# Architectural foam products



## Mike Reilley (Jan 2, 2008)

I'm having my home stucco'd and it includes installing trim around the windows and doors that is stucco'd over. I was watching the contractor install the trim pieces today and was surprised how rigid these pieces are. Has anyone thought of using architectural foam for roadbed? I think I'm gonna give it a try in some yard areas where the track is level. Here's my idea.


The material being installed on my house is 1 pound density polystyrene foam cut into 2" x 4"s that are 8' long. Before the foam is put on the house, the foam is covered with fiberglass backer-board mesh tape (joint tape for concrete backerboard/wonderboard that is used behind tile installations) and then that is slathered with thin set. When the thin set dries, what results is a markedly stiffer 2x4 that is impervious to weather and insects. 


This stuff is cheap too. An 8' length of the 1 pound variety is $2.25. If you desire even stiffer boards, 2 pound foam 2x4s is also sold for $4.10 for 8'. The mesh tape is around $4 for 50' at HD. A 50 lb bag of thin set is another $8 which outta do 100s of feet of roadbed. This would be cheap roadbed by any standard...I'm figuring around 40 cents a foot (my current ladder roadbed is over $1 a foot.) My contractor bought the fiberglass mesh in a 1' wide roll that he attached to the foam with a spray on adhesive (one that doesn't attack foam)....he just wrapped the mesh around the 2x4 shape before he put the thin set on it.


I think curves are easy to fabricate from the foam...you just make cuts in the foam to ease it around the curves...then apply the tape on the top and sides and slather it with thin set. You can nail the foam onto wooden stakes in the ground to hold the foam in the right curve shape...and after the three sides are coated and dry, pull it up, tape the bottom, and slather it with more thin set...encapsulating the foam completely on four sides. As you place the shapes end to end, you can tape apply thin set to the ends to "glue" then together. What you have is a pretty rigid curved "board" on which one can place track. Once all four sides are covered with thin set, you'd just put it back in place and nail/glue it down to the posts below...or just dig it into the ground.


Thoughts? Pros/Cons?


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## vsmith (Jan 2, 2008)

Dont step on it. Its not THAT rigid. Just make sure you have good solid support under it. ;-)


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## Rod Fearnley (Jan 2, 2008)

Mike if it is the same stuff that we have over here? We call it beading. It is plastic with a hard foam center(?) The costings that you quote for a strip equate to what I pay. I made ladder for my track where I needed to hold track to a particular radius. It works well.


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## Dwight Ennis (Jan 2, 2008)

Foam is used extensively in the smaller scales -especially for modules where weight is a factor. Many build a box frame of 1x4's and attach a thin layer of birch plywood to the underside, then use 2" foam as the main support for both track and buildings/scenery. Not sure if it's been tried on an outdoor layout.


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## jake3404 (Dec 3, 2010)

I would have to agree with Vic on the foam. It can not be stepped on at all. The thinset and mesh will not make the stuff strong enough that you can stand on it. The foam would break under your weight. However, with that in mind I think you could use it in a limited capacity. As long as there will be no standing on it. 

This gets me thinking. My MR club used foam on our large HO layout. It works great for that, but we aren't standing on the roadbed at all. But, i need to build a storage area and been thinking about how I was going to do it. The foam idea might be the way to go. I'm definately not going to be standing on it and the foam has much better insulating characteristics than plywood and CHEAPER!!!


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## Mike Reilley (Jan 2, 2008)

Posted By Rod Fearnley on 24 Oct 2011 04:19 PM 
Mike if it is the same stuff that we have over here? We call it beading. It is plastic with a hard foam center(?) The costings that you quote for a strip equate to what I pay. I made ladder for my track where I needed to hold track to a particular radius. It works well. 
Don't know what it's called over there Rod...here it's called architectural foam shapes. The one pound density stuff has is soft foam...without any hard foam center. The two pound density is allegedly stronger, but I haven't seen it. Here's what one of the 2x4s looks like taped and coated. The one pound stuff, even coated, is not rigid but looks appropriate for putting on the ground. The stakes I mentioned above were just to hold it in place laterally. I don't see using this stuff if it's elevated off the ground...even like ladder roadbed...unless there was structure below it which would defeat the low cost approach.


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## vsmith (Jan 2, 2008)

Mike if that stuff is like the Blue Foam I use indoors I should warn you that using screws to hold the track down will pull out with extreme ease, you might need to glue a plywood strip under it and use screws long enough to bite into the ply to hold the track in place. Have you tried any experiments yet with how to secure the track?


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## Mike Reilley (Jan 2, 2008)

Not yet Vic....gonna try it in the yards.


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## JPCaputo (Jul 26, 2009)

For the price, it would be cheaper to get a 4x8 sheet and rip it on a table saw...


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## Ron Hill (Sep 25, 2008)

Mike, is this stuff polystyrene foam and who makes it? Dow Chemcial makes the blue board available in thicknesses from 1/4" to 4". Ownes Corning makes the pink board and Green Guard makes the green board. 
Ron


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## Mike Reilley (Jan 2, 2008)

This is cheap, polystyrene foam...the kind they make cheap coolers out of. BUT...you can buy this architectural foam in several densities. The stuff on my house is the cheapest kind. 

Now...I had to affix a pool controller to this foam...through the stucco coating. It makes for a VERY CRAPPY affixin'. It holds...but only because the stucco is 1/8" thick. 

This is NOT looking like a good idea for roadbed unless you plan to float the track on top. It certainly makes for a firm footing though....but any foam could be used IMHO. 

As I said in the beginning...I was wondering if anyone had tried to use this stuff for roadbed since it's impervious to the elements once you've covered it with stucco. It's waterproof...bug proof...rot proof...cheap...fast to install...easily bendable (with saw curfs) around curves...etc. Once track is on top of it, I would NOT think it would compress much if you stepped on it...but I haven't tried that yet.


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