17C Timber Frame Rot

[malcolm]

I've removed the lime render that had been painted in waterproof masonry paint. On the first floor I've exposed the original 1650ish timber frame complete with wattle and daub infill panels.

Unfortunately it is completely rotten. All of the wood is soft all the way through apart from one post and some of the bressumer beam, but they are 50% woodworm holes. The wattle has rotten away and the infill panels are loose.

I will speak to the conservation officer before doing anything but want to think through a proposal first. The existing frame is beyond repair, and I don't like the idea of a beetle ridden bressumer holding up my chimney. I wonder if replacing with a new timber frame and rendering over would have any conservation value. Also would someone paint the render with waterproof paint when it starts to look scruffy?

I could commission a new oak frame and expose the beams to the outside in modern fashion. The ground floor is already bricked up, so I could replace with nicer bricks and half timber the rest. That would explain to the outside world why there is a silhouette of a building in the gable wall, and would nod to the Edwardian timber frame on the front.

Otherwise I'm thinking about using brick set back to the original render position so you can still see the outline of the original building and either leaving as brick or maybe rendering. It might be a better solution structurally and would allow more freedom for insulation. The building has been extended with brick rearwards and upwards so the original part is just an unusual feature in the wall.

Anyone have any ideas?

 

[Penners]

I don't like the idea of a beetle ridden bressumer holding up my chimney.

Actually it's probably the other way round - the chimney is more likely to be supporting the bressumer (unless you have an unusual structure).

I could commission a new oak frame and expose the beams to the outside in modern fashion.

I'm not sure that that would qualify as the modern fashion - more likely the Victorian fashion. Many timber frame houses had their frames externally exposed by the Victorians to create the "chocolate box" look when they were never intended to be seen (or deleteriously weathered) like that.

The ground floor is already bricked up, so I could replace with nicer bricks and half timber the rest. That would explain to the outside world why there is a silhouette of a building in the gable wall, and would nod to the Edwardian timber frame on the front.

Otherwise I'm thinking about using brick set back to the original render position so you can still see the outline of the original building and either leaving as brick or maybe rendering. It might be a better solution structurally and would allow more freedom for insulation. The building has been extended with brick rearwards and upwards so the original part is just an unusual feature in the wall.

Anyone have any ideas?

I think your Conservation Officer's views will be paramount in this. I imagine he/she will probably want you to repair/restore the timber frame to its original condition. I don't know whether wattle and daub infill will be required, or indeed lath and plaster over the top of it, but I really don't think there's too much point in your planning anything until you've had that conversation with the CO. You can, of course, float your other ideas to him/her, and see what the reaction is.

 

[Zebra]

Also would someone paint the render with waterproof paint when it starts to look scruffy?

Just on this point alone, you could think about a through-coloured lime render product. Mine (a through-coloured lime render to go over woodfibre external wall insulation) has only been on since 2012, so I can't say how it will look long-term, but it shouldn't ever need redoing or painting. You can also leave a "house manual" with explicit instructions for future owners about which bits should be painted in what. Of course, there's always the risk that a future occupant will ignore you, but........

 

[malcolm]

The house isn't listed but is in a conservation area. From a planning point of view I would be entitled to rip out the old stuff, bung up the hole with concrete blocks, concrete render, then paint in waterproof paint so as not to change the appearance.

That's probably not the most sensitive approach. I'm looking for ideas for something a little more sensitive that might keep the house going for another few hundred years. I don't think any of the original frame can be saved even by splicing new bits in. It is very rotten and has probably been soaking wet for 105 years, getting wetter on the invention of waterproof paint for lime render. I'm looking at new build.

I'm leaning towards a new half timbered gable in the same pattern as the original using any existing parts that can be re-used (likely none at all). The rest of the house was largely rebuilt by Edwardians so is Arts and Crafts ish with contributions from just about every architectural style all muddled together. I like the style which is why I bought the house and a bit more of that sort of thing might be even more nice (if historically inaccurate).

The beam does appear to support the chimney, though the chimney also supports the beam - it runs through the outside face of the chimney and the outer face is covered with inch thick brick tiles that you can just about see in the first photo. I don't deny having an unusual structure.

 

[Zebra]

Malcolm, I sympathise very much. I think that to rebuild it from scratch will be your only option. I had a part of my house which, although very old and a real shame to take out, was really beyond sensible repair, so I applied for planning permission (it's not listed but is locally listed and in a conservation area) to demolish it and rebuild it in modern materials, to exactly the same dimensions. This may be what you have to do. Then it would have to comply with building regs, but that would give you the opportunity to incorporate some insulation.
This is the thread where we discussed my similar dilemma, if it is of any interest:
http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=12322&hilit=+impossible+to+save

 

[malcolm]

Thanks Zebra, This one is mostly not savable as well. Possibly I can retain one or two bits, though new wood would need to be scarfed in to extend the timbers to the joints, and the surface of the very best timbers have rotten to a depth of maybe an inch. I suppose this is the sort of question that is impossible to answer if you are not here to look at the thing.

The frame is really interesting (to me). There are at least two beams that pass right through the chimney and I believe these are the oldest part of the frame. There are various peg holes which don't line up with the current timber positions.

I think the chimney was a later addition and the frame was modified to accommodate it. New timbers to support the infill panels were cross nailed in place rather than jointed and pegged. Other timbers were jointed in but were not drilled for new pegs. The deterioration has been long term - there is a steel lintel holding up an interior floor where one of the failed posts would have supported it.

Shouldn't be too much bother to fix. The structure holds a purlin which might better be supported by the chimney anyway. I would like to replace the wood in the chimney with brick as there has been movement. That will ruin the only beams that would be worth keeping.

Is daub re-useable if you wet it again, or is it bad to re-use old beetle infested daub?

 

[livias]

Daub is clay and straw (plus various unnecessary additives). The clay will be fine to reuse, but the straw gives it tensile strength so push the boat out and spend two pounds on a new bale of straw which will be far more than you need

My patent daub creation strategy which minimises hard graft is ...

Allow clay / old daub to dry. Wrap it in an old tarp and hit with mallet
Run resulting grains through a coarse sieve
Lay down the tarp and on one half make a multithinlayer sandwich of chopped straw and sieved clay, watering well
Put other half of tarp on top
stomp up and down on it, roll the tarp, add more water repeat until satisfied. It is not an exact science

An even less hard work method ideal for anyone who needs large volumes of daub
An old cement mixer with a cannonball inside
or the traditional one
Bullock hooves and a whip

 

[malcolm]

Thanks livias, I'll probably not use wattle and daub in the repaired frame, but the old stuff will have to come out so I'll keep it for repairs elsewhere. Not sure what to use for the infill - wondering if some sort of breathable insulation might be sensible. I'll seek out some advice as I don't want the dew point inside the timber.

 

[livias]

Sheepswool is popular

 

[xanthe]

Check out hempcrete.

I have to replace and also repair some daub panels (mine are on laths not wattle and thankfully un-nibbled - just abused) and I looked into hempcrete.

SPAB then said I should just use daub for the repairs and save the hempcrete for new work. Having thought I would need to find a friendly farmer with a large herd of cows to stomp me some daub, Zebra came up with this: https://www.lime.org.uk/products/mortars-and-plasters/daub/clay-and-dung-daubs/

We have zero insulation on our gable wall so I'm looking at either using daub or hempcrete as an insulating material as they're both flexible, fairly light-weight, breathable and can be moulded - so thin at the top, thick at the bottom or following contours. You can also lime plaster straight onto both which saves having to mess about with plaster board.