# Forum Home Renovation Decking  Decking Screws - Getting them Straight

## wombat74

Hi all, 
Great info in here. 
I'm after some advice on how best to get the screws for the decking boards lined up. 
I'm putting down 140x19 boards on 90x45 joists. I've got around 30 boards with 15 joists so any time savers will be very useful. 
From what I've read I need to progressively screw in each board from one end to the other to ensure it's flat and square. With that in mind I'm not sure how I'll line up the screws. I first thought of making up a jig but I saw on another thread here that this might not work if the joists aren't perfectly straight. Mine are pretty good but I'm sure they're not perfect. 
I've seen a few suggestions to use a string line but I can't see how to do that other than putting it up and down for each joist and each board (that would make an already mammoth task ridiculous). 
Any suggestions? 
Also I was told by the timber merchant that for 140mm boards the sawmill recommends 9mm gap between the boards. Everything else I've seen seems to recommend 4-5mm gaps but maybe that's for 90mm deck. Any thoughts? 
Thanks in advance.

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## binda

OK, my suggestion is use a chalk line to mark the centre of your joist. This line can be moved around a little to allow you to keep a straight line down the joist. I would also use a jig to line up with that chalk line for the screws. Then drill through the jig (if you are pre-drilling which is always a good idea) or mark the spot to nail to with a pencil. 
If you are offsetting your screw holes then any deviation away from a perfectly straight line will be masked a little bit.  
I don't know if noggins can be used to straighten bowed joists but i'm sure the chippies in here will know of the correct technique to use. It won't take em long to respond. 
Also a string line should be used every few boards to ensure the boards are staying straight. ie run the string line at 90 degrees to the joist (the same way the boards are running)

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## fdip

I have used similar boards for my deck, but as it is mostly undercover I went with a 3mm gap that was advised by most. Never heard of a 9mm gap, seems excessive. 
Re getting straight screw lines you could do what I did. Lay the boards down first, tap in a nail at each ends of joists and set up your string lines. Worked a treat and not too time consuming. See attached.

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## oohsam

It is a pain in the @ss to move the string line every time you have to drill. 
It would be better to use a chalk line and then remove the string line so you can just drill in its place 
It takes the same amount of time, about 15 mins to setup the nails on 15 joists, and then do one chalk line at a time or it will rub off as you move down the deck to screw the remaining screws in.  
Also, if your joists are not straight, your screw lines will not be straight however you can do nothing about this as you have to screw into the joists. 
DOnt worry bout it too much. I built a massive deck and didnt even use a stringline and just used my eye, and you couldnt even tell they are not 100% straight.

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## wombat74

Thanks all, good advice. I think I'll have to get into it to find out what works best. Will report back with results.

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## bimborocks

I layed my boards buy laying the first board and then say the 5th board and screwed them down using the centre of the joist as a guide.
I then cut all boards to fit rows 2,3,and 4 and used a straight edge to line up the screws in the 1st and 5th board to mark all the boards inbetween. 
Not sure if that makes sense at all.
Also 9mm is excessive and would be an absolute pain as if you drop any cutlery off a table it will go straight down the gap, same goes for pencils etc
I went for a 5mm gap and some ended up around 7mm which is getting a fair sized gap

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## wombat74

Yeah thanks. Just been reading about this "5th board" technique, sounds like the way to go. 
Also had doubts on the 9mm gap after layoug a few boards out today. Not really sure hwo small to go though. So you think there is much risk of the gap being too small? Will the wood swell or shrink? 
I want to make up a jig to position the screw holes....any tips?? 
Using the 5th board method do you complete each row for the full length of the deck or move across the deck to the end before moving down the deck? Does that make sense?
In other words would I lay the first board then another with a join above a joist (6 metre deck span) then do the same for the 5th row or just put down the 1st board then straight to the 5th row? 
Another option I've considered is stagering the screws on each board. Others have suggested this will hide any minor errors in getting them straight. Any thoughts? 
Thanks for the advice and tips.

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## binda

> I want to make up a jig to position the screw holes....any tips??

  Well actually here is a pic or two of the jig I made for laying down my deck. The jig is made from 65*6 flat bar steel cut and wielded at 90 degrees for a right angle. The depth is less then the thickness of the boards I was using. 
The small section fits in between the boards to create the exact same gap every time. There was a centre scribe line on the larger section to line up with the chalk like I had already laid down on the joist earlier. The holes are for the drill bit so I every nail hole was the same. As a side note I quickly discovered that off setting the nail holes like this mask as deviation away from a perfectly straight row of nails. The original holes where not countersunk as the appear in the pic, thats just the jaws of my Ryobi drill chewing in. Stupid drill was cheap and not expected to last past this job, and its still going strong. 
Being made from steel the jig could take a lot of knocks, which it did. I love a good jig. Go here to check out the master of jig making. http://woodgears.ca/
Just quietly, his jigs give me a bit of a horn. :Blush7:

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## binda

sorry for a repeat post but the original post didnt pick up my pics.

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## wombat74

Great looking jig. Thanks for the pics. 
I've had one made up by a local metal shop, looking forward to picking it up.

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