Victorian stone house & cement render/pointing...

Robby1988

Wondering if anybody could offer up some advice as to how best to approach rectifying the wall on my house.

It's a terrace and the bottom half of the rear wall has been cement rendered (right down to ground level) to match a little utility room that was built off the back door. As time goes by this render has been deteriorating, it's got numerous hairline cracks, hollow patches and it's causing interior damp. It's also doing the stonework above where the render ends no good, moisture seems to be trying to escape from the top of the render causing decay on the stonework, can see salts. All the stonework at the top half of the house is of course all cement pointed *holds head in hands* and spalling as a result.

Really wish I knew about all this stuff before I bought, but regardless I know need to get it sorted to save the wall long term.

1) Whilst I find tradesmen, is it worth/advisable to knock off any loose render myself to give the wall a chance to dry out? Would doing this make any damage caused by the penetrating damp worse in the meantime should we get bad weather?
2) Given the erosion on the stone, would it be worth re-rendering the house all the way up? Must admit i'm not confident the stonework underneath the render will be in amazing shape.
3) Is there any alternative to using a lime render? I've had loads of tradesmen in the past come in the house with a K-Rend brochure before they have even seen the wall & swear by it and say it'll let the wall breath etc. Not sure I buy it, but K-renderers and certainly MUCH easier to find than lime renderers.
4) Would anybody have any idea how much lime rendering the rear elevation of a terrace would cost?

Any input appreciated.

As a side note, the front of the house is all in it's original state with lime pointing. 150+years going strong and not a jot of spalling stonework or damp.... go figre!

FreeBear

The more preparation work you can do, the less a tradesman needs to spend time on. This will save on the overall bill. A flat bolster should get the worst of the cement render off. And if you can rake out the cement pointing with a small chisel, that will save more time for the tradesman.

There are cutting disks and routing attachments for angle grinders, but they create a lot of dust, and I wouldn't recommend them for an inexperienced user.

As for finding a tradesman experienced in using lime, without knowing the area you're in, it is difficult to provide any recommendations. Companies such as Mike Wye or Ty-Mawr might be able to furnish some names. As for K-rend, it is a synthetic resin based product, and I have yet to see any data to back up claims of "breathability". Take what suppliers and applicators say with a good dose of salt and ask to see independent lab reports.

Robby1988

Thanks for your reply.

I think I will have a go at hacking off some of the loose areas so that the damp stonework behind can get some air.

Really got a decision to make regarding whether going to the large effort & expense of having the job done properly with lime and a quality lime contractor is worth it with this property. I'm in Manchester and the only companies I can find that are interested in this kind of stuff seem to be specialist restoration outfits. First home with a £130k market value & not the 'forever home'. Would anybody else be tempted just to get the easy to find K-renderers in instead and hope for the best that the K-Rend blurb isn't all total BS before we can afford to move? :-/

Furts

Traditional cement based render works. If it did not millions of 1920-30s houses would have failed generations ago. However, the problems are various and include cement render being incorrectly specified, incorrectly applied, marketting of K Rend. All this also means countless render jobs in recent decades have been poorly undertaken - which may be the case with your home.

Part of your decision is what state your current stonework is in. If it is loose, if the joints are bad, if it has deteriorated then this needs sorting. Many people slap a coat of render over all this and expect a long lasting job. This is no different to spraying paint over a rusty car - the problems will come to light.

You have to look at costs, how long you expect matters to last and how long you will be living there. If you have any interset in eco, sustainability, quality, and so on, then you will also be concerned by Specification and workmanship.

FreeBear

Robby1988 wrote: »

I'm in Manchester and the only companies I can find that are interested in this kind of stuff seem to be specialist restoration outfits. First home with a £130k market value & not the 'forever home'.

Had a quick google for lime specialists in the Manchester area - There appear to be several that can do the job. I came across a couple that offer general plastering & drylining services as well as lime plastering. The difference between lime plaster and lime render is the former is internal and the latter, external. The materials and methods are the same, so if they can plaster, they can also do render.

just avoid the outfits that use a cement/lime/sand mix and call it "lime render". It isn't, nor does it have the properties of a pure lime render. It is just a cement render with a bit of hydrated lime (type S) added to improve the workability.

As to the "worth of the job", only you can decide - As you have seen, cement render on a solid wall has caused problems. If the damp is allowed to continue, there is every chance that it could affect the joists on the upper floor. If these rot, the repair bill is going to dramatically increase and/or severely reduce the value of the house.

Furts wrote: »

Traditional cement based render works. If it did not millions of 1920-30s houses would have failed generations ago. However, the problems are various and include cement render being incorrectly specified, incorrectly applied, marketting of K Rend.

But then the vast majority of 1920-30s houses benefited from cavity walls - Mine being typical of thousands built in this area, is cavity on the ground floor, and solid double brick on the upper half. The top half is rendered with a cement pebble dash finish. It has blown in a number of places, has numerous cracks patched, and really needs to be stripped off and done again.

Robby1988

I think i'll defiantly make efforts to at least get a quote or two for lime rendering & go from there.

The wall is very exposed to the elements & the back walls of all houses on my row of terraces are sand/cement rendered top to bottom, mine is the only one with any of the original stonework on show. None of the neighbours seem to have any problems with damp or excessive cracking which is whats getting me thinking really, I guess mine was just poorly applied. I'm actually convinced its a DIY job, especially given how they only bothered going half way up.

Robby1988

Thought i'd post an update.

Found a tradesmen with old house know-how, turns out the render on the wall is actually lime but has been damaged over the years by copious amounts of plastic masonry paint (Sandtex and the like) being applied over the top of it by previous owners trapping moisture. Seems these fancy masonry paints aren't so 'breathable' afterall. :doh: Such a shame, as somebody clearly had the know how to do the job right once upon a time.

It's all coming off and being redone with lime putty, same for the cement pointing on the upper elevation.

All the research I have done on this makes it clear that our period housing stock is being butchered en masse by modern building materials/paints, sheer ignorance and mis sold products.

FreeBear

Robby1988 wrote: »

It's all coming off and being redone with lime putty, same for the cement pointing on the upper elevation.

All the research I have done on this makes it clear that our period housing stock is being butchered en masse by modern building materials/paints, sheer ignorance and mis sold products.

As I understood, external render is usually done with NHL lime and internal plastering used lime putty - But at the end of the day, once it has fully hardened (carbonated), it shouldn't make any difference. The advantage of lime putty is that as long as it is stored in a frost free spot with an inch or two of water covering the surface, it doesn't go off - Pulled out a bucket of plaster that I'd mixed some 18 months ago, Still good to use after a quick stir

If your guy is using lime putty, ask him for a small tub of the render so that you can patch any small cracks & dings if/when needed. Also worth getting a tub of lime putty so that you can mix your own lime wash paints.

Modern materials do have their uses within old properties. For example, with renders, I wouldn't hesitate to use polypropylene fibres in place of animal hair.

Furts

Robby1988 wrote: »

Thought i'd post an update.

Found a tradesmen with old house know-how, turns out the render on the wall is actually lime but has been damaged over the years by copious amounts of plastic masonry paint (Sandtex and the like) being applied over the top of it by previous owners trapping moisture. Seems these fancy masonry paints aren't so 'breathable' afterall. :doh: Such a shame, as somebody clearly had the know how to do the job right once upon a time.

It's all coming off and being redone with lime putty, same for the cement pointing on the upper elevation.

All the research I have done on this makes it clear that our period housing stock is being butchered en masse by modern building materials/paints, sheer ignorance and mis sold products.

Does anybody care? Yes this is so, and always has been for perhaps the last 30+ years. The building industry knows the breathable paints are not breathable. But this is just a small part in a far bigger picture. Which neatly comes back to .. does anybody care?

Robby1988

Furts wrote: »

Does anybody care? Yes this is so, and always has been for perhaps the last 30+ years. The building industry knows the breathable paints are not breathable. But this is just a small part in a far bigger picture. Which neatly comes back to .. does anybody care?

Well I care & I think most homeowners of period properties would care if they knew the building materials being used on their property and the paints they are being sold aren't really suitable.

I've got an expensive problem on my house now with damp & excessively spalling stonework, simply because somebody in the past has used the wrong paint & material for pointing. Totally avoidable acceleration of decay on a property. People should care, surely?

I suppose it's all worked out quite nicely for the building trade though, all those period properties inappropriately pointed/rendered with cement in the past can now be flogged expensive damp proofing treatments, which ultimately won't work and will kick the can down the road for another expensive round of works again in future :beer::beer:

FreeBear

Furts wrote: »

Does anybody care? Yes this is so, and always has been for perhaps the last 30+ years. The building industry knows the [modern] breathable paints are not breathable. But this is just a small part in a far bigger picture. Which neatly comes back to .. does anybody care?

The National Trust care, as do a growing number number of private owners. There is also a growing interest in traditional materials based on their green credentials. As an example, a 25Kg bag of cement is responsible for generating 20Kg of CO2 during manufacture and use. A similar quantity of lime is almost carbon neutral as it will absorb CO2 from the atmosphere as it cures.

As for the bulk of the building industry, many of the unsympathetic "slap a bit of Sandtex on and shove a bit of cement in" crowd certainly do not care. After all, they won't be around to see the long term effects of their handywork, and the next generation get repeat business out of it. In the worst cases of using inappropriate materials, peoples lives could be at risk. Using synthetic paints or slapping cement renders on old cob buildings will often result in stories like this - https://www.bbc.co.uk/news/uk-england-devon-36926950

Despite the above comments, modern building materials do have their place in period properties if used in an appropriate manner and place.