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3/4BC or 1/2 AC plywood

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  • Member since
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  • From: New Hampshire
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Posted by ChrisNH on Saturday, March 1, 2008 9:11 PM

I dont think that seams would be a problem.. but I use cork on top of plywood just to keep thickness down for wiring and switch machines. It has worked great for me. To get a better profile for my n-scale layout I laid N cork on top of HO cork. I have not yet ballasted and scenicked the layout but it looks like its going to work out pretty well.

Chris 

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Posted by roknrail on Friday, February 29, 2008 12:09 AM

 

thanks for all the great advice

i'm thinking on using cork roadbed on top of the plywood   I cannot find blue foam in 4x8 sheets in my area and Dow doesnot have any idea who stocks it. i can only find 2x8 sheets and i dont like the idea of having too many seams

its a little too damp for homasote in my basement  so i think 1/2 plywood will be best

scott

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Posted by Autobus Prime on Thursday, February 28, 2008 12:01 PM
 roknrail wrote:

Which is better to use: 1/2AC plywood or 3/4 BC plywood ?

There is a big price difference between the two.

rnr:

Use the cheaper one, especially since you're just using it under foam.  All you need is a decently sturdy base.  We're not building Steinways here.  The important thing is that it be exterior grade.

A lot of people use CDX.  That's what I used, 13/32" thick, for my solid-top 4 x 8.  It works well. 

 Currently president of: a slowly upgrading trainset fleet o'doom.
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Posted by ham99 on Wednesday, February 27, 2008 10:44 AM
If expense is not an issue, the best plywood is Baltic Birch.  It comes in 5'x5' sheets and all the plies are birch.  No voids, but some solid patches.  This is cabinet grade plywood, and comes in a variety of thicknesses.  I use 3/8" for bench tops and 1/2" for roadbeds.  I used 1"x4" ash hardwood for framing and rip it for L-girders. 
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Posted by ChrisNH on Wednesday, February 27, 2008 9:24 AM

I have read a number of MRR articles suggesting 3/4" 5-ply (or better) plywood is needed to ensure no sagging over the years. I made my small layout test layout using 1/2" which I had lying around which has been fine, but not enough time has gone by to really tell. 

I am still up in the air about what I will do with my next layout which will be a 10x10 walk-in rather then the 3x5 I have now. 1/2" would definitely be easier to work with. 

I definitely concur that fancy plywood does not seem needful. I used birch on my small layout because its what I had but am planning on the fir stuff sanded on one side for my larger layout. 

Chris 

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Posted by CascadeBob on Tuesday, February 26, 2008 4:46 PM

To Margaritaman:

Glad to hear that you had a good experience with the Arauco brand plywood.  I'm almost to the point in my layout construction when I'll need to purchase plywood.  On my last trip to my local Lowes, I discovered they are also carrying the Arauco plywood in both 1/2" and 3/4".  I didn't count the plies in the 3/4", but, as I said earlier, the 1/2 " has 5 plies.

Bob

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Posted by CascadeBob on Tuesday, February 26, 2008 4:41 PM

Peter,

I picked up several 12' and 8' 1 x 4 Radiata select pine boards at my local Home Depot yesterday with the intention of using them to fabricate "L" girders.  They are sold under the Black Label brand.  You might want to check to see if your local Home Depot carries them.  They also have them in 1 x 2, 1 x 3, 1 x 6 and 1 x 8.  They're nice looking lumber, but you do have to pick through them to get very straight pieces.  I have the impression that the product is relatively new to Home Depot.  I've not seen the Radiata pine at Lowes or any of the other home improvement stores.  I'm going to start doing the "L" girders this week so I'll let you know how they hold their shape.  They're in my train room now acclimating.  According to the info flyer I got at Home Depot, the density of the Radiata pine is comparable to that of Pondorosa Pine and White Pine.  Supposedly, they're kiln dried to 8-12% Moisture Content.  I think this is fairly dry, so they should be stable.

Bob 

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Posted by Margaritaman on Tuesday, February 26, 2008 4:34 PM
 RFinch wrote:

 Recently, Lowes started carrying Arauco brand (imported from South America) 1/2" pine plywood in A-C grade at $23.44/4' x 8' sheet. 

I just used this exact stuff and had nothing but a pleasant experience.

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Posted by BurbankAV on Tuesday, February 26, 2008 3:38 PM

Sorry if I wasn't clear -- you're correct: arauco ply is made from Radiata (true arauco is also known as "monkey-puzzle".  It's not a true pine, and not generally used for this sort of thing.)  So I'll try to rephrase: there's Arauco (the company) and arauco plywood (which is actually Radiata).  Arauco is headquartered in Chile, and is a major producer of arauco ply.  But not all arauco ply comes from Arauco.  (Confused yet?)

I've never seen Radiata in non-ply form, so I'd be really interested to know what your experience is with that.  As I said, I really like using arauco plywood, even though it's not Arauco plywood.

I need a drink....

Peter

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Posted by CascadeBob on Monday, February 25, 2008 7:28 PM

To BurbankAV:

When I looked at the website for Arauco Plywood I thought I read that they were using Radiata pine in their plywoods.  Radiata pine is imported from New Zealand according to a flyer I picked up in Home Depot which is selling Radiata 1 x lumber as clear select pine.  According to the flyer, the lower limbs of the growing pine tree are removed to produce a knotless clear pine lumber.  I think the flyer said that the Radiata pine was a type of Monterey pine.  Earlier today I picked up several pieces of 1 x 4 Radiata pine at my local Home Depot.  It's the best pine lumber I've seen at Lowes or Home Depot although you still have to do some picking to get good straight pieces and they aren't cheap.  Hopefully the pieces will hold their shape until I can get to use them.

Bob

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Posted by CascadeBob on Monday, February 25, 2008 7:17 PM

To bogp40:  Thanks for the additional info on the plywood.  I'll check some of the lumber yards in my area to see if they have any of the 1/2" PTS 5-ply fir plywood.  I'm also going to see if I can find any 1/2" Luan plywood which you said was very good for benchwork.  Several years ago we bought about 50-60 sheets of the 1/2" Luan to use as a double thickness sprung subfloor to support a dance floor when my daughter opened her new ballet studio.  As I recall, it was recommended by the floor manufacturer because it had a very low misture content and therefore was very stable dimensionally.  I think the lumber yard where we bought it required a minimum order to get it for us.

By way of clarification,  I plan to support my 1/2" plywood and 2" foam on risers so I have the flexibility to raise or lower the height of the terrain.  On my last layout I supported the 1/2" fir underlayment plywood with 5 plies with Homasote glued on top on risers on 12" to 15" centers.  I never had any problem with sagging.

Bob

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Posted by jeffrey-wimberly on Monday, February 25, 2008 2:50 PM
With L-Girder benchwork and 1/2" plywood I use joists spaced 14" to 16" apart. For use with 3/4" I space the joists 24" apart.

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Posted by BurbankAV on Monday, February 25, 2008 2:40 PM
 RFinch wrote:

IRecently, Lowes started carrying Arauco brand (imported from South America) 1/2" pine plywood in A-C grade at $23.44/4' x 8' sheet.  This plywood has 5 plies and seems to be reasonably flat. 

 

Just a side note on Arauco plywood: although Arauco may be a brandname, it's also a wood species from South America (native to Chile.)  I use exclusively 3/4 arauco ply (7 ply) for my benchwork and love it.  I've found it cuts really well, is (so far) void-free, and has great screw-holding.  I'm using pocket holes, and, since the plywood holds the screws so well, I only use glue in a couple of critical areas.  It can be a little finicky about finishing -- but then how many of us put a finish on our benchwork?  There are a few bad iPhotos on my blog...

Just my My 2 cents [2c]

Peter

 

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Posted by bogp40 on Monday, February 25, 2008 7:13 AM
 RFinch wrote:

I'm building the benchwork for a large N scale layout and had decided to use 1/2" plywood supported on 16" centers to which I am going to apply a top layer of 2" extruded blue foam insulation.  I have checked the Lowes and Home Depots in my area (Martinsburg, WV) and found their 1/2" plywood is mostly junk.  Recently, Lowes started carrying Arauco brand (imported from South America) 1/2" pine plywood in A-C grade at $23.44/4' x 8' sheet.  This plywood has 5 plies and seems to be reasonably flat.  I've not seen 5 ply 1/2" plywood in our area for a number of years.  In my last layout, a number of years ago, I used 1/2" 5 ply fir underlayment plywood.  I believe this is the same as what you refer to as 1/2" PTS.  When I checked back with the lumber yard where I had bought it, I was told that it was no longer carried because it had become so expensive or it was no longer manufactured.  I'd love to be able to get some of this or its equivalent in my area.  Could you be more specific about what to ask for to be able to get the 1/2" PTS fir plywood without voids that you metioned?  What does the PTS stand for?  I thought about using 1/2" luan plywood, but it's a special order item around here with a minimum order size.  I need only 10-12 4' x 8' sheets.

It seems to me that 3/4" plywood of any kind, especially in my N scale application is expensive overkill.

Bob

The underlayment grade of plywood, PTS stands for "plugged touched sanded".  It's common use has always been as a solid void free subsrtate for vinyl flooring and for under ceramic tile. Since vinyl is less common a choice for flooring and tile is now reccommended over Hardibacker or Durarock, I could see that it may not be a readily stocked item.

You say that you are only using the ply as a base under 2" of foam. I feel that for your use you could easily use 3/8 or 1/2" w/o any problems. A good 4 ply douglas fir 1/2" CDX would also be fine. My comments about the structural integredy of the PTS, Luan or hardwood plys is directed more to those using it for a subroadbed on risers. In this case the ply needs to be stable enough to handle the span between risers.

Many using 2" of foam only will use a 1/4" ply, just something to secure wiring, switch machines etc under the layout. Some will glue the foam to the joists, bad idea as far as I'm concerned- don't ever lean on this and how do you attach anything underneath. 2" of foam bonded to even 1/4" luan supported ever 16" is a very strong surface.

Modeling B&O- Chessie  Bob K.  www.ssmrc.org

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Posted by CascadeBob on Sunday, February 24, 2008 10:02 PM

I'm building the benchwork for a large N scale layout and had decided to use 1/2" plywood supported on 16" centers to which I am going to apply a top layer of 2" extruded blue foam insulation.  I have checked the Lowes and Home Depots in my area (Martinsburg, WV) and found their 1/2" plywood is mostly junk.  Recently, Lowes started carrying Arauco brand (imported from South America) 1/2" pine plywood in A-C grade at $23.44/4' x 8' sheet.  This plywood has 5 plies and seems to be reasonably flat.  I've not seen 5 ply 1/2" plywood in our area for a number of years.  In my last layout, a number of years ago, I used 1/2" 5 ply fir underlayment plywood.  I believe this is the same as what you refer to as 1/2" PTS.  When I checked back with the lumber yard where I had bought it, I was told that it was no longer carried because it had become so expensive or it was no longer manufactured.  I'd love to be able to get some of this or its equivalent in my area.  Could you be more specific about what to ask for to be able to get the 1/2" PTS fir plywood without voids that you metioned?  What does the PTS stand for?  I thought about using 1/2" luan plywood, but it's a special order item around here with a minimum order size.  I need only 10-12 4' x 8' sheets.

It seems to me that 3/4" plywood of any kind, especially in my N scale application is expensive overkill.

Bob

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Posted by bogp40 on Sunday, February 24, 2008 7:48 PM
 roknrail wrote:

Hi all

 Which is a better to use 1/2AC plywood or 3/4 BC plywood ?

 i'm using L-girder benchwork so how far apart should i space my joists ? space them closer if i use 1/2''

 there is a big price differnce between the two

 thanks scott

There's really no need to use the AC. Check into a quality lumber yard for 1/2" PTS (underlayment quality plug and sanded ply). This is generally 5 ply fir and has no voids. It is about the least expensive yet sound plywood that I've found. It is strong and stable as most better and hardwood plys. I use it for hidden cabinet interiors and sides for some of the economy jobs..

BC interior can have many voids and in interior glue. There is no real need to use 3/4" even on 16" centers if you use a decent grade of fir or hardwood plywood. My club uses the 3/4" for subroadbed, but then we are building to an extreme (possibly overkill). The only time you may ever experience any issues w/ 1/2" is the cuts for turns. The 1/2" py is not as strong once the surface graining passes 45 degrees to the cut. At 90 degrees it is at it weakest, especially on subroadbed cuts of 3-4" wide. If this is an issue then just use the 3/4" and have no worries.

Luan plywood in 1/2 and 3/4" is fairly inexpensive and is quite strong.

The key is the number of plys, 5 min for 1/2" and 7 for 3/4".  Any pine instead of douglas fir should not be used.

I would stay away from the inferior big box plys. There is no comparision. The home centers usually only have decent hardwood plys.

Modeling B&O- Chessie  Bob K.  www.ssmrc.org

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3/4BC or 1/2 AC plywood
Posted by roknrail on Sunday, February 24, 2008 6:25 PM

Hi all

 Which is a better to use 1/2AC plywood or 3/4 BC plywood ?

 i'm using L-girder benchwork so how far apart should i space my joists ? space them closer if i use 1/2''

 there is a big price differnce between the two

 thanks scott

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