Repairing decayed mortar/cement to make weatherproof?
Discussion
Can anyone advise? I have areas around Paolow Castle that need a little bit of attention after the very wet winter we have had. One such issue is pictured (and is really what we are talking about here). There is damp on the inside - first time it has turned up - but that face experiences driving rain so clearly this is a thing to address. The house is a poss 1895 build (or thereabouts) and I know you can get mortar repair sleeves/cartdridges/tubes for a skeleton gun to just squirt in the crack - but these just dont sit right with me as they are (or seem to be) acrylic based.
I know there are schools of thought re using sand and cement to repoint old houses at all - but clearly this has already been done - so we are where we are - and I thought maybe this wasnt as alien as some of the mortar repair things...
My thought process is to get rid of the old cement in the area and replace with S+C from a premixed tub from one of the sheds - possibly with the use of a loadable skeleton gun cartdridge to make the application deeper and also not as horribly messy. I think that if I make a half decent job it will make it at least weather tight? Does that seem like a good idea?
I suppose the second question is that, if it does, I will then have a tool to I can then use again - and every hole in the brickwork or similar I find will have me reaching for it - such as, for instance the drilled hole on the left of the image. Is there anything massively wrong with this approach? Its an old house and there are bits that arent perfect - but I dont want to go merry hell with this technique if it is 'wrong'?
I know there are schools of thought re using sand and cement to repoint old houses at all - but clearly this has already been done - so we are where we are - and I thought maybe this wasnt as alien as some of the mortar repair things...
My thought process is to get rid of the old cement in the area and replace with S+C from a premixed tub from one of the sheds - possibly with the use of a loadable skeleton gun cartdridge to make the application deeper and also not as horribly messy. I think that if I make a half decent job it will make it at least weather tight? Does that seem like a good idea?
I suppose the second question is that, if it does, I will then have a tool to I can then use again - and every hole in the brickwork or similar I find will have me reaching for it - such as, for instance the drilled hole on the left of the image. Is there anything massively wrong with this approach? Its an old house and there are bits that arent perfect - but I dont want to go merry hell with this technique if it is 'wrong'?
You may do better with a more flexible mortar.
Which might be 'lime' based.
OR it might be a modern mortar with some additives.
As well as flexibility, there may be issues with porosity.
A mortar which has different porosity to the brick may increase the tendency of the wall to absorb rain.
DYOR!
Mind how you go, this subject is a minefield of strong opinions!
Which might be 'lime' based.
OR it might be a modern mortar with some additives.
As well as flexibility, there may be issues with porosity.
A mortar which has different porosity to the brick may increase the tendency of the wall to absorb rain.
DYOR!
Mind how you go, this subject is a minefield of strong opinions!
Thanks - and yes you are quite right there are quite polarised opinions on this kind of thig. I guess, in the absence of dissenting opinion that my plan isn't howlingly bad, and, although arguably not perfect it will nonetheless (hopefully) at least be waterproof (which it currently isnt). I am a bit constrained in terms of materials as to what I can get my hands on as im going to be looking at premixes - but I think that will have to be what it is...
It's a long time since I've had these problems, but I think if you look around, you might be able to get pre-mixes of all sorts of stuff.
It's really not hard to mix small quantities of 'stuff' either.
Also, you can get cement dyes, so it's possible to make repairs more discrete.
The other thing is, when it comes to actually keeping the rain out, I'm aware that coatings/surface treatments have moved on, but personally I've not had to play that game since Thopson's Weather Seal went waterbased some time in the 90s (IIRC).
I may be getting a bit interested again with a possible house move. Right now, I'm aware there is more to know than I do!
It's really not hard to mix small quantities of 'stuff' either.
Also, you can get cement dyes, so it's possible to make repairs more discrete.
The other thing is, when it comes to actually keeping the rain out, I'm aware that coatings/surface treatments have moved on, but personally I've not had to play that game since Thopson's Weather Seal went waterbased some time in the 90s (IIRC).
I may be getting a bit interested again with a possible house move. Right now, I'm aware there is more to know than I do!
The general principle is that mortar should always be weaker than the material it is bonding.
Consider joints to be the 'drains' of a wall - yes if the joints are badly weathered they will admit water but conversely a mortar that's too strong, and thefore impervious relative to the parent material, will have the effect of holding water within the wall which has been absorbed by the brickwork.
That's why you often see walls with bands of pointing standing proud and the brick weathered back around it by frost action and other agents of decay because the strong mortar has assisted the wall in retaining moisture.
I would cut the joints back to x2 joint width in depth and repoint using something like a 1:1:5 or perhaps a bit stronger if the wall is particularly exposed.
And yes mortar guns are useless as you need such a wet mix to get the gun to work it's usually too weak even when you up the cement content.
Consider joints to be the 'drains' of a wall - yes if the joints are badly weathered they will admit water but conversely a mortar that's too strong, and thefore impervious relative to the parent material, will have the effect of holding water within the wall which has been absorbed by the brickwork.
That's why you often see walls with bands of pointing standing proud and the brick weathered back around it by frost action and other agents of decay because the strong mortar has assisted the wall in retaining moisture.
I would cut the joints back to x2 joint width in depth and repoint using something like a 1:1:5 or perhaps a bit stronger if the wall is particularly exposed.
And yes mortar guns are useless as you need such a wet mix to get the gun to work it's usually too weak even when you up the cement content.
Useful points - thank you.
I am wary of the tubes of 'mortar fix' precisely for the points raised - that the finished pruduct will be stronger than the brick - and so land me in issues further down the road. I just want to fix it properly.
That said, given that a skeleton gun loaded with mortar may not practically work - what actually is the solution? In my mind I would cut out the loose cement and then replace with, I guess 3:1 sand and cement - Which I appreciate is not entirely correct - but it both seems better to do that and be more waterproof than not?
If S&C isnt going to work in a skeleton gun - I mean - it will, it just depends on the size of the nozzle - but you get what I mean - then just getting rid of that old loose cement and replace seems most practical?
I am wary of the tubes of 'mortar fix' precisely for the points raised - that the finished pruduct will be stronger than the brick - and so land me in issues further down the road. I just want to fix it properly.
That said, given that a skeleton gun loaded with mortar may not practically work - what actually is the solution? In my mind I would cut out the loose cement and then replace with, I guess 3:1 sand and cement - Which I appreciate is not entirely correct - but it both seems better to do that and be more waterproof than not?
If S&C isnt going to work in a skeleton gun - I mean - it will, it just depends on the size of the nozzle - but you get what I mean - then just getting rid of that old loose cement and replace seems most practical?
I can highly recommend this product: https://www.sealantsandtoolsdirect.co.uk/everbuild...
My house is also Victorian with cream/buff pointing and have used this for very similar applications (small pointing repairs and around a new wooden front door & windows). Apply with a putty knife. The consistency is like a sticky mortar that bonds well to the bricks/existing mortar and is easy to manipulate and finish. It stays flexible too so less likely to crack or shrink in the way a sand cement mix can. I think it would do just the job for your purposes.
My house is also Victorian with cream/buff pointing and have used this for very similar applications (small pointing repairs and around a new wooden front door & windows). Apply with a putty knife. The consistency is like a sticky mortar that bonds well to the bricks/existing mortar and is easy to manipulate and finish. It stays flexible too so less likely to crack or shrink in the way a sand cement mix can. I think it would do just the job for your purposes.
paolow said:
Thanks - and yes you are quite right there are quite polarised opinions on this kind of thig. I guess, in the absence of dissenting opinion that my plan isn't howlingly bad, and, although arguably not perfect it will nonetheless (hopefully) at least be waterproof (which it currently isnt). I am a bit constrained in terms of materials as to what I can get my hands on as im going to be looking at premixes - but I think that will have to be what it is...
My advice would be to read the Historic England advice/technical reports on the best method of repair.they are evidence based and not polarised opinion based.https://historicengland.org.uk/images-books/public...
Edited by PlywoodPascal on Saturday 18th May 01:05
T1547 said:
I can highly recommend this product: https://www.sealantsandtoolsdirect.co.uk/everbuild...
My house is also Victorian with cream/buff pointing and have used this for very similar applications (small pointing repairs and around a new wooden front door & windows). Apply with a putty knife. The consistency is like a sticky mortar that bonds well to the bricks/existing mortar and is easy to manipulate and finish. It stays flexible too so less likely to crack or shrink in the way a sand cement mix can. I think it would do just the job for your purposes.
That job looks really neat and very smart, and what a lovely door, too. If you have/had no damp issues I think the product you used will perform well even if it is synthetic/plastics based. On an old building though, and definitely one with damp issues/water penetration, I’d suggest burnt sand mastic instead - https://www.lime.org.uk/burnt-sand-mastic.htmlMy house is also Victorian with cream/buff pointing and have used this for very similar applications (small pointing repairs and around a new wooden front door & windows). Apply with a putty knife. The consistency is like a sticky mortar that bonds well to the bricks/existing mortar and is easy to manipulate and finish. It stays flexible too so less likely to crack or shrink in the way a sand cement mix can. I think it would do just the job for your purposes.
Maybe the one you used is a simple linseed oil/sand one like the one I linked but it’s impossible to know because there is scant information about what it actually is available!
Edited by PlywoodPascal on Saturday 18th May 09:00
PlywoodPascal said:
T1547 said:
I can highly recommend this product: https://www.sealantsandtoolsdirect.co.uk/everbuild...
My house is also Victorian with cream/buff pointing and have used this for very similar applications (small pointing repairs and around a new wooden front door & windows). Apply with a putty knife. The consistency is like a sticky mortar that bonds well to the bricks/existing mortar and is easy to manipulate and finish. It stays flexible too so less likely to crack or shrink in the way a sand cement mix can. I think it would do just the job for your purposes.
That job looks really neat and very smart, and what a lovely door, too. If you have/had no damp issues I think the product you used will perform well even if it is synthetic/plastics based. On an old building though, and definitely one with damp issues/water penetration, I’d suggest burnt sand mastic instead - https://www.lime.org.uk/burnt-sand-mastic.htmlMy house is also Victorian with cream/buff pointing and have used this for very similar applications (small pointing repairs and around a new wooden front door & windows). Apply with a putty knife. The consistency is like a sticky mortar that bonds well to the bricks/existing mortar and is easy to manipulate and finish. It stays flexible too so less likely to crack or shrink in the way a sand cement mix can. I think it would do just the job for your purposes.
Maybe the one you used is a simple linseed oil/sand one like the one I linked but it’s impossible to know because there is scant information about what it actually is available!
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