Hello everyone, I am new to this forum and back into a hobby I did when I was a kid. I am a inexperienced model railroader. I have decided to put together my trains that I got when I was younger. I have bought a couple knew loco’s and have plenty of track. I started a layout but I am going to change it. I have built the L grider frame for for 4’x8’ layout. I was wondering what thickness of plywood and grade I need. I have a couple sheets of 7/16" osb. I was wondering if that would work or do I need gradeA/C. Thanks for all suggestions.
Hi. You will get a wide range of answers because so many of us have made things work with just about any material you can name. However, OSB seems to be one product that doesn’t get a lot of favourable response here. You are better off with the thinnest plywood you can purchase and support so that it doesn’t sag. An advantage to that is where you want to make transitions into grades, and then the grades, themselves. The thinner product will be easier to flex as a strip that is anchored flush with the main level, but lifted up to its intended grade at the other end. You can put risers here and there to support the rising span, although the tension should stiffen things nicely.
Humidity and dimensional stability are problems on layouts where wood is used. OSB…I don’t know how it fares, but many of us will paint/seal what we use so that we don’t get track separations and kinks when there are uncontrolled changes in humidity that cause grain swelling.
Weight may or may not be a factor, as would the span for supports…the joists. If you have spans wider than about 15", you should consider 1/2" as a minimum for use on an HO layout where individual items may not be very heavy. Sag at those spans should not be a problem.
That said, I used 5/8" plywood sheets on my first layout, three of them side by side, and had only three supports under them. To the best of my knowledge, there was zero sag.
Not going into specific uses for the plywood as Selector did, I will say that AC is a much better choice. There are so many ways the OSB can fail, not the least of which is humidity. Of all the money you spend on the layout, investing in a good solid foundation is some of the best money spent. I’m sure you can find another (non-railroad) use for your OSB that doesn’t have such a large investment in time and money depending on it.
Concrete formers use MDO plywood which is usually 3/4 inch and has one very nice finished side. This stuff is fairly pricey. However, there is a ten ply Phenolic plywood, from China, that is 5/8 inch and much cheaper. It is not structure rated, which shouldn’t make a difference in this application. I’m told it’s finished side is black.
I was really impressed with the finish, it is quite smooth and would make a very good sub-bed for track. You need to go to a building material supply for this stuff.
I use cabinet grade hardwood plywood. It will have a smoother surface and fewer internal voids (some of the inner layers in plywood have holes in them) and will normally have more layers which results in higher strength. If you buy paint grade, the price will be less as there are cosmetic defects (patches and color variation) not allowed in stain grade plywood.
I use 1/2" birch/maple on flat and level surfaces and 3/4" on cookie cutter surfaces.
The type and thickness of plywood to be used is determined by the frame that supports the plywood.In other words if you use a 2x4 at 2’ on center (oc) you should use a thicker plywood to elimanate bounce/flex usually it would be 5/8 or 3/4 inch for 2’oc. If you wish to use a thinner plywood your framing should be 16"oc. On my layout I used 1/2 MDO framing below at 16’ oc. The framing can be also determined by the “layering of the sheets themselves. For instance 7/17 plywood with the traditional 3 strand orientation will not be stiff as 7/16 4 layer strand plywood. It is ultimately determined by how much weight you wish to support. In homes the laoding for a typical floor plan is 50 to 60 pds per sq. ft a roof will only be at 20 to 40 pds per sq ft (depending on the roofing material) shingles vs slate. For a train layout 7/16 (commonly called 1/2 ) should be sufficient with framing at 16” oc. I would not recommend OSB (Oriented Strand Board) it is tough to nail thru and for my tatse a little to flexible. Part of the reason I chose MDO is because of its smooth surface and it is generaly cheaper than a cabinet grade plywood. Hope this helps.PS if you are worried about moisture and drying (shrinking and expansion) you may consider installing a humidiefer on your heating system. This will greatly reduce the amount of expansion and contraction and more importantly be a healthy choice for you and your family,especially if you live in a northern climate where there are long dry winters.Good luck.
First-toss the OSB
Second, build a perimeter frame of 1x4 or 1x3 and put in 1x4 cross pieces laid flat every 12"-18" at the bottom edge of the perimeter frame. That will leave a recess so that you can lay in pink or blue closed cell foam from HD or Lowes.
Third-Over the foam, find 3/16 5-ply birch plywood. That can be glued onto the foam and secured around the edge into the perimeter frame. You don’t need a lot of thickness to hold track screws into place and the sandwich of foam and plywood reduces the drumming sound of train operations.
All the best!
GT,
In addition to being a journeyman carpenter in cabinetry, finish and rough carpentry, I just finished the benchwork on 20 x 20 layout. The benchwork consists of 2 x 6, 3 x 3, and 3 x 4 modules made up of 1 x 4 D/Fir braced 16" o.c., topped w/ 1/2" Homasote or Soundstop over 7/16" OSB. These modules will be set atop base cabinets or a 2 X 4 framework screwed to the walls. All fascia will be stained to match existing cabinets in the room.
The reason OSB works best in this application is that it’s bi-directional lay up actually helps disapate sound, as well as give it strength. While it’s not a good idea to soak in water, unless you live in a swamp any OSB w/ certification for exterior sheathing has enough glue and chemicals in it to remain dry and solid, provided proper underlayment and roofing materials are used. Don’t worry about interior applications- OSB is just as stable as plywood for subtop use. Cabinet grade plyood, 3/4" exterior or marine-grade ply is overkill for our application. If you have moisture issues in a home (blocked vents, drains running back to foundations,etc.), even plywood will soak up water- in a properly vented home OSB will stay dry and straight.
I built four 2 x 6 modules w/ OSB in Oregon back in 1998, and they sat in my damp garage for three years before I moved to California. Those same modules spent another 4 years in an outdoor storage facility before we bought our home, where they went straight on top of my layout’s base cabinets. None of the OSB on these modules warped or delaminated in any way.
My modules are glued and pinned w/ 16 GA 2" finish nails, and they more than strong enough to support my 200 lb. frame. The base cabinets and 2 x 4 framework make them even more solid.
Open grid frames are another matter- high-grade plywood works much better there for a roadbed support.
Geno
I use 1/2" BC plywood - the Lowes / Home Depot stuff. Like so many wood products these days, it tends to be a bit wavy, but I’ve had no problems with supports every 12-18 inches straightening it out. Plenty strong for HO scale.
I like Geno am a journeyman Carpenter in addition to having a degree in construction management and have built everything from an outhouse to multi million dollar projects. I agree with Geno if you plan to cover the OSB with another materialOSB is fine. If you do not plan to cover the OSB with another material dont use it spend a little extra money and buy a product that has a better finish. Again size the thickness by the supporting structure. See earlier post