemed to agree on an acrylic thread that is not affected by the swing in humidity, but your idea is worth looking into if it provides a more realistic "line sag" than the acrylic thread.

    Billk, moisture doesn't affect Homasote to any noticable extent, at least from what I've seen. Surprisingly, you can even have a water spill and it will dry without a trace. Rubber cement could be an interesting buffer, but imagine the quantity you'd need for the job. You'd probably have to leave the windows open over night as well. [​IMG]


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