Decking - grooved side up or down?

[sawdustmike]

Jarrah has only the good side grooved. The guy at Gunns (what used to be Bunnies) assured me that groove down was only invented by some wan*er on a tv show. However... it does make some sense to go groove down as per other posts or groove up, as per other posts. Ah this is just like the daylight saving arguement - perennial.

[Harry72]

I reckon lay'em groove up then next one groove down... at least then yer only half way wrong!

[russ34]

GROOVES DOWN...the way it was always meant to be...also,a knock on the surface of the smooth face is less likely to damage/splinter as if it were laid the upside down.....but if anyone insists on their deck holding water and mould on the surface, splinters in their feet and a deck that is difficult to sweep dirt from, go the grooved look

[russ34]

just as importantly, the pine has excessive expansion and shrinkage, looks horrible and buckles terribly

[Gumby]

One other major factor is cleaning. Much easier with grooves down with less trapping up dirt and dust.

[silentC]

I have built acsess ramps that always have the groove up and running across the slope. I wouldn,t do them any other way.

That's one situation where it might actually be a good idea.

Most decks are treated pine and should be able to stand being damp.

I wouldn't say that. Most decks I've seen around here are hardwood. There are T/P decks but most people consider them, cheap.

If the smooth side was the face then the ripple side would be on the outside of the pack when they are delivered.

I got a heap of Merbau decking earlier this year. Many of the boards are still showing the original rough sawn surface. Without exception, this is on the groove side.

Jarrah has only the good side grooved.

I've haven't bought jarrah decking but don't know why it would be any different to any other hardwood decking. See above.

The guy at Gunns (what used to be Bunnies) assured me that groove down was only invented by some wan*er on a tv show.

You actually believe what someone who works for Bunnings tells you?

As for non-slip, the grooves might help improve traction perpendicular to the grooves, but they are even more slippery parallel to the grooves because of the reduced surface area under your foot.

[pharmaboy2]

oh, why not just jump in. I was having a read of the public works specs for buildings, the modwood product and treated pine was mentioned and specified that in non weather protected areas that it is to be laid groove side up perpendicular to the usual direction of travel across the space.

As for manufacturers, CHH recomend reeded side down for air flow, but gunnersons say, reeded up for grip or down for look - your choice. So probably the only people who are wrong are those that categorically say that one way is right, given there's a debate amongst manufacturers, and I'm pretty comfident that the people who make the stuff know their product pretty well.

My best guess is that reeded side was introduced to try and minimise cupping, but the marketing dept decided that would be admitting a failure, so some have changed the message to helping dry out, and some for grip.


For those that are convinced as a certainty that its to stop rot, and should be laid face down - think about this for a second - cca is immune to fungal attack and will not rot without seriously improper installation. Further proof of the longevity of the product can be found in any boardwalk over wetlands where they use , guess what?

The answer is 42

[bennylaird]

Exactly

6 x 9 = 42

[silentC]

Well, there are really two questions that need to be answered:

1. Why was the practice introduced?
2. What is the best way to install it, the above notwithstanding?

It seems as though getting an answer to number 1 is going to be difficult. Everyone thinks they know why it was first done. I know why I think it was done but I don't have any way of proving it. However, it doesn't really matter very much, does it?

As for number 2, it probably depends on the situation. I will always put it groove side down because a) I don't like the look of the reeded side, b) it seems to me that this is the way it's meant to go, and c) it's harder to keep clean with the reeded side up.

I have lived in a house that had a grooves up deck and you have to sweep it with the grooves, which doesn't always work out to be the direction you want the dirt to go.

Finally, if you install it groove side up, some people are going to tell you it's upside down. If you install it groove side down, or use the non-reeded variety, no-one is ever going to notice.

[silentC]

For those that are convinced as a certainty that its to stop rot, and should be laid face down - think about this for a second - cca is immune to fungal attack and will not rot without seriously improper installation. Further proof of the longevity of the product can be found in any boardwalk over wetlands where they use , guess what?

They do it on hardwood decking too, not just treated pine. The rot argument suggests that the reeds help prevent the joists from rotting, not the decking.

[Ashwood]

I agree with SilentC. I lived in a rental place previously with the grooves side up. It's a bloody pain trying to sweep any leaves, flowers or dirt if the grooves are side up.

[outback]

Why not use cement?

[bennylaird]

To keep the deckheads out.

Too many deckheads in China

[Donno]

Wow

there certainly are a few reasons for and against grooved side down or up. I have decided, and in fact have laid the decking groove side up. (Sorry to those advocating the opposite ). The deck is covered and is not likely to become damp at all so I really have no rotting problem. Yes I get leaves blown onto the deck and yes it is a pain in the @rse to sweep the leaves up as well as dog hair. However I tried a few strips of decking prior to screwing them into place and I liked the look of the grooves on the surface. I guess that is the best guide I would offer if anyone asks me the same question after reading all of your most welcome and highly respected responses.

Thanks for the information because it really assisted in ensuring any decision I made would not be too drastic.

Donno

[silentC]

Thanks for the information because it really assisted in ensuring any decision I made would not be too drastic

But you laid it all upside down. You can't get any more drastic than that :eek: