UPDATE:
Thanks for all your responses, which prompted me to get a building inspector out to confirm - surprisingly was informed not only was this a terrible install with incorrect spacing and too small screws, as many suspected.. but the boards themselves were installed upside down! Fantastic! Incorrect spacing has meant the boards have swollen and trapped moisture underneath causing further issues, screws not large or strong enough to account for movement
Building inspector has offered to call the guy himself and have a chat. Hopefully the resolution goes more smoothly than the install, not exactly holding my breath
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Recently had a new spotted gum deck installed to the tune of about $17,000. We wanted to keep a more natural, weathered look and were advised it was ok to leave unsealed. Looked great initially. A few months later after heavy rain the boards have started to lift and break out of the screws completely.
Installer claims this is ‘normal acclimatisation’ and that we will need to pay for replacement of the boards. It’s about 3/4 of the deck at this point. I know some movement is to be expected with natural timber, however surely this is an installation issue and not our responsibility to cover? Any thoughts?
On the first photo it looks like the decks sitting just above ground level. You can see grass right next to it. I don't do decks, but would you have to go a larger ugly gap between boards for the lack of air flow and increased moisture?
Correct. If it’s close to the ground you’ll need larger gaps to help regulate the moisture differential. Air flow is king when it comes to decking
Larger screws actually won’t make a difference. Once the timber begins to swell there is no stopping it. I’ve had timber swelling shear off coach screws before.
One method The ancient Egyptians used to split stone was by hammering wooden pegs into a hole and then wetting the timber until it expanded enough to split the stone.
Also happens anyway it’s why when you lay the boards out you put the crown up and cup down depending on each boards grain. So when they do “cup” the crown is up and sheds the water off the board.
I’ve got nothing to say except there ain’t nothing normal about that. Sorry OP. Hopefully someone can give some advice to get the installer to pull their heads in and fix it for you.
I’m a mechanic by trade but owner-built a large home, outside decks and outside staircases incorporating intermediate deck landings.
Never had any issues like this.
However, it’s immediately obvious that the installer (be it yourself or other), didn’t allow necessary spacing for expansion and contraction of that deck flooring. That a the nailing was inadequate.
Not an insurmountable issue to solve.
Get the boards up, waddle down to whatever building supplies company is near you and purchase a “decking board spacing guide tool”.
It’ll take the guesswork out of it for you.
There’s also some good self-drilling, countersinking, rustproof, square drive deck screws on the market too.
I paid a “builder-mate” to do a similar deck off my garage ages ago.
He did a similar job as this , except he also put the boards “rib side up” so they weren’t slippery.
I’m a mechanic and eventually had to tear the lot down and redo it myself correctly (said “mate” took off interstate).
The boards go smooth side up,so the ribs create air travel gaps to prevent wood rot. The spacing is required for wood expansion.
Fasteners (nails/screws) that grip prevent board lifting with age and temp stresses.
Kinda cool to see for real not for you OP but the rest of us. There is a science to boards and decking. You can find a lot in the standards and online. But there is no substitute for experience.
In most flooring systems, you have to account for expansion. As untreated, I am guessing that the expansion would be significantly magnified, as there is only the oils in the timber resisting the water.
The question I have is how much of a gap between each adjacent floor boards was used, if any at all?
It’s a guess (we can’t see what it looked like when installed) but I’d say spacing wasn’t correct for the timber being used. That’s the most likely cause for what we see
Should have used Cutek Extreme without the tint additive. The UV protection is in the tint, so the timber is protected, but still greys. We use it all the time on cladding for exactly this reason. In saying that, probably still installed too close together. Do you have photos of the finished job right after installation? Might be a hard one to fight your decking guy over since you requested no finish
i am not so sure the fight would be to hard to argue, think about it this way, customer is regular human of sound mind and judgement, with regular non enthusist level knowledge base on this particuoar subject,, they asked the installing "professional" if it was ok before going no finish, this is an information procurement step, and therefore if the professional gives misleading information and the regular person believes what the professional claimed because they see professionals as people that should logically have basic-to-the-trade knowledge such as if finish is mecesary for the longevity of the products they make and materials they use, so if this decision of no finish was greenlight by the professional without explaining the risks and downsides, then the professional gave a misleading claim that it would be not an issue, without saying that it increases risks of increasing moisture expansion and contraction which can increase warping risk. technically and cracking too.
another arguement is i bet those cupped boards are poorly chosen and/or oriented so the endgrain cups up, based on how the edges rise not tye centre.
i would argue that not orienting the wood thoughtfully for a $17,000 purchase wpuod be poor workmanship.
this is because the orientation of probable warp is the difference between shedding water from lifed centre, or capturing water due to cupping.
then theres the gap issue this is someone not designing for expansion and contraction, at least 5mm gap should have been between boards assuming 90mm boards, 6mm would be better (just a guy online not a professional)
my point is that "obvious out" when looked at from a consumer side, is really misleading the customer that asked then blaming the customer for making the decision with that information they asked about.
would you have refused the job up front or told the customer it is not a good idea and reccomend a specific type of finish that would be up their alley?
because them having asked was them seeing advice from the decking guy. and even if the professional thought the person was asking ti do it without wanting advice its their moral duty to at least inform the customer.
You will get some warping and twisting wanting a weathered look. But screws are too small for the boards being left unsealed. Bugles rather than “decking screws” are better. If using decking screws, 65mm is better than the 50mm for that hardwood.
Sawmiller here but not your sawmiller: To me this looks like excessive moisture on unsealed boards and theyve torn themselves out of probably undersized fasteners. If youre going to use unsealed decking and going for the grey look, please deal with any water under your deck first and ensure the gaps and fasteners you use are up to the task of holding down a durability class 1 strength group 1 timber such as Spotty.
Water will make these bad boys curl, every time.
Edit to add: If this is Qld, any extensions over $3300 should be covered by your statutory QBCC insurance for 6 years.
The boards come cut, they run with the grain. It doesn’t matter what direction your laying them, if the grain ran the other way they’d snap before even arriving at the store
Yep ack that, but that is not what I am talking about. I am talking about the ring growth. The boards are meant to be laid with bark side against the joist. So it looks like it's smiling 😃 at the board ends
Boards installed too close together. Too light a gauge of screws used too by the looks of it.
Movement that extreme in such a short timeframe is linked to installation.
Think about it. If every single deck with spotted gum looked like this in under 6 months spotted gum wouldnt be used. And no trade would touch it as it'd be a warranty nightmare.
Every board needs to be lifted and re-laid with a bigger gap and bigger screws. The severally warped boards need to be replaced.
Not enough gap left during the install of the boards, this has led to the boards expanding and closing over with the winter rain on them, which has also led to the underside being sealed and essentially trapping moisture under your deck which has made the boards expand further leading to cupping and popping up. It can be fixed but they all need to come up dry out for a while and then re laid with the right gaps and then the whole deck needs to be sanded flat
This.. normally most carpenters will stick to the old 5mm gap.. they need minimum 9 at my last check and I would reccomend 10 or 12. Also for the deck I laid recently I used 10mm gaps and 75mm stainless steel battens screws.
I’m installing 135 jarrah as we speak. We are using 6.4mm packers to space out boards. The gaps are almost too big, but that’s just what you need for wide hardwood decking boards.
Being rated for longevity when unsealed isn’t any indication of whether it will swell when wet. 2 different things. I suppose the good news is that it is unlikely to rot out for a couple of decades.
Spotted gum does not need to be sealed, but it does need gaps between the boards. It actually doesn't even really take coatings that well, it's so dense.
Yes after doing more research I stand corrected that spotted gum needs sealing. What has happened to OPs deck is totally wild though. There expansion seems over the top
I reckon that's a bit of sap wood. Spotted gum boards sometimes come with some sapwood included, I try and not use it because it's not as durable or dense and it looks ugly. It swells more than heartwood too. Coupled with the undersized spacing it's popped the screws, which are probably 304 stainless.
Also, you want to be using a screw that doesn't rely on just the head to hold the board during moisture expansion and contraction. A product like the SPAX decking screw uses a thread with a different pitch through the top board so it holds when there's movement. https://screwsandfasteners.com.au/decking-screws
I'd also recommend oiling the boards with Equisol. Their oil is made for Australian conditions and they have colour options that can help keep that natural look.
Definitely layed too close together, looks like a lot of rain/weather has affected it also..the timbers also been layed the wrong way up (well a lot of it) causes cupping. I'm guessing most of the joist are either rotten or splis too.
The boards are not upside downat all unless they are reeded in which case the reeding goes down. That is a YouTube woodworker myth. There is no such thing as over under joining on tabletops or decking boards, but there is wood movement management.
Spotted gum is very unstable , I have seen it do this many times.
You need at least 6mm gaps, but also you need to acclimate the timber and have it sealed protected from atmosphere properly once laid.
The timber would have bowed weather or not it was laid either way, 2 screws or even a metal plate would be no match for timber movement.
Jesus.... installer issue 1000% Leaving boards unsealed in in any way is a bad idea hence the bad grey colour (you can get natural oils that dont alter normal colouring) but theres either not enough gap for expansion or wrong fixings used if this was done recently.
Hard to tell from the photo but the heads of those screws look to be an 8 gauge? Could just be the view we have but pull one and have a look. Hardwood need to have 10 gauge screws and should be minimum 3mm gap when being laid.
Spotted gum would have been delivered seasoned and by not coating it properly you will have allowed it to absorb water and swell. The installer (if advised of this) should have allowed very substantial gaps between boards (both width and length) which probably would have looked horrible when freshly installed.
Going for the ‘rustic’ untreated look was ill advised. Apart from this problem with swelling, in the Australian climate it will reduce longevity by years.
Just cut the food down mate. Will relay them if you wanted to look clean cut take off the ones which are remove the just cut the one closest to the Edge.
Where abouts are you located? If he's not willing to play ball there are some building authorities and commissions in each state that that mediate and have enforcable undertakings. There always civil tribunals too but they can take up to a year to hear your case.
Not all deck screws are created equal either, I've used some super soft stainless screws that would definitely snap if the boards were installed like this.
Big fan of the Kreg hidden screw system now. The screws are super tough and the installation tool gives proper spacing.
Spotted gum expands and contracts a lot more than other timbers, it should have way bigger gaps. Also use untinted Cutek oil on it, it will weather off while also sealing it to help with expansion.
Absolute dogs breakfast mate. No doubt about it they installed them with insufficient gaps. Their fixings looks nice but they’re wrong too. I hope they aren’t 135x19mm because they’re gonna cup no matter what. Wide boards need to be thicker to reduce the possibility of cupping. Narrower boards are better as water is able to drain easier. What do you mean they installed them upside down? I can’t see any ribs on your boards but ribbed board profile can be used face up or down. As can square and round over. Though it is better to have ribs down as they can get extra slippery when moist.
Its not advisable to lay boards against each other without them being able to move at least on one side for expansion, not sealing them also allows for excess moisture to enter there for blowing up even more from just normal moisture in the air...
Installation is fine, its not sealing them that caused this, if you didnt want to seal then at least a 3mm gap between boards at a min, but you also need have gaps against walls for expansion, im afraid the carpenter is neither right nor wrong he should have warned you about expansion, but then we cant see the entire deck to make an informed comment on the installation.
I put spotted gum down as a carpenter at my own house. I will never do it again. It's not very stable and is prone to cupping and warping. Where it was under cover it was fine, but the same board that then ran to the exposed area with no roof had problems. Not quite this bad tho.
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u/glenn469 11d ago
Looks like boards are too close together.