Oak frame Wood movement - what would you do?

[sawdustandwax]

Looking for some thoughts/advice on this.
As part of some other work I've been asked to 'hide' the wood movement in an Oak frame extension. A picture tells thousand words.

In brief they want to cover the gaps that have appeared due to oak moving through drying out. Apparently the company asked whether they wanted green or dry oak and they specified 'dry', of course that can and will still move. Regardless the objective now is to 'tidy it up' and specifically cover the gaps that have appeared.. The extension is 3 years old now
The oak beams are, or rather where, 6" square, roof is tiled with some velux windows. The front, i.e outside has stayed mostly flat, within a couple of mil at most. Assuming this is largely down to the windows frames and weight of the roof. The gap under the first pillar on the inside in the photo is about 12mm.

Client had the idea to use some oak trim to go around each pillar and run trim along the length of the ledge. That's a lot of work for something that will look, well poor.
I'm thinking of using a window board, probably only about 12mm thick, with a front lip lock mitred to it, which will run half-way across each pillar, be joined to the next piece, with a further piece on top of the lip so the end result will look like one continuous board. But I can see issues. Ideally I'd like to rebate the board into the sides of the pillars, but the glass is right up against the frame and I'd rather not take a chisel to it, just in case. So it just a lot of careful undercutting, scribe work and some judicious planing?
On the window board itself it could either be oak, or a completely different wood such as black walnut. I've left some samples. In some ways the walnut I think would help not only to cover the gap, but helping to divert to the eye from any small ones that may remain.

Any constructive thoughts welcome, even ones that say 'run for the hills'.

 

[rogxwhit]

Since the glass seems to be rebated into the sill, there's no room for a windowboard - you'd see its edge from outside the window. Also the whole composite edifice would begin to look like a dog's dinner. I would think more in terms of filling the gaps with judiciously cut oak wedges trimmed to the posts. Yes they'd be visible as a 'fix', but they'd be neat. And it would minimise cost, so they ought to thank you for that!

 

[Fitzroy]

I was thinking oak wedges also. Just a little concerned if it moves back it will then shove the vertical timbers upwards. I'd ask if the gaps are constant or vary with the seasons before fixing them closed.

 

[rogxwhit]

It's not going to move back .... indeed it may be still shrinking / distorting ....

 

[MARK.B.]

Hard to tell from the picture but is the gap just under those two pillars ? the others look to still be close fitting on the ledge. The placement of the radiator (is there more than one on that wall? ) could well be the cause or at least a contributing factor of the ledge moving in the way it has . Not expert in any way when it comes to joinery or timber frame construction/repair but imho trying to make things look straight and true by putting a window board in to cover things up would look out of place and may given time make things look worse as the thin board would /could move at a different rate than the existing timber underneath, if it does then the two will want to part company. I would leave the ledge as it is for now and let the wood do it's thing . The gaps under the pillars/posts could as others have suggested be filled with carefully cut and placed wedge of oak but this would be visible and possibly quite hard to match to the existing pillar . Another way that might be worth considering is that you fill in the bulk of the gap with a softwood wedge that is inset by a few mill and then use some quality wax filler sticks to fill in the remainder , you would carefully have to blend the colored waxes together to get a mix of of lighter and darker shades but with a little practice you can get a surprisingly good match to the original timber . Make sure the wax is pressed in well and then scrape it flat to the existing pillar to give an almost invisible join, a light buff with a soft cloth will give a soft sheen and help it even more to blend in to the original. Should the timber move more over the years then you or they may need to add a little more if the gap increases or scrape a little away in the unlikely event that the gap shrinks . If you do want to do this then i advise you get quailty wax filler sticks and can recommend having used them, those made by Konig, you can get them in singles or packs of various shades.

 

[MJ80]

I'd go with wedges, it seems to be the way of doing it externally on the old oak frames buildings round where I am in Germany. No reason to do anything different inside.

 

[sawdustandwax]

Thanks for all the replies, very much appreciated.
I've kicked the window board idea into touch. Just way too much potential for it to go wrong, not least because that framework is still liable to move. The consequences of that have been pointed out above. If this was a solid wall then there'd no issues but this framework isn't that.
So I'll steer towards wedges and wax filler.
Sometimes it's too easy to have the desire for an end result drive the solution, forgetting what it is you're working with, and this was nagging at me, hence the post and resultant reality check.

 

[toolsntat]

Personally speaking this is just best left alone unless suitable embellishment is used to cover the problems.
I can never see the point in plugging up gaps that quite likely will still be detectable.
Now, if it's causing a draught, by all means plug it up but tucked in and unseen.
I think the owner needs to accept that this is a RUSTIC construction and enjoy it's foibles.
Cheers, Andy

 

[Jameshow]

How about quarter beading and then half circle beading on the front?

Just a thought!

 

[HOJ]

the owner needs to accept that this is a RUSTIC construction and enjoy it's foibles

I'm with Andy, its an Oak timber frame, its going to move, and probably move some more as well, why do people buy into this construction method and not live with it as it is, I would leave well alone.

 

[Sgian Dubh]

I'm with Andy, its an Oak timber frame, its going to move, and probably move some more as well, why do people buy into this construction method and not live with it as it is, I would leave well alone.

I agree with both you and Andy. I'd just leave as is and not try undertake 'cosmetic' improvements. It's the nature of the material. One thing I did find interesting was the company offered a choice between green and 'dry' oak. 'Dry' certainly wouldn't have meant an MC approaching anywhere near 10 - 12% MC. More likely 'dry' would be stuff that had been air drying for a year or two and had reached perhaps 20 - 25% MC at the shell, but at the core was most likely somewhere up there at 30- 50% MC, so still quite a significant moisture gradient. No-one kiln dries large oak baulks (4" x 4" and bigger) at all that I'm aware of. It takes far too long and is very difficult if not near enough impossible, it's massively expensive, and oak, being a refractory species, is all too likely to develop kilning faults that buyers wouldn't accept. But informed buyers (customers) will accept large sections of partially air-dried or green oak inside habitable buildings with the understanding that it will gradually continue to dry in situ inside the fabric of the building, and that the wood will shrink, develop shakes, and warp. It will also get significantly stronger as it dries. Slainte.

 

[Adam W.]

Personally speaking this is just best left alone unless suitable embellishment is used to cover the problems.
I can never see the point in plugging up gaps that quite likely will still be detectable.
Now, if it's causing a draught, by all means plug it up but tucked in and unseen.
I think the owner needs to accept that this is a RUSTIC construction and enjoy it's foibles.
Cheers, Andy

To add.....

Rant on/

If anyone took even the most fleeting, cursory glance at an old timber framed building, they would realise that they aren't built like that anyway, and they are now expecting an old construction method to conform to a new style of building for which it is most unsuitable.

/rant off.