Meranti double driveway gates

[SJ_Wood]

I agree about needing a gap between the boards, they will swell up.

Glue wise I like PU something like this

https://www.everbuild.co.uk/product/45-minute-polyurethane-wood-adhesive-liquid/
PU can get a bit messy if you are not used to it but it's 100% waterproof. The 502 stuff can start gripping quite quickly and make assembly a bit fraught if you don't get a move on, also it's only D3 rated, a D4 rated adhesive is more waterproof. Everbuild do a D4 pva type glue or Titebond 3 is D4 rated.

You say the boarding is captive on 4 sides, how have you finished the bottom of the boards, it's traditional to just let them fly over the front of the bottom rail so the water can run off?

Hi Doug,

ok may revisit the glue choice, thanks.

I needed a 'beefy' bottom rail due to the below ground automation I have, good point on the rain though, may need to put a bevel on it?
Shown here with the adapter plate, there will be a metal plate added to take some of the force;

 

[furnace]

looks good!, I think you are right that would have been better!

Having just repaired a gate with a insufficient gap between the boards, and biscuits used for the diagonal braces I'd strongly suggest leaving a generous gap between them and bit use biscuits. In wet conditions (like UK winters) they'll swell and buckle if insufficient room is provided. Similarly, moisture will rot a beech biscuit over time, and there's insufficient structural integrity to accommodate the shearing load on those diagonal braces. I'd suggest notching them in accurately and allowing the mechanical strength of the wood rather then glue and biccies.
Great job. They look smashing.

 

[SJ_Wood]

Having just repaired a gate with a insufficient gap between the boards, and biscuits used for the diagonal braces I'd strongly suggest leaving a generous gap between them and bit use biscuits. In wet conditions (like UK winters) they'll swell and buckle if insufficient room is provided. Similarly, moisture will rot a beech biscuit over time, and there's insufficient structural integrity to accommodate the shearing load on those diagonal braces. I'd suggest notching them in accurately and allowing the mechanical strength of the wood rather then glue and biccies.
Great job. They look smashing.

thank you!

yes will defiantly revisit the bracing and notch in!

 

[profchris]

On the boards swelling. I would take an off cut, measure the width then dunk it in water for 24 hours . Measure the width again when it's swollen with water and that gives a worse case scenario of how wide the boards could expand (not that they will be submerged in water when they are in the gate but it gives you an idea of possible expansion) . I've seen boards bulging out in gates because not enough room was left for them to move so worth getting it right at this stage.

It's really worth doing this!

I looked around for humidity expansion figures for meranti but they are hard to find - it appear that meranti might move around 50% more than mahogany. That suggests that a 10% increase in moisture content (seems plausible) could lead to 3.6% expansion.

Those boards look around 75 mm wide, so each one might expand by over 2.5mm. You have 12 boards there, so that's 30mm + in total!

Philip's method will let you measure the worst case scenario, and others have shown how to deal with it. I believe the main point of T&G is that you see the gap, but the tongue is still there so you can't see right through. That's exactly to allow for humidity changes.

 

[SJ_Wood]

It's really worth doing this!

I looked around for humidity expansion figures for meranti but they are hard to find - it appear that meranti might move around 50% more than mahogany. That suggests that a 10% increase in moisture content (seems plausible) could lead to 3.6% expansion.

Those boards look around 75 mm wide, so each one might expand by over 2.5mm. You have 12 boards there, so that's 30mm + in total!

Philip's method will let you measure the worst case scenario, and others have shown how to deal with it. I believe the main point of T&G is that you see the gap, but the tongue is still there so you can't see right through. That's exactly to allow for humidity changes.

scary ! think I will go with 2mm and 5mm each end.

could swap out the Meranti T&G for a better wood I guess?

had my head around flooring T&G where you don't gap (obv as internal) so glad you all put me right before too late!

 

[SJ_Wood]

Great idea re pinning each board. Pre drill in the 't ' and fix with a copper pin.

so copper pin, any links please?

 

[Fred48]

I should have written brass. 25 mms available on Amazon

 

[SJ_Wood]

I should have written brass. 25 mms available on Amazon

right! that threw me thanks!

 

[katellwood]

You say the boarding is captive on 4 sides, how have you finished the bottom of the boards, it's traditional to just let them fly over the front of the bottom rail so the water can run off?

Yes you are right Doug, however as a barefaced rail is narrower than the main frame (the thickness of the boards) as, no when they swell they are likely to bow the barefaced bottom rail DAMHINT

 

[Sgian Dubh]

It's really worth doing this!
I looked around for humidity expansion figures for meranti but they are hard to find - it appear that meranti might move around 50% more than mahogany. That suggests that a 10% increase in moisture content (seems plausible) could lead to 3.6% expansion.

White meranti has shrinkage factors of: Radial = 3% and Tangential of 6.6%
Yellow meranti's figures are: Radial = 3.4% and Tangential = 8%.
Mahogany (Swietenia macrophylla) has figures of: Radial = 3.7% and Tangential = 5.1%

So yes, Tangentially, yellow meranti's shrinkage/expansion factor is approximately 57% greater than mahogany's, but white meranti's shrinkage/expansion factor is about 30% greater. However, there are lots of species (60 - 70) sold as meranti of various shades of white, yellow and red, so each species could have different shrinkage/expansion factors.

I don't think we know for sure which meranti is being used here, and I don't know the figures for quite a number of the species within the Shorea genus that get lumped together, as above. But the dumping of a sample in water idea is probably a pretty good one. Slainte.

 

[SJ_Wood]

White meranti has shrinkage factors of: Radial = 3% and Tangential of 6.6%
Yellow meranti's figures are: Radial = 3.4% and Tangential = 8%.
Mahogany (Swietenia macrophylla) has figures of: Radial = 3.7% and Tangential = 5.1%

So yes, Tangentially, yellow meranti's shrinkage/expansion factor is approximately 57% greater than mahogany's, but white meranti's shrinkage/expansion factor is about 30% greater. However, there are lots of species (60 - 70) sold as meranti of various shades of white, yellow and red, so each species could have different shrinkage/expansion factors.

I don't think we know for sure which meranti is being used here, and I don't know the figures for quite a number of the species within the Shorea genus that get lumped together, as above. But the dumping of a sample in water idea is probably a pretty good one. Slainte.

so this was on the order if it helps?

will let you know tomorrow on the wet test!

 

[Lazurus]

Loving this thread and WIP - great work.

 

[johnnyb]

I used sapele and used my flexible friend as a spacer. overwintering fine(I built them 12 months ago.) it's not that easy as some had warped a bit. also I used sadolin classic on the t and gs first.

 

[Robbo60]

Great job. Been thinking about something similar so can I ask how you shaped the top piece? Why did you alter the diagonal brace from the original design. i.e. Corner to corner?
What wood would be best value for this project

 

[SJ_Wood]

Great job. Been thinking about something similar so can I ask how you shaped the top piece? Why did you alter the diagonal brace from the original design. i.e. Corner to corner?
What wood would be best value for this project

thank you!

top piece was done using a template I made then simply using a band saw, others on here have used a router.

I changed the diagonal bracing as it would have been under 45 deg angle which would have compromised the support imo, also going to redesign further and notch in after advice on here.

the wood I used was expensive , should have sourced it from a ‘proper’ timber shop , mine came planned/treated.

not a expert by any means so will let others guide you on selection

 

[Sgian Dubh]

so this was on the order if it helps?
View attachment 106764

I don't have shrinkage percentages for dark red meranti, I'm afraid. But if you assume they're similar to the ones I provided for yellow meranti you should be safe enough. Anyway, you've got your sample soaking up water so that will give you a good idea of the absolute maximum expansion you might expect over its moisture content from when you started the experiment. Naturally, that won't tell you how much potential shrinkage is in those pieces because you don't seem to be undertaking a shrinkage test, i.e., drying the wood completely. Naturally, in use your wood is likely to only experience about 1/3+ of all the expansion and contraction it could because the MC is likely to vary anywhere between about 9 - 22% MC seasonally. In other words, it's highly unlikely to go through cycles varying from 0 - 30% (FSP) and above which would cause the wood to go through its full range of expansion and shrinkage in response to variations in MC. Slainte.

 

[SJ_Wood]

I don't have shrinkage percentages for dark red meranti, I'm afraid. But if you assume they're similar to the ones I provided for yellow meranti you should be safe enough. Anyway, you've got your sample soaking up water so that will give you a good idea of the absolute maximum expansion you might expect over its moisture content from when you started the experiment. Naturally, that won't tell you how much potential shrinkage is in those pieces because you don't seem to be undertaking a shrinkage test, i.e., drying the wood completely. Naturally, in use your wood is likely to only experience about 1/3+ of all the expansion and contraction it could because the MC is likely to vary anywhere between about 9 - 22% MC seasonally. In other words, it's highly unlikely to go through cycles varying from 0 - 30% (FSP) and above which would cause the wood to go through its full range of expansion and shrinkage in response to variations in MC. Slainte.

ok so 24h in water;

120mm width now 122.5mm

Shrinkage test, just leave in the sun now?

 

[profchris]

I'd say you have your answer!

The maximum width your boards will reach is an extra 2.5mm. In practice they'll never get that wet , so you could allow a little less. That might mean:

2.5 mm per board to be absolutely safe

2mm per board should be fairly safe.

1.5mm per board is being brave.

If it were me, I'd line up 2 or 3 boards at each spacing and stare at them. Then I'd build it at the widest spacing I felt looked acceptable.

 

[SJ_Wood]

I'd say you have your answer!

The maximum width your boards will reach is an extra 2.5mm. In practice they'll never get that wet , so you could allow a little less. That might mean:

2.5 mm per board to be absolutely safe

2mm per board should be fairly safe.

1.5mm per board is being brave.

If it were me, I'd line up 2 or 3 boards at each spacing and stare at them. Then I'd build it at the widest spacing I felt looked acceptable.

agreed! , already cut my spacers at 2mm so committed !

 

[Sgian Dubh]

ok so 24h in water;
Shrinkage test, just leave in the sun now?

To be honest, I think you have all the information you need. Your boards are never going to experience the full range of potential movement. As profchris has suggested, allowing approximately 2 - 3 mm per board for shrinkage and expansion should cover it.

But if you really want to dig around and explore a bit further into how wood reacts to water as it's adsorbed and desorbed, you might look here. It's only a start into the fascinating world of timber technology (well, fascinating to me anyway), and perhaps not directly relevant to what you're doing now, but you may find it of interest. Slainte.