Repointing with Lime

[alfabus]

Just had a builder come round to quote for repointing the front wall of my 1890s terrace... all of the mortar can be flicked off with a finger, and it is in dire need of repair, some brick faces have blown off.

The guy who came round (he spoke to my girlfriend, because i am at work) said that he would not use lime mortar because it would stain the bricks.

I was under the impression that lime was the way to go, I think that the mortar that is currently falling off was cement based, and this has probably caused the blown faces.

Is there any truth to what he says, or should I keep looking for a better builder? Everything else he said seemed reasonable, and the price was in the right ballpark (horrible americanism, but i can't think of a better way of saying it)

the bricks are yellow london stock with a few lines of orange lesters (i think), if this makes a difference.

Thanks,
Dave (my first post... woohooo!!)

 

[JohnD]

It's usual to use cement mortar to point up bricks that have been laid in lime mortar.

this is because (as you see) the lime mortar is very soft, and the cement mortar provides a harder and weather-resistant layer. It needs to be done with skill and care to look neat and last well.

If you have doubts, ask your builder for the addresses of a few local houses that he has done over the past few years, and have a look at his work. this is always a good move. The householders will probably tell you if they were pleased with him. If he is proud of his work he should be happy to show it off.

Pointing is one of the few jobs where you can tell if it has been done well just by looking at it (after it has been exposed to the weather for a few years).

 

[alfabus]

Hi John,

He has given us an address locally that i'll go and take a look at.. The bit that concerned me was that he was refusing to use lime mortar to point with.

Is cement based mortar OK, should I insist on lime? most of the other posts i have found by searching seem to suggest that I should get lime.

Confused now!!!

Dave

 

[JohnD]

If he points with lime it will be soft and will fall out again. I can see why he wouldn't want to do that. You would probably be demanding that he repairs it for nothing.

My mother's house in outer London was built with soft red bricks and lime mortar, but was pointed from new with cement mortar (this seems to have been done on more expensive houses). Most of it is still there after 103 years. Where the lime is exposed it is very soft and crumbly. You could wear it away with a paintbrush.

Go and have a look in your district at the Victorian pubs, and the library or town hall if of similar age. they were usually built to a higher standard than most of the houses and will probably be pointed with cement.

 

[The-brickie]

Got to pull you up on this one John, lime mortar mixed to a correct ratio will not be too soft.

Cement mortar is too strong for the lime and as such does not remain flexible, it will still stick to the brick tho, this leads to water penetration blowing the pointing and parts of the bricks going with it.

I would go on about cement trapping moisture and lime being able to breathe and self heal, but some people on here think its twaddle.

http://www.oldhousestore.co.uk/acatalog/Plasters_&_Mortars.html

Do a search on lime mortar yourself to see why you should use it and avoid cement based pointing like the plague.

Just a note also to John, just because its hard doesnt mean its cement pointing, lime when mixed with a catalyst will set as hard as cement mortar.

 

[CG]

I agree with "The Brickie" too many houses have been repointed in cement rather than lime and have caused the blown face look due to the cement being harder than the old fired clay bricks.

Have a look at the following sites for info, also some conservation areas insist on lime pointing rather than cement as it looks much better and is also much better for the building.

http://www.mikewye.co.uk/faqs.htm

http://www.buildingconservation.com/articles/limegauging/limegauging.htm

http://www.periodproperty.co.uk/article028.htm

and the catalyst "The Brickie" is on about is called a "Pozzolan" and brick dust is regularly used in this country as this and is very good

http://www.buildingconservation.com/articles/pozzo/pozzo.htm

Many people who dont understand or have lots of experience in cement pointing but have never had the chance to use lime scoff at the old ways but they should give it a go and try it. You can then charge for some extra skills that are in demand!!!!!

 

[Nige F]

just my 2penny`oth.......but it should be weatherstruck too shouldn`t it.....it`ll take a time to do properly

 

[CG]

Nige F I dont think they used weather struck pointing before 1930s so just a flush finish is best

http://www.tmbc.gov.uk/assets/Policy/GPGuide.pdf

Here is a listed building guide from down in Kent that the council have done, there is a good bit on types of pointing and weather struck gets a big NO NO!

This is because of the shadow it casts, you should also get the mortar matched so it does not look too diffrent.

 

[alfabus]

i am planning on going for weatherstruck.

i am not in any kind of conservation area, and to be perfectly honest, with the state of most of the houses in my road (particular my neighbours house which has pvc cladding) a slightly different style of mortar is not going to detract from the character of my place.

i was seeking opinions on lime mortar for its compatibility with my bricks, rather than for purely cosmetic reasons. I think that weather struck pointing will be the best thing to do because there are some damp issues. I'd like to give the wall a fighting chance of repelling damp without resorting to dpc injection.

i've had a couple of other builders round, and none of them had any problems with using lime and sand mortar.

thanks for the opinions guys, please add anything else you think of... i haven't made my final decision yet.

dave

 

[CG]

Is that the same injected DPC that is sold by the same people who used to sell Upvc windows and before that time shares in Spain!!!!!

If your gutters work and you dont have any odd drainage issues around your house such as concrete footpaths that go right up to the wall or blocked drains etc there is vitually no need to inject a DPC into any property, using proper ventilation and drainage will stop damp belive me.

Not living in a conservation area does not mean you dont have to care about your property (sounds like you do by the fact you are using lime mortar) and as someone how deals with lots of period properties and also lives in one I am just advising that you dont use the weatherstruck as it will make the house look totally diffrent and bland.

Glad to hear you have found some brickies that will use lime, try and get them to match the sand with your existing as when you have finished it make look a bit white as the modern lime putty has much less impurities than days of old.

good luck

http://www.spab.org.uk/html/advice/...g/?PHPSESSID=60e65eefb9e54f935b09e34a5bb712a9

SPAB are the experts on this stuff

 

[The-brickie]

Woohoo! Nice one CG, good to see others around that know whats best for the old buildings and your views on injection dpc's are spot on too, waste of time, break down over time, dont need them. Just find the problem and put if right job done.

Also agree about weatherstruck, hate it, flush jointing all day long.

 

[Stevis2002]

Right then,

As was suggested, using the correct mix for Lime Mortar will not make it too soft.
Lime should be used for your building, as the use of cement is defeating the whole object and can, and probably will, cause damp.

Cement will also cause the type of bricks you are using to crumble prematurely, as they too will hold water around them.

I found a good point of reference

These guys have worked on my property and did an excellent job.

Steve

 

[amwc]

Hi
Pure lime mortar is difficult to use it takes ages to go off and if it rains before it goes off will stain the bricks. A far better solution is to use hydraulic lime. Its more expensive than cement/lime mixes but is far superior.And on older buildings just does a far better job. You mix it 1 :4 with your sand.

 

[jeds]

Lime every time but it must be the right stuff (see the link for MikeWye above) and you must protect the work when it sets. Also keep the pointing damp after initial set.

Struck pointing would be completely wrong and isn't practical anyway if you use the right mortar. Flush joints would be authentic.

 

[Shytalkz]

It's usual to use cement mortar to point up bricks that have been laid in lime mortar.

this is because (as you see) the lime mortar is very soft, and the cement mortar provides a harder and weather-resistant layer. It needs to be done with skill and care to look neat and last well.

Is this for real?

The reason lime was used is that it is sacrificial and will weather away in preference to the masonry. If you repoint soft porous bricks with cement mortar, it is relatively impermeable in comparison to the bricks and will trap moisture in them; freeze/thaw action will result in the faces blowing and the repointing dropping out.

A 4:1 sand:hydrated lime mortar will look much softer too. You will need to do some text mixes with different sands to get a close match with existing areas.