Grades of Pressure Treated Wood


Old 01-29-06, 04:50 AM
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Question Grades of Pressure Treated Wood

I am having a deck built in the northeast and plan on using pressure treated wood. I want to use the best available. Is there a difference between # 1 and premium pressure treated wood?

Also, I plan on using the existing frame which was the old pressure treated wood built about 15 years ago. It is still in great shape. Is there any concern about screwing or nailing new PT deck boards into the old PT joists?
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Old 01-29-06, 06:58 AM
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Premium PT usually has less knots in it and the grains seem straighter. I am not sure what the official differences are. You may get away with using the old framework, but if it is 15 years old, it will reach its life expectancy in 5 years, and you will have to replace all of it. If you are comfortable with it (and you can see it, I can't) It will present no problem attaching the new deck boards to the old joists. I would just use screws this time, because the wood is aged somewhat and you will need the added holding power.
Old 01-29-06, 08:48 PM
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I'm agreeing with what Chandler is telling you. The difference between #1 and 'premium' is all about the knot size, and what part of the log the board came from.

You can see your framing -- we can't. But WHY go to the extra expense of laying 'premuim' decking over the existing frme work if the frame work will only last another 5 or 10 years?? You could lay composite or plastic decking on it -- stuff that has a warranty of from 10 to 50 years -- and pay big bucks for it. But if the framing only lasts another 5 years or so, WHAT WAS THE POINT???
Old 01-30-06, 04:34 AM
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There is an issue about corrosion of the fasteners and the new PT wood.
Check out for more on this subject.
Old 01-30-06, 08:47 PM
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Yes, ACQ PT lumber needs to be fastened with APPROVED fasteners. Basically, that is either HD galvanized or stainless. You DO NOT want aluminum to be anyplace close to it. This stuff eats aluminum for lunch. It takes it until the next day before it gobbles steel for dinner.

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