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Discussion Starter · #1 ·
I guess this is more of a survey. When you guys do pressure treated decking, do you gap it or butt it tight and let it shrink?


I do mostly all composite now, but when I occasionally use PT decking I always gap it depending on how wet it is. Usually either an 8d nail or 16d nail.

It would save a decent amount of time when using soaking wet boards just to butt them together and let them shrink.

Years ago my dad built a deck and butted the boards tight together figuring they will shrink. Well the area the deck was in never saw any sun and the boards never really shrank. I've been scared after seeing that:laughing:


Dave
 

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John Hyatt
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I wish I didn't have pt lumber shrink ( and a lot of other things ) but it always does.

Not understanding at all builders that don't have a lot of movement. We always jam the decking up with no gap at all unless making up for the really bad mill and using spaces to come out right in the end.

I am finishing up an econo pt decked project with incense cedar rail now. The decking is 3 days down and has 3/8'' gaps so far. The finish is going on today but it is cosmetic only I don't expect it to help with the movement. I don't understand waiting to put the finish on either.

What kind of world could it be where pt decking doesn't shrink in width ?

JonMon www.deckmastersllc.com
 

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Always lay them tight and end up with 1/4" gaps in about 1 -2 weeks. Don't forget the boards shrink in height also. It is not uncommon for us to go back and double check screws.
If we would sink our screws a little deeper we might not have to do that, but I don't want to have a screw head very far below the surface. Just a little deeper than flush is my goal.
 

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No gaps here either.
I know it was standard practice years and years ago to gap about an 1/8" or the thickness of a 16d nail.

But, I don't know if the material changed our what, but if you did that today you'd have over a 1/2" gap when the lumber had time to dry.
 

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Discussion Starter · #11 ·
Thanks for the input guys.

Looks like this PT deck I have coming up will be going in with no gaps. The decks get full sun all day too, so that wood should dry out in no time!

I'll be going back to a PT deck job I did last year for some other work in a month or so. I spaced those boards with 8 pennys. I'll be curious to see how big those gaps are.



Dave
 

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Thanks for the input guys.

Looks like this PT deck I have coming up will be going in with no gaps. The decks get full sun all day too, so that wood should dry out in no time!

I'll be going back to a PT deck job I did last year for some other work in a month or so. I spaced those boards with 8 pennys. I'll be curious to see how big those gaps are.



Dave
Don't wear your Stilettos over there.
 

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We must get drier PT wood up here cause it really doesn't shrink that much. I did a balcony deck last year and butted up the boards and to my surprise, this year they're still the same. Now all sorts of crap get stuck in there and it's a real pain. I'm a proponent of a slight gap every time now........
 

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John Hyatt
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With the job I mentioned before putting the finish on was interesting.

Most of the time I try to talk the Wallet out of PT decking but this one was on the north side with a lot of big trees providing shade most of the day so I figured they had a fighting chance with it. They were also real tight on the money with a new born and a recently purchased older home and they were honest with me.

By the time the finish went on some of the gaps were a strong 3/8 ''. I mixed up three colors of TWP giving the light green PT a red /brown look but getting the finish on the sides of the decking in-between the gaps was a must as they showed up almost white in contrast same with the top of the exposed joist.

Ace hardware sells a 4'' high quality brush with threads in the back of the handle. Screwing in an expandable paint pole made it possible to get into the gap standing up. It worked so well and the 16' x 16' deck was not all that big so I used the little thing to brush the finish on the whole thing, really didn't take all that long.

I recommend Ace Stores all together. Their prices are comparatively low, high quality, and well informed sales Folks. They really beat out the box stores completely. That brush was $11 and they sell TWP two dollars a gallon less than even my local lumber yard's contractor discount. Using their free Rewards Card I get a check from them every month or so.

So a big Hell Yes shout out to those Guys. :thumbup:

Only time will tell if the shade helps out with the split/crack/ splinter PT thing down the road.

JonMon www.deckmastersllc.com
 

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I always slam PT decking tight knowing it will shrink here, usually a lot. I've seen some decks built with PT decking that under roof or large trees & they do much better than out in full sun.

Heck even ipe shrinks alot here, putting down some last week that went from 5 1/2" wide to 5 1/4" in a week.
 

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Not to ask a stupid question, I assume you are talking about injected pt with the knife marks? I have used Elite Wood dipped pt decking in the past and haven't had much shrinking on the few I did.
 

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Not to ask a stupid question, I assume you are talking about injected pt with the knife marks? I have used Elite Wood dipped pt decking in the past and haven't had much shrinking on the few I did.
Our PT doesn't have the knife marks, but still shrinks like crazy. I butt them tight and get .25" gaps in a year.
 

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John Hyatt
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The incisions are used on lumber that can not absorb the pressure treatment. The lumber is placed in a retort that is pressurized with several chemicals not really injected at all.

Yellow pine has so much sap wood there is no reason to go through all that .PT hemlock needs it.

J.
 
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