What wood and what varnish?

[Dave&Sarah]

Hi, hope someone can help and educate me a little here!?

 

We made a new outside door for the stern of our boat out of kiln dried European oak, very pleased with it indeed and finished it off by sealing it with 4 coats of Ronseal outdoor varnish.

 

We made the door by biscuiting together the oak to form a panel which we then surrounded with a frame (all glued up which I understand to be an error as we should have made the panel to float)

 

All was well through summer and into autumn but over the winter the wood has swelled by over 3/4", the overall width is around 16".

 

On a few occasions we had to plane the door down to fit and ended up taking around 3/4" off in total.

 

I have asked around as I think kiln dried oak is dried to around 13% humidity, air dried oak is wetter but can't seem to locate any. Is it a case that the wetter the better?

 

Some joiners have said that this is unavoidable and should avoid large panels and design it in a way that if it swells it can be easily planed down. Won't the wood shrink back though when it dries?

 

I have read that ash is a more stable wood so we're thinking of starting from scratch using ash.

 

I also would have thought 4 coats of varnish would have sealed the timber but obviously not, can anyone recommend the best varnish to use for an outside application.

 

Some houses have wooden doors but don't have this problem, oh well if I leave it growing it'll have acorns on it by the summer or I'll cut it in half and do the front doors too!

 

Any advice appreciated, many thanks.

 

David

[Guest wanted]

Talking to a joiner mate of mine he would suggest Jarrah, it's been keeping boats floating for ages, failing that if the money stretches a good bit of cherry would outlast steel if looked after well.

[Ray]

I'm not sure which way to suggest you go based on what you've said. I'm a little puzzled that the door has grown by ¾" as that represents a significant change in what I presume is a relatively small door - the front door of a house is much bigger and wouldn't be expected to move so much.

 

What kind of boat do you have - a cruiser stern would presumably have a much larger door than a trad stern boat and the door is thus susceptible to more movement.

 

I wonder if you made the door at home and took it to the boat so the wood had acclimatised to the warmth of the workshop, drying out even more than when you obtained it.

 

Where have you had to remove the excess wood from?

 

I think these questions need answering before anyone will be able to give you more definite guidance.

[soldthehouse]

Hi, hope someone can help and educate me a little here!?

 

We made a new outside door for the stern of our boat out of kiln dried European oak, very pleased with it indeed and finished it off by sealing it with 4 coats of Ronseal outdoor varnish.

 

We made the door by biscuiting together the oak to form a panel which we then surrounded with a frame (all glued up which I understand to be an error as we should have made the panel to float)

 

All was well through summer and into autumn but over the winter the wood has swelled by over 3/4", the overall width is around 16".

 

On a few occasions we had to plane the door down to fit and ended up taking around 3/4" off in total.

 

I have asked around as I think kiln dried oak is dried to around 13% humidity, air dried oak is wetter but can't seem to locate any. Is it a case that the wetter the better?

 

Some joiners have said that this is unavoidable and should avoid large panels and design it in a way that if it swells it can be easily planed down. Won't the wood shrink back though when it dries?

 

I have read that ash is a more stable wood so we're thinking of starting from scratch using ash.

 

I also would have thought 4 coats of varnish would have sealed the timber but obviously not, can anyone recommend the best varnish to use for an outside application.

 

Some houses have wooden doors but don't have this problem, oh well if I leave it growing it'll have acorns on it by the summer or I'll cut it in half and do the front doors too!

 

Any advice appreciated, many thanks.

 

David

Ash is certainly not as dimensionally stable as oak nor is it suitable for exterior use.for the rlatively small amout you are to use Iroko or one of the bastard mahoghanies would be better If you think about it for a moment where are the doors.... outside in the elements.. therefore you ewere on a loser straightaway using kilndied timber. Design asways needs to take into account seasonal ambient moisture changes. the frame sections wont move much but wider panel will, as long as you allow some slack in the grooves for the timbe to move slightly with the seasons european oak will be great. dont use american oak as it is not durable

Edited February 15, 2012 by soldthehouse

[Guest wanted]

Ash is certainly not as dimensionally stable as oak nor is it suitable for exterior use.for the rlatively small amout you are to use Iroko or one of the bastard mahoghanies would be better If you think about it for a moment where are the doors.... outside in the elements.. therefore you ewere on a loser straightaway using kilndied timber. Design asways needs to take into account seasonal ambient moisture changes. the frame sections wont move much but wider panel will, as long as you allow some slack in the grooves for the timbe to move slightly with the seasons european oak will be great. dont use american oak as it is not durable

I had to drill 8 10 mm holes in over 300 Iroko sleepers once, I can vouch for it's durability. Might be a good idea for the OP to search reclamation yards for old school science table tops. Probably best treated with teak oil...

[lexicon]

Having built the frame for my roof in iroko recently I can say that it is a good durable wood to use and being oily it doesn't react to moisture as much as some, but use good tools that are sharp to cut/drill or route it as it is hard to work

[RobinJ]

We made the door by biscuiting together the oak to form a panel which we then surrounded with a frame (all glued up which I understand to be an error as we should have made the panel to float)

 

All was well through summer and into autumn but over the winter the wood has swelled by over 3/4", the overall width is around 16".

Yes, normally a panel is inserted into the frame during assembly, and has a taper to the panel edge and a gap between the edge of the panel and the bottom of the groove. This allows for expansion of the panel, especially as the grain may run in a different direction to the frame.

Provided the frame has not been forced apart by the panel? Then eventually the frame will 'settle', but even I am surpised if you have to plane off 3/4". Only time will tell whether the wood is up to the job!

[alan_fincher]

I may be missing something obvious here, but if you have had to plane of 3/4", if you then get a long spell of very dry, very hot weather, will you not then end up with a gap of something approaching that amount ?

 

It seems a huge amount to me, given how relatively small narrow boat doors are anyway.

[PaddingtonBear]

The main door on Bakewell was made 35 years ago by Rex Wain, it is still perfect, need more be said?

[Dave&Sarah]

Thanks everyone for help on this, really appreciated, never heard of Iroko, I'll do some research and take a look, thanks.

 

The boat is a semi trad and the door from memory was around 20" wide with the grain running vertically and the wood has grown in width as expected but have also had to shave a little off the top as the panel is framed with wood and the frame grain at top and bottom runs horizontally but the frame strips are made from memory around 4" wide hence the minimal growth here.

 

The wood had been stored in a garage for around 6 months, not particularly dry in humidity but certainly drier than outside. As mentioned a little has been trimmed off the top but the bulk off the side which is where I expected movement but not this much.

 

I agree that the design needs to account for swelling but am just astounded by how much and as Alan points out, in the summer, given dry weather will the door shrink by a similar amount leaving huge gaps.

 

I have concluded that the door needs replacing as where we have mitred the frame, due to the swelling and angle of the top bit as the door top is angled, the frame is being pushed apart by the swelling of the middle panel as RobinJ mentioned.

 

I have asked around wood yards and they say that ash is much more stable but when I built the oak door, asked the same yards and they said it would be ideal.

 

I would have thought the 4 coats of varnish would have sealed it up though.

 

The last time I went down it had stopped growing, thankfully!

 

Thanks again for everyoned comments.

 

Dave

[David Schweizer]

The main door on Bakewell was made 35 years ago by Rex Wain, it is still perfect, need more be said?

Snap!! but only 30 years ago. I took it off last year to instal a new bottom panel (Decorated by Ron Hough) and re varnish it. Apart from sanding it to remove the faded varnish, and knocking the fox wedges in a bit to tighten the Mortice joints, it was in excellent order - made fron 2" thick solid mahogany.