What spacing between boards on a deck?

[Tom Wassack]

Dennis,
I visited the Wolmanized website (http://www.archchemicals.com/Fed/WOLW/Docs/Outdoor/Building_Maintenance_Tips_7-07.pdf) and per their building tips, dry lumber should be gapped no more than 1/8 inch. That's close to my 16 penny nail diameter and after nearly a year of exposure and many wet dry cycles, my decking gap has never opened up enough to present a trip problem. So to answer your question, if using lumber dried after treatment, rather than wet dry lumber, I would leave some space between decking boards. Of course all is contingent on the dryness of the lumber at installation.

Respectfully,
Tom Wassack
Asheboro, NC

[Chris Padilla]

Overall, you want your wood ACCLIMATED to its environment. That is when it is at its most stable. Yeah, it'll still move if your climate has large swings between summer and winter but it should move less after it has acclimated....

[Steve Sawyer]

This thread really pees me off!

Not at you guys, certainly, but with the results I got after trying to things "right".

VERY CAREFULLY oriented the growth rings so the boards would cup down, and butted the very wet PT lumber so a gap would form as they shrank.

Like Charles above, the gaps are so small that everything and anything gets stuck in 'em, and the only way to get 'em clean is to use a pressure washer or go between every board with an awl or something. I'm getting ready to build a PT porch on the other side of the house, and I'll be putting at LEAST a nail-width gap between the boards.

Also, the stupid boards STILL cupped upwards!! Needless to say, the deck hasn't held up real well, but my dog loves to drink from the puddles that form on all the boards!

[michael osadchuk]

I butt the p.t. 5/4 decking and it's worked out find - no "stress" (buckling) and the rain still falls through.
The issue about "debris" not falling thru the cracks: I sweep off the seeds from a linden tree growing in the middle of the deck.

Remember, it's not only debris that falls thru cracks but also keys, that precious screw, etc. that will fall thru.....

good luck

michael

[Bob Aquino]

Overall, you want your wood ACCLIMATED to its environment. That is when it is at its most stable. Yeah, it'll still move if your climate has large swings between summer and winter but it should move less after it has acclimated....

I am putting a deck down (rebuilding actually) right now. The wood you get is very wet. If you wait till it acclimates, you will have nothing but bent and warped boards. It HAS to go down wet so its reasonably straight. I also agree with butting it up or going with a minimal gap.

[John Callahan]

Dennis, I think KDAT(Kiln Dried After Treatment) would be the exception to butting them up as Tom's experience indicates. KDAT is usually dried, iirc, to 19% or so- much drier than non-KDAT. Non- KDAT, you should probably be safe to butt them up. It all comes down to MC.

[Myk Rian]

We did our deck 20 years ago with 2x6 PT. I used a 1/4" drill bit to space them. They are now at 3/8". All the maple seeds go right through them.

[Chris Padilla]

I am putting a deck down (rebuilding actually) right now. The wood you get is very wet. If you wait till it acclimates, you will have nothing but bent and warped boards. It HAS to go down wet so its reasonably straight. I also agree with butting it up or going with a minimal gap.

Yes, you will have bent and warped boards if you don't sticker it PROPERLY: level and with weight on top. This is true for drying ANY lumber....

[Rick Gifford]

Using pressure treated limber that is wet you want to butt them tight. They will shrink and make their own gap. Otherwise a 16 penny nail is about the right spacing.

I have seen others leave a gap when laying pressure treated and wow, once it shrinks the gaps are huge!

I always butt them tight. 100% guaranteed advice or your money back.

[Ed Henderson]

Well, it's now 7 or 8 years since this thread discussion. I am preparing to redo a deck I built about 1990 or 91. I used nails and spaced the boards one nail width apart. The wood was spruce. I did stain the boards all 6 sides before putting them down. After installation I covered the deck with outdoor carpet. The carpet lasted about 5 years before it got ratty. I removed it and was astounded at how well the deck boards looked so left it at that. Since then I have replaced several boards that rotted. Now I want to remove the existing boards and replace them with pressure treated 2 x6 and 2x 4's.
I have been wondering if I should space them the same or butt them. I do not intend to cover them with outdoor carpet. Scraping our winter snow and ice off ruins the carpet.
I suspect that the boards I get will be a bit less solid than the boards I bought 27 years ago so they may absorb water more and faster. I do intend to stain them before putting them down but am apprehensive that when the top gets some use from feet and snow/ice scraping the boards may hold water and rot quickly.
I would appreciate some thoughts and recommendations.

Thanks
Ed

[Eric Anderson]

As one of the posters stated 8 years ago. think about your deck's location. I get a huge drop of cedar elm leaves each fall (which in Texas means August through December). They are small, and if you don't leave a sufficient gap to push them through, they will get stuck and rot the boards (I used redwood for decking material). So I leave a good 1/4" gap. If I wasn't fighting leaves, I would use a smaller gap, but I had to replace most of my decking after about 15 years due to rot from having wet leaves stuck between the boards and the elm leaves are hard to remove.

[Mike Henderson]

As one of the posters stated 8 years ago. think about your deck's location. I get a huge drop of cedar elm leaves each fall (which in Texas means August through December). They are small, and if you don't leave a sufficient gap to push them through, they will get stuck and rot the boards (I used redwood for decking material). So I leave a good 1/4" gap. If I wasn't fighting leaves, I would use a smaller gap, but I had to replace most of my decking after about 15 years due to rot from having wet leaves stuck between the boards and the elm leaves are hard to remove.

That's the same problem I ran into with composite decking. If you space them too close, the space fills up with stuff that falls off the trees. It's almost impossible to clean.

Mike

[Mel Fulks]

Plywood sloped at least 1/8 per foot and covered with glued canvas ,then painted. Lasts a very long time ,like the same treatment with boards used to. Has a long proven history.

[Phillip Mitchell]

I'm of the mind that you make the call based on the moisture content of your decking combined
with the deck's location in relation to sun, wind and rain exposure as well as any falling leaves / organic material that will inevitably get stuck in between deck boards.

I built a deck at my house nearly 2 years ago and used 2x6 western red cedar decking that was in the 20-30% moisture range at install. I spaced it with a jig using a 16d nail (light 1/8") and still have very consistent gaps that don't exceed 3/16". To me, that is the perfect spacing visually and not very much debris clogs in there. My deck has full sun, rain, wind exposure but doesn't have any trees above it close by.

Most PT decking that I've laid elsewhere has been sopping wet (water sprays out when you drive deck screws into it) that I would not space it 1/8", but the problem I've found is that when installed butted tight under those circumstances, the decking does not shrink at the same rate from board to board. Different moisture contents and grain patterns cause inconsistency, and can lead to a sloppy looking deck.

If I was using PT and cared about a consistent deck board spacing (for looks, drainage, etc) then I would use KDAT and space it 1/16-1/8" at install, expecting it to shrink a bit if exposed to direct sun.

[Andrew Hughes]

My deck is also spaced with a 16d nail.5/4 port orford cedar.The gap is a little big in the summer but perfect in the winter.The wood was dry installed in the fall.