Hey All, I’m looking for the best technique,and products to finish pt tongue and groove porch flooring. I’ve tried priming three sides, installing it and letting it sit, but the gaps opened up so wide you can practically see through them. Does anyone have any other ideas.
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The short answer to your question is that an awful lot of PT lumber starts out life as plantation-grown jack-pine, which is cut when the butt is sometimes no bigger than 8-12", slab-sawn, has thicker'n'heck growth-rings from all the fertilizer, and consequently swells, cups, and shrinks like a bastid. So I don't think anything you could do to it is gonna give you a nice tight T&G floor. Learn to live with the joints open like that, or do something else instead.
The real question is, why are you trying to use PT T&G in the first place? That seems like a contradiction in terms, somehow: Most places you could justify the use of PT, you shouldn't be using T&G flooring because it will trap and retain water.
Dinosaur
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But it is not this day.
Which three sides? The board has four sides, and all of them need sealed.
But the first thing to do is to dry the lumber first. PT is wet and wetter. We call it "pond dried". You need to let it dry, shrink, and stabilize, THEN preprime it, and finally install.
IMO, PT T&G is about th worst choice you could make for such a project. CVG Fir or Tendura would be far better, or T&G IPE` if you can get it,
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Around here I can go to a speciality lumber yard and get "KDAT" PT lumber, including PT T&G 1by and 2by flooring. KDAT - Kiln Dried After Treating. I think it is a good choice for lumber that will installed in a very exposed location and be painted. Very little shrinkage, and I believe it holds paint better. I am using it for the front porch & step handrails and window sills on the houses I'm building now. The only down side is ya gotta ba a bit picky when you select your boards as the KDAT process will definately make the wild ones go wild... I go to the yard and pick it up, or order an extra measure for returns. That, and it costs about 1.5x as much as of regular PT.
Matt
Edited 6/19/2005 9:13 am ET by DIRISHINME
That is astep up, but even kiln dried is not dry. I don't know if they use same standard as for framing lumber or not, but that would be 19% surface tested. Interior of board could still easily be 24% or more. although a one by would probably be only 20%, but I would want it down to 12% before painting/ prepriming just for the paint to stay one well.
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I see your point but just for discussion's sake, let me ask a Q:
If you install a board that is at ~19% moisture content, wait 3 weeks during which the humidity is averaging 80%, is the board dryer or "weter" after the 3 weeks?
Matt
Those two percentages don't line up. one is relative humidity of air. The other is by weight percentage of the lumber.But the general point is valid. It is hard to get lumber to dry out when the air is already so satuated that it can't carry anymore water. You have to heat the iar for the RH to drop, and run a dehumidifier in a controlled access room.
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>> Those two percentages don't line up. << Sometimes I feel so blond ;-) Beats the heck outa the gray, which is quickly taking over.
When I think about it, the whole thing about 19% moisture content is pretty theoretical anyway. I thought lumber dryness was checked via weighing the hacks of lumber - is that not true - is it just done with a moisture meter? That would explain your comment about surface moisture content...
Matt
The moisture meter carries a current that will run differently ( I don't know if it is speed, current in milliamps, or voltage drop that is measured) in wood with different amounts of moisture. It is programmed to convert this measurment into some comparative information to tell you what the moisture content as a percentage of weight is.The more accurate readings will come from a moisture meter with the prongs that you push into the wood a bit. They make a vampire mark but are worth it for more important readings, like doors and cabinets.
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