How to treat cracked Merbau decking?

[David10]

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

[Dave-1]

Good Morning @David10 

Thats a pain to deal with 😕 

Going forward I would be replacing the boards ( I do have the same thoughts as @Nailbag as to remove, using a glue and clamping together to repair the splits but not confidant it will work well)

The concern over screing more screws into your supports -

- Id probarly be concerned as well even tho I know it really shouldnt make a huge amount of differance. You could always paint waterproofing material over the supports with the boards being replaced.

Reusing the boards -

Even tho I have hesitation on repair of the boards id still give it a go. There is nothing to loose if it works. In theory you could put the same piece back in (therefore reusing the existing holes) and then redrill the holes near the splits that you have repaired. (with a countersunk pilot hole)

Dave