Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Plywood base and thickness

1950 views
25 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    September, 2013
  • 4 posts
Plywood base and thickness
Posted by chuck319 on Saturday, September 22, 2018 8:43 PM

Hi, I am planning on building a layout in my garage using l- girder benchwork. What kind of plywood and what thickness should I use for the best results.

Thanks, 

Chuck

  • Member since
    June, 2007
  • From: Northern Virginia
  • 5,871 posts
Posted by riogrande5761 on Monday, September 24, 2018 9:02 AM

One half inch plywood should be fine for HO layouts.  IMO, 3/4-inch ply is overkill costs more than necessary and heavy too.

Rio Grande.  The Action Road

  • Member since
    November, 2013
  • 627 posts
Posted by snjroy on Monday, September 24, 2018 11:53 AM

Since I am not a carpenter, I tend to overbuild to avoid problems later. Your benchwork needs to be pretty sturdy to avoid cracks in your scenery. I have a long yard that sits flat on a piece of plywood. I chose 3/4" for that and never regretted it. No risk of sagging there... For the legs and cross-overs,  1/2" ply is probably OK. I went with 1X4 spruce, that is fairly inexpensive here in Canada. I did not regret that either - I bolted the structure directly on the  4X4 studs and that thing will not budge from there, I can guarantee that!  Overkill? Maybe, but I prefer that to a shacky or sagging structure. 

Simon  

  • Member since
    June, 2007
  • From: Northern Virginia
  • 5,871 posts
Posted by riogrande5761 on Monday, September 24, 2018 12:27 PM

Half inch plywood is definitely sturdy enough and as long as you support it properly with cross members about every 16 inches, you will have no issues with sagging.  In fact in my last layout I used cross members in the open grid framing of 24 inches and no issues.  It will support your weight if you need to get up on it; I have.

I've built 3 layouts so far and 1/2 inch plywood is very sufficient.  I like to use sheet Homasote for my yards and sandwich it with drywall screws.

For the open grid framing that supports my yards, I use 1x4 framing and 1x3 cross members - works great.  Most agree that 2x2 legs are very strong.  Some will go "overkill and use 2x4's for legs; I read some discussion and it is overkill.

Lumber is getting more expensive in recent months so overkill is going to cost even more; your choice.

Rio Grande.  The Action Road

  • Member since
    May, 2004
  • 5,631 posts
Posted by 7j43k on Monday, September 24, 2018 1:19 PM

A variant I have used is 1/4" plywood with support at 30" spacing.  If that was ALL I used, there'd be a problem.  But I also attached a 1 x 2 on edge underneath the track. I did not go all the way to the supports, stopping short by about 1/4", for ease of construction.

I suppose you could go nuts and use a 1 x 3.

A reason I went this way is that I wanted to used the 1/4 ply also as a scenery support, and I wanted to save weight.  So there would have been a lot more plywood than just under the track.

Whether this method saves money or time over using 1/2" is debatable.  But remember the span of 30".  That would save you alternating supports compared to using just 1/2 ply.

 

Ed

 

  • Member since
    June, 2007
  • From: Northern Virginia
  • 5,871 posts
Posted by riogrande5761 on Monday, September 24, 2018 1:42 PM

Half-inch ply could be considered overkill for scenery but if you have track laid across much or most of it, it's a good happy medium.  Thats why I use 1/2 inch for yards and Homasote as well as it is nice to spike:

For other areas, I only use 1/2-inch under track (and cork for a profile):

Under scenery it depends on the topography, it could be cardboard webbing, it could be luan such as under my river (coated with sanded drywall mud in the photo below), it just varies:

Rio Grande.  The Action Road

  • Member since
    June, 2003
  • From: Culpeper, Va
  • 7,736 posts
Posted by IRONROOSTER on Monday, September 24, 2018 6:58 PM

I use 1/2 inch plywood on 1x4 pine grid benchwork with cross members on 16 inch centers.  This works very well for me.

Keep in mind that there are different grades of plywood.  One thing to do is count the plies.  If you see any that is 3 ply, skip it.  4 ply is marginal, try for at least 5 ply, 7 is better.  Baltic Birch 9 ply is the best 1/2 inch, but overkill for this application.

Oh, stay away from any pressure treated or concrete form types of plywood.

Paul

If you're having fun, you're doing it the right way.
  • Member since
    March, 2012
  • 88 posts
Posted by PC101 on Monday, September 24, 2018 10:37 PM

Hi chuck319, I'd think you might first want to know what the humidity and temperature could be year round in that garage. 

  • Member since
    July, 2006
  • From: Bradford, Ontario
  • 8,707 posts
Posted by hon30critter on Monday, September 24, 2018 10:57 PM

My club went with 3/4" ply under 1/2" Homasote with cork roadbed. We didn't want to take any chances.

However, we encountered one small problem with the Tortoise machines. The throw wire that is supplied is too short to work with the above combination of materials. If we had used 1/2" ply I believe that the wires would have been just long enough to reach the throwbar. For many people it is a moot point because they change the wires anyhow, but if you plan on using the supplied wires the depth of material is something to take into account.

Dave

  • Member since
    June, 2007
  • From: Northern Virginia
  • 5,871 posts
Posted by riogrande5761 on Tuesday, September 25, 2018 6:11 AM

Dave, I don't think your club would have taken any chances with 1/2-inch and I am risk averse.  Then again, maybe they want the layout to double as a dance floor?  Whistling

Rio Grande.  The Action Road

  • Member since
    January, 2014
  • 723 posts
Posted by ROBERT PETRICK on Tuesday, September 25, 2018 10:16 AM

I went with 1/2" BC plywood at 24" centers support. No structural problems whatsoever. The BC part might be a little bit of an overkill, but I wanted a fairly smooth relatively splinter-free ground plane for landscaping and scenery. 1/2" CDX would have worked perfectly well and would have been considerably cheaper, but the stuff available in the big box stores these days is pretty ugly. I specifically did not use OSB even though I had some from a recent demolition.

Good luck. 

Robert 

LINK to SNSR Blog


  • Member since
    September, 2018
  • 28 posts
Posted by agrasyuk on Wednesday, September 26, 2018 7:23 AM

On subject of bench tops, what would you recommend to achieve a very thin one? I'm planning for a hidden lower staging level and the best vertical separation I can do is 9 inches rail to rail.

 Buiding the usual way with ply and floor joists will mostly work it seems , I was also thinking to use aluminum square pipe for cross members. With a bench depth of 24" is there perhaps a sheet material that can hold it's own weight without sagging? 

 

Regards

Anton.

  • Member since
    July, 2006
  • From: Bradford, Ontario
  • 8,707 posts
Posted by hon30critter on Wednesday, September 26, 2018 8:16 AM

riogrande5761
Then again, maybe they want the layout to double as a dance floor?  

It would have to be a slow waltz! We're all too old to boogie!!

Actually, one of the reasons was that we had just moved into a new clubhouse in an old concrete industrial building, and we didn't have any idea what the humidity swings might be. The room does not have any HVAC other than a heater on the wall. We were looking at spending several thousands of dollars of the club's somewhat limited assets so we said we wouldn't take any chances by cutting corners. In terms of the whole cost the price difference between 1/2" and 3/4" was peanuts. We only needed 12 sheets.

And now we can dance on it!!!Smile, Wink & GrinLaughLaughLaugh

By the way, we added up our costs to date and we are about $1300.00 below the budget!Big SmileYesBeerMusic That is going to allow us to upgrade some of the structures from the typical Walthers style offerings to more craftsman level kits, and it will put a whole bunch more trees on the layout. So far nobody has offered to make trees for us.Grumpy

Dave

 

  • Member since
    May, 2004
  • 5,631 posts
Posted by 7j43k on Wednesday, September 26, 2018 10:58 AM

agrasyuk

On subject of bench tops, what would you recommend to achieve a very thin one? I'm planning for a hidden lower staging level and the best vertical separation I can do is 9 inches rail to rail.

 Buiding the usual way with ply and floor joists will mostly work it seems , I was also thinking to use aluminum square pipe for cross members. With a bench depth of 24" is there perhaps a sheet material that can hold it's own weight without sagging? 

 

 

The picture looks to me to be showing a pretty decent design.

If a span between risers of 24" works with 1/2" ply, then a depth of 24" should also work.  For insurance, I would attach a "beam" at the back of the top shelf, either on top or on the bottom.  If you have a fascia on the front of the lower shelf, that would do nicely.  But it would be nice to skip the fascia on the upper.

You CAN use square aluminum for crossmembers.  Probably the most cost effective would be 1" x 1" x 1/8" steel angle.  Bigger would be stronger, smaller would be weaker.  My choice of 1" is a stare-at-the-ceiling estimate. 

So it would appear that, if you have a 9 inch vertical distance between rail tops, that the "reach clearance" would be about 7 1/2".  Is a 7 1/2" clearance enough to get back 22" to deal with a derailed car?  If there's trains on the forward track, that 7 1/2" shrinks to about 5".

My arm thickness is about 4".  So that would leave a clearance of 1" as I reach back with my claw-crane.  Might work.  Your arm will likely be pressed up on the bottom of the upper level while you reach.  Which means that any wiring below the upper level is going to get rubbed on.  Possibly to bad effect.  I suggest that all the wiring for the upper level, when travelling the long-ways, be at the back.  And that, when you need to come out to feed a track, or something, that it come out very near the spaced supports, which will then protect the wires.

You COULD put some strip LED lighting in the back of the lower level.  I might even say "should".  Of course, it might shine in your face as you reach.  You'll want to minimize that effect.

 

Ed

  • Member since
    August, 2006
  • From: Nashville, TN area
  • 441 posts
Posted by hardcoalcase on Wednesday, September 26, 2018 1:04 PM

On a related topic, rather than regular lumber, I use 3/4" 6 ply plywood, ripped to 1x4's for my benchwork framing, both in L girder and grid applications.  It stays straight with no warping.  Cost is about the same as stick lumber, and the ripping is free in some places, or at minimal cost.   

For subroadbed, I use 1/2", 4 ply plywood, supported at 14" to 16" intervals.  Going on my 3rd layout now, and never had any issues.

Jim

  • Member since
    February, 2009
  • 918 posts
Posted by railandsail on Wednesday, September 26, 2018 5:37 PM

How about this alternative for thin decks, and 8" clearance for staging,...

Over the past year I have been thinking and experimenting with ideas for my benchwork for my new layout in a shed.

I was over at my local metal scrap yard this past Fri and noticed some hollow square steel tubing they use to mount street signs with. Its 2" square verses my flanged 1-1.25" bed rails, and its really strong, and its galvanized. So now I am definitely considering this stuff.

 

I was originally considering making vertical brackets at each of the wall stud location to support the plywood shelves. then I ran across these steel square tubing at the local metal scrap yard.

My contractor friend. who was going to weld up the considerable number of vertical brackets I had sketched up, came back with an interesting idea. Why not lay these square tube 'beams' horizontally along the walls and lag them into the wall studs. Then the plywood shelves (decks) could be attached along their wall edge and cantilevered out. And where the shelf/deck is of a substantial depth, the outer edge might also be supported primarily by another long piece of this horizontal square tubing with only an ocassional vertical support.

I am now planing on utilizing this 'horizontal framing' idea on my staging track level and my lower primary deck. I may even utilize the idea for my upper deck, particularly as they will be more shallow than the primary deck. I will definitely utilize the larger 2" square tubing to support the lower primary deck. For the staging level (relatively shallow), and the upper deck I may utilize my 'bed frame angle iron'. I'll document this more thoroughly as I get to building it.

Quick update,....the first piece of horizontal steel tube framing along the back wall of the shed. The large size square tubing is the type that will be utilized to support the edge of the plywood deck next to the walls.. This will be selectively placed around the perimeter of the shed. There will also be central pieces at the inner edges of the shelf somewhat like shown on this preliminary dwg.
 

 

 

 

 

 

more here...
http://cs.trains.com/mrr/f/11/t/265524.aspx?page=2

  • Member since
    January, 2004
  • From: Canada, eh?
  • 8,503 posts
Posted by doctorwayne on Friday, September 28, 2018 1:15 AM

chuck319

Hi, I am planning on building a layout in my garage using l- girder benchwork. What kind of plywood and what thickness should I use for the best results.

Thanks, 

Chuck

 
Based on the wording of Chuck's query, I'm guessing that the plywood is going to be the material for constructing the L-girder benchwork, rather than a table-top to sit on such benchwork. 
It seems to me that open grid benchwork is better suited than L-girder for a plywood top, as its edge members offer better support against sagging, compared to no-edge L-girder.

In either style, though, if you're going to cut plywood into material to make the benchwork, 3/4" would be preferrable.
 
Wayne
  • Member since
    January, 2017
  • From: Southern Florida Gulf Coast
  • 2,880 posts
Posted by SeeYou190 on Friday, September 28, 2018 6:21 AM

Galvanized square steel perforated box beam will be more than strong enough for anything you want to do.

.

I used 1/2" plywood for a couple of layouts and had problems. I only use good quality 3/4" plywood now.

.

-Kevin

.

Happily modeling the STRATTON & GILLETTE RAILROAD located in a world of plausible nonsense set in August, 1954.

  • Member since
    May, 2004
  • 5,631 posts
Posted by 7j43k on Friday, September 28, 2018 9:11 AM

I found this on ye olde internet:

http://www.woodbin.com/calcs/sagulator/

 

Plywood is near the bottom of the drop down.  It's a bit tricky to use properly if you're not used to construction/cabinetmaking.

 

Ed

  • Member since
    February, 2002
  • From: Reading, PA
  • 24,900 posts
Posted by rrinker on Friday, September 28, 2018 11:30 AM

Yeah and if you apply proper load values (30 pounds per foot that it defaults to is WAY more than any model railroad weighs - even the 15 I used is probably huge overkill), 1/2" plywood 2 feet wide supported on 16 inch centers has neglible sag. So does OSB and particle board. It's amazing what a 1x2 run along the front edge will do, too. For a shelf layout sitting on metal shelf brackets, with that strip of 1x2 to hold a fascia, you don't even need to support it on 16" centers, every other stud at 32" centers is fine. 

 I think that calculator shows how overbuilt a lot of model railroads actually are. I'd love to know the exact conditions that caused 1/2" plywood supports every 16" to sag more than a few thousandths of an inch. Even scaled out - a 3 thou actual sag equates to a bit over a 1/4" in HO scale. Your HO people wouldn't even stub their toes on that.

                                          --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    May, 2004
  • 5,631 posts
Posted by 7j43k on Friday, September 28, 2018 11:49 AM

I get a sag of almost a half inch with 1/2" ply, and 1/8" with 3/4" ply.

Using these variables:

Shelf Material--Plywood, fir

Shelf attachment--Floating

Shelf load--10 pounds--total

Load distribution--uniform

Span--32"

Depth--2"

Thickness--.5, .75

No edging

 

If the span goes down to 16", even keeping the same load, the deflection goes to .03" for 1/2".

I picked a 32" span, at first, because I've heard talk of people using that distance.

Which seems to demonstrate the need for closely spaced supports.  Or, of course, a stronger span (for example, attaching a 1 x 3 underneath).

 

Ed

  • Member since
    February, 2003
  • From: Morristown, NJ
  • 342 posts
Posted by nealknows on Friday, September 28, 2018 6:01 PM

I used 1/2" AC plywood for my layout. I use 1"x3" cross sections every 12" (overkill), with supports on 2"x2" legs. I can lay on it. I went with the AC plywood instead of the BC ply as the tops weren't as smooth as I wanted it. Also looked at Sandeply and the reviews were horrible, despite the smooth surface. Yes, the AC ply costs more from the local lumber yard, and I have no regrets. 

Neal

  • Member since
    February, 2002
  • From: Reading, PA
  • 24,900 posts
Posted by rrinker on Friday, September 28, 2018 7:03 PM

It's the width that matters, I was doing it like an 18" wide shelf layout, not cookie cutter style.

 However, with 1/2" plywood 2" wide, on 16" support centers, I got .004" per foot sag - the ends will typically be fixed, I don't know too many people who just lay the subroadbed on top of the risers and don't screw them together. 3/4" ply - .001 per foot, might as well not even count.

                                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    May, 2004
  • 5,631 posts
Posted by 7j43k on Friday, September 28, 2018 7:26 PM

Randy,

I chose "floating" because I read that to mean the shelf is not attached to the cabinet back.  I did not read it as, say, sitting loose on pins (which is common in bookshelves).

I don't see why there'd be much difference in deflection between just resting the plywood on risers, as opposed to attaching it with screws.

On t'other hand, if a shelf IS attached to the back, the back contributes greatly to lessening deflection.

I do wish they'd been clearer on what they meant.

 

Ed

  • Member since
    February, 2002
  • From: Reading, PA
  • 24,900 posts
Posted by rrinker on Friday, September 28, 2018 11:36 PM

 Good point, it's not clear on that. Though I'd think fastened along the entire back should be incredibly sturdy.

 The solution seems to be just make the strips wider - 2" is a little narrow for a double track HO while still allowing room to attach the scenery along the edges.

                               --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    January, 2017
  • From: Southern Florida Gulf Coast
  • 2,880 posts
Posted by SeeYou190 on Thursday, October 04, 2018 6:19 AM

I cut my subroadbed (plywood) very narrow. Since it is so narrow, just barely wider than the roadbed, I am sure I need more supports and thicker plywood.

.

Plywood become almost easily breakable at 2 1/2" wide.

.

-Kevin

.

Happily modeling the STRATTON & GILLETTE RAILROAD located in a world of plausible nonsense set in August, 1954.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!