I have started an expansion of my layout and was planning on using 2" and in some areas 1" thick foam insulation board, the kind you buy in Home Depot or Lowes. After reading comments in the foam core discussion thread I have some concerns about expansion and/or contraction. Should I be concerned?
Hello all,
On my pike I used two 1"x2’x8’ pieces of blue foam as the base. These are tongue and groove on the 8’ side.
I used carpenters glue along the tongue and groove to mate them.
The foam is attached to 1/4-inch sub-roadbed with wood screws and finishing washers.
The inclines are Woodland Scenic Incline/Decline sets (3%) and the elevated areas are 1/2-inch extruded foam layered with carpenters glue to achieve the desired forms.
I then attached the foam roadbed to the foam bases with silicone caulk.
Next I painted the entire layout with latex paint just up to the edges of the roadbed.
I harvest my own ballast from local sources. This is mixed with powdered Plastic Resin Glue.
When the ballast is smooth, and to my liking, I spray it with isopropyl alcohol and a few drops of India ink to set it.
As I posted in another thread, I live in an extremely dry environment; 20% to 30% humidity all year.
I have not noticed any perceptible shrinkage from the foam in the three years this pike has been in existence.
Hope this helps.
Yes.
Ed
Here’s the data sheet at the Owens Corning web site:
http://insulation.owenscorning.com/assets/0/428/429/431/0538f0de-3893-4e8a-a0c0-5de11b913061.pdf
For dimensional stability they say the maximum linear change is 2.0%. That’s pretty scary… although I’ve never heard a model railroader report that much.
WHat they don’t say is what the conditions are for maximum change - heat? Humidity? Combo? Under the maximum pressure of 150PSI?
There are some people using it in VERY hot climates with no problems. I’ve used it on two layouts now with no problem, and one of those was in a basement with very variable humidity throughout the year.
There is NO reason to be concerned with using foam. ANd you say long term? If it was a long term problem, Bill Darnaby’s entire layout would have come crashing down already. He even has less support structure than many put under the foam. I believe his first foam board article appeared in MR back in 1995.
–Randy
There you have it, folks:
Be concerned!
Don’t be concerned!
Yikes!!
Ed
Since the appalling tragedy of the Grenfell Tower fire in London, there has been much in the UK press about combustibility of materials used in such rennovations. Today I read a piece about certain foam insulation board that was used behind the rainscreen cladding and, when ignited, emitted hydrogen cyanide gas.
So, perhaps we should urge caution and apply large doses of common sense when choosing materials for our projects - it is all to easy, it seems, for a seemingly innocuous material to become a source of deadly fumes in the wrong circumstances.
I am not an expert and I am sure that there are several types of “foam insulation board”, and that not all of them may be hazardous. So please check first.
It not the quietest or safest material out there. The MSDS shows the hazards. Best to check
i had a large problem occur with pink two inch years ago. The edges curled under a six inch width on both sides just rolled under pulling the rest up off the benchwork. Had to start over I dont use foam all the much Since then i have seen curled edges on foam a lotout on theconstruction sites i have been on . Not sure if it becacuse it is not cured right at the plant or something in shipping
shane
I also am no expert, but this is consistent with the advice about not using hot wire cutters on this foam.
Thankfully these threads don’t come up nearly as often as “the hobby is dying” or “what is the best DCC system” but we have been through all this before.
There used to be a video on YouTube of someone debunking the fire dangers of the pink extruded foam - basically with ost cobustion sources like a hot soldering iron or even a lit candle, the foam melts a hole around the heat source until the edes are far enough fromt he heat source as to be below the meltign temperature. It took them considerably effort to actually ge tthe foam to catch fire, and it quickly extinguished itself.
The kid of foam I was always aware of as giving of hydrogen cyanide was the stuff foam coffee cups (the white ones) are made out of. This was way before extruded foam insualtion was available that I heard this, and still cringe any time someone throws one in a fire or burn barrel. There are other white expanded foams that don’t, or else a hot wire selas it instantly - Woodland Scenics forms and risers and so forth they specifically sell a hot wire cutter for. There was also a vendor selling hot wire cutters who would always set up at the Timonium train show and would demonstrate carving with it in various foams, included the pink extruded stuff. No fumes. Less, actually, then you get by scoring and smapping it.
No granted, if your house is buring around the layout, the foam will likely burn as well, it’s not fire proof. But there are plenty of other plastic type materials inthe layout, not to mention objects in the home plus construction materials in the walls, floors, and ceilings. If you’re in there breathing that stuff in, foam or not foam on the train layout isn’t going to make a difference. Plastic or wood structure kits on the layout aren’t going to make a difference. Acrylic vs solvent paints aren’t going to make a difference.
&nb
[quote user=“rrinker”]
Thankfully these threads don’t come up nearly as often as “the hobby is dying” or “what is the best DCC system” but we have been through all this before.
There used to be a video on YouTube of someone debunking the fire dangers of the pink extruded foam - basically with ost cobustion sources like a hot soldering iron or even a lit candle, the foam melts a hole around the heat source until the edes are far enough fromt he heat source as to be below the meltign temperature. It took them considerably effort to actually ge tthe foam to catch fire, and it quickly extinguished itself.
The kid of foam I was always aware of as giving of hydrogen cyanide was the stuff foam coffee cups (the white ones) are made out of. This was way before extruded foam insualtion was available that I heard this, and still cringe any time someone throws one in a fire or burn barrel. There are other white expanded foams that don’t, or else a hot wire selas it instantly - Woodland Scenics forms and risers and so forth they specifically sell a hot wire cutter for. There was also a vendor selling hot wire cutters who would always set up at the Timonium train show and would demonstrate carving with it in various foams, included the pink extruded stuff. No fumes. Less, actually, then you get by scoring and smapping it.
No granted, if your house is buring around the layout, the foam will likely burn as well, it’s not fire proof. But there are plenty of other plastic type materials inthe layout, not to mention objects in the home plus construction materials in the walls, floors, and ceilings. If you’re in there breathing that stuff in, foam or not foam on the train layout isn’t going to make a difference. Plastic or wood structure kits on the layout aren’t going to make a difference. Acrylic vs solvent paints aren’t going to make a difference.
&nbs
That was a sincere not a sarcastic post. 2 inch Owens Corning pink insulation foam board is widely used in Minnesota on the exterior framing of homes before siding goes on. It is rated don’t quote me from 50 below zero wind chill factor to 100 degrees plus humidity. It is a very good product. It’s called closed-cell for reason. It does not absorb moisture. It has a less expansion and contraction ratio than open grain wood by far. Nobody’s siding is buckling up here because of this Superior foam insulation product.
I’m quite sure it would burn just like anything else.
Ten years ago I looked for 2" foam and had to settle for doubling up 1" foam. I glued them to the plywood and to each other with latex caulk. I ran a bead around the perimeters and diagonal beads from corner to corner.
After 10 years there has been no shrinking or expanding. As for them being a fire hazard a dropped hot soldering iron produced a cave like opening. It all happened so fast I only remember a slight odor.
IMO you can’t beat foam for your layout top.
Bob
Sounds like your stuff might have been aged 6 months before you used it. Or so. Or perhaps your foam came out of the good end of the batch.
I do notice that, while the manufacturer said the product might shrink 2%, they did not mention a time span. Considering they are BIG, and all that, I find it odd that they acknowlege a shrinkage problem, but also neglect to share data.
Ed
Clearly the dangerous off-gassing from the foam has caused you to suffer permanent memory loss. [:)]
But seriously, I believe the fire related argument is based more on the gasses released by the foam when it burns rather than the fact that it is flammable.
One of my favorites is the “exploding fan in the paint spray booth”.
Robert
You know what else emits hydrogen cyanide when it burns? Wool. Cotton. Silk. Nylon. Leather. Pretty much everything.
Your mattress and carpet are bigger sources of it than your layout foam.
Glad to hear my memory loss is connected with model railroading. I thought it was because I’m 88.
We all know that metal expands and contracts due to temperature changes and memebers have reported their track buckeling. There is no question about this.
But I have yet to hear a complaint about pink or blue foam shrinking. No doubt it may and or does when used for the purpose and in the environment it was intended. On a layout in a controlled environment with track and paint IMO it is very stable.
A 2% shrinkage on my layout would equal 3.36" X .96" and I think I would have seen some evidence of that.
Has anyone actually experienced any shrinkage and if so what were the results??
Bob
My layout is in the basement, humidity and temps do change a little with the seasons, and has been up and running since 2010, and no problems.
Mike.
Re extruded foam board shrinkage: I have seen it on some 2ft x 4ft modules that were foam within a wood frame. In some cases, the shrinking foam caused the glue joint to break. In other cases, where a very strong glue was used (Gorilla is among them), the foam split or the wood frame was bowed.
Most modules do not experience the shrinkage. As near as anybody can tell, the shrinkage from off-gassing is highest immediately after manufacture. Six plus months after manufacture, most of the shrinkage has already taken place.
FWIW, in the cases I personally observed, some of the pink foam modules had shrinkage issues, but only one of the blue foam ones did (a 4ft x 4ft blue foam in frame Christmas layout I had built had the frame bowed). My explanation is that in my neck of the woods, Home Depot carries the pink foam, and Lowe’s carries the blue. Home Depot has a much faster turnover of foam board than Lowe’s, and hence the foam board would be newer.
Based on what I have observed, the 2% is a maximum figure. What I have observed is in the 1% range or less - enough to pull the glue joint apart but not much more.
Based on a lot more than the shrinkage issue, I have gone away from extruded foam use for my modules and layouts. I am currently using 5mm plywood frame construction with 3/4" plywood end plates - very similar to what the Sipping & Switching Society uses. I use open top grid with 3/4" plywood subroadbed that runs from end plate to end plate. Scenery shell is to be Bragdon foam on screen wire for very light weight.
And I am experimenting with foam core construction of a module (will not be Free-mo).
Fred W