Fluted decking...Up or down?

I've built about 250 sq.m of decking around our house, about half replacing existing deck which had the fluting facing up. Some tradies I spoke to reckon this is correct.

Advice direct from manufacturers/importers specify the design is to face the fluting down (which I have done) to allow ventillation and prevents rot between the joists and boards and prolongs the life of the deck. My own experience with fluting up is a build up of mildew which becomes slippery.

Is there a definative answer to this or is it just personal preference regarding asthetics?

Manufacturers are right, reeding goes down for the reasons they stated.

Sorry...didn't do a search for "reeding" or "grooving". :doh:

Found it.:-

Reeds always down :2tsup:

Cheers

Really simple one ribs DOWN

Ribs are to give ventilation between the top of the joist and the underside of the decking

cheers utemad

I know of one instance where the deck was being installed with the ribs facing up - the reason the tradie gave was for traction in wet weather. Luckily the person having the deck installed caught him before he had laid too much decking. He told him to rip it up and put it around the other way.

Logic would dictate that ribbing facing up would not only rot the timber underneath where it hits the joists but also it would also allow water to sit on the deck (in between the ribs) for longer (no ability to run off) and hence degrade the wood faster...but then again logic doesn't always come into it.

What reasons did the tradies give for ribbing facing up?

What about all the 140mm decking that is dressed on both sides (no ribbs)?

Dr - 307.

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Originally Posted by Dr - 307

What about all the 140mm decking that is dressed on both sides (no ribbs)?

Dr - 307.

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In that case the timber has to be laid on its edge.....

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Originally Posted by Brickie

In that case the timber has to be laid on its edge.....

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.....That would be called dicking...No?:rolleyes:

Gees that'll incrase your lineal to m2 rate to something like 40 lineal / m2...

Might try that as a new selling pitch could be a winner but i would need seriously long screw to fix it down

Food for thought thanks bricki


cheers utemad

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Originally Posted by UteMad

Gees that'll incrase your lineal to m2 rate to something like 40 lineal / m2...

Might try that as a new selling pitch could be a winner but i would need seriously long screw to fix it down

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liquad nails FTW :2tsup:

Never thought of that ... a shot of liquid nails on the joist and a brad driven through on the angle would do the trick.. we definately are onto a winner here.. i can hear the timber merchants getting ecited already


cheers utemad

Funnily enough I built a deck once with the decking on its edge - the look being sought was for a 'grid with depth' and as client is always right that's what I built.

Just used threaded gal steel rod steel rods hole drilled through face and a nut between each board as a spacer. It was not a huge area (3m x2m) and I used timber of identical lengths. A little fiddly, but simple enough. It was being painted so was primed and painted before assembly then put together. Used brackets underneath to attach to joists which were spaced at 900.

Solid and good looking result, if not my to own liking . . .

BTW - flutes DOWN

Definately flutes down for appearance sake, and least chance to retain water up top.

Now playing devils advocate, would it really matter if you are laying treated pine planks (uggh) over treated pine joists?
Most caravan park cabins I see are done just this way, and everybody assumes it is right for grip. :no:

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Originally Posted by zathras

Definately flutes down for appearance sake, and least chance to retain water up top.

Now playing devils advocate, would it really matter if you are laying treated pine planks (uggh) over treated pine joists?
Most caravan park cabins I see are done just this way, and everybody assumes it is right for grip. :no:

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Yeah it will matter as treated pine grows algae as bad if not worse than hardwood.. Also treated pine dries out worse than hardwood and splits sooner with the little ridges curling up like spikes making the deck unwalkable in bare feet in a not so long time frame if exposed to a lot of sun... Treated pine decking might not rot in the way hardwood does but it deteriorates in its own way which still renders it useles

cheers utemad

Hi all,
Getting back to the topic, after that little sidetrack by brickie:-) here's my take on it.

Going for the lower end of the price range an architect once specified Selangan Batu hardwood decking.

So with about four packs on the job I say to the owner before we start, "which way up", "smooth side up" sez he.
I then lay out about six boards smooth side up for him to look at.
At least two of them have patches of rough saw marks on them because the boards are a touch on the thin side.
"That's no good, you will have to cut the bad bits out". So I explain to him that these boards are all like this, they are milled with the best looking face to be the reeded side. They go through the six header and the bottom cutter is the reeded one, any variation in timber thickness shows up on the so called smooth side.

When he was given the option of having smooth side up and paying 15% extra for waste, he saw my point and we compromised. We put ever 5th. board reeded side up. (the rough patches out of sight). It looked OK too. Everybody happy. Ten years later it still looks OK.

We always whack heaps of preservative on both joists and boards before fixing and I've had no comebacks whichever way we lay them.
We do it the way that the customer wants. I quite like reeded up.

When asked why I usually say that it holds a lot more decking oil and allows more of it to soak in.

You say you want the interface between the boards and the joists to breath, so how come you don't apply the same logic to every other external timber to timber joint?

To my way of thinking it is personal preference, nothing else.

Cheers
Bill.

How funny heres me thinking the topic would have died in the a#rse with the first reply of reeds face down but obviously not......

This might have to go with the topic of screws or nails which never seems to end either LoL


Billbee don't you allow 12 - 15 % wastage anyway due to random length and rubbish bits? Time is money i will go even higher on wastage just to know i have no quality concerns and chuck the leftover on the ute for next time.. Can understand DIY trying to use every last piece but not tradies... It comes down to how long do you waste getting in the ute to get another piece and at what inflated price will you pay to get it close to the job your on... I build a deck once and to put down a board that is sub standard is a waste of my time cause if the customer refuses to pay until its replaced its a bigger waste of my time than leaving the board out and putting in a good one to start with...My way of looking at it i spose but not necessarily the right or only way


cheers

Utemad