Timber expansion

[Geoff_S]

Hi there, I need some help please. I'm not trade but have done a lot over the years, and this has foxed me completely.

I've made a gate/door for outside, 2100mm x 900mm.
It's made out of kiln dried European Oak, 90mm x 21mm planks.
I left the planks in the garage for 3 months to acclimatise.
I then T&G'd the planks and glued them together with Titebond 3 to make the door.
I then glued & screwed 3 horizontal cross braces, 90mm x 21mm, a screw in each vertical door t&g plank.
I then glued and screwed 2 diagonal cross braces, again a screw in each vertical plank.
I then finished it in 3 coats of Sadolin Extra Durable clear coat.
I the hung it on 3 heavy duty 400mm cast iron gate hinges.

3 months later the whole door has curved in the vertical! it looks like each vertical t&g plank has expanded, but of course the horizontal braces haven't, hence the curve.

What have I done wrong? How could I have avoided this happening?

 

[Beau]

With T & G dont glue the joins and leave expansion space. Never easy to work out how much to allow for expansion and shrinkage though and feel your pain.

I did the same many years ago with some garage doors and glued up the T & G. They have survived but crack to hell during the summer and become convex during the winter.

Oh and welcome to the forum

 

[thetyreman]

also nails instead of screws would be a better choice, it allows for more movement.

 

[Phil Pascoe]

Stainless nails?

 

[Beau]

Stainless nails?

I use sheradised and they seem to hold up well.

 

[kevinlightfoot]

Oak expansion and contraction is approximately a quarter of an inch over width of one foot,this is for boards of One inch in thickness.So overall you can expect movement of three quarters of an inch.In a door of the type you have built I would not use glue at all and as has already been said nails are the correct way to fix.For those who may be interested a good guide to the expansion and contraction of wood can be found in a book called,Understanding Wood,the author is Bruce Hoadley,I think the spelling is correct but you may find a copy on a well known auction site.Hope my input helps.

 

[Geoff_S]

Thanks for the replies, I guess I just over engineered it all, like most of my stuff. It would never have occurred to me not to use glue and that nails are a good idea, now I know and it makes sense.

It just astonishes me that my gate is going to expand and contract 3/4", but I know that it probably has. Just astonishing.

And Understanding Wood book has now been ordered.

One last question, how old do I have to be before I know everything?

 

[Droogs]

You can only know everything as a man if you were born the week before Adam and on the 32nd of Julember or be born female :roll:

 

[Phil Pascoe]

The Hoadley book is cheaper 2nd hand on Amazon than Waterstones Marketplace.

 

[ED65]

It just astonishes me that my gate is going to expand and contract 3/4", but I know that it probably has. Just astonishing.

Sorry to maybe confuse things a bit but expansion of a given species of wood shouldn't ever be given as a single figure, as it is as much as 50% lower for pieces that aren't flatsawn or plainsawn.

There's a lot of information on this online now, unfortunately mostly American (so related to common NA species), but regardless you'll see two columns of figures provided in many tables, one for flatsawn and the next for quartersawn with much lower numbers.

And Understanding Wood book has now been ordered.

Again this is American-centric so expect quite a bit of the specifics to have little or no practical application for what you do unless you commonly use NA species.

If you're in a buying mood might I also recommend "Hammer and Nails Carpentry" by Charles Hayward? As with most Hayward books copies are usually available inexpensively on the secondhand market.

One last question, how old do I have to be before I know everything?

Methuselah?

 

[kevinlightfoot]

Just remember the man who never makes a mistake probably never does much!

 

[Sgian Dubh]

... how old do I have to be before I know everything?

No idea on that one - sorry.

Most other posters have covered the essentials. But here's another point to consider. If you're making a wooden item that's going to be used outdoors it's generally a better idea to try and source air dried material. Here in the UK air dried wood rarely seasons to much below about 18 - 20% MC unless it's subjected to further drying either in a kiln or through stickering up the boards in a drier environment, e.g., a dry shed or similar. 20% MC is at about the middle of the MC range exterior wooden items range around, so it's sensible to use wood that's slightly under that during construction if you can find it: it's not always easy to find if you don't know where to look. You evidently made efforts to acclimatise your wood, but air dried material is usually somewhat cheaper than kilned stuff, so little or no acclimatisation would likely have been required. Slainte.

 

[Geoff_S]

... how old do I have to be before I know everything?

No idea on that one - sorry.

Most other posters have covered the essentials. But here's another point to consider. If you're making a wooden item that's going to be used outdoors it's generally a better idea to try and source air dried material. Here in the UK air dried wood rarely seasons to much below about 18 - 20% MC unless it's subjected to further drying either in a kiln or through stickering up the boards in a drier environment, e.g., a dry shed or similar. 20% MC is at about the middle of the MC range exterior wooden items range around, so it's sensible to use wood that's slightly under that during construction if you can find it: it's not always easy to find if you don't know where to look. You evidently made efforts to acclimatise your wood, but air dried material is usually somewhat cheaper than kilned stuff, so little or no acclimatisation would likely have been required. Slainte.

Now that makes a lot of sense as I've just remembered that I did exactly that with two pairs of garage doors that I made. I had got a fantastic deal on some French green oak that I cut into planks and had left in my workshop for a couple of years. I
t&g'd those as well, glued and screwed and I've just checked them after some 10 years and they are still OK ( apart from one that's dropped on the tenon, must fix that some time (hammer) ).

Hmmmm, so much to consider.

 

[Sgian Dubh]

Hmmmm, so much to consider.

One other consideration. If you do use air dried wood for a project destined for external use, and you're not absolutely sure all the wood is below 20% MC, the only adhesive that will work is polyurethane adhesive. All other adhesives are designed for use on dry wood. By definition, dry wood has a moisture content of less than 20%. If it's at 20% or greater all the other adhesives fail, so it's pointless using them, and you need to incorporate joinery that mechanically locks without adhesive, e.g., M&Ts locked with cross dowels, etc. Slainte.

 

[dickm]

Sorry to maybe confuse things a bit but expansion of a given species of wood shouldn't ever be given as a single figure, as it is as much as 50% lower for pieces that aren't flatsawn or plainsawn.

There's a lot of information on this online now, unfortunately mostly American (so related to common NA species), but regardless you'll see two columns of figures provided in many tables, one for flatsawn and the next for quartersawn with much lower numbers.

Am I missing something here? Earlier posts give expansion as a single linear measurement; as well as the way it is sawn, surely expansion can only sensibly be quoted as a fraction (or percentage) for a given change in moisture content?

 

[Droogs]

Am I missing something here? Earlier posts give expansion as a single linear measurement; as well as the way it is sawn, surely expansion can only sensibly be quoted as a fraction (or percentage) for a given change in moisture content?[/quote]

It is not given as a % due to the fact that the expansion ocurrs at a differrent rate dependent on whether it is a face that is long grain (a greater range of change) or end grain (minimal)

 

[rafezetter]

You can only know everything as a man if you were born the week before Adam and on the 32nd of Julember or be born female :roll:

Women aren't born knowing everything - it's the wedding ring that contains the full download, and the reason why it only seems to occur after that. I tried one on once but all I got was garbled static, I guess it must be in Venusian.

 

[Giff]

Hi Geoff S, another Geoff S here....Similar to you I am not trade but have done quite a bit over the years. When I first started I couldn't get anything outside to remain stable. I started using reclaimed pitch pine and yellow pine, re-sawn into boards from large beams. Of all the stuff I made, including exterior shutters using yellow pine (painted) nothing has moved or rotted. I know the yellow pine might be considered a no no but it works ( +30 years at the moment)....
The pitch pine is heavy but bomb and water proof.....Geoff