Should a deck have an expansion joint?

[BeeGees]

I was wondering if when the Merbau deck is 6.5m wide, you need to run an expansion joint in the middle so it can expand and contract. My builder wants to have 2 picture frames on the bottom section of the deck. I'm not a fan. And if not, can he just run 3.3m planks up next to each other, or does it need to be scattered? Lastly, why is my builder constantly splitting the timber when he puts the screws in, he says he is pre-drilling. I'm feeling like I am being misled and it would be really great to get advice. It's expensive and I want to get it right the first time. 

[MitchellMc]

Welcome to the Bunnings Workshop community @BeeGees. It's sensational to have you join us, and many thanks for your question about constructing a deck.

Expansion joints are only required on composite decking, not natural timbers, as they don't suffer from the same swelling and contraction issues.

Timber decking can be laid however you want. It can be in straight lengths or staggered. Depending on the available lengths, there could be considerable wastage and additional cost one way or the other. 

Can you show us some examples of the spilt timber? In your images, I see one section where there's been some tear out, likely when pre-drilling. I can't see any splits as such in those images.

Please let me know if you have any questions.

Mitchell
 

[BeeGees]

[BeeGees]

Is it normal to have some 'tear out'? There seems to be quite a lot of it, I don't believe it is being pre-drilled or is it perhaps the screws being used?

[MitchellMc]

It is not unusual to have some tear-out even when predrilling @BeeGees. It's likely the countersinking bit that is causing the tear-out. I would suggest if they were not pre-drilling, you'd see almost every board split from the screw. They've likely predrilled and then driven the screw in a little too far, and it's caused the split. I'm no professional deck installer, but when I built my deck, I did have a few splits like this and tears out around the place; it's somewhat inevitable, even for a professional. If that's all the damage over the whole deck so far, I wouldn't say it's terrible. You obviously want the deck to be as nice as possible, but I think you'd find a split here and there on most decks if you look closely.

Mitchell

[BeeGees]

Thanks, Mitchell, that's good to know, but that is a few pics, the tear-out is in quite a few places. But that's okay.

I do have issues with the splitting of timber, but that's me and my problem. 

Thankyou so much for getting back to me. 

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