Laying pine decking boards - keep it square?

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boland

545 posts

Ultimate Geek

#239965 13-Aug-2018 13:37

I'm laying a pine decking board with 140x32 premium pine decking boards. I'm using 3mm spacing, as they have been stored inside and seem dry.

Need to butt join them as boards are not long enough, which is fine. However, they are not EXACTLY the same widths. Some boards are 1400mm, some 1398, some 1402. So, it can be that I butt join a 1398 board with a 1400.

On the next board, can't use 3mm spacing everywhere I figured. So, using 3mm next to 1400 mm board, and 2mm extra (= 5mm) next to the 1398 board. That should keep it straight & square I thought.

However, after laying 4 lengths, when I measure the total width at each end, one side is 5mm longer?

I need to lay 38 lengths in total so plenty of time to correct this, but why did this happen? Or can it be because one single board is not exactly same width everywhere?

mdf

3490 posts

Uber Geek

Trusted

#2072697 13-Aug-2018 14:30

A banana bend in the boards? Variations in the cut width of the boards? +/- 4 mm is quite a lot.

Regardless of why though, the best way to keep it even is to measure the diagonals corner to corner every 4 boards or so. If it's genuinely square these will be the same. Even if all four sides are the same length, you might have a parallelogram going on.

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boland

545 posts

Ultimate Geek

#2072702 13-Aug-2018 14:49

Thanks @mdf will measure diagonals. Already done that with the frame.

wellygary

8217 posts

Uber Geek

#2072703 13-Aug-2018 14:50

5 boards @140mm, = 700mm, 5mm is well under a 1% variation,

If you think its going to become a bigger problem you could run 3 or 4 string lines that are true and when you start to get close to each one deliberately start spacing the boards so they line up, this will factor out any splay before it gets too noticeable....

Kickinbac

414 posts

Ultimate Geek

#2072893 13-Aug-2018 19:01

Pine shrinks and swells at is dries and gets wet. You can install them all perfectly and a few weeks later all the gaps will have changed.

mattwnz

20045 posts

Uber Geek

#2072941 13-Aug-2018 19:45

I am wondering if 3mm gaps isn't a bit close. That variation in thickness is very small, and when I was installing a deck, the variation was a lot more, but I had bigger gaps, so it wasn't as noticable. But as mentioned above, the boards will likely shrink, and also may swell when they get wet..

Bung

6357 posts

Uber Geek

Subscriber

#2072970 13-Aug-2018 21:11

boland:However, they are not EXACTLY the same widths. Some boards are 1400mm, some 1398, some 1402. So, it can be that I butt join a 1398 board with a 1400.

On the next board, can't use 3mm spacing everywhere I figured. So, using 3mm next to 1400 mm board, and 2mm extra (= 5mm) next to the 1398 board. That should keep it straight & square I thought.

However, after laying 4 lengths, when I measure the total width at each end, one side is 5mm longer?

Those measurements seem screwy to me. If you've missed a decimal that's still less than .5mm from 139.8mm to 140.2mm

One way of doing it is to lay every 5th board square to the start using 5x(nominal width + 5mm) spacing and wedge the intermediate boards to get even gaps.

Yogi02

238 posts

Master Geek

#2073065 14-Aug-2018 07:30

Pine is a PIA for decking

Had a deck laid and it has gone from looking awesome to quite scrap with the gaps/heights/joins etc.

This obviously knowledge in hindsight.

What I now know is that pine needs to be flatly, fillet stacked so it can dry properly

Premium timber is only graded on presence of knots on one surface

Timber products like this are now milled from wood that is way too wet and way too young for building and the amount it moves after it is laid is just ridiculous (I had a 4m length shrink in length by about 25mm and rip through screws.

Not to put you off as there are not many options, just a massive problem with timber (not kiln dried) at the moment. expect to have to replace sections.

As others have suggested, do 3-4 rows and reset with a string line then go again.

boland

545 posts

Ultimate Geek

#2073192 14-Aug-2018 11:12

Thank you everyone for your replies!! The decking has been stored inside for 1-2 weeks, and at my house they are stored outside under cover.
They do seem dry though, but probably still wet inside. That's why I thought 3mm should be fine as they would shrink anyway.

Should I leave them to dry for longer? They are all stacked, so would probably have to change how they are stored.

boland

545 posts

Ultimate Geek

#2073194 14-Aug-2018 11:14

Bung:
boland:However, they are not EXACTLY the same widths. Some boards are 1400mm, some 1398, some 1402. So, it can be that I butt join a 1398 board with a 1400.

On the next board, can't use 3mm spacing everywhere I figured. So, using 3mm next to 1400 mm board, and 2mm extra (= 5mm) next to the 1398 board. That should keep it straight & square I thought.

However, after laying 4 lengths, when I measure the total width at each end, one side is 5mm longer?

Those measurements seem screwy to me. If you've missed a decimal that's still less than .5mm from 139.8mm to 140.2mm

One way of doing it is to lay every 5th board square to the start using 5x(nominal width + 5mm) spacing and wedge the intermediate boards to get even gaps.

Yeah made a mistake, should have been 139mm and 141 mm.

Great suggestion!

Disrespective

1921 posts

Uber Geek

#2074544 16-Aug-2018 15:57

boland:

Thank you everyone for your replies!! The decking has been stored inside for 1-2 weeks, and at my house they are stored outside under cover.
They do seem dry though, but probably still wet inside. That's why I thought 3mm should be fine as they would shrink anyway.

Should I leave them to dry for longer? They are all stacked, so would probably have to change how they are stored.

The deck is exterior correct? The timber will swell and contract through the seasons, but it will expand as moisture is absorbed if you have kept it dry. I spaced my hardwood boards at >4mm at ends and sides and many have come to touch the neighbour over the winter. I also found many were not identical widths at the ends but I was able to get most to fit close enough. I reckon the worst boards were easily 5mm different, but like has been mentioned, if one is a bit bigger, and the other smaller, it is within tolerances.

To keep the boards square I measured off the edge I was building off of after every second board and adjusted my spacing to suit. Most boards had a decent warp in them so it was a bit tricky but they're natural timber so some natural variance doesn't feel out of place.

Yogi02

238 posts

Master Geek

#2074582 16-Aug-2018 17:36

boland:

Thank you everyone for your replies!! The decking has been stored inside for 1-2 weeks, and at my house they are stored outside under cover.
They do seem dry though, but probably still wet inside. That's why I thought 3mm should be fine as they would shrink anyway.

Should I leave them to dry for longer? They are all stacked, so would probably have to change how they are stored.

Prob wouldn't hurt to have a look through.

Ideally, you would fillet stack the boards - Think of Jenga type arrangement.

mattwnz

20045 posts

Uber Geek

#2074641 16-Aug-2018 21:21

Yogi02:

Pine is a PIA for decking

Had a deck laid and it has gone from looking awesome to quite scrap with the gaps/heights/joins etc.

This obviously knowledge in hindsight.

What I now know is that pine needs to be flatly, fillet stacked so it can dry properly

Premium timber is only graded on presence of knots on one surface

Timber products like this are now milled from wood that is way too wet and way too young for building and the amount it moves after it is laid is just ridiculous (I had a 4m length shrink in length by about 25mm and rip through screws.

Not to put you off as there are not many options, just a massive problem with timber (not kiln dried) at the moment. expect to have to replace sections.

As others have suggested, do 3-4 rows and reset with a string line then go again.

Are they thin boards? We installed one about 3 years ago and it still looks great, apart from greying and getting tree slime on it. Some of the gaps in the end joins have grown a bit, but not too bad. I think as long as it has lots of support under, not using cheaper thinner boards, and a decnet number of fixing, there shouldbe less problems. Next deck will be kwila though, becuase I like the look better.

Yogi02

238 posts

Master Geek

#2074650 16-Aug-2018 22:11

Its meant to be good stuff we had - usual premium grade measurements. The big problem is that that there has been such a demand for timber over the last 2 years that the mills are manufacturing these products out of young green timber that was never used previously.

My very experienced builder had never seen it before, but now seems commonplace after checking with others.

boland

545 posts

Ultimate Geek

#2076235 20-Aug-2018 14:05

Thanks everyone for the replies! I've decided to pause laying the deck, I've stacked all the decking with spacers in between to let it dry out first for a month. That was recommended as well by the manufacterer.