Lumber and Siding - Question on 3/4 PT Plywood

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fatclemenza
09-14-09, 09:52 AM
Hello,

I'm in the process of getting material quotes for my shed and would like to know if someone here can explain the difference between the two different plywoods below.

A. 3/4" FIR PT&S UNDERLAY 4X8 T&G

B. 3/4" EXT UDL CCA TREATED


B is about 37% more in price than A which is substanial. I'm assuming B is a better quality wood.

Thank you

FC

lefty
09-14-09, 03:20 PM
Where are you finding CCA?? That was outlawed about 8 or 9 years ago!!

Current treating processes are borate and ACQ.

I can understand a 37% difference in the cost of borate and ACQ.

ACQ is usually rated for ground contact -- borate isn't.
fatclemenza
09-14-09, 11:19 PM
Hi Lefty,

Thanks for the response. I'm getting the lumber from Rings End Lumber - Ring's End (http://www.ringsend.com)

So, which is better for the floor of my shed? Should I go with the CCA?

Sean

lefty
09-15-09, 02:18 PM
I'm not sure why you are thinking that you need PT plywood for the floor. Hopefully you will have adequate ventilation under the floor. And there shouldn't be any earth-to-wood contact under the floor.
fatclemenza
09-17-09, 09:34 AM
Lefty - I'm going with the solid concrete blocks on top of item#4 gravel tamped down and building from there with PT 2x8joists. I'm thinking of laying down some thick .6 mil plastic on top of the gravel before puttign the blocks down. What are your thoughts on that?

FC
lefty
09-17-09, 06:41 PM
I wouldn't use 6 mil plastic. I would use landscape fabric (I assume that you are concerned about weeds or grass coming up), and I would put it in before putting down the gravel.

6 mil plastic wouldn't allow water to drain through it.
fatclemenza
09-18-09, 07:04 AM
Thanks lefty. Appreciate it