I have a 21' x 8' layout with 1/2" plywood topped with 1/2" foam on 2" x 4" benchwork with 20"centers and it held my 217 lb body when I installed my track lighting.
I have had no issues with 1" foam on 1/2" plywood and the benchwork is 10 years old.
Bear "It's all about having fun."
Wayne II From what I'm hearing in the posts the 1/2" plywood doesn't seem to be thick enough.
I'm using 1/2 inch plywood with about 20" centers--but I'm using high grade plywood with glue that resists deterioration from moisture. If you buy the cheap stuff off the rack at Home Depot, you need to go with your 14" OC supports or less.
Chip
Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.
SOUNDWhen I was considering foam for my subroadbed, I read quite a few forum postings on a number of forums. Basically it appears that 2" form is perfectly adequate for strength even between 24' supports. There were a number of questions about how it transmitted sound, and there were a number of observations that this could be significantly reduced by adding a thin (even 1/8 wood) skin to the bottom side of the foam. Naturally this would assist with 'attaching' items to the underside.
Brian
My Layout Plan
Interesting new Plan Consideration
I used all 3" foam with no plywood under it. About 12-14" between supports and I have not had any sag problems.. Main reason I can think of for an underlayment of plywood is if you need to attach stuff like like turnouts motors to the underside. I used all Kato Unitrack turnouts so I did not need to attach anything under the foam.
A big benefit of thick foam is that you can carve depressions in it (ditch, etc) if needed.
Paul D
N scale Washita and Santa Fe RailroadSouthern Oklahoma circa late 70's
I think the 1/2" plywood would be fine, with the supports at 14"o/c, or maybe 12" o/c if you are worried.
I'd just make sure it was all fastened together good, with screws.
Mike.
My You Tube
IMHO.
1/2 in ply is more then enuff to hold up a couple pounds of plastic,on 14in OC you could even go to 16inOC.Your support frame is more inportant then the material on top.
I'm a firm believer in foam. 2in over open box frame will take anything you can put on it.
Cabnet grade plywood is nice, if you got the money. But you don't need it.There are other,cheaper ways to get it done.
Do what your comfort level allows,do not let the ''over thinkers''overwhelm you
Sorry about the all caps, will watch that in the future. I gather you think I should use thicker plywood, which would not be a problem?
Hi Wayne:
Welcome to the forums!!
If you are going to use plywood I would suggest using 3/4". Even then you will still get some expansion and contraction as the humidity changes.
Our under construction club layout is constructed with 1/2" Homasote over 3/4" G1S plywood. We noticed a little bit of track movement when the track was first nailed down in February. Since then the problem seems to have mostly gone away. We are using cork roadbed too, but as others have said, the cork is not necessary. We are doing it for profile as much as to quiet the track sounds.
If I were doing it again, I would use 3/4" Baltic Birch 11 ply or 13 ply furniture grade plywood. It is more stable. It is also more expensive, but if you consider how much you are going to spend on what goes on top of the plywood and Homasote, I think it is worth the expense. Why invite problems?
One thing to note is that you can cut into the Homasote with a carpet knife (box cutter) to create ditches. It takes a few passes and a bit of effort, but it is quite doable.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
I do not use a roadbed,no issues
Why not use 2'' foam, instead of plywood and hom. You could lay the track right on it, and be able to cut your pond,ditches ect.
BigDaddySome people may quibble about the thickness of your plywood.
The issue here is sagging and warping. The determining factor is the distance between your supports and the quality of your plywood. Cheaper plywood tends to be more prone to losing it's shape than exterior grades and or hardwood venier plywoods.
to the forum. In all the internet forums in the known universe, typing in all caps is considered SHOUTING
Yes you don't need roadbed in a yard area. Some people may quibble about the thickness of your plywood.
Henry
COB Potomac & Northern
Shenandoah Valley
BUILDING A LOGGING LAYOUT, 1920-1940'S ERA. FOR THE YARD AREA, SAWMILL AREA, TOWN AREA CAN I JUST USE 1/2" HOMOSOTE ON TOP OF 1/2" PLYWOOD AND THEN LAY FLEX TRACK ON TOP OF THAT? THEN EASILY SCENIC BETWEEN THE TRACKS. OR DO I HAVE TO USE A RAISED TYPE OF ROADBED? FROM PICTURES IN BOOKS OF OLD LOGGING RAILROADS THE TRACK LOOKS FAIRLY FLAT, NOT MUCH RAISED ROADBED. THANKS
WAYNE II