Cement render and crumbling mortar

[ShelleyM]

Hi Lacan still chipping away at the mortar as unfortunately some unplanned circumstances have taken me away from it for awhile, but anyway hope to get it finished within the next two weeks but was wondering what is the likely cut off date for lime repointing re weather etc and if there is and I have to leave it until Spring.
I am supposing is there anything I should do in the interim to provide some protection from the elements to prevent the wall becoming saturated ?

 

[Cubist]

Just in case Lacan can't get back to you soon. The key driver is to avoid frost damage, ideally the new render needs to fully cure before the onset of any freezing. Also, if theres a threat of heavy wind driven rain its as well to make sure that exposed recently applied render is sheltered somehow if at all possible.

 

[ShelleyM]

Thanks Cubist much appreciated

 

[ShelleyM]

Sorry Cubist should have asked how long roughly does it take then for lime repointing to fully cure ?

 

[Lacan07]

Hi Lacan still chipping away at the mortar as unfortunately some unplanned circumstances have taken me away from it for awhile, but anyway hope to get it finished within the next two weeks but was wondering what is the likely cut off date for lime repointing re weather etc and if there is and I have to leave it until Spring.
I am supposing is there anything I should do in the interim to provide some protection from the elements to prevent the wall becoming saturated ?

If its Lime putty based mortar (non hydrated lime) you're now way out of season. Its takes roughly 3 months for the lime to carbonise so the window is usually considered to be April to July (August if you're brave).

NHL lime mortar is different, a bit less fussy and much quicker to cure, but I wouldn't risk external work now. It still needs to be protected against frost, extreme temperatures, etc.

 

[Lacan07]

Hi Lacan still chipping away at the mortar as unfortunately some unplanned circumstances have taken me away from it for awhile, but anyway hope to get it finished within the next two weeks but was wondering what is the likely cut off date for lime repointing re weather etc and if there is and I have to leave it until Spring.
I am supposing is there anything I should do in the interim to provide some protection from the elements to prevent the wall becoming saturated ?

Sorry, not had time to re-read the whole thread, have you established the cause of the wall saturation yet? Looking at the photos again the area is covered and the damp appears to be at the bottom of the wall, the concrete render won't have been helping which you've now removed. I wonder if that concrete pathway might be pumping water into the wall. Does the wall have a DPC?

 

[a twig]

Definitely a vote for “leave it until spring” from me.

“Needs to be kept above 5 degrees C” is often bandied about but that’s primarily to protect from freeze/thaw and doesn’t take into account the carbonation process will be much slower in colder temperatures. i.e. it takes longer and needs to be above 5’C for all that time.

Trades wise you won’t find any honest stonemasons or plasterers doing external work after September.

There’s a few threads on here about this topic, I vaguely remember Ivor referencing some lime repointing work done on his local church around October time and it all having fallen out within 2 years.

 

[ShelleyM]

Sorry, not had time to re-read the whole thread, have you established the cause of the wall saturation yet? Looking at the photos again the area is covered and the damp appears to be at the bottom of the wall, the concrete render won't have been helping which you've now removed. I wonder if that concrete pathway might be pumping water into the wall. Does the wall have a DPC?

Hi Lacan

I found some missing pointing along the slate roof above this wall plus some slates broken which I have now repointed and replaced missing broken tiles. there was also guttering missing which I replaced. No the wall does not have a DPC I agree with you re think the concrete pathway isn't helping , still trying to work out a solution for this but I've decided re the advice to leave the repointing until springtime and in the interim try and determine if the pathway is a factor and think of a remedy

 

[ShelleyM]

This was today after persistent rain I am still not sure how to tackle this water pooling. I'm thinking after I complete the lime repointing in Spring would an inch of bitumen along the base keep the water from leeching up the brickwork?

 

[ShelleyM]

Sorry, not had time to re-read the whole thread, have you established the cause of the wall saturation yet? Looking at the photos again the area is covered and the damp appears to be at the bottom of the wall, the concrete render won't have been helping which you've now removed. I wonder if that concrete pathway might be pumping water into the wall. Does the wall have a DPC?

Hi Lacan

Just to update you I just finished removing the mortar render today and I am going on a lime potting course next weekend. I'll probably not get the weather conditions to repoint until spring but was just wondering do you think a bead of bitumen or even external sealant along the base of the wall would prevent the water ingress at the base or leeching up the walls etc

 

[Cubist]

Congratulations, that wall looks sooo much better that it did and I hope you enjoy the course you're taking. If you haven't already considered it, it may be an idea to have chat with the instructors and even the other attendees as well about this challenge.

Not to preempt Lacan but... If you are still getting water pooling or puddling against the foot of the wall somewhere then, in my view you have no choice but to find some way to stop it making direct contact with the extant brickwork and its mortar. A lime mortar render rising to about the 2nd or 3rd course of bricks and finished with a coat of Blackjack would I think do the job and last at least through the coming winter. If this approach doesn't work, then the render, and its Blackjack coating could easily be removed in the Spring.

 

[malcolm]

That looks fabulous. Removing cement always damages the bricks but you won't notice after it's been lime pointed. I would leave it as it is over winter and point in the spring. You'll probably find any water getting into the wall through puddling will evaporate away when it stops raining. And there seems to be a fall to get rid of puddling anyway.

The ground underneath the bricks is wet 100% of the time and will likely be the biggest source of water you need to evaporate away. The path outside will likely only be wet 5% of the time. If waterproofing were a good idea then the cement render would have worked.

 

[Lacan07]

Hi Lacan

Just to update you I just finished removing the mortar render today and I am going on a lime potting course next weekend. I'll probably not get the weather conditions to repoint until spring but was just wondering do you think a bead of bitumen or even external sealant along the base of the wall would prevent the water ingress at the base or leeching up the walls etc

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Not really, in my opinion not a good idea.

Cubists' temporary fix of a protective lime plinth has some merit but plinths are usually reserved for exposed walls that are prone to back-splash from rain. Are we any wiser yet as to where that ground water at the base of the wall is accumulating from? Can it be diverted?

 

[ShelleyM]

That looks fabulous. Removing cement always damages the bricks but you won't notice after it's been lime pointed. I would leave it as it is over winter and point in the spring. You'll probably find any water getting into the wall through puddling will evaporate away when it stops raining. And there seems to be a fall to get rid of puddling anyway.

The ground underneath the bricks is wet 100% of the time and will likely be the biggest source of water you need to evaporate away. The path outside will likely only be wet 5% of the time. If waterproofing were a good idea then the cement render would have worked.

Hi Malcolm

Congratulations, that wall looks sooo much better that it did and I hope you enjoy the course you're taking. If you haven't already considered it, it may be an idea to have chat with the instructors and even the other attendees as well about this challenge.

Not to preempt Lacan but... If you are still getting water pooling or puddling against the foot of the wall somewhere then, in my view you have no choice but to find some way to stop it making direct contact with the extant brickwork and its mortar. A lime mortar render rising to about the 2nd or 3rd course of bricks and finished with a coat of Blackjack would I think do the job and last at least through the coming winter. If this approach doesn't work, then the render, and its Blackjack coating could easily be removed in the Spring.

Hi Cubist yes I agree it does look so much better I am really pleased with the way it has turned out and yes looking forward to the course and yes I was intending to pick their brains.

 

[ShelleyM]

That looks fabulous. Removing cement always damages the bricks but you won't notice after it's been lime pointed. I would leave it as it is over winter and point in the spring. You'll probably find any water getting into the wall through puddling will evaporate away when it stops raining. And there seems to be a fall to get rid of puddling anyway.

The ground underneath the bricks is wet 100% of the time and will likely be the biggest source of water you need to evaporate away. The path outside will likely only be wet 5% of the time. If waterproofing were a good idea then the cement render would have worked.

Hi Malcolm

Yes thanks it does look fabulous its surprising how many people in the street have stopped to comment same! Yep I intend to wait until spring and as Lacan I see has also commented I will still endeavour to remedy the puddling. When you say the biggest source of water underneath the bricks will need to evaporate away do you mean just by the natural course now the cement mortar has been removed and repointing with lime ?

 

[ShelleyM]

Not really, in my opinion not a good idea.

Cubists' temporary fix of a protective lime plinth has some merit but plinths are usually reserved for exposed walls that are prone to back-splash from rain. Are we any wiser yet as to where that ground water at the base of the wall is accumulating from? Can it be diverted?

Hi Lacan. no not yet still working on that