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Hi Community,
We've just had our deck redone and we've noticed a lot of cracks in the merbau where the screws are. Our carpenter has completed about 95% of the screws and there are about 100 cracked areas on our 60m2 deck. He's been using these screws, which do not require a pilot hole, as long as you're far enough away from the edge and ends of the boards, I believe:
- Simpson Strong-Tie 12G (5.5mm) x 65mm 316 Stainless Steel DHSD No-PreDrill Hardwood To Softwood Decking Screws
He's advised us that he hasn't been drilling pilot holes when in the middle of the boards, but has been on the ends of the boards with a regular drill bit the same size as the screws, but not a countersinking drill bit.
The decking is pre-oiled 90x19mm merbau.
He will likely replace the worst of the boards, but with about 100 cracks, we won't be able to get everything.
Reaching out to see if there's anything we can do with the cracked boards that are left. Currently planning to wash, oil and maintain regularly, but also considering trying to seal cracks with Selleys Aquadhere PVA Wood Glue Exterior Adhesive, removing adjacent screws, wedging boards closed, re drilling screw holes and then screwing again. To try to seal up the cracks as much as possible.
Any advice would be greatly appreciated.
We understand that predrilling all screws with a countersinking drill bit 15-25mm from the edges and ends of the boards is best practice and how to avoid this happening, but the deck is almost finished now and we're looking for a solution moving forward.
The wedges in the photos are marking some of the cracked areas.
David
Hello @David10
Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your merbau decking.
The PVA wood glue might work for a while, but I'm not sure how long it will last out in the weather. With the constant movement of the decking boards as the temperature changes, those timber splits will reveal themselves soon enough. One way to reuse some of the boards is to cut them to meet up with the next joist in line, however, I'm not sure if this technique will work for all the damaged pieces. Plus, the shorter pieces will be noticeable especially if they are all gathered in a single area.
You could transfer the location of the screw and plug up the hole made in the panel. This will at least secure the panel to the frame. The drawback of course is that it will not look uniform. My only other suggestion is to replace the split pieces and turn the pieces you've removed into planter boxes.
Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.
If you have any other questions we can help with, please let us know.
Eric
Hi @David10,
I'm really sorry to hear about the issues with your new decking.
Replacing the affected boards is likely the best solution to ensure the deck looks and performs as intended. Thankfully, removing and re-screwing boards shouldn’t compromise the integrity of your joists, especially given their size and treatment.
It might be worth speaking with a manager at the store of purchase. I trust they'll do their best to help resolve this situation.
Mitchell
I wonder if the screws are too close to the edge? We've just done our deck and while we pre-drilled (hardwood joists) and pre-countersunk, we also kept them in a bit from the edge. (Edit, sorry, I missed that you did mention this)
I also wonder if it's worth flipping a board, pre-drilling, countersink and then re-screwing using the existing hole, if that would work. Save replacing so many boards if it comes to that. Hopefully installer will replace though.
Do you know if they laid joist protection down before laying deck? If the deck needs to be re-done, fresh joist protection would cover existing holes.
Morning @David10
The benefit of pilot holes as you may know is to both stop wood from splitting and provide a much more secure bond of the top material. As the bit is drilling each hole, wood is being removed which provides the relief of pressure from the fastening screw. When using those types of 2-in one deck screws the wood isn't being removed, so there will be outward pressure. This means it's even more critically important to place the screws 20mm - 25mm with 140mm boards and 17mm - 20mm with 90mm ones. Your photos show that the screws are all very close to the edge making the boards easier to split. The other reason for additional pressure, is those screws are not providing a countersink for the head. So, more pressure is applied as the screw is driven home and leaves those very rough edges around the head.
Here is an example of way to close to the edge
I would recommend as @EricL has to repair the boards buy removing and repairing one board at a time. I would recommend using this high-strength wood glue by Gorilla and then clamp until the recommended curing time has expired. I would drill out each hole before re-laying. The same length screw should be fine if the joists are new. Otherwise you can get longer ones for greater peace of mind. Alternatively you can use pre-drilled and countersunk batten screws which I use.
Nailbag
The same
