New Oak Upright - Treat it?

[skier-hughes]

We are having a new Oak upright put in to support a rather large beam. Would it be best to treat it with anything before fitting it?
Like woodworm treatment?
Thinking more of the back where it is against the wall?
Is there a benefit to this?
Is it not worth it?
I have some treatment, so it's not a problem doing it.
Anything else?
Nothing at all?

It is going against a wall which gets a rather lot of rain - when it does rain, used to have gypsum plater on, but is now awaiting lime plaster. The beam has rotted away a lot at the end, hence the suport beam. Plain brick outside.

We plan on removing the black paint from the other beams and having them all bare.

 

[Matt Green]

Isolating the back of the beam from the masonry will have more effect than any treatment. a strip of DPM or similar will suffice. Additionally, orientate the beam so that a heartwood cut surface is closest to the wall.

That done, no treatment should be necessary.


Matt Green

 

[biffvernon]

A little bit of air round the back of the beam might be best. It doesn't matter if it gets wet - it just needs to be able to dry out again. Chemical treatment is no use as they wont soak into the oak very far. Anyway, the oak heartwood has enough tannins to protect it for a few centuries.

 

[skier-hughes]

So, the wall has to be plastered as well, would it be best to plaster the wall, fit beam to iregular plaster, or fit beam to iregular wall and plaster to it? Thus stopping the air from getting behind it totally, or 3 iregular plaster to the beam leaving an air gap?

 

[biffvernon]

Er...I think you lost me round the back of that beam somewhere. Really if the oak is set in lime plaster I think it will be pretty safe. Any moisture blown in through the brickwork should be able to dry out through the lime plaster. As Matt said, if there is any sapwood, (there shouldn't be) make sure that it faces into the room. Inserting a sheet of dpc plastic is tempting but I don't think I'd do that. There is just an outside chance that you could hit the dew-point at just the wrong place and get condensation forming on the oak side of the plastic with nowhere for it to go except into the timber. And you'd never be able to know about it. I've used dpc plastic underneath the bottom of an oak post to prevent 'rising damp'. What is your post standing on?

 

[skier-hughes]

Quarry tiles sat on what could be cement on top of earth.

They all seem quite dry.

I just wondered whether any special care should be taken. I do assume though at some point the whole house would have been timber framed, then bricked up, so the posts which have rotted away on the ends would have been exposed outside at some point?

 

[Paul Hopper]

Graham

Matt has the right idea I think...

dpm is great but can ocasionally encourage moisture due to condensation.

Better to stand the bearer in a little and plaster behind leaving an air gap. if you can tolerate the small space. from memory I do not remember if you have room to do this. The orientation of the beam is critical however.

I'd go for the air gap meself.

paul