Thread: Timber swelling on new pool deck

G'day circular one and welcome to the fun factory.

Firstly the swelling and shrinking is a process of moisture absorption and drying.
I tis probably a little exaggerated in treated pine but nothing to worry about really.

Did the slats swell to the extent that there was any noticeable deformation?

If not I would simply proceed as normal, once everything is dry.

Thanks artme. No, no noticeable deformation.
re - "proceed as normal, once everything is dry" . Should I wait for the slats to shrink back to 4-5mm gapping or try and match the current gaps? I have no idea how long they would take to "dry".

I would say you would have to try and determine if the material that you have not yet installed is as wet as the material already installed to determine what size gap to use for the rest

Do what I did, throw the boards to be laid in the pool and drag them out as needed.

Originally Posted by Mini

Do what I did, throw the boards to be laid in the pool and drag them out as needed.

Just make sure the current laid timber is also wet and expanded before you start.

Probably easier to keep em wet and o it then. Never know how long they will take to dry.

Thanks all! It took a couple of (dry) days for the gaps to be mostly right again.

Further info for novices (like me) ,
I was just freaking out about how much the deck slats expanded. I thought the recommended gaps in decks was overkill. I would go at least 5mm next time.

I am using square drive SS screws. First time using them, and they are brilliant. No issues whatsoever. I have read on this forum some people having problems with them in hardwoods, but in pine, its easy peasy.

Its not just deck slats that will expand with water. Any pine will do some big time expansion.

What you have to decide is something horrid. Guess the spacing to finish the job and make a wrong guess and have a patchy job or hope it all dries out fully and then continue.

One thought and has bee posted is to make sure it is all wet and fully expanded. then while keeping it wet install the rest.

Have fun..

Having built a host of decks in my past (all still standing save one where a room addition was added)

What I have done in the past when Weather changed during my task. Acclimate the wood (timber) to the conditions. If the deck is exposed to the rain and has swelled (as would be expected) then expose the remaining decking to the same conditions, Use the newly determined gap as a clue for setting the gap of the rest of the decking and they should naturalize together in the future. Or If you have time to wait till the decking dries, allow the remaining to properly dry (place on stickers to assume an even air flow and prevent warpage till equally acclimated.

easiest way to expose the boards to the same moisture content is lie them where they will be installed, on top of eth joists, in one layer. And as above just allow the same gap as the already laid board

Originally Posted by bpj1968

easiest way to expose the boards to the same moisture content is lie them where they will be installed, on top of eth joists, in one layer. And as above just allow the same gap as the already laid board

Way cool... Lay out tjhe board on the joists and when ready to attach, use the gap established by the ones already instslled