EL

I have the foundation built and now will be topping it with pressure treated lumber. I have read several different ideas:

1. No spaces between boards. They will shrink more that non PT lumber
2. Wait anywhere from 1 month to 1 year before sealing PT lumber.

Do any of you have experience with PT lumber? I was looking at Thompsonized PT lumber, it is a few $ more but looks less green or wet.

Any advice or ideas is greatly appreciated.

Phil DiCostanzo

I haven't built a deck, but I use pressure treated Southern Yellow pine for a family business building back-yard swing sets. Our manufacturers get the lumber from treatment and seal it immediately at the factory. In fact, we use it as a selling point since the customers won't have to do it for at least a year.

Our guys are also rabidly anti-Thompson when it comes to their water sealing products, but I don't know much about their pressure treatment.

As far as the spacing of the deck boards, we see the fresh stuff check like any pressure treated lumber, but I don't know how much it actually shrinks. I would be worried about having deck boards without any gap, since if you don't have at least some shrinkage, then water will not easily drain through that area and cause problems.

suny507

I had a deck business for almost 10 years. I always butt the boards up tight, and in about a year you will have the "nail" gap. As far as treating wait at least 6 months or you are just wasting money as it will not penetrate properly and you'll just do it again next year. Olympic Maximum, not olympic regular is by far the best stuff out there now. I have a 15 year old deck and it looks like new. Also I refused when building to use 5/4 decking even if it is Thomponized, I have always used 2x6. You are looking at a few hundred bucks most additional, but well worth the investment. It will not cup or warp nearly as bad. Stick with 16" on center with 2x6 and you will have a 25 year plus deck easily.

av8tr4610

I agree with you, except for not spacing the boards. you have got to give them space to expand and contract, and also so water and debris can drain off the boards. I use 1/4 in tile spacers to help keep the distance even down the length. Def use 2x6 boards, and wait at least 6 mo before sealing. When you seal them try to do it when the deck has been dry (no rain) for at least 5 days prior. I like the Behr product alot and would use thier sealer, you can find it at home desperate, i mean depot. good luck........also use deck screws, not nails!

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Kevin Griffin
IAH FO

Worth......Just because you're necessary doesn't mean you're important.

EL

Thanks for all the advice. Unfortunatly I have already build the foundation for use with 5/4 deck boards, it will meet just below the door threshold so water doesn't get in the house. I am leaning towards no gaps in the boards, I'll let you know how that goes.

I heard that using oil based stain rather than water based is best on PT lumber. Any thoughts on that?

Deck Captain

If we spaced our boards we would have huge gaps between them now! When we built our deck, Home Depot had 2 choices of deck boards. We went with the more expensive ones. Glad we did.

We originally used the water based stain sealer, but then my wife mistakenly bought the oil based and put that on. It actually looks darker and seems to last a bit longer. We stain it every year even though it says you don't need to. It just looks better. We used the Behr stain.

Good luck.

n61870

Spacing depends on WHERE YOU LIVE! If you live here in houston, there is no need to put that much of a gap between them, 1/8" should be more than plenty. The boards will shrink and depending on the moisture content at the time of install, will determine how much. If you live in an area with a lot of rain and not much heat (Oregon for example) you should put at least 1/4" between them because as they shrink in the heat, they will swell when wet especially when it is cold. Either way, it is not wise to have no gap between the boards. Otherwise, you will end up with a lot of debris that will be difficult or impossible to remove, especially when you go to stain or re-stain.

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