I am building a deck at my home in northeast Ohio. Obviously it will see sun, rain, and snow. I will be using 2×6 pressure treated for the deck boards. I have found differing opinions as to how wide I should space these boards.
Some things I’ve read say to space the boards with a 16d nail, another article recommends a three-eighths inch gap. The author of the article recommending the wider gap says that water and debris will fall through more easily and air will flow easier through the wider gap. A local carpenter is building a deck for my friend and he butted all the boards tightly together. His reasoning is that they will eventually shrink and leave a small gap which will be adequate for water drainage.
I’m confused. What’s the best spacing for something that will see all four seasons? Or does the spacing really make much of a difference?
Replies
the nail
I'm not flippin' you off.........just counting cubits
Go with the 16d for your spacer, it's consistant, and you can just tack them in on your joists, pull the next board in. Keep it simple. Nice size spacing.
I just built a deck using PT decking for a customer. Spaced the boards with a 10d nail. If I did it over I'd have butted them or spaced the just a touch (a finish nail or equivalent). In a month or so the spaces have grown more than I'd like. The customer is happy, and they will drain water and clear plant detritus petty well, but to my eye they are a bit too big.
Wood moves. PT is pretty well saturated, and my guess is that even if it's kiln dried after treatment it will sit in the same deadpile outside at the lumber yard and swell up again. Check with your supplier and see what they recommend. Plan accordingly or pay for a more stable and premium decking material.
-Rob
I would butt them up tight. You'll end up with gaps larger than 1/4" inch.
16d nail... BUT.....if the stock is especially dry....then i'd go wider...
AND... rethink if you even want to use PT... it's not a very good decking material... almost anything is better than ptMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Butt them tight, even tight you may get a 1/2" gap in very dry weather.
mike
It depends on how long you've had the PT decking on site, and what conditions you're storing it in.
BUT, every PT deck I've ever done I butted tight and I have never been disappointed. About five years ago, I was doing several a week with a guy I was working with (new construction development) and we used a Bo Wrench to lever them down tight.
It's quite possible that the decking material that we get is more wet or a different grade or something than the others who have said to gap it. But, if you were my neighbor, I would tell you, unequivocally, to butt it tight.
Your gaps, when dry, may not be as even as you're hoping for, but that's the nature of PT lumber. It is a fine decking material IF you are willing to maintain it and are not expecting if to look like it's new 7 years down the road. Mike's right, in reality, that it is not a good decking material if you can afford something more because few will put the time necessary in to their deck.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
I usually use a nail spacer but in any event it's just a guess as to how much each board will shrink. To me it's wood exposed to the weather and a little variety of crack is life outside, more with how it should look. But that's just my taste, embrace reality. Once in a great while a typ board will shrink enough in length to have to be replaced. The voodoo of typ.
If the wood is wet, make the gap small or zero. If the wood is dry, leave a slightly larger gap.
I use a flat carp's pencil as a spacer. And I lay the heart up so the boards crown as they dry and not cup.
Also, as Mike Smith said, forget using PT for the deck. It's garbage and will make a lousy looking deck, plus, it's just loaded with poisoned splinters waiting to attack the feet of anyone who walks out there barefoot...like your children or grandchildren. Use cedar, or ipé.
Top your joists with roofing membrane or 100# felt before nailing on the decking.
Use stainless or HDG nails.
And make sure to flash the frame properly to protect the ledger.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
another thought....I haven't read all the other posts yet but PT for the deck isn't a good idea due to possibility of splinters into bare feet.............
got kids or pets?....reconsider and maybe go with something else......I'm sure some of the pros or medics that lurk here can elaborate better......
ever have a splinter from PT wood?.........can be painful to some and easily infected, or allergic reaction to the chemicals
I'm not flippin' you off.........just counting cubits
Edited 6/6/2009 11:55 pm by oldbeachbum
so... consensus says "tight"... but consensus is wrong... depending on your micro/macro climate
here if you lay a deck tight in summer...it will buckle next spring..not enough expansion room
your Ohio climate has very wet Springs too.... i'd be gapping in your area
also... if you have any kind of trees in the area, the small /non-existing gaps will clog with debris
basically,pt (SYP ) is too unstable to make a good deckMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
I've laid every deck tight when using PT and the gaps are always too wide after shringage for my tastes.
About 2 years ago I had to replace a couple of PT boards in a deck.Got the replacements and no way would they fit. Kept them in my garage and went about about 4-5 weeks later and they slipped right in place. And these where dampish feeling. Not the squirting wet that you sometimes get..
William the Geezer, the sequel to Billy the Kid - Shoe
My opinion is unqualified because I have never done a PT deck, but otherwise I agree with you. Strange, ain't it?Helen busy this year?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
If the pt is wet, we make it tight. If it's dry, space it with speed squares... just make sure they're all tHe same brand <G>http://www.tvwsolar.com
Now I wish I could give Brother Bill his great thrill
I would set him in chains at the top of the hill
Then send out for some pillars and Cecil B. DeMille
He could die happily ever after"
you have noticed different thicknesses too? hopefully didn't have to remove too many boards because of that.
Aren't you glad that's settled? Got any other questions for us? :-) Seriously, the guy I worked with did a lot of bad things, but we always butted PT decking, because, as others have said, it is wet to begin with and will shrink. I have had it "splash" when screwing the fasteners into it or hammering a nail in. If it were cedar, I would do what we used to do when I worked with another guy and use spacers. Cedar makes a nice looking deck--though it is sort of splintery too.
Since this is your house, your best bet is to answer the questions about spacing and material all at once. Don't build a deck. Build a something else.
A 16d nail is good. The gap will be double that in time. 3/8" will eventually catch all the girls wearing high heals and you'll have to rescue them, not that that's a bad thing but some of those big legged women are hard to carry off.
Beat it to fit / Paint it to match
If you're using new PT lumber, I'd do it without a space. The stuff is wo wet when you buy it that it's sure to shrink enough.
And if you don't do it all the same day - adjust accordingly according to your best guess. I did mine over a week or two with PT, and since it dried while waiting, there is a visible difference between where I started and where I ended.
Excellant point BobRat.
From my own experience with pressure treated lumber, i'd say no gap at all. I dont lnow about other woods but my decks with PT tops have good gap After a season or two of drying out.
Family.....They're always there when they need you.
I only used a pt 2x6 for decking once and didn't space it at all. 5/4 decking NEVER space, alwyas nailed/screwed tight and you will have a space 1/4-3/8 shortly after the deck is done. Obviuosly things are done different. Where I'm from pt decking is never spaced.
I agree with you on that.
I wonder where Mike gets all of his dry PT, that he doesn't space.
The poster should know that the 5/4x6 is a decent product for PT wood and really doesn't need the 2x6, but what do I know?
i could show you picture after picture of PT decks,,, 5/4 x 6 Premium....
with no gaps, debris and moss, and buckeling boards...
but i don't have any picture allocation leftMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
show you picture after picture of PT decks,,, 5/4 x 6 Premium....>>>>>>>>>>>..
I wondered who got all of the dry PT wood, now I know!!>G<
Mike, I'm curious......You say that with no gaps, buckling, moss, and debris are an issue. Is it your experience that starting with a gap prevents buckling?
(IMO, moss is a function of sun vs shade, and debris is a function of the size of the debris vs the final size of the gaps -- and leaves and such seem to need a 2" gap at least.)
Politics is the antithesis of problem solving.
moss is also a function of food and moisture... if the boards can't drain easily they will stay wet longer... debris and dirt will also hold moisture and feed moss
buckeling occurs when the boards have no room to expand, so one edge lifts and the boards "buckle"... i'm not talking about "cupping"Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Installation is hard without a minimum gap. Using a 16d helps you cheat things a little as you go. Otherwise the boards may start to have a curve develop mid way across the deck. It isn't easy to get them all perfectly tight and if there are any small problems, it starts to telegraph through the next pieces. A little gap gives you some fudging room that won't show the way curved rows will. There can also be some variation in the width of the 5/4 PT. In my area there is premium PT 5/4 decking available. It's knot free and a big improvement over standard PT 5/4. Eventually the face will check as will all PT. If you keep up with the maintenance, applying a good deck coating every few years, the premium PT isn't too bad and it will last a very long time, coated or not. It's still the least expensive choice if you don't have to have a designer deck. There is a lot of work in keeping a fancy deck looking good over the years, it's not for everybody.Beat it to fit / Paint it to match
The first thing I do is to check out how many trees are going to be shedding leaves and such onto the deck and also how much sunlight and moisture in the immediate surrounding area. More trees means more debris. More debris means I want to end up with a wider deck board spacing. Then I consider the material I am going to use. If it is man made I will defer to the manufacturers suggestions. If it is wood I will consider the species and how much moisture is in it at the time of installation. If the board is wet I will leave less or no gap. So I don't use a rule of thumb except that every one has to been considered individually. And I always make sure the deck has adequate ventilation from below. I got bit on an Ipe' deck (12'' off the ground with a 2 rise wrap around step) that was specked by an architect one time. We built as specked and the some of the boards warped and we ended up cutting ventilation into the riser and replacing some of the deck boards.
QS
Deck Board Spacing
Many years ago I was helping an EXPERIENCED contractor put down 1x6 and 1x8 subflooring over floor joists in a new house. Somehow he decided to tightly "space" all these boards side by side ...we even used crow bars on the really crooked ones ( you buy very cheap #3 boards for subflooring) to "nudge" them into alignment. After we got the whole subfloor in place and were ready to raise the walls ..it rained ..IT RAINED HARD on that new "perfect" tight sub floor.
The wood expanded ... as much as two feet breaking the cinderblock foundation in 5 places and required complete tear-down and rebuilding the floor joists too.
The moral of this story ...from the University of Experience ...is don't ever ... EVER close space boards exposed to weather.
Can you imagine the damage and cost to repair if it had NOT rained that day ... and the whole house had been completed. The expansion and contraction from normal weather humidity changes through the years would have totally destroyed the whole NEWLY BUILT house. Sooooo when you are in the basement looking up at all those gaping holes and spaces in the sub flooring ... marvel at the skill and experience of the builder and framing sub-contractors.
Ol' Mike
no space
some people use a speed square as a spacer. Personally, I did a double herringbone deck 24' x 12' last spring and i butted all my boards tight, the boards have a nice 1/8" gap now
jeff with all the y's
The real question of gap or not is a bit more complicated.
Is the wood wet? if yes, will it shrink? How much?
Is the wood dry? if yes, how much can it expand?
If a composite-will it expand or contract according to temperature and if so, how much.
PT woods
I'm going through the same dilemma about PT spacing. I called the manufacture of my premium PT. I'm in the NothEast and will be installing in September. You want to dry the wood by putting some woods sticks on the ground and PT over it. Let it try between 6 to 8 weeks. Install it butt up against the other piece or 1/16" max. In the cold it will shrink up. It is important to stain the wood before snow. Since you dried the wood you can stain early. This guy had 27 years experience.
The pressure treated lumber nowadays shrinks so rapidly. I always butt them tight and draw them in and they still manage to sharing enough for ample spacing. Large gaps between boards are not attractive.
One point: With real wood (yes, it does still exist) the boards will rarely be completely straight and often cannot be forced completely straight when setting. A decent sized gap (at least 1/4") will hide minor imperfections in straighness better than having the boards tight together.