Decking wood cracking just after few days

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KS

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#228981 1-Feb-2018 18:53

Hello! We just purchased Premium decking wood (pine) to renovate our old deck. Just after few days, we noticed that the significant amount of the boards get cracked.

It is not related to the screws - as the boards which haven't been installed also have the same cracks. We got back to the supplier, but they were very unhappy and irritated about our request. They said the wood is "natural material, and it is normal for it to crack".

I do understand that it is weather related issue, and the cracks are result of the wood getting wet and dry after that. My question: is it normal for the decking wood, premium (!) decking wood to start cracking just after several days after installation?

It is a large deck, and approximately 30% of the boards now have cracks in it. Is the supplier right? Is there any standard in New Zealand, which specify this kind of things?

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#1950274 1-Feb-2018 19:19

That does look like quite thin decking which potentially could be affected by it more. But some cracking is normal, and the amount of it looks similar to mine.

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djtOtago

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#1950292 1-Feb-2018 19:52

If its Pine then yes.

jjnz1

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#1950294 1-Feb-2018 20:01

Sorry mate - premium pine decking is not premium decking. It just means less knots etc.

If you wanted a perfect deck, maybe change to an engineered product IE composite decking. Even kwila is not perfect.

Hope this helps

KS

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#1950350 1-Feb-2018 21:05

It was actually wet at the time of purchase, and when it is getting wet, the cracks are not that visible. As soon as it getting dry, the cracks are getting wider, and more visible. Nobody warn me about that at the time of purchase. My understanding, they keep it wet intentionally, to hide the existing cracks. The main point here is that I would never purchase this product, if know about the cracks. And I am sure, there is breach of the Consumer Guarantee Act. I paid crazy, CRAZY money for this rubbish. In fact, they should not sell the wood of this quality, or offer it for free as fire wood.

Now, the main question is is it worth to go to the Dispute Tribunal with this issue...

Anyway, thanks for your responses, guys. Could you please suggest, what can I do to prevent the cracking? It looks like it's getting more and more cracks every day! ... and the existing cracks are getting bigger.

mdf

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#1950356 1-Feb-2018 21:18

All wood, but particularly soft wood like pine, expands and contracts due to moisture/humidity (wet = expands, dry = contracts). Wood will acclimatise (somewhat) to your relative humidity and the expansion and contraction will reduce. If the wood was delivered very wet, it will take longer to acclimatise. Your's looks like its been flat sawn, so will expand and contract more.

Once it has acclimatised, a finish (e.g. decking stain) will slow the rate of expansion and contraction somewhat. Decking stain will also stop the pine from going that weathered grey look (which I personally do not like). It will also lengthen the overall life of the deck, particularly at the ends.

It does just look like surface cracking in the photo you've posted. Most woods will get some surface cracking. It doesn't affect the utility or structural integrity of the deck.

wally22

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#1950358 1-Feb-2018 21:24

Premium grade pine decking is about 2 grades down from the best you can get.

The others are 1. Clears, which means no visible knots, or 2. No. 2 Clears, which means 2 faces clear of knots, usually 1 broad face (width) and 1 edge (thickness). there are variations on that amongst suppliers though.

We endeavour to not sell 25mm pine decking (finished size approx 19mm) as it invariably creates disputes with the customer. 40mm (finished size 32mm) is much more robust and doesn't require as much framing, so ends up costing about the same.

In the OP's case, thinner boards split more easily, the cut from the log may not be optimal, or the log itself may be unsuitable. Or a variety of other reasons.

Composite has a bad rep amongst 'mature' builders, but I don't know anything about that.

If I was building a deck I would overspec like crazy, as the code is a MINIMUM standard. But even 50 or 100mm boards can split in the weather.

wazzageek

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#1950361 1-Feb-2018 21:27

@mdf beat me to it - I was going to suggest a decking stain / oil, although mdf suggests waiting for the wood to acclimatise as well ... which is something I would have neglected.

The other thing you can do is put up a shade sail to aid in the timber not getting as hot during the day (assuming that it's hot where you are)

When you come to staining your deck, I'm a stickler for not using a high pressure water blast to clean before - I use water and a brush ... and loads of elbow work.

mdf

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#1950366 1-Feb-2018 21:48

wally22:

<snip Composite has a bad rep amongst 'mature' builders, but I don't know anything about that. </snip>

I've never been able to bring myself to use composite. The hollow stuff looks like plastic, and (apparently) the solid stuff heats up sufficiently that you cannot walk on it in bare feet. Mrs MDF also invariably vetoes such things.

That said, by the time you've straightened out your 122nd banana board, something that is guaranteed straight is *mighty* appealing.

Bung

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#1950416 2-Feb-2018 06:22

As soon as you commit to building a deck buy the decking, stack it properly and cover it. The timber probably arrived "wet" and now is drying too quickly.

scuwp

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#1950440 2-Feb-2018 08:18

Bung: As soon as you commit to building a deck buy the decking, stack it properly and cover it. The timber probably arrived "wet" and now is drying too quickly.

This^. Would have been better to let it dry gradually before installation.

I note it looks like the thinner decking (25mm) so I hope whoever built it allowed for additional support beams underneath otherwise the problem with movement is likely to continue. Definitely get some good quality oil or stain on it as soon as it is dry.

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jjnz1

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#1950496 2-Feb-2018 08:44

We just installed a composite decking, it's 48% bamboo and the rest recycled plastic. It is fantastic - less expansion and contraction, very straight, looks perfect, can be sanded if damaged, no staining or oiling required, resistant to all stains including oil.... Fantastic.

BUT, I would say it's the most dense material in the world - certainly feels like it when your trying to lob around only 1 piece by yourself. Way to heavy, very floppy, just like a dead bouncing weight. My 4m 290x45mm H3 was easier to carry.

I can see why builders would shy away from it - hard to maneuver, and very expensive normally. Plus you most definitely have to screw and predrill. But who doesn't love nice 316 SS torx screws right?

But it looks beautiful the day it's installed, and beautiful many months after. (I haven't had mine installed long enough yet so time will tell).

Sorry you're not happy with your pine deck, but I'm sure it looks as good if not better than most pine decks.

ZollyMonsta

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#1950503 2-Feb-2018 08:53

Built a large deck, used premium decking (150x40mm). Yes, that's normal. Although ours took a couple of months before we started seeing this occur. Hasn't progressed too much and adds to the 'character' of the deck.

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kryptonjohn

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#1950507 2-Feb-2018 08:58

We've been steadily expanding the decking around our place. First the back of the house (ground level) then an elevated deck at the front. Most recently the front door porch. We stained the back deck after 6 months and it still looks pretty good (2 years old now, due a scrub and restain). The front porch is brand new and the kiwla looks beautiful but still leaking out brown stain all over the place. The front deck we stained with what I thought was the same Cabots product but I must have screwed up as it looks different. Instead of maintaining the rich red kwila look, it has made it look orange. Hoping it will eventually wear back and I can have another go at it.

Wheelbarrow01

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#1950522 2-Feb-2018 09:22

Pine has an extraordinary ability to expand and contract. A couple of years ago I built a fence with premium machined ship-lap pine. When unpacking the pallets of palings it was clear that they were damp in the centre of the stack, and I knew that these palings would shrink but I didn't have the time or the place to lay them out for drying prior to installation. The dampness is actually a combination of the chemical process used to treat the wood, and also due to the timber being stored outside in the weather until I bought it. On some of the worst palings, I could actually see moisture oozing out as I drove the nails in with the nail gun.

About 6 months after the fence was finished, I could see that the palings had shrunk significantly, creating many small gaps in the fence as well as cracking. I was so unhappy with the gaps that I ended up removing all the palings from the fence and reinstalling them. I had to use additional palings to fill in the shortfall caused by the palings now being narrower than they were the first time around - over the length of a 30 metre fence it really added up. Fortunately I had saved a bunch of leftovers for this purpose. And praise be to the guy who invented the nail gun, because it made the job so quick both times around.

Pretty much all the palings cracked, some more than others, but more or less uniformly. If you look at any pine structure exposed to weather you will see cracks. It's pretty much guaranteed and unavoidable. It's not a fault with the product. Laying the timber out to dry evenly under cover (ie in a garage) for a few weeks, then applying a sealer or stain on all sides prior to or straight after installation will help minimise cracking but you cannot prevent it entirely (as far as I know).

Essentially, as soon as you lay the deck, you trigger the cracking process - this is because the top side is exposed to sun and wind which dries the top out, while the underside is usually exposed to water vapour rising from the ground underneath, which makes the underside more moisture laden than the top. This imbalance is part of the problem which causes cracks, hence why you started noticing the cracks within a few days of installing it.

If you had laid the timber out to dry evenly under cover, then sealed or stained each length of decking on all sides prior to installation, it's possible you could have minimised the potential for cracking. Unfortunately laying the timber out to dry has its own problems which can lead to bowing and twisting of the timber, so care it required there as well.

As one of the other responders has mentioned, premium pine refers to the quality of the grain and lack of knots and imperfections, however it has no bearing on the potential to crack as far as I am aware, so I imagine that premium pine is just as likely to crack as low grade pine. Even if you had bought kiln dried pine for your deck, without protection it would still expand after the first rain, and would then crack as it shrinks again. There's pretty much nothing you can do to stop it (notwithstanding the suggestion to dry and seal it prior to installation)

Your claim that they keep the timber wet intentionally to hide the cracks sounds incorrect to me. The timber is wet from residual chemicals from the treating process, and in almost all cases it's bulk stored outside prior to shipping and again while it's awaiting sale which obviously exposes it to the weather. The centre lengths in a pallet of timber will always be wetter than the lengths on the outer edges of the stack.

I am not a timber expert by any means, I just did a bit of googling before I started my fence project so I had a better idea on what I was getting into. And unfortunately you can't rely on the timber merchant to spot an amateur and offer up additional advice on what to do and what to expect.

With regard to your question on how to prevent it cracking any further, depending on the volume of timber involved, and how much of the deck you have already completed, I would possibly remove the timber from the deck and lay it out under cover for controlled drying for a few weeks, then seal or stain it on all sides prior to reinstallation.

mclean

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#1950541 2-Feb-2018 09:32

Decking timber is nearly always supplied "treated wet" which means it hasn't been re-dried after treatment. You can feel if it's wet when it comes off the stack. To avoid movement or cracking you need to air-season it before using it, either by stacking it in a filleted stack out of the sun, or by laying it face-down over the deck framing so the drying cracks are on the back. On a good ventilated stack it takes about 3 weeks to dry, by which time the surface feels quite different.

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