ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Online since 2002, it's one of the oldest and largest model railroad forums on the web. Whether you're a master model railroader or just getting started, you'll find something of interest here.
I'm approaching the point of attaching 2" extruded foam to the drywall. The foam shelves are 8" wide and just glueing them to the wall should provide the strength needed to support double track operations.
I will be putting up about 6 scale miles of foam, so the glue is going to be a cost factor. A tube of foam freindly construction caulk/glue is about 3-4 bucks. Epoxy cement is kinda pricy too as well as Gorilla glue.
Is there a less expensive adhesive available that is foam friendly?
I was convinced by Randy Rinker over on modelrailroader.com to use the cheapest acrylic latex caulking you can find, even stuff discarded in a dumpster. Two layouts later I am not in a position to disagree with him.
You can get stuff that goes on whitish and dries clear, grey coloured stuff, white, brown.....the trick is to spread a wavy thin bead and then spread it thin with a trowel or spatula. Also, use stacks of magaxines here and there to ensure the surfaces meet and cure closely pressed.
Use the same caulking for your roadbed, whether cork or foam, and also for your tracks adhering to the roadbed.
It's really the way to go.
To cap the nib on the tube over night, I just jammed a chunk of discarded foam onto he nib...it worked very well.
Have you actually used this on foam for support of the shelf? People that I know who have tried to use the Elmer's glue, say it doesn't setup because it needs air to dry it out. The foam blocks the air flow to the Elmer's glue and leaves it in a liquid state for months and with that, dimishes the support needed for the shelves.
Now, I not just asking for a listing of all glues in the hardware store. Petroleum based glues will eat the foam away. Tacky glue is ok for assembling non-load bearing items but I'm not going to risk putting a $1,000 dollars worth of trains on something that is at the threshold of coming loose and dumping it all on the floor.
I would like to know from those who have first hand knowledge of what works with the extruded foam.
Just to reiterate what I am asking.
I am using 2" thick extruded blue foam that is cut 8" wide. I intend to mount this to the wall as a shelf layout for most of the running length. The part that I will be applying the glue to is the 2" edge of the shelf so that it will stay stuck to the wall when trains are on the double track that I will be laying on it.
The glues that I have found so far are rather expensive for the amount that I will need for this application.
Ok wait ...you want to glue the foam to the wall and then add track to it for your layout??? If so, I would not recomend that as you say you may have $1000 of trains on top of it. I advise some sort of framework tied into the studs every 16" or every other stud. this is just my view as I would not trust the glue or the foam to hold if it was under any stress.
Gosh, your new information changes everything. I had understood that you were wanting to adhere the foam to some wooden or other material joists on a framework of some kind.
You won't find a glue that will provide the security you need, except for perhaps epoxy or Gorilla Glue, and even then I wouldn't think of using them alone...well, I would if I didn't mind the heeby jeebies one gets thinking someone has just walked on their future gravesite.
Seriously, the glues I mention would be very good, but you would also want some brackets very 20" or so for good measure and engineering practise, and the insurance against damage to your valuable models would cost only what it would take to afix two or three such brackets in place every 8' or so.
The glues can be had, although I appreciate that cost is a factor for you. However, it would be their purchase on the wall surface that would worry me. I don't trust gyproc...it's too friable. I trust those coarse threaded white plastic wall anchors much more.
Ok wait ...you want to glue the foam to the wall and then add track to it for your layout??? If so, I would not recomend that as you say you may have $1000 of trains on top of it. I advise some sort of framework tied into the studs every 16" or every other stud. this is just my view as I would not trust the glue or the foam to hold if it was under any stress.
As Trent advises, you need a strong mechanical bond for support. An adhesive will be subject to cantalever forces under load from vibrations varying from foot steps to thunderstorms. Are you expecting a latex painted surface between the foam and drywall paper to to withstand long-term stresses?
Build simple wooden angle braces or the pressed metal "L" brackets to support the investment in time and money you expect to display.
Actually, I am planning to put 3" wide strips of 3/8" playwood on the drywall for two purposes. 1) to provide additional screw anchor to support the drywall as it is not standing on the floor, and 2) as a clean wood glue point for the foam.
Ken,If you going to screw plywood to the wall you might as well just make the proper brackets to support the layout and be done with it. Sure the foam will stick to the wall and plywood like steel with the right glue, but... the foam will just snap off just behind the glue joint the first time you rest your arm on the layout or use it as a hand support.
again just my .02
I just see problems coming with that design.
The point of useing self supporting foam was to make a clean layout without brackets and 2X4s all over the place. Somehow, I got the impression from other posts here that a 9" wide foam shelf was strong enough to support itself with the edge glued to the wall. Now I'm wondering if that was just opinion or from real experience. I thought I laid out my plan pretty well to gather information from those who had been there and done it.
anything can be done but I just dont see how safe it will be for you. I would hate to see you build a nice layout and then one night half of it falls on the floor!! Im a little old school so hopefully some more guys chime in about your idea and if it works. Who knows I may be worng but the way Im picturing it makes me scratch my head LOL
Im not knocking it I just really dont think it would work out as planned
Ken, there's no question that a 9" wide piece of 2" foam that's glued to the plywood strips the way you've proposed will support your layout. I think the question was not framed correctly. There's a difference between structural strength that will hold a dead load and one that will hold a live load. You can run trains all day on the foam with the track, trains, and scenery considered the dead load. A live load is a sudden, additional stress to the foam in a vertical plane. The elbow that Trent talked about would be a good example. The unsupported foam will tend to bend and then snap at the point of greatest tension. That would be right at the wall. By adding supports every 12", you can transfer some of the live load to the supports and away from the one point of support you'd otherwise have. It wouldn't be hard to do since you're already adding a plywood "shelf" as a gluing point. Just some steel shelf support brackets like you can buy at Walmart, screwed to the wall and then glued to the foam, would make the structure much more resistant to catastrophic failure.
Rethinking the support for the foam. I will keep the 2" strip of plywood on the wall for the foam edge to be glued to. In addition, I will secure 2X4s to the bottom edge of the plywood with the edge to the wall to provide a ledge for the foam to sit on. I will apply glue to the plywood and the 2X4. The easements into the grade changes will not have the 2X4 under it to allow a gental bend in the foam but still glued to the plywood. The easement area going into and out of a .5% grade will only be a couple feet at most.
That sounds like a better plan since you'll at least have a total 6" of support for 9" of foam if I understand your idea correctly. Are you planning a fascia board for the outside edge of the layout? I'd recommend that both for looks and dent protection for the edge of the foam.
Well, no. It's not a 6" shelf that the foam will be sitting on. Only 3.5" of the 2X4 that the foam will be glued too. The 2" strip of plywood is on the wall, so you would measure the 2" up the wall and the edge of the 2" thick foam would glue against that.
The foam shelf will be 8" deep with the 2" edge glued to the plywood.
