When is a crack more than a crack?

arbrighton

FreeBear wrote: »

If you had a "free survey" done by a damp "specialist", they are nothing more than salesmen trying to sell you expensive treatments.

A lot of old properties do no need DPC injected/replaced as a layer of slate was often used just above ground level - If you have damp problems, look at the ground levels outside, and if need be, dig away some of the soil.

Don't be conned in to having waterproof screed & plaster applied to the lower one metre of the walls. All that will do is trap moisture in the walls, and when it freezes in the winter, the mortar & stone will disintegrate.

If you are OK doing DIY, lime plastering isn't too difficult, and is a lot more forgiving than gypsum plasters.

Our early victorian house had a DPC done by our predecessors- we are pretty sure from what the guy said that there is a layer of slate at the base, plus a plinth of engineering brick so it's pretty redundant! Sadly a lot of the brickwork has been repointed with cement mortar rather than lime and it's done inside with plasterboard/ gypsum plaster.

They did fill in the cellar though (the house is adjacent to the river) which was probably wise.

We have more problems with damp/ leaks in the 2yr old extension than the main part of the house!

Gloomendoom

I've plastered with lime and it can crack badly as it dries unless you add horse hair or straw to the mix. The latter gives a pretty rustic appearance.

ST1991

FreeBear wrote: »

If you had a "free survey" done by a damp "specialist", they are nothing more than salesmen trying to sell you expensive treatments.

A lot of old properties do no need DPC injected/replaced as a layer of slate was often used just above ground level - If you have damp problems, look at the ground levels outside, and if need be, dig away some of the soil.

Don't be conned in to having waterproof screed & plaster applied to the lower one metre of the walls. All that will do is trap moisture in the walls, and when it freezes in the winter, the mortar & stone will disintegrate.

If you are OK doing DIY, lime plastering isn't too difficult, and is a lot more forgiving than gypsum plasters.

For advice on old properties, you might want to have a chat with the guys over at http://www.periodproperty.co.uk/forum/viewforum.php?f=1 - A lot of them are involved with listed buildings and have a good knowledge about traditional building methods.

Thanks for the link. Not come across that forum before so i will have a look

It was a free survey, however my mum has used them before and they were very reasonable, advising her of damp problems that didn't need repair, but could be fixed by changes she could make. Other quotes she had were extensive but this company were honest. They were the same with me too, telling me about areas not to worry about - but that the guarantee would only be valid if i had a new DPC put in as they cannot put it against previous work, of course.

Is Lime plaster obvious to spot? I've been in next doors house as they are lovely and invite us over for a cuppa - theirs just looks normal...
They have a patch of damp on one of the adjoining walls to us where the previous owner used to run her non-condensing tumble dryer in a cupboard with no ventilation.... But this has since dried up dramatically since we've been there.

ST1991

Gloomendoom wrote: »

I've plastered with lime and it can crack badly as it dries unless you add horse hair or straw to the mix. The latter gives a pretty rustic appearance.

My husband is very allergic to animal hair and suffers with bad hayfever that affects his asthma so that wouldn't be ideal :rotfl:

FreeBear

Gloomendoom wrote: »

I've plastered with lime and it can crack badly as it dries unless you add horse hair or straw to the mix.

One can also use polyester fibres in place of animal hair - I've done a few patches this way. Yes, cracking can be a problem as the plaster dries, but the cracks can be closed up by going over it with a wooden float and lots of pressure.

ST1991 wrote: »

Is Lime plaster obvious to spot?

Generally, lime plaster will be white in colour whilst gypsum is normally pink - That said, gypsum can be white (plaster of paris), and jointing compound is also white. The latter doesn't always contain gypsum, but will have a whole bunch of modern chemicals in it.

If you can chip off the outer skin of lime plaster, you will generally find the stuff underneath to be fairly soft and friable. Depending on the mix, it could contain a range of sand particle sizes and if you dig in far enough, some animal hair.

Another way to test is to apply a drop of vinegar - If it fizzes, it will be lime.

Another question for you. What sort of paint were you going to use on the walls ?

Gloomendoom

ST1991 wrote: »

My husband is very allergic to animal hair and suffers with bad hayfever that affects his asthma so that wouldn't be ideal :rotfl:

When I was doing it, the room smelt like a freshly mown field in summer.

ST1991

FreeBear wrote: »

Another question for you. What sort of paint were you going to use on the walls ?

Hadn't thought of that, as up until this point we thought when the re-plastering was eventually done it would just be normal. Can you not paint Lime plaster? Has just planned on getting a tub of Matt from B&Q.

For the time being we have used thick lining paper over the awful plaster and painted it (downstairs) in silk emulsion.

FreeBear

ST1991 wrote: »

Can you not paint Lime plaster? Has just planned on getting a tub of Matt from B&Q.

For the time being we have used thick lining paper over the awful plaster and painted it (downstairs) in silk emulsion.

Yes, you can paint over lime plaster, but... To maintain breathability (vapour permeability), you should be using the correct paint - Nothing B&Q or any of the other DIY outlets are suitable. Unfortunately, most of the suitable paints are comparatively more expensive in the short term*

A couple of links for you -

• http://www.auro.co.uk/auro-paint
• http://earthbornpaints.co.uk/faqs/what-is-claypaint-and-why-is-it-so-special/
• https://www.mikewye.co.uk/product-category/paints-oils-waxes/internal-paints/

Whilst suitable paints may be expensive, over time, they will not give rise to damage to the fabric of the building which would cost even more to fix. Using a modern acrylic emulsion effectively seals the plaster and stops it breathing - Putting lining paper on first and then painting with emulsion still seals the surface, but is fairly easy to remove at a later date without major expense.

Another aspect of lime plaster which is often overlooked - Due to the materials used, lime plaster doesn't suffer from mold problems to the same extent as modern gypsum plasters (it is due to the pH of the lime). A selling point for asthma sufferers.

"Proper" paints need not be expensive if you are interested in mixing your own from scratch. A simple paint can be made from casein, lime, and raw pigments. Casein can be made in the kitchen by mixing some vinegar into warm milk and then washing the curds. Raw pigments are readily available from ebay or any decent artist shop (Cornellisen is one). Small quantities of lime might be a problem, but if you have your walls replastered in lime, ask the plasterer for a small bucket of putty.... Or if you get stuck, send me a PM.


Lots to think about when owning an older property :think:

ST1991

FreeBear wrote: »

Lots to think about when owning an older property :think:

Thanks, your posts have been so helpful! None of these things ever crossed my mind.

I know the house is old (1900) but never thought of it as that old!

FreeBear

ST1991 wrote: »

I know the house is old (1900) but never thought of it as that old!

If it was built before your parents were born, it is well old.

My house was built in the 1920s, and I regard it as old - Part solid brick, part cavity walls with lime plaster all over the place and gypsum plaster in the 1970s extension.