# Forum Home Renovation Decking  Lining up deck board screws and straightening bowed boards

## HomeReno

Hi All, 
2 quick questions which require the assistance of the Renovate Forum Decking gurus.  
1. Struggling to work out I am going to line up the decking screws such that the 2 screws into each board/joists form a perfectly straight line along each row of boards? The total row of boards (90x19mm) will end up covering an area 5.4m wide and I really want the screws lines as straight as possible, I was thinking running a string line along the joists as a guide but that still does leave room for error. Any other suggestions here.  
With regards to bowed Merbau decking, There could be a few pieces in the order I get as no timber order is ever perfect and I saw a clip on youtube for the Bow Wrench which is a device that locks onto the joists and applies force to bowed area of the board forcing it into place. Wondering where I can purchase something like this or if anyone has any other suggestions on dealing with bowed boards? 
Suggestions and advise is greatly appreciated. 
Thanks in advance
Cheers,
HomeReno.

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## GeoffW1

Hi, 
I've been spacing the board properly at each end, and screwing down there with one screw only. Then at the most bowed point I've used a small flat end wrecking bar to pry it straight before screwing down just there. If it bowed away from the last fixed board I just put a temporary screw in the joist  and pried against that. It was enough. 
For lining up the screws lengthways I'd just use a plywood or cardboard template to mark the board at each joist before drilling. 
Cheers

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## cherub65

Best method is lay first full length board, then multiply board width + gap by  five. Then lay a full length board at this distance from the first.
place all internal boards, use timber wedges to achieve gap distance. boards will be gun barrel straight.

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## jimfish

> Best method is lay first full length board, then multiply board width + gap by  five. Then lay a full length board at this distance from the first.
> place all internal boards, use timber wedges to achieve gap distance. boards will be gun barrel straight.

  Exactly how i do it.
When screwing of every 5th board use a straight edge to ensure screws are in line then once the rest of the boards are cut and wedged straight i use a chalk line with yellow chalk to give me a screw line.

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## Gaza

5 board method is way we do it  
Just make sure joists are straight   
Sent from my iPhone using Tapatalk

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## METRIX

> Exactly how i do it.
> When screwing of every 5th board use a straight edge to ensure screws are in line then once the rest of the boards are cut and wedged straight i use a chalk line with yellow chalk to give me a screw line.

  Have you tried the violet Chalk, ? cleans off really easily but can be disturbed if not careful, purple is our first choice, then White.  Dust-Off Marking Chalk - Tools - IRWIN TOOLS

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## DEMAK Timber

Some builders will tack the boards first with a brad gun, then chalk line and back screw. If you are working towards a wall it's probably more important to work the gaps slightly to finished square... 
Similar to the Bow Wrench, in Australia we have: ArchiDeck Straight and True Blue Deck Board Straightening Tool - Demak Timber & Hardware

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## michaelcb

To straighten boards I used a "Board Boss" with a pipe clamp. Worked like a charm

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## METRIX

I do it the same as the guys above, lay your boards using the starter board method (lay every 4th 5th or 6th board to a string line) and fill in each set, using timber wedges to get the gaps right, works every time and dont need to muck around with straightening gadgets etc, the more tools / jigs you involve just slows everything down. 
This alsostops your boards runing out of square to the house, as you are limiting the error to 4,5 or 6 boards which can be fixed in the next set if required, I use a home made jig to get the screws lined up perfectly inthe center of the joist / board, then you can chalk line the rest of the boards and your screw lines are perfect (as Gaza sadi, your joists must be spaced evenly and straight to use this method as you are following the joist lines. 
See below for example, and finished results, straight boards all parallel the house, and even gap at the house. 
 I have plenty of past posts which explains how to do it.

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## HomeReno

Thanks Metrix, your explanation and pics make it the concept of the started board method easier to understand.  
I am planning on laying the first board up against the brick wall of the house (hoping the wall is straight enough for this exercise, them measure the width of 5 board + gap and mark and string line and screw off a board in this location as you mention.  
I would be interested in looking at a pic or a brief explanation of your home made jig to line up the screws as that's something I am struggling with.  
Lastly what size gap have you left between the boards I am tossing up between 3.5mm 0r 5mm, I am thinking 3.5mm as the Merbau will shrink over time and the gap may become 5mm eventually. Your thoughts? 
Cheers,
HomeReno.

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## METRIX

> Thanks Metrix, your explanation and pics make it the concept of the started board method easier to understand.  
> I am planning on laying the first board up against the brick wall of the house (hoping the wall is straight enough for this exercise, them measure the width of 5 board + gap and mark and string line and screw off a board in this location as you mention.  
> I would be interested in looking at a pic or a brief explanation of your home made jig to line up the screws as that's something I am struggling with.  
> Lastly what size gap have you left between the boards I am tossing up between 3.5mm 0r 5mm, I am thinking 3.5mm as the Merbau will shrink over time and the gap may become 5mm eventually. Your thoughts? 
> Cheers,
> HomeReno.

  Just take your "standard" measurement for the amount of boards / gaps, and keep adding this amount as you go, try to be exact, as a mm here and there will matter, this will ensure you are running parallel to the house, make sure to use a string line from end to end and keep the board right on the stringline screwing the ends first, always double check referenceing back to the parallel of the deck (if its parallel to the house  :Wink: ). 
The home made jig is simply a piece of angle which hooks onto the joist and has two pre determined holes for the width of board, I have used retail plastic ones in the past and these work fine, but end up chewed out by the end of the deck, (obviously they want this to happen so they can sell you another one) the metal version lasts many decks before the holes elongate, and you are only using this to quickly mark the board, then you remove it and use a smartbit or similar to drill the actual holes, I would like someone to manufacture a metal version but have not found this yet. 
Deck spacing minimum 3mm, I like to use 4mm for 90mm boards, and 5mm for 140 wide boards.

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## HomeReno

Thanks again Metrix, 
With regards to spacing I am using 90mm boards and was planning in using spacers available form bunnings but have only been able to find these in 3.2mm and 5mm, no 4mm.  
Given 3mm minimum I should be OK with the 3.2mm? below is the link to the spacers avaiable at bunnings which I was planning to use.   Macsim Fasteners 3.2 x 75mm Window Packer - Box of 200 I/N 1040468 | Bunnings Warehouse

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## phild01

> Thanks again Metrix, 
> With regards to spacing I am using 90mm boards and was planning in using spacers available form bunnings but have only been able to find these in 3.2mm and 5mm, no 4mm.  
> Given 3mm minimum I should be OK with the 3.2mm? below is the link to the spacers avaiable at bunnings which I was planning to use.   Macsim Fasteners 3.2 x 75mm Window Packer - Box of 200 I/N 1040468 | Bunnings Warehouse

  Personally I wouldn't be bothered with those spacers but if you do, I would be choosing the 5's.  Bear in mind that while you can significantly straighten the boards out, some can be very single minded and over-rule the strength of the fixing by a small margin.  The boards may not be of perfect width through their length either.  Maybe the degree of precision you envisage is not practical.

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## METRIX

> Thanks again Metrix, 
> With regards to spacing I am using 90mm boards and was planning in using spacers available form bunnings but have only been able to find these in 3.2mm and 5mm, no 4mm.  
> Given 3mm minimum I should be OK with the 3.2mm? below is the link to the spacers avaiable at bunnings which I was planning to use.   Macsim Fasteners 3.2 x 75mm Window Packer - Box of 200 I/N 1040468 | Bunnings Warehouse

  Make some timber wedges from 0 to 6mm and use these, they are much easier to get the spaces right, they cost nothing to make, and allow for finer adjustment. 
Using any plastic spacers is just a pain, they dont come out easily once all boards are butted in, they slip through the boards and you lose them, and are basically a fiddly way of doing the spaces. 
Every board is not exactly the same width, there are slight differences, wedges will allow you to adjust for this, use your eyes to judge the board spacing is even, or the eyecrometer as we call it..

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## shauck

the eye is an incredibly accurate tool

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## Veithy

> the eye is an incredibly accurate tool

  Using your eye is guessing. I do agree that standing back every now and then and having a look can tell you if something is out but it will never tell you your a mm out on 2 joins and 2 over then next one along. 
When building the frame I like to always know the width of the board to be used before starting, this allows you to make the frame to the correct width to avoid ripping boards (This is not always possible as sometime other objects prevent working to a full board). Skinny ripped boards look terrible and are sometimes hard to fix. Don't forget to also allow for overhand and riser thickness around the edges. Decking is generally not all exactly a perfect width and those boards that are not correct width are nearly always under size. So I tend to aim for a slightly tighter joint than I want at the end when working the frame width out. The smallest joins possible always look better.  
90mm boards want a 3mm gap therefore work out measurement for a 2.8mm gap = 90+2.8 = 92.8. 
140mm boards want a 5mm gap therefore work out measurement for a 4.8mm gap = 140+4.8 = 94.8. 
There are times when a slightly larger gap is required. Such as when the deck is built between 2 fixed objects such as a fence and a house etc. Remember I like to work to a full width board if possible so in this scenario I  
1. measure between the objects,
2. subtract 1 joint from this,
3. then divide buy a board + 1 gap,
4. which will tell me the number of boards required 
(If this number is not a whole number a board needs to be ripped with this spacing)
So to remove the need for a ripped board
1a. Take the number obtained from steps 1&2 and Devide by the number obtained in step 4 rounded up or down to the nearest whole number
2a. This gives you a number that is made-up of 1 board width + 1 gap (the correct size to avoid rips). 
Eg. Space between objects 2925, Board with 140, 5mm gaps 
Step 1. 2925
Step 2. 2925-5=2920
Step 3. 2920/145=20.137 (you don't want 0.137 of a board look bad and is sometimes difficult to fix off)
Step 4. 2920/20= 146 
Therefore to work to a full board 6mm gaps would be required instead of 5mm gaps. As mentioned above if you work out for 5.8mm you will probable get 6mm. 
I use the 5 board method already mentioned above. measure and markout every fifth row at both ends of the deck (eg 1st row = 144.8 x 5 = 729 2nd row = 729 x 2 =1454 3rd row = 729x3 = 2187 etc.). Try to pick out some reasonably straight (small bows) boards for these row and attach them along the chalk lines ensuring you are always on the correct side if the chalk line. If there is a bow in the board start at one end and screw off the board one joist at a time working along the board. Starting at one end and working along allows you to gradually bend the bow out instead of trying to bend it out in one go. If you are having trouble pushing the bow out use leverage by pushing the board further away from the last joist the board was fixed to. To get the screws in a straight line I use a yellow plastic Stanley roofing square which a mark so I can quickly line it up at half the joist and I also mark on it the screw location 
Once these rows are in start filling the space left with boards. Again start at one end. Put in enough boards so you can get the first row of screws in. Make sure the ends are cut well (I undercut slightly to improve the joints) and are butted tight to the picture frame etc. Space the boards evenly. Some people use wedges however I find this inaccurate as the joint size is determined by how deep you drive the wedge, It is very hard to consistently put the wedge in the same depth. The other problem with this approach is that with badly bowed boards the pressure can cause the wedge to slide back out (usually when you are trying to drill/screw the board and there are vibrations). I like to use tile spacers as they are cross shaped so therefore don't slip through the gaps, they about $3 for 250 of them, they come in 3mm and 5mm and if you turn them sideways they are 4mm. Once I get over 5mm I use plastic window packers as I always have them around and a mixed box contains a variety of thicknesses from 1.5mm - 10mm. What ever you decide to use get lots of them so you can space near a few joists at a time again working from one end. Chalk a few lines of screws and the them drill a few line and then screw a few lines. move the packers down the board and repeat the process until all boards are screwed off. 
Other tips would be make steps to board heights so that face boards do not need to be ripped or planed. 1 x 140 board + 1 x 5mm gap = 145 step. 2 x 90mm boards + 2 x 3mm gaps = 186 step. Frame to this size. The top of the board should be flush with the gap begin at the bottom. 
White or interior chalk is easiest to remove. I use blue which a wet and brush off at the end of the day. Don't leave it over night as moisture makes it a lot harder to get off. 
This is just what I have figured out as the easiest and most accurate way of doing things, it is by no means the only way.

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## METRIX

> Using your eye is guessing. but it will never tell you your a mm out on 2 joins and 2 over then next one along.

  I disagree, your eyes are very accurate at picking a difference, any difference, It does not matter if you are a mm out here and there, timber is a natural product and expands and contracts all the time, so today you could be 1mm under, after some rain it will be 2mm over. 
I also disagree with your comment about using wedges and this being inaccurate, I have built many decks including the one pictured above, the boards have all been laid using the starter board method and wedges to achieve the board spacings, I have never had a complaint from any client regarding inaccurate spacing of the boards, including the one pictured above which was for an engineer and he was very particular about board spacings, screw lines being straight. 
A comment was made by the client that the Merbau ordered was rubbish as not every board was perfectly straight, I explained the product was made from timber not steel, and being a natural product would have some slight variations over the length of the board (ie: some will be bent), and it was my job to ensure when the boards were fixed that any discrepancies in the boards were removed and not noticeable. 
Once this deck was finished the owner was very pleased with the result and nothing was raised in regards to non straightness of the laid boards, neither was anything raised in regards to spacing issues between the boards, if this client had no complaints then I can say my methods for using wedges is not inaccurate.    
I could not think of anything more fiddly than using tile spacers, and I  have found using packers as spacers is a real pain as they keep  dropping through the boards, and when your 6 foot off the ground that  can be a real pain to keep going under the deck to retrieve the packers. 
And yes I also am very particular to ensure only full width boards are used over the entire width of the deck, this comes back to simple calculations before you build your sub frame. 
Personally I would trust Shauck's "inaccurate" eyes at guessing spacing any day, and your eyes WILL tell you if you are a mm or two out if you know what to look for.

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## fredgassit

Off topic, but a quick question for Metrix; 
I 'm trying to read all your posts and educate myself. But your posts seem to go back to only 2014. How do I get access to all your posts pre-2014? 
Thanks.

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## Marc

The eye is, I agree, an incredible tool. 
Think about this scenario: 
A car goes past you, you only catch a glimpse for a fraction of a second of part of the back of the driver's head. Most of the time you can tell the drivers gender, age, and sometimes even ethnicity.  
The eye is best at comparing, that is, you look at two decking boards and you can tell which one is wider. You can easily tell the smallest variation in the gaps between boards, the difference between the size of the head or the shank of nails.  
When it comes to absolute measures, you have to train your eyes. If you see and think about sizes long enough you will be able to tell if the timber is 90x45 or 100x50, next may be you can see if it is 90x45 or 89x44 ... and with training you can see if a nail is 3mm thick, 3.25 or 2.5 without comparing with another nail, but just by looking at it. 
When I worked as a fitter, I could tell the size of any bolt just by looking at it, I could tell if it was metric or imperial and the type of thread it had. A glimpse at a spanner was all I needed to tell the size of it yet I have lost some of that ability because I no longer work as a fitter. 
A hand plane takes off incredibly thin slices of timber, yet when you are planing a bit of cedar for a window, you can tell if you need to take some more off or if it is enough. How is it possible when the amount you are taking off can not be measured with a tape and would need to be measured with a caliper? 
I think it boils down to confidence. If you prove your eye to be a good measuring tool enough time you learn to rely on it more and when you confirm your "guess" if you want to call it that, by measuring with a tape, you then know you are right and you can go with what you eyes are telling you.
And if you can not ... then put your glasses on!
Ha ha  :2thumbsup:

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## ringtail

> I disagree, your eyes are very accurate at picking a difference, any difference, It does not matter if you are a mm out here and there, timber is a natural product and expands and contracts all the time, so today you could be 1mm under, after some rain it will be 2mm over. 
> I also disagree with your comment about using wedges and this being inaccurate, I have built many decks including the one pictured above, the boards have all been laid using the starter board method and wedges to achieve the board spacings, I have never had a complaint from any client regarding inaccurate spacing of the boards, including the one pictured above which was for an engineer and he was very particular about board spacings, screw lines being straight. 
> A comment was made by the client that the Merbau ordered was rubbish as not every board was perfectly straight, I explained the product was made from timber not steel, and being a natural product would have some slight variations over the length of the board (ie: some will be bent), and it was my job to ensure when the boards were fixed that any discrepancies in the boards were removed and not noticeable. 
> Once this deck was finished the owner was very pleased with the result and nothing was raised in regards to non straightness of the laid boards, neither was anything raised in regards to spacing issues between the boards, if this client had no complaints then I can say my methods for using wedges is not inaccurate.    
> I could not think of anything more fiddly than using tile spacers, and I  have found using packers as spacers is a real pain as they keep  dropping through the boards, and when your 6 foot off the ground that  can be a real pain to keep going under the deck to retrieve the packers. 
> And yes I also am very particular to ensure only full width boards are used over the entire width of the deck, this comes back to simple calculations before you build your sub frame. 
> Personally I would trust Shauck's "inaccurate" eyes at guessing spacing any day, and your eyes WILL tell you if you are a mm or two out if you know what to look for.

  
Spot on.

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## DEMAK Timber

> I use a home made jig to get the screws lined up perfectly inthe center of the joist / board, then you can chalk line the rest of the boards and your screw lines are perfect

  I'm not sure if these are new or not (I only just stumbled upon them the other day...) but thought they were a good idea for marking screw holes. Similar to what you use Metrix?  Buy Online, The Deckhand Decking Template | DEMAK Outdoor Timber & Hardware

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## David.Elliott

In printing we called it an Eye-crometer. Very accurate...

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## METRIX

> I'm not sure if these are new or not (I only just stumbled upon them the other day...) but thought they were a good idea for marking screw holes. Similar to what you use Metrix?  Buy Online, The Deckhand Decking Template | DEMAK Outdoor Timber & Hardware

  Similar, I have used these before and they do work, but the plastic gets chewed out from the drill bit after a few hundred holes, even if your only using it to quickly mark the position, then the position of the holes moves because the hole has turned int an oval. 
If they only had one made from steel, it would be a good pro type tool, but I guess they want you to chew them out so you need to buy another one,  :Biggrin:  
I have a few of these somewhere, and some 3mm steel sheet, I might look into a slight modification of them.

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## shauck

They could make them out of plastic and use a metal ferrule for the holes. Would make them cheaper and lighter than all steel.

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## METRIX

> They could make them out of plastic and use a metal ferrule for the holes. Would make them cheaper and lighter than all steel.

  Problem is the holes have to be drilled onsite to suit your board width.

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