Underlay, what's your poison ?

Discussion in 'Permanent Way' started by 3 LINK, 26 January 2015.

  1. Scale7JB

    Scale7JB Western Thunderer

    Hi Martyn, think we've chatted about the underlay in the past, and some of the nightmares we've had on crosscombe magna...

    Chatting with Susie recently though we came up with a reasonable compromise. The problems we were having was that the foam was causing differences of rail heights at board joins which in S7 can cause running issues.

    We thought though about using foam as normal under the sleepers, but perhaps using 2 or 3 inches of matching height mdf in place of the foam at board joins to give a nice firm base that won't move anywhere near as much.

    Not something we've tried but on paper it might be the answer...

  2. PMP

    PMP Western Thunderer

    I'm quite keen on the Woodland scenics foam underlay at the moment. I've only used it in 4mm scale, and my guess is in a larger scale it could be pretty expensive quickly. On the plus side it is easy to work and sticks down well with no more nails types of glue and accepts acrylic paint and superglue with no notable degradation so far in the 18 months or so since laying. I glued the plastic sleepered track down with lo-viscous superglue and for sound decoupling it works a treat. There my blog post here for a bit more info,

  3. 3 LINK

    3 LINK Western Thunderer

    Hi JB,

    When you say the difference in rail heights, was it the weight of the locos passing over the joins that was pressing the foam down causing the problem ? So I suppose you had no choice but to use something solid to keep the rails aligned, thanks for the heads up as I will be starting the track laying within the next two week hopefully.

    Hi PMP,

    I have not heard of using super glue to fix the track to the underlay before, I will be using timber sleepers but I am sure the adhesive properties would not be affected in any way. I will be buying the closed cell foam in a large roll from a firm in Birmingham which a friend recommended .

  4. PMP

    PMP Western Thunderer

    Hi Martyn,
    I hadn't heard of using Superglue either until I tried it! Seemed a good idea at the time and I'll be using the technique again.

    On my shelfie I was using C&L Flex track which helped as it has a plastic base. Your wooden sleepers may be porous which may give an advantage in that it'll be a light strength fixing to start. I just used small amounts on the end of a few sleepers to start until the formation was in place. I then went back and ran it along the edges, with it being lo-viscosity it bled under the edges using capillary action. I then dropped some accellerator onto it which 'flashed' along the joint setting it immediately. You can see that 'flash' on the white staining on the blog picture.
  5. ceejaydee

    ceejaydee Western Thunderer

    I am not a necromancer but before starting a new thread seeking experiences about different types of cork and underlay and copydex as an alternative ballast fixative I carried out a search and came up with this useful information.

    From reading the replies it would seem that if you don't worry about a ballast shoulder or sound-deadening then using cork or any other type of underlay is unnecessary?

    I have been reading Railway Modelling - The Realistic Way bu Iain Rice and he advocates the use of school pva glue for ballasting as it does not set like concrete where wood-glue containing resin-W does.

    I'm now pondering track laid straight onto the board with ballast fixed with school glue.
  6. westernfan

    westernfan Western Thunderer

    Hi Ceejaydee. On my last two layouts I used pva watered down to a milky liquid to glue the ballast to the board it takes 24/36 hours to set before sucking up the excess . I needed to relay some of the ballasted track but by just wetting the ballast and leaving it for 5 the track was easy to rework .

    ceejaydee likes this.
  7. Lancastrian

    Lancastrian Western Thunderer

  8. 3 LINK

    3 LINK Western Thunderer

    Hi Ian,

    That product is exactly what I am using, it is easy to cut and use although I cannot comment on the sound deadning qualities at present as the track work is not ballasted. But I would think that any noise reduction will be cancelled out due to the bonding of the ballast to the surface of the baseboards once the glue solidifies.

    So I'm afraid it's either install sound in the locos or have radio 2 on in the back ground :thumbs:.

  9. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    Interesting conundrums.

    I build my baseboards from 6mm ply as I want to make them as light as possible. However this turns them in to effectively 'open backed' guitars and resonate.

    For what it's worth my approach to sound deadening is:
    - Stick the foam roadbed to the baseboard with Copydex (I used left over laminate floor underlay).
    - I cover the foam roadbed with brown wrapping paper stuck at the edges leaving it free float over the foam (this also gives me the shouldered roadbed profile).
    - Track is laid on Copydex. Once in place I sprinkle the first layer of ballast then weight the track until the glue has set.
    - Once set I then ballast the track with using dilute PVA.

    The diagram below is a better explanation and one idea I haven't explored yet is the application of a sound deadening material on the underside of the baseboard.

    DI track.jpg
    3 LINK likes this.
  10. mickoo

    mickoo Western Thunderer

    Dave, likewise I've considered sound deadening under the baseboard as this is where the sound is resonating from, traditional baseboard construction is effectively a drum with no bottom.

    For brown paper I was simply going to leave the Templot template in place with an appropriate edge, pretty much along the lines you've shown, of course, I need a trainset first to try all of this out :rolleyes:

    3 LINK likes this.
  11. Ei-Turkey

    Ei-Turkey Member

    Being partly deaf, the noise really doesn't bother me, same reason as I have zero interest in loco sound, but even in flat earth situations I do raise the track either on 5 mm closed cell, or 2 layers of expanded polystyrene, cause I want a regular datum for my track, but I think it's best to raise the track as it gives more flexibility modeling the ground, as it's very hard to find somewhere truly flat and it's better to give yourself some leeway in this respect.
    3 LINK likes this.
  12. Lancastrian

    Lancastrian Western Thunderer

    We've used spray on carpet adhesive to glue templates to the EPDM underlay, and unfortunately due to moisture from watered down Copydex, they have all come loose. In fact, virtually all of the first ballast glued down on the SR7mm Group layout has dried out and will need remedial work to put it right. Later ballasting of a terminus station with diluted latex glue has worked fine, but I am now ballasting with good old PVA again.


    Also, I moved to gluing templates down with UHU or Evo-stik, and then doing the same with sleepers and flexi-track.

    Last edited: 2 February 2017
    AJC, BrushType4, 3 LINK and 1 other person like this.
  13. LarryG

    LarryG Western Thunderer

    I discovered by accident that quieter track was on the section of layout that was open plan and an embankment was solid 1" thick timber rather than ½" plywood. It is what I am going with on the latest layout. The solid wood curved trackbed (1" thick) will be screwed down on a camber through the station so it makes super-elevation dead simple. The usual 1/8" cork underlay will also be used of course. Doubling the underlay leads to even quieter running. For glue & ballasting, I stick with neat PVA regardless. Each to their own.
    Last edited: 6 April 2019
  14. Focalplane

    Focalplane Western Thunderer

    Penmaenpool uses the following procedure. First of all it uses open frame or L Girder construction with few “sounding boards” except where buildings will be placed. I use 6mm marine grade ply on uprights spaced no more than 40cm apart, cut to the shape of the track design. On this I glue with exterior grade wood glue a footing of 3mm cork, bought from a company in Walsall (Charles Cantrill) who do an excellent service. The cork should be stored flat before use. Once the cork is in place I lay the track using Copydex, weighted down until set. No pins or screws between track and plywood. If an error is made the track can easily be lifted and 95% of it is reusable.

    The sound levels are reasonably low, actually quite good as the room itself has acoustic tiles, etc., having been a home cinema in a previous life. There is little drumming and the sound fitted locos come across as they should, sometimes working hard, mostly coasting.

    I hope this helps, Paul
    BrushType4, Peter Cross and simond like this.
  15. Peter Cross

    Peter Cross Western Thunderer

    Is 6mm ply going to support itself over 400mm. I would want a vertical ply under it. Or you will end up with dips and ridges.
    Phil O likes this.
  16. Focalplane

    Focalplane Western Thunderer

    OOPS! Sorry - I meant 10mm thick ply. Even then there are times when a support is needed underneath, usually to assist a degree of super elevation on curves.

    Last edited: 28 April 2019
  17. Phil O

    Phil O Western Thunderer

    I have used 6mm ply and even 4mm ply for track beds and have always used 25mm verticals after noticing a dip starting, as far as possible under the centre line or two one down each side for double or more tracks.
  18. borgrail

    borgrail Member

    The stuff that C&L sell (sold) and Woodland Scenics for that matter is I believe
    Closed cell polyethylene sheet EFP30 - I have purchased it from EFoam in the past still listed 3mm and 5mm thickness with or without self-adhesive backing.
  19. paulc

    paulc Western Thunderer

    Hi Jim , what do you use to dilute it with ? I have a problem with my sleepers which are mdf and have been down for years and are now as dry as #$^:%#@ Anything diluted with water is instant death to them as they absorb it and swell up . I am going to try floor polish and see if this affects the mdf . Sorry if i hijacked your thread Martyn .
  20. JimG

    JimG Western Thunderer


    I'm afraid that it was water used to dilute it so your sleepers might suffer. I'm not sure if dilution with any other chemical might work - like IPA - since that might introduce other problems as yet unknown.

    I can sympathise with track material swelling. I ballasted my switching layout with ballast which I had had lying around for years and I used diluted Copydex to hold it down. The carefully levelled ballast swelled overnight after the application and the track was unuseable and required a lot of digging out and clearing to restore it to a working layout. I assume the ballast was a dried organic material of some sort (bark?).