Decking ridges up or down?

April 5, 2005 11:48 PM

Wooden decking ridges up or down?

I have an extensive area of decking out the back of my house, installed by the previous owners. The ridged side faces up, which I assumed to be for traction when wet.

Then, at a party, I was chatting with a friend about the decking, and the fact that I will be replacing some sections of it, and he commented that it was upside down, because the ridges are there to prevent moisture build up where the decking planks rest on the beams.

Both ways make sense to me, but I'm confused. Which way is the best way?

posted by tomble to home & garden (5 comments total)

I think you are right. The ridges are for grip.

I don't see how having ridges down and in contact with the beams would prevent moisture, if anything it'll create channels where more moisture can get it.

Of course as the wood is usually pressure treated, and should be painted or treated with a waterproof coating the moisture reason is a moot point.

(Note: I am not an expert but have seen plenty gardening TV shows!!)
posted by snowgoon at 12:47 AM on April 6, 2005

Timber Decking Installation

"Pine decking is often supplied "reeded" i.e. with ridges dressed along the length of each board. Although often laid reeded face up, reeded decking is actually intended to be laid reeded face down so that the reeds form an air gap above the joist to allow any moisture to escape. Also, by laying the reeds downwards, any splinters of timber formed by the reeds will not be hazardous."

(First result when Googling for +"timber decking" +"ridges". It's also what I learned as a kid from my family of builders.)
posted by Pinback at 1:42 AM on April 6, 2005

Also, if you lay them face up, they'll be a royal pain in the ass to keep clean.
posted by Optamystic at 2:51 AM on April 6, 2005

Thanks Pinback! I googled for it but still couldn't work out which was the right way.
posted by tomble at 6:00 AM on April 6, 2005

Caveat: IANACarpenter but I play one in my basement. My experience is with cabinetry-esque stuff, not decking.

I haven't dealt with reeded decking but if it's only reeded on one side I'd expect that the reeding would therefor be done on the 'inner' side. Wood in an application like this should be set bark-side outwards, or with the curve so that the grain looks like a dome, not a cup.

Sites like http://www.woodworking.org/ have information on grain orientation and the like if you want to learn more.
posted by phearlez at 10:22 AM on April 6, 2005