Trackwork Underlay

[GNRi1959]

I have always turned my nose up at foam underlay of any description but I have observed it being used on many layouts here and it doesn't look too bad. Is it really intended to be an alternative to ballast?

[Noel]

17 minutes ago, GNRi1959 said:

I have always turned my nose up at foam underlay of any description but I have observed it being used on many layouts here and it doesn't look too bad. Is it really intended to be an alternative to ballast?

It was very much the in thing 20-30 years ago, and I used it when I originally built our layout, but always with the long term intention of re-ballasting once the track plan was locked down.  Foam underlay allowed me the ability to tweak the track work in the early years (i.e. very easy to move or relay sections).  It's not until you start operating a layout and particularly shunting stock you realise if a track work tweak is needed or not.  Some folk use foam underlay and ballast around it and a few speckles over it.

Believe it or not this section below is actually Peco foam underlay with woodland scenics ballast added to make it blend in.  If I was starting to again I would either lay cork or dense 3mm foam as a flat base under the track and then wet/pva mix ballast the track. Using a glue such as copydex to fix the cork or 3mm foam to the baseboard minimises the noise transfer.  Peco foam underlay main advantage is its almost total elimination of noise transfer to the baseboard but at the cost of looks unless you ballast up to it like below.

[PaulC]

I think some use foam underlay as an alternative to ballasting. Others use it as a method of dampening the noise of trains running over the boards whilst it can also be used to create a realistic shoulder for the ballast. Foam underlay does have a tendency to deteriorate over time resulting in many using cork underlay instead to counter this. 

I, personally, can't be bothered with the faff or cost of either, preferring to just lay the track direct to the baseboard. The sound deadening of cork or foam is not a foolproof solution as the construction of most boards means noise still resonates in the voids beneath and if ballasting this also acts as a conduit for the sound to reverberate. 

Paul

[GNRi1959]

Good point Paul, i'd imagine the foam would perish. Might just paint the birch ply grey before I start laying track.

Edited February 6, 2018 by GNRi1959

[Dave]

Most of the layouts that I build the track goes straight onto the baseboard.  Most people don't mind the noise. They method of construction of my boards help reduce noise over ply and softwood boards.

A trick if the noise is too much is to glue blocks of 18mm MDF to the underside of the layout. They absorb the sound really well.

I use PU foam over cork and I stay away from the Peco open cell foam as it can degrade over time. The PU foam (closed cell) is good and for clients that want a quiet layout I cover the whole baseboard in it. Then glue the track onto it then ballast, this way there is an insulating layer between the baseboard and the track. However the ballast becoming one hard piece will be noisy. 

[GNRi1959]

Dave, thank you for a bit of advice from the 'man of experience' - cheers.

[David Holman]

Ballasting is undoubtedly a pain, but a necessary evil that just has to be done. Agree re underlay, the sound deadening effect is minimal. Hence for station boards not worth it, but on mainline sections where there is a 'cess' beside the track, underlay lifts the rails enough to create this.