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Jonathon,

Interior Grade plywood may delaminate faster than OSB, but Exterior Grade does not!  Exterior Grade can take moderate direct water exposure for up to six months without delaminating.  The reason is, that it is made with waterproof glue, while OSB and Interior Grade Plywood are not.  That is why I only use the Exterior Grade on all repairs, whether an interior or exterior repair.   (Sooner or later, for one reason or another, water is always going to leak into or spill onto plywood inside a house!)   What good is OSB if the wood chips are held together with water soluble glue?

If you got involved in the construction industry around 30 years ago, that is about 10 years after the time that contractors really shifted big time to the much cheaper OSB.

I heavily researched all of this online about 15 years ago,  and came across studies from Virginia Tech that confirmed that given equal thickness, even interior grade plywood is always stronger than OSB if properly laid with the exterior grain running perpendicular across the underlying rafters or joists, assuming properly spaced joists.

At the big box stores, you can tell the Exterior Grade from the Interior Grade because the Exterior Grade has green stripes painted on the butt edge of the plywood, while the Interior Grade is painted with black stripes on the edge.  The number of stripes corresponds to the thickness of the sheet of plywood.   Nominal 3/4 inch plywood, for instance, has 5 stripes.

And, as you will see, the Exterior Grade plywood can cost almost double what the Interior Grade costs.  :-)

About a year ago, it was running at $81 a sheet.  :-O

Mannyrock

@Tom Tee posted:

Hi John,

I entered your zip code in the Huber Industries web site for retail locations and that produced eight retailers within 25 miles of your zip code.  Granted, information can change but if you want it, it is available.

I did that search and pulled up the eight.  Four of them are Home Depot (they don't have it in stock and haven't).  I am going to call one or two of the others.

Thanks Tom,

John

@Mannyrock posted:

Jonathon,

Interior Grade plywood may delaminate faster than OSB, but Exterior Grade does not!  Exterior Grade can take moderate direct water exposure for up to six months without delaminating.  The reason is, that it is made with waterproof glue, while OSB and Interior Grade Plywood are not.  That is why I only use the Exterior Grade on all repairs, whether an interior or exterior repair.   (Sooner or later, for one reason or another, water is always going to leak into or spill onto plywood inside a house!)   What good is OSB if the wood chips are held together with water soluble glue?

If you got involved in the construction industry around 30 years ago, that is about 10 years after the time that contractors really shifted big time to the much cheaper OSB.

I heavily researched all of this online about 15 years ago,  and came across studies from Virginia Tech that confirmed that given equal thickness, even interior grade plywood is always stronger than OSB if properly laid with the exterior grain running perpendicular across the underlying rafters or joists, assuming properly spaced joists.

At the big box stores, you can tell the Exterior Grade from the Interior Grade because the Exterior Grade has green stripes painted on the butt edge of the plywood, while the Interior Grade is painted with black stripes on the edge.  The number of stripes corresponds to the thickness of the sheet of plywood.   Nominal 3/4 inch plywood, for instance, has 5 stripes.

And, as you will see, the Exterior Grade plywood can cost almost double what the Interior Grade costs.  :-)

About a year ago, it was running at $81 a sheet.  :-O

Mannyrock

There is an exterior grade OSB, Type IV.    It is not water soluble.  Then again we are talking about building a layout, not a house.

@Craftech posted:

I did that search and pulled up the eight.  Four of them are Home Depot (they don't have it in stock and haven't).  I am going to call one or two of the others.

Thanks Tom,

John

Home Depot (including the one in Wappingers Falls, NY) stock a product similar to Advantech that's made by LP.  It's also considered a premium sub-flooring product that uses Gorilla Glue (polyurethane) as the binder, that seems similar to the unspecified resin in Huber's Advantech.  I've used both of these 23/32" tongue and groove products in multiple sub-flooring installations and can't tell a difference between them structurally.  Both are very good at shedding water and resist mold much better than traditional OSB.

Here's a link: https://www.homedepot.com/p/Le...8-ft-41499/304947013

@SteveH posted:

Home Depot (including the one in Wappingers Falls, NY) stock a product similar to Advantech that's made by LP.

Yes, they sell mostly LP which is why I responded when Tom said Advantech was taking over the sub flooring industry that it depends upon where you live and that where I live it would have to be other brands.
They do stock Huber 7/16" 'Zip' wall sheathing and 5/8 'Zip' roof sheathing , but I am not familiar with them.
Thanks Steve,
John
Last edited by Craftech

Well we have seen there are many options to make a base for a train layout.

For myself it was simple, What material was available?  Plywood was very expensive and rare in Jamaica in 1977.  I found out an expatriate we knew was the plant manager of a plant that made particle board from sugar cane pulp called bagasse board.  I asked him where I could buy a couple of sheets and he said he would have two delivered to my house for no charge!  Problem solved.  The board was more than adequate at 3/4 inch thick.  So even particle board will work as a base.

When I got back to the states and later in 1988, I wanted to expand and bought 1/2 CD plywood from Home Depot.  It was noisier and I added tie size strips of truck inter tube under the tracks and under the switches which solved the problem.

Any of the ideas above will work but I do not think there is a need to spend a fortune on say multi layer plywood for a base that will not even be seen.  Regular wood working practices will work well and should be plenty strong.  It is worth effort to find a way to make the base system quiet especially if running several trains at greater than scale speeds!

Charlie



From  Kingston, Jamaica

Last edited by Choo Choo Charlie

I went with homosote over OSB for cost reasons and am not aware of that as a source of any issues. I did prime my benchwork in hopes of limiting moisture changes in the wood--not sure how necessary or effective it was.

I ran 12 gauge copper busses under the layout for both power and ground, with a soldered 20 gauge copper feeder to each separate piece of rail.  

If you have decent connectivity for the pins, IMO every 10 inches is overkill.  When I initially had most of my track down but no drops wired yet, I connected a PH180 brick to one end, and I was able to run trains on the whole 12 x 24 layout.  This was with all new track and switches.   Ross switches, some Ross O72 sectional track, and three cases of Gargraves flex track.  Needless to say, I didn't plan on actually running that way, I just wanted to see how bad it would be, I was pleasantly surprised that it ran at all!  Now I have 500 feet of track and a drop every 6-8 feet.  I've never seen any voltage drop issue anywhere on the layout.

It likely is overkill, but I'm told everything on the railroad is over-engineered, so I'm just following prototype .  Some of this track has been down 20 years with I hope many more ahead, and this is in a basement with some dampness.

BTW, in some places where feeders were impossible, I soldered tinned 20 gauge copper across the rail joints

I also want to mention that in the first portion of the layout, I used 3/4" plywood (been so long, I forgot) and have experienced no difference between it and OSB.

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