Lime Grouting Walls Cornwall

[Oldschool]

Like so many people after this weekend we are still battling the ingress of liquid through our walls....I've posted before since this has been ongoing since we purchased the property 11 years ago, albeit we don't now need buckets catching water, quick recap Victorian old school granite, killas, washed out rubble infill we know there are voids/rat runs some of which have been filled by opening up from the outside and above when corbels were off by filling with lime mortar but I'm now thinking should be bite the bullet and try to fix this for good with lime grouting. I am SURE I read recently on a recentish thread someone had had this done to the walls of their barn conversion in Cornwall....I've tried searches but can't see to find this thread..it's probably me! If the OP sees this would they mind very much letting me know which company undertook this work, what it involved and roughly what it cost? Thank you, I'm feeling so very fed up, after years and thousands spent on lime pointing, lime rendering inside, checking roof, upstands in lead, parapet corbels off I just want to finally do something that will fix it!!!! Not even going to mention the expense of new carpet due to falling off a ladder whilst re lime washing (lime wash does not come out of wool carpet by the way) prior to hours of removing black mould

 

[aockenden]

I’m sorry you’re suffering with this. What do you mean by “lime grouting”? Is this something you’re proposing to do to the walls? Pics are always helpful, both interior and exterior of the areas of ingress.

 

[Oldschool]

many thanks Aockenden yes it's a bit soul destroying, basically lime grout..runny, is pumped pneumatically under pressure from above into the head of the wall so that it can go down and fill the voids and thereby consolidating and making the wall ..in theory better able to deal with the weather we are South West facing near the coast and when the storms come the rain is blown often at high speed! at the both front gables and they just can't cope and neither can I! There are lime specialists in Cornwall, well at least one that I've found that undertake this work I'd just feel happier if I was able to speak to someone who'd had this undertaken since I don't think it's a cheap option, we have LBC to render the front elevations but it would so radically change the appearance of the building that I am resisting plus I don't have any faith that a three coat system of render will be able to actually deal with this (probably harling would be better but maybe that would look even worse!) and the quote I've had for rendering is over 10k and if I am spending 10K I want to be as confident as possible that it's going to get solved! Our lime person who has undertaken removal of cement pointing replaced with lime and rendered with lime inside has opened up one of the places from the outside where we have an issue and found a huge void which he filled with lime mortar however thanks to Burt inside at the back of this area is really damp again this has still not solved the issue I'd imagine the mortar inside has not yet carbonated and we have the same issue the other side underneath where John Loughborough Pearson saw fit to detail the corbels as horizontal this detailing means water pools and wears the jointing ..am thinking replacing all corbel jointing with prompt may also help. You see I've got the theory but not the confidence that things will get rectified I'd like to have tile hung but there is scant overhang and lots of granite detailing quoins, mullions etc that this is just not an option with no depth for battening then tiling.

 

[aockenden]

Wow, well the good news is it’s a gorgeous house!

I’ve never heard of that procedure of pumping lime slurry down into the walls. That’s very interesting and sounds like a good tool in the tool belt in certain circumstances. Thanks for informing me of that.

I’m afraid I don’t know enough about that complex roof construction to be of much help. It just looks very complex and I would be very suspicious the water was getting in some poor detailing on the flashing / slates / stonework up there vs blowing in through your nicely pointed walls. But you know the history better than me of course.

 

[Oldschool]

thank you....it's a spoilt Victorian child! We've had all the coping stones off membrane underneath and lead upstand, believe me we've investigated that avenue....my advice to anyone though if you are looking at a house with parapets run for the hills!!! Oh yeah many valleys, lead gutters and a cross wing, roof oh and the berk who converted it when it was unlisted put some polycarbon on one side of the porch roof as a roof light and that's the least worst of his misdemeanors!

 

[Stevers]

Is that damp patch under any of the valleys? Even when sound they can overflow if blocked with leaves or snow.

 

[Oldschool]

No as you look at the front right facade it's to the right and below the horizontal corbel.. Yep valley's can leak with leaves, snow, hail....then someone needs to get up there and risk life and limb sweeping them out.....this house is a love hate rollercoaster!

 

[Stevers]

It's a fine example of the sort of Victorian architecture that needs a fair bit of luck to keep the water out. I'd anticipate that an impervious granite is a worse case for this than a porous limestone as it allows any water ingress to travel further internally, hence your interest in grouting.

 

[Cubist]

Wow - what a lovely building.
Wow - that's a lovely Landy. I hope you still have it and that its still going strong.
Wow - do you ever stop to breathe?

Sorry but I had to copy your text above to another editor so that I could dismantle your stream of consciousness to get a grip on its content. It may be an indicator of just how frustrated you've become with this properties trials and tribulations but please, for your own well-being, take a step back and try to relax a little. You're coming across as someone who is in a flat panic on the verge of hysteria. No offence.

I may not be able to add much in the way of a technical solution or comment on the basis of first hand knowledge but....

I have come across the idea of filling similar cavities in stone/brick walls with a cement slurry in the past and understand that it can be successful. However, there are obvious issues concerning the final extent of the slurries penetration and occupation of the voids and, indeed, whether all such voids can be reached by the slurry in the first place. The use of a lime slurry would bring further challenges and issues and not least those of its production in the needed volumes, transport, the making of appropriate points of entry to the cavities around the property, and not least the potential implications of the load pressures resulting from the weight of the slurry on the walls. There are also implications regarding damp penetration through the walls internal and external stone skins and mortars. I have no idea what the curing time may be but I wouldn't think it would be short.

Frankly I think this may be a very expensive option with a number of imponderable risks that need careful consideration against the backdrop of little certainty that the real problems will be beaten.

Beyond the above, and noting your comments regarding the flat corbels, I can only make one constructive suggestion at this time - have you considered 'wedging' the corbels to force water run off in a more desirable direction? It strikes me that doing so, and adjusting the 'lie' of the lowest stone of the gable to compliment the wedged corbel MAY prevent future damage and water ingress at that joint. This I think could represent a vastly less expensive and troublesome solution to one of your challenges.

Good luck.

 

[Oldschool]

Wow - what a lovely building.
Wow - that's a lovely Landy. I hope you still have it and that its still going strong.
Wow - do you ever stop to breathe?

Sorry but I had to copy your text above to another editor so that I could dismantle your stream of consciousness to get a grip on its content. It may be an indicator of just how frustrated you've become with this properties trials and tribulations but please, for your own well-being, take a step back and try to relax a little. You're coming across as someone who is in a flat panic on the verge of hysteria. No offence.

I may not be able to add much in the way of a technical solution or comment on the basis of first hand knowledge but....

I have come across the idea of filling similar cavities in stone/brick walls with a cement slurry in the past and understand that it can be successful. However, there are obvious issues concerning the final extent of the slurries penetration and occupation of the voids and, indeed, whether all such voids can be reached by the slurry in the first place. The use of a lime slurry would bring further challenges and issues and not least those of its production in the needed volumes, transport, the making of appropriate points of entry to the cavities around the property, and not least the potential implications of the load pressures resulting from the weight of the slurry on the walls. There are also implications regarding damp penetration through the walls internal and external stone skins and mortars. I have no idea what the curing time may be but I wouldn't think it would be short.

Frankly I think this may be a very expensive option with a number of imponderable risks that need careful consideration against the backdrop of little certainty that the real problems will be beaten.

Beyond the above, and noting your comments regarding the flat corbels, I can only make one constructive suggestion at this time - have you considered 'wedging' the corbels to force water run off in a more desirable direction? It strikes me that doing so, and adjusting the 'lie' of the lowest stone of the gable to compliment the wedged corbel MAY prevent future damage and water ingress at that joint. This I think could represent a vastly less expensive and troublesome solution to one of your challenges.

Good luck.

"Wow" - thank you
"Wow" - yes we do still have the Land Rover, yes it is still going strong, I hope that you in particular have clocked the number plate.....

I was merely trying to explain what the issue was and what we had already tried to rectify it, I thought that might be helpful. I think having your main bedroom uninhabitable for most of the year, covered in black mould and seemingly nothing you try solves the issue after 10 years is probably quite hysteria inducing to many people. Not to mention the expense. We'd have 'fun' selling it. If we lift all the corbels the entire head of the wall is exposed allowing access to pump the slurry under pressure, you can buy it bagged at most Lime outlets and mix it on site, yes I doubt the cure time would be short but that is least of my worries.

Thank you for your "constructive" suggestion however, at best that will look a hideous bodge I can't even see how you could make that look half decent without cutting the quoin below which I doubt very much that our CO would find acceptable what with the building being Grade II listed an all.

 

[Cubist]

Sorry but I forgot to mention that as lime mortars are quite permeable, filling those cavities will inevitably form a solid 'bridge' between the outer and inner skins of the stone walls. As a consequence the incidence and extent of damp appearing indoors is likely to increase and perhaps spread to more and larger areas. At present you will have some benefits accruing from airflow between those skins which is in turn helping to reduce the amount of water reaching the inner skin from the outer stonework and its presumably lime mortar joints.

Fortunately there is often more than one way to skin a cat and perhaps temporarily removing the - forgive me, I picked up your incorrect use of the term 'corbel' rather than using the proper name - capstone(s)/coping stones will still afford you some opportunities, beyond my initial offering, to remedy your dilemma.

Unfortunately I can't be of more immediate aid, some new thoughts on the topic have occurred to me but I'm a little pressed for time right now. However, as you mention it, I do recall seeing that Landy of yours during many of my frequent visits to that part of the world, perhaps a face-to-face discussion might be more helpful?

 

[Oldschool]

yes the horizontal coping stones sit on granite quoin, sometimes the terminology is confusing to a lay person however much reading one does. Would the original rubble infill not also have formed a bridge? Do let me know if you are in the area you are welcome to visit, quite the trek for you, presuming you know exactly where we are.

 

[Cubist]

Would the original rubble infill not also have formed a bridge?

Quite possibly, but more likely it would operate much as French Drain does and excess water would quickly percolate toward the ground floor area rather than appearing higher on the internal walls.

quite the trek for you, presuming you know exactly where we are.

Not really. We normally come down via Bristol and then stop off at our favourite ports and haunts to meet up with friends and family.

 

[Cubist]

An afterthought. An alternative suggestion would be to use slate to bridge the cavity between the wall skins and lay a strip of DPM over this before re-laying the coping stones over same and re-pointing to make the modification near/truly invisible.

 

[Oldschool]

An afterthought. An alternative suggestion would be to use slate to bridge the cavity between the wall skins and lay a strip of DPM over this before re-laying the coping stones over same and re-pointing to make the modification near/truly invisible.

many thanks just to clarify so looking down into the wall head once copings off would you slot a slate behind the front wall skin or the back or the middle between the two..or have I completely misunderstood?

 

[Cubist]

Apologies, my language was a little confusing. I meant the arrangement below as you look down at the two skins with the slate bridging them to prevent water ingress into the cavity. Width of the slates would be approximately 40mm less than the total width of the two walls and laid to stagger the points at which any two slates meet on the run down the gable to ensure it does not coincide with then ends of the cap/coping stones when these are laid above.

This emulates the traditional method of using slate as a Damp Proof Course in older brick built houses. The 20mm gap left on each side of the slate is intended to allow it to be hidden behind the pointing for the cap/coping stones when these are mortared into place.

If the gap between the two wall skins is consistently fairly narrow you have the alternative of omitting the slates and simply using a felt type DPM which is sold by most building supplies companies in various widths in roll form.

 

[Oldschool]

ok thank you diagram makes it really clear, sorry I may not have been that clear in that we do have membrane under the coping stones but could incorporate your suggestion in addition by way of belt and braces. I think it's running down the joint and getting in around the quoins under the horizontal coping stone when water gets inside all its meeting is a big void practically to the inner wall skin (we backfilled the worst side with lime mortar but I imagine this mortar has not yet carbonated (only done about a month ago) hence why the damp on inside is still reappearing. I'm guessing also water is being channelled by the coping stones both above and underneath the overhang into that area. I wonder if we could also try to utilise your slate idea if we open up again from the outside and insert a slate(s) vertically inside and then re mortar to seal in for these two sections of the facade around the horizontal copes? I really appreciate your time and suggestions re this issue.

 

[Cubist]

Please correct me if I am wrong but but: -

• I am assuming the quoins are sold blocks of stone - Yes/No
• The void you find after removing the coping stones is the cavity between the gables inner and outer stone skins - Yes/No
• Beneath the coping stones there is an continuous waterproof membrane that from top to bottom of the gable - Yes/No
  • This membrane covers nearly all the width of the gable inner and outer walls including the cavity between them - Yes/No
  • This same membrane extends without break under the horizontal coping stone above the quoin - Yes/No

If you answered 'No' to the last question only - then all you need to do is add a small a short run of membrane starting beneath the extant membrane under the last coping stone of the gable AND under the coping stone above the quoin. This will prevent any water penetrating into the void and help any that may be absorbed into the mortar to exit to the front or rear faces of the gable.

That aside, I believe that some of your expectations are too high or ambitious and also that perhaps unsafe assumptions may have guided some of your earlier thinking.

Theres a general rule of thumb that stone/brick/concrete walls and floors typically require up to 1 month of drying time per inch of thickness/depth. As some parts of those gables may now be almost solid then an elapsed year may be needed for them to thoroughly dry. At the very least it would be likely to require 6 months to achieve that goal. Clearly one month will not make an appreciable difference. Where a significant cavity is present the drying time for the inner and outer skins may be somewhat different as these will be affected by ambient conditions indoors and outdoors respectively.

Your conclusion regarding the origin of the water ingress may be incorrect. Given the location of the apparent damp on the ceiling I can see that this broadly correlates with the location of the quoin and its capstone outdoors. However, there is an equally likely source associated with the roof and the lead flashing presumably used at the junction between the tiles and the gable wall. High winds striking the front face of the gable will produce an area of low pressure immediately behind the wall and directly above the roof causing an almost complete reversal of the winds direction at the surface of the roof. This can then force any rainwater borne by that wind or already lying on the roof under the the leading edges of the flashing or, should the rainfall be heavy enough, be sufficient to overtop the flashing altogether. Such conditions can also force rainwater back under the leading edge of a tile and across its surface and beneath any tiles above it. In both cases that water may then re-appear inside the house on the ceiling.

Besides rainwater ingress there is also the possibility that the damp and mould seen in that corner of the room indoors is caused by the heating and ventilation system.

I notice in the photos that the gables each have what appears to be a louvre vent. Is it same to assume these are kept closed for the obvious reasons or have they been permanently blocked? Regardless, that corner where damp and mould is appearing must also represent a 'cold spot' to which warm water-laden air circulating in that room would be likely to condense out. Is this room the site of the heating system or most frequently used part of the house?

Can you categorically rule out these possibilities?

 

[Oldschool]

Thank you so much. Yes to bullet one. Yes to bullet two. Re the next bullet I am going to have to speak to the stonemason/lime person who installed the membrane as to whether it's continuous and also it's relation to the lead upstand behind which has also been filleted with lime mortar, since you could well be right to suggest the membrane solution re the last two coping stones. On inspection behind the parapet when installing the lead upstand conditions underneath were dry so we ruled out it getting in under the leading edges. The room is our main bedroom we have a large radiator in there but two sides are external one obvs the front facade which gets the type of weather you describe. Those louvres are open with chicken wire behind, I am concerned they could be the source of ingress which is appearing more centrally above the window....I'm not even sure if they should be open for ventilation or if not best way to block them up...they are just slates they do not open or close and are in the loft.....probably a bit stupid on our part not to have rectified that earlier! Your replies really have been food for thought and I think it would be most helpful for me to run through them with our tradesperson and go from there. Don't want to monopolise you but any other thoughts/suggestions v welcome. Thanks again.

 

[Cubist]

To close this one off then, you might also want to use the following old trick to verify the source of damp in your bedroom.

Tape a sheet of kitchen foil to the wall over the affected area and leave it there for 24hrs or so. Then, if the foil is wet on the room side your problem is condensation but if dry and the side next to the wall is wet then its an external water source.

Regarding the louvres, it would be unwise to block these as they support air-flow through the attic spaces and around the roof timbers. Closing these off can induce/promote rot. You might consider an external screen of some kind, or if easily accessible indoors an internal shutter, to prevent or minimise driven rain incursion.