Celotex is the high density insulation foam, I think, which you can buy from B&Q, Wickes, and the like, in sheets of 8 x 4 foot and in thicknesses between one and several inches. It generally has a silver foil type paper on both sides.
I've looked at the 2 inch variety and found it to be very strong, which for a rectangular baseboard of say 6 x 3 foot seems to be ideal as it is also very lightweight.
Any of you out there with any experience of this and what might be the pros and cons of having a baseboard made of this?

I'm using it, my previous layout used the plain white 2" foam  which worked OK, but when I started this one Wickes were out of stock of it so I got Celotex instead, makes less mess when cut, otherwise most considerations are about equal.

I covered with cork flooring tiles, they hold track pins better and as I use wire in tube for point controls it's easy to cut a channel for the tube.

I also found that Celotex being easy to cut it is easy to make incline supports, you can even contour the sides for embankments or cuttings.

I used the smaller pieces 4'x2', easier to transport than an 8x4 sheet, see my post #31 #32 on this page -

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=26311.30

Quote from: Only Me on November 18, 2015, 12:41:23 PM
.... wont it flex a bit ?

My thoughts exactly, and doesn't it 'snap' if over stressed?

Quote from: Dorsetmike on November 18, 2015, 01:24:47 PM
I'm using it

Unsupported?

I have used similar foam in the past and edged it with a timber frame the layout stayed flat and intact for a couple of years until I stripped it down to start a new project.

The 2 inch one is very strong indeed, and yes it may flex a bit but only in the middle !
If you were interested then go to a B&Q Warehouse shop, not a smaller branch shop cos they don't have it on the shelf,  and give it a good bending. You may find that 2 inches upwards you can barely move it. The smaller the baseboard you are going to make then the stronger and more solid it feels.
I don't think it would snap, unless you jumped on it a few times.
I like the idea of the cork sheets for pinning things down.
I'd also be tempted not to strengthen it with battens but each to his own on that.

Mine sits on some kitchen units (cupboard and drawer space) on top of those is a frame of 38x25mm supporting 3mm fibre board on which is the Celotex.

I tend to lean on it to reach the back, negligible flexing. It's a 2 level layout, a roundy roundy on the bottom, with an incline up to the top level which has a terminus, yard, MPD and carriage sidings.  The top level is also 2" Celotex, so much of it is on 4" of Celotex, A fiddle yard is off to one side of the lower level.

The whole layout is inclined at about 1:115 which means the incline from low level to the top can also be about 1:115, so even the Dapol M7s should be able to haul coaches up that.

Most of its strength is in the foil covering, remove that and it becomes very brittle and easy to break, even small lumps can be snapped.

If it's a fixed layout I can't see a reason not to use it, but for a mobile layout I think it would need some form of protection from knocks.

Don't peel off the silver film - the foam will instantly warp! 

Quote from: Simon D. on November 18, 2015, 08:40:58 PM
Don't peel off the silver film - the foam will instantly warp! 

you dont say 

If you can still get the Cellotex /Kingspan without the foil it can work really well with a ply surround
The foil backed stuff will work but needs to be treat more carefully....Ie dont just rip the foil off in one go... or take care when using it as a sub surface to attach the ply trackbed to, etc

Don't US modellers routinely use high density foam boards as baseboards? Of course they have a wider selection of products readily available, without the foil covering.

As  a modeller in Aus, all I use is a foam board. Stuff called foamular, which is available in UK. Last time I used 1" sheets, but glued them together. That is then absolutely rigid enough for a layout 6'x3' without any support, but I do use a 1"x1" brace round the edges and with 2 crossbars just to give that bit of insurance!
Personally love the stuff and could rant on about it all day!! BTW, no connections to them, just a big fan.
Some of the benefits:
Offcuts can be used to make hills and mountains
easily carved and gouged to make ditches, dykes, creeks,  hollows in the ground and all sorts of other dips and creases.
lightweight and easily moved by one person
easy to stick "stuff" to, including track and buildings
a quick coat of cheap paint ( I normally use a pale brown to emulate local earth) sets the base nicely for scenery etc.
very easy to drill holes in for lighting, wiring etc.
easy to drill holes for positioning all sorts of things like signals, telegraph poles, fencing lines and all the other things that we insert in the name of realism
Only rider I would add is that you do need to predetermine where you are going to place under board motors, as you need to drop a bit of ply or similar between the sheets so you have a place to screw the mounts to. You can always chop out a larger square completely and then put some ply on the surface, but pre-planning saves that hassle.
As you may have gathered, love the stuff.
George Bealman will be on my back soon for raving too much 
cheers, Bill.

Quote from: ozzie Bill. on November 19, 2015, 06:34:27 AM
just a big fan.

I'd never have guessed................

Extruded polystyrene is readily available here in France, 1.25m x 0.6m sheet 20mm thick costs about £1.50. Thicknesses go up in 10mm to 50mm and this costs about £4. Using this material as my baseboard supported on Ikea Gorm shelving, sadly no longer available, the replacement doesn't have the 90° corners.

I'm using Celotex but over a battened ply base.

The 50mm version allowed me to carve out a deep river and (plan) to use WiT point control that can be buried into the foam. Building hills and tunnels is easy with Celotex.

The edges will need finishing off with ply as left as is it will be prone to damage.

I'd worry about using the wider board(s) without any additional support. It certainly does warp if you remove the foil.

Dave G