Replacing cement with lime mortar

ilikewatch2

Morning all,

I've just received back the building survey from a property we're hoping to buy - the property was built in the early 1700's and has a Victorian extension to the rear.

The survey is mostly positive, but highlights that there are numerous localised repairs to the pointing/brickwork with have been made with portland cement where the original material would have been lime mortar. The survey recommends that the cement is replaced with lime mortar as a matter of urgency as it is causing damage to the bricks and causing moisture to be retained.

I doubt it will be easy to get anyone to quote for the work before we've even bought the house, and since we're not likely to complete the sale until November I shouldn't that will be the ideal time to be undertaking the work anyway.

Can anyone offer any advice as to how big a job this is likely to be, and how urgent it really is? I'm thinking it would be best left till spring to get get quotes. Attached picture shown repairs to the pointing made with cement, and the wet brickwork the surveyor says this is causing.
 

tacpot12

We had a similar sort of issue at home due to cement render being applied over the brickwork on a small gable wall. The area was larger than shown in your photo and we got a contractor to remove the render and repoint for about £500. I had trouble finding a contractor to take on the work, so ended up going with someone off Check-A-Trade who disappeared the moment the work was done, which I found bizarre as the work was done to a good standard. They never came back for the extension cord they left with us despite being reminded about it. 

We arranged the scaffold, which cost £800 because it had to span the full width of the house. You should be able to get the scaffold a bit cheaper as it only needs to reach across a small width.

While the scaffold is up, I would have a good look at the  chimney and include any repairs to the haunching on the top of the chimney. I'd also recommend gettings cowls fitted to the chimney pots of any fireplaces that are not going to be used.  

stuart45

I wouldn't leave till spring to get some quotes, as it would be better to try and start it in spring. The cost will depend on which area you live in, as well as how much work you want done on it. 
It looks like there are quite a few damaged bricks on the wall faced with a sand/cement parge. 
With very soft bricks pointed in a hard cement mortar, a fair bit of care is needed when cutting out the old joints. Worth picking the best colour for the mortar as well. Finishing up with large, bright white joints can look a bit of a mess, especially when someone not experienced with lime mortar has wacked it with the churn brush too early and got it all over the facework. 
The wet bricks look like they could be following the line of the flue, which is quite common in older properties.

FreeBear

ilikewatch2 said: I doubt it will be easy to get anyone to quote for the work before we've even bought the house, and since we're not likely to complete the sale until November I shouldn't that will be the ideal time to be undertaking the work anyway.

Can anyone offer any advice as to how big a job this is likely to be, and how urgent it really is? I'm thinking it would be best left till spring to get get quotes.

I would suggest getting quotes as early as possible (Nov-Jan) with a view to having the work done late April/May next year. You want it done after the risk of frost has passed but before hot weather sets in. Both are difficult to gauge what with global warming & stuff, but April/May is as good a time as any. Most trades are on a long lead time, so it may be six months or more before you can get anyone to start work.

ilikewatch2

Thanks all - I'll look to get a quote for the work sooner rather than later.

FreeBear

When getting quotes, ask what sort of mortar mix they intend to use - It should be 2-3 parts lime to 1 part sand. If they mention cement and/or hydrated lime, a swift kick up the backside is required and ignore anything else they have to say.

stuart45

Ideally the mix should be similar, but slightly weaker than the original. A lot of people will go for NHL 3.5, which is fine for some masonry units, but too strong for others. Really soft bricks will need a softer lime. Recent anaylsis of NHL 3.5 mortar has shown that after a few years it is  harder, less breathable and less flexible than originally thought.
As your property is 1700 it might be worth getting the original mortar tested. Not worth spending out a lot of cash for something that is still too strong. 
Having worked on some older properties I know that NHL isn't allowed on some of them.