hi,
wondering if anyone could give me a little guidance here. i live in a semi-detached house that need some repointing doing to the brickwork. i'm thinking of having the whole lot done including the chimney. it's standard red brick, nothing fancy but i was wondering if anybody could give me a general idea about how much it's going to cost me. thanks for any help
Suggest you contact Gun Point
Peter
Peter Taylor wrote
Whoever you use, first check to see that you don't have lime mortar. If modern cementious mortar is used to repoint a lime mortar house, you could cause serious damage and some of the brain dead spods that get contracted to do the work wouldn't have a clue.
Christian.
I'm probably going to need some repointing done soon. I'm assuming that my house (1900's terraced) will have been built using lime mortar, right? Assuming so, what are my chances of finding a brickie who will use it these days? Won't they all just want to use cement-based stuff instead?
David
Nah. Its very fashionable. juts bang in hydrated line instead of portland and slap it in.
And hope it doesn't rain for a couple of months. Hydraulic lime might be a better bet
Hi.
One point not mentioned yet is that sound mortar should never be stripped out of old houses built with soft bricks. One should only replace mortar that is loose and can be removed by hand. So you never do a complete repoint, but always patch, and be prepared to patch again several years later. The reason is that most of these houses have been repointed already with cement, which is much stronger than the bricks, and if you remove the cement it breaks part of the brick away with it. You can do a lot of damage this way.
Regards, NT
Just use 1:1:6, or even approach 1:2:9.
J.B.
1:1:6 is very common, but has been widely criticised by the experts, since the lime content causes thr cement to not checmically set properly, and the cement clogs the pores preventing the lime going off properly as well. The result is regular failures. But its still commonly used. I expect it'll take another 10 years for the knowledge to permeate.
Regards, NT
So what would you suggest, or an expert recommend?
I've always used a readymix general purpose mortar with 4 water:1 PVA. It needs to be fairly thick to avoid getting it on the brick faces.
I'm no expert on this, I've just read a few papers on it, so I'd stick my head in the sand and suggest asking an expert :) Seriously, when I read it I was boggled with the complexity of what I thought was such a simple thing.
I did discover one thing though, which is inclusion of 1% plastic fibres increases longeveity by controlling cracks and increasing strength under tension. The Victorians knew this principle, and it was standard practice to include horsehair in their mixes because it extended mortar life significantly.
I wish I could give us all a better answer. I still dont know what to repoint the house with.
Regards, NT
I think we are in the same situation. This house has had about 10% repointed with cement, and a survey stated it was poor, although doesn't seem at all bad to me. Trouble is the front has very thin joints hence easy to make a mess of. As this place will get sold within 5 years, I think I'll just give the facade a scrub; this should give the mortar a fresher appearance so may pass a casual inspection. I've used 1:1:6 mix on small jobs such as window reveals and it seems to have performed just fine.
On the flip side, lime mortar houses circa 1900 are great for putting holes in, as easy as Lego.
You've got to be joking! My 1909 house is terrible for putting holes in. The mortar and brick are so soft, it is hard to drill anything without whole bricks disintegrating.
I can often get one in by turning off hammer until it is an inch in. After that, the hammer is required to advance, and very careful and delicate hammer can sometimes get deeper without smashing the thing.
Christian.
Well, I meant window sized holes, being careful not to end up with patio door sized holes ;-) But yes I agree. I have an intriguing 1st floor brick/lime mortar internal dividing wall supported on a regular joist. I think the bricks must be the Victorian equivalent of thermolites as there just does not seem to be any substance to them. A stubborn finger is all that is needed to transform them to dust (Discovered after attempting to fix basin to wall... :-(
It sure isn't simple, and neither is it the case that it's completely understood. I used to have a neighbour who taught brickwork, and his comment was that we're discovering what we don't know about cement based mortars faster than we're working how to use them properly. We know (or at least used to know) much more about lime based mortars, since we've been using them at least 200 times longer.
However, I recall reading somewhere a few years ago (possibly in this newsgroup) that the BRE had experimented with various cement/lime mixtures, and the 1:1 was quite good. Any less lime and the mortar loses all the movement and self-repair qualities of lime, so you'd be back to the problems you get repointing a lime mortar house with cement. I think there were problems with mixtures containing more lime too (until you get to pure lime of course), but I can't recall what that was.
I've not come across it in mortar, but it's certainly used in scratch coat lime plaster. This stops it cracking as the lime mortar walls move around. The dot-n-dab plasterboard fixing is loaded with plastic fibres too to give it tensile strength. The tutor on my plastering course demonstrated how effective that is by hanging his weight on a piece of board fixed up with the stuff, and it showed no sign of giving way.
Silicone bath sealant? ;-)
Wickes (in their Good Ideas Leaflet no. 12 at
David
I always use it when I'm not using lime. However, not everyone is convinced it's a good idea.
I always use waterproofer too, with either lime or plasticiser. (Sometimes I use all 3 if I only have a combined plasticiser/waterproofer and want to use cement/lime mortar mix.)
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