Acrow props and inglenook advice...

[Penners]

Would normal lime putty be good for mending the half-dome and the area between the bressumer and the soldier brick, or can you add things to make it stronger (if that is even needed)?

Useful to know that limewater can strengthen friable bricks - is there anything similar for consolidating old lime plaster or reattaching it when it's hanging away from the daub underneath?

I'm no expert on lime mortars but from what I have read on this forum, your repointing would probably best be done with a mortar consisting of 1 part lime putty to 3 parts sharp sand. As you'll be mortaring an overhead structure, I would make the mortar fairly stiff, so that it doesn't slump. I agree with your decision to avoid any kind of rough treatment of the dome in its present state, but if a decent repointing job is done, I reckon you should probably find that it will stabilise satisfactorily.

If old lime plaster is hanging off a substrate, I would remove it and replaster with haired lime plaster.

I must emphasise again that I'm not an expert - if others with more knowledge than mine give you different advice, I urge you to follow theirs.

 

[xanthe]

Thanks Penners, your advice is pretty much in line with what I was thinking.

Husband is buying an endoscope and that should let me have a good look at what is going on up above without having to shake things about too much. Lots of places one of those is going to be useful.

Given that the builder is scrapping all the loose stuff in the Grade I a few doors down, I think it's probably best to record and then strip off the loose stuff if it's just commonplace plaster.

 

[Penners]

If you're removing old lime plaster that has "blown" and are replacing it with more of the same, surely that counts as a repair, doesn't it? I wouldn't have any qualms.

 

[xanthe]

It is a repair, but they like you to keep as much of the old stuff as possible and I feel guilty pulling off stuff that has been there for 100's of years and won't be there for someone else to uncover in future like I am. Probably doesn't make sense and overly sentimental of me!

 

[MatthewC]

If you're removing old lime plaster that has "blown" and are replacing it with more of the same, surely that counts as a repair, doesn't it? I wouldn't have any qualms.

That's what I understood when I re-did my lime plaster (damp, blown, falling off, held on by the wallpaper etc), then I found somewhere that if you take off more than a certain percentage (25%??) then it falls subject to Building Control (I think). But I had done the job by then... In any case, it wasn't clear if the percentage was for a house, an individual room or a single wall or ceiling. Perhaps someone could provide more info?

 

[malcolm]

When you renovate 50% of the wall or 25% of the whole building you are supposed to inform building control so they can tell you to hack the rest off and insulate to latest regs. If you happen to be in the middle of a change of use then you can't really avoid involving building regs, but otherwise I would imagine only terminally nutty people would involve building regs when repairing a bit of plaster.

 

[xanthe]

Does renovating a wall not refer to something like rebuilding rather than plastering? Otherwise I'm screwed as basically every wall in the place needs stripping!

 

[Penners]

Do you know what is above and behind the arches? There might be something in a hidden space, Shoes are popular I believe. I found a pony saddle.

With or without attached pony?

 

[malcolm]

Building regs assume when they see a bare wall that it will be dry lined with plasterboard. Their logic is insulated plasterboard doesn't cost that much more so you may as well fit it instead. There is no appreciation that you might want to use lime plaster.

In a solid walled house you will be sure to have timbers in the wall like lintels, joist ends, plugs for skirting, even a timber frame. These will get damp and you'll have beetles and dry rot mushroom eating them if you dry line like a cavity wall. There is an exemption in the regs that says you don't have to insulate if it will damage the fabric, but there is so little knowledge in the building regs profession about breathable buildings it might fall on deaf ears. Another exemption excludes listed buildings at the conservation officer's whim.

My approach is to spend about 10 times the money on insulation systems that won't damage the building, generally with a ventilated cavity behind, but this gives a payback time of over 200 years which cannot be environmentally friendly and I get very annoyed about it sometimes. In a change of use every thermal element is considered new.

But I am assuming you are not of a nutty persuasion xanthe and will simply be repairing decorative materials like for like.

 

[xanthe]

Absolutely of a nutty persuasion - but not when it comes to houses!

Ugh. All so complicated keeping everyone happy and abiding by regs.

CO has signed off in writing on what I'm up to with internal walls and would definitely rule against any attempt to put anything potentially damaging in this house. Both he and the surveyor recommended chopping all the gypsum off the front walls of the ground floor where they put in the injected dpc.

We're attached to next door at one end - have peered through the hole in the wall and there is a cavity about 2ft across between the buildings. Both sides appear to be daub on laths (all in good nick) with lime plaster on top. So no insulation issues on that side.

Front wall has gypsum plaster straight onto brick on the bottom metre of the ground floor with daub and lime above, and daub and lime up upstairs.

Gable wall is as the front wall, but much of upstairs is purely brick with gloss paint!

Back original wall is now internal and is covered in wooden boards where visible - much is taken up by cooker etc in the kitchen. External back wall is 1970's extensions.

Attic is a disaster with the roof having insulation board shoved right up against the joists, no ventilation and no membrane. There are no walls as we have a very steep gable and catslide so it's all eaves. The gable end is just painted brick.

Plan is:

Downstairs - remove all gypsum and replace with daub and lime plaster. The old back wall will be tackled when we do the kitchen and bathroom and use daub and lime plaster where possible.
Upstairs - repair all daub and lime plaster.
Attic - re-do entire roof and put in membrane and ventilation. Probably use sheeps wool for insulation.

The only bit I'm wondering about is the gable wall where there is just painted brick. I really need book storage, so I'm wondering whether I should strip the gloss paint and just repaint with casein distemper and then put book cases in (leaving a ventilation gap) and use the books as insulation. If I use insulation there won't be space for the books.

That way, the whole shebang bar the roof should fall under repairs.

 

[Penners]

the whole shebang bar the roof should fall under repairs.

Perhaps an unfortunate turn of phrase, but I understand what you mean! :wink:

 

[xanthe]

Lol! I believe it will remain upright for a while still!