Lime Mortar Harling Project
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- Опубликовано: 8 сен 2024
- In this video I use a hot lime mortar to re-render the rear wall of my property. It's a technique used widely in old building conservation known as 'Harling' and involves casting or harling the lime mortar onto the wall surface.
The aim is to create a even rendered finish which will be completed later with the application of a lime wash
Hot lime mortar has been used as a way to conserve the property which has some degree of dampness within the wall - the lime helps with moisture transfer from within the wall to the outside
Great video. Looks like some farmhouses in the scottish countryside which haven't been tampered with by modern cement builders
Thanks - I was pleased with the outcome and it’s still looking good. Certainly feel that it’s far better than the cracked cement render that was on there before. All the best…
@@solway17carlisle Would be really nice to see an update video. I'm in the process of doing something similar (haven't quite worked out the plan yet) on my cottage's front wall which has been severely tampered with in the past. Cheers!
@@lordracula2461 Hi - yes I may do an update at some point. Essentially, from my point of view, I would prefer not to use coarse chippings in the mix but just use the slightly finer aggregate I bought from Eden Hotlime. It’s still on the wall, and I later lime washed it so it looks ok. Thanks and hope your project goes well
Thank our very much, some innovation and guesswork to fill lost traditional knowledge. So important to keep this tradition and knowledge alive, well done and thank you for guiding my project.
This is a crazy looking wall lol
Thank you for sharing your progress, very helpful to see how others apply old ways and techniques! Your harling technique is satisfyingly consistent compared to my trials and errors when re-rendering an old russian-style clay-mortared oven using traditional lime render.
Sorry to see you had to endure such caustic damage to your hands! Here in Finland you are hard pressed to find any quicklime for construction, the most readily available variant (and even that one is getting harder to come by close to the modern, comfortable capital) is non-hydraulic, slaked powdered lime in bags of 30kgs. It does the job well enough with proper mixing and letting it sit and "wet up" for a few days before use. All the best!
Thanks for your comment and very interesting to hear of your project in Finland. Glad you are able to use some sort of lime in your oven project. All the best…
Great job. That's a lot of work both on the inside and outside and very informative.
If I can pass on some information that I learned the hard way myself dealing with similar situation, to complete the job and ensure your walls will dry out you need to go one step further. A French Drain needs to be installed along the perimeter of the outside wall, with the slotted drainage pipe placed at least a minimum of 100mm below the interior floor level. This will allow water to drain away from the wall, which before was being wicked up. Now having the cement replaced with lime is great, however the issue of where the moisture comes from needs to be addressed. If you install a French drain and fill the trench back in with stone only, then the walls will be dry and you will have the ideal solution in place.
One last point is to check the gutter downpipe drain to ensure the pipe is intact and not cracked under ground (requires camera to check condition) - often you can find that the clay pipes have cracked under ground over time and this is a constant source of moisture into foundations every time it rains.
To protect your skin, an old trick is to first spray vinegar onto your hands before you put on gloves - in case the lime comes through the glove material and contacts your skin - the vinegar will counteract the lime.
Hi Paul - Firstly, Thanks so much for a detailed comment- all your advice is really appreciated. I wish I’d used the vinegar tip ahead of working with lime as a Doctor tells me the scars on my wrist are permanent. I have taken your advice regarding the French drain and may do a quick RUclips update to show this. I realised that saturated soil standing against the wall well above interior floor level was a problem. In the end and over the past couple of weeks it has been dug out and I am in the process now of back filling with perforated drain, pea gravel and stone. Still a work in progress.
Very good point about the clay gutter and drains - I will need to get a drain specialist to check with a camera…
Once again, Thankyou so much for the detailed comment with such great advice- All the best 👍
Solway17 Carlisle that's great to hear and looking forward to see your next video on the topic. The drying out time takes a while. It takes approximately a month to dry about 2 inches, so for thick walls you can expect it to take maybe up to two or more years before they fully dry out naturally.
J Finlay a French Drain has been proven to be the most effective way to manage moisture removal against a wall. Having soil up against a wall is counter intuitive - you are placing a material that by its nature will absorb and hold moisture. The examination of the exterior ground level compared to the interior ground level is key - when the exterior level is above that of the interior you end up with moisture penetration / damp issues. Even if you slope the soil away from the wall, it's still soil at the end of the day and will wick up moisture - especially if it snows.
Further, at some point some bright spark will come along and decide to plant flowers/bushes in this 1- section of soil .....watering them....not knowing that they are introducing water to the area you are trying to dry out.
The correct method is to trench against the wall, line the soil and bottom with geo textile and fill only with stone, having a slotted drainage pipe placed below the interior floor level to drain away from the building. The walls are thick constructed, so digging a small trench by hand will not undermine the stonework above.
Hi - just by way of update. I have removed very wet/saturated soil from the rear of the property - a skip load! Whilst I’d like to have slope the soil away the ground level adjacent is much too high to do this. In effect I have an access ‘trench’ where I have installed a French drain and partially back filled with locally sourced cobbles. Ironically, the slight problem I now have is that the ‘drain’ fills up very quickly in persistent rain, such as we have had recently, with standing water getting worryingly close to the foundation boulders. It eventually recedes but I’ll need to keep an eye on this as Winter progresses. Ideally the ‘trench’ should continue around the gable end to drains at the front of the property but that would involve digging up the neighbours access path & more involved groundwork’s. I’ll see how it goes over the coming months.
Thanks all for commenting 👍
Solway17 Carlisle if you cannot connect the French drain tench pipe directly to existing drainage then you will need to install a drainage soakaway pit. If you search on RUclips - there is an episode done on "Build with A&E" Chanel - titled "Single Story Extension #7 - Digging the Soakaway". You will need to go to the furthest point away from your house to dig soakaway pit and then connect to your French drain afterwards - this should solve your drainage issues. Having standing water is a big problem and highlights the French drain is not installed correctly - it will cause issues throughout winter for you unless you address immediately. A French drain should freely flow water away from the building - there should never be any standing water.
Looks great, well done. Good detail to the video too - the big question is how is it holding up 2+ years later?
Hi - It’s still looking good - no hollows or cracking. I also painted it with lime-wash. Thanks for watching 👍
Good to hear @@solway17carlisle, sounds like a job well done!
Nice work, I would of probably given it a scratch coat then butter
Coat the harling ,
Hi Kevin - I was a bit worried that laying on the mortar might have loosened or cracked later. By throwing on a watery mix it seems to have ‘stuck’ onto the wall pretty well. Thanks for watching and your comment. All the best…👍
By chance I am currently repairing and rendering the walls of an old brick built wash house in S Cumbria using not hot lime but NHL 3.5 lime. The previous cement mortar and render was made far too strong and sharp sand made them essentially concrete. As a result the bricks have badly spalled and even cracked due to frost. Removing the render and raking the joints has been a nightmare as the usual tools barely make an impression on them. I'm repointing between the undamaged bricks with a 1:5 mix to hopefully help the bricks to dry out in future. On the spalled bricks I'm using a harling coat with sharp sand to form a fully bonded layer with a good key for the thicker dubbing out coats that will level up with the good brick surface. I haven't decided whether to use a wet dash finish or to float a flat finish. Either way I intend to use a lime wash in order to maximise the transmission of water out of the render and hopefully avoid the terrible effect of the wrong cement render of the past. Sorry to see the burns to your arm, I discovered the caustic effect of lime years ago when it turned the skin around my fingernails black and they were sore for a week.
Sounds like you’ve thought it through and have a plan for tackling the damp in the brickwork. From what I have picked up along the way, lime will help any moisture move through it to the outside to evaporate, rather than going into the brickwork where the pointing is done in cement. All the best with your project - it’s hard work (and at times hazardous, as I’ve found out) but surely worth it in the long run. All the best with it. Cheers 👍
@@solway17carlisle Thank you for your encouragement and informative videos. I'm becoming more converted to using lime-based solutions to renovate my own property with the increasing evidence I see with the longterm effects of poorly applied cement mortars and renders. We haven't even mentioned the better effects on global warming as a benefit too.
John Davenport Hi John, I get the impression that most historic buildings need to be treated with compatible materials and finishes for them to 'work' in the way intended. My harled back wall is drying out but still looking damp at the base and I may need to look at the surrounding ground level to promote further drying. It's also a very messy process so make sure you cover all nearby surfaces if you do harling or you'll be left with a lot of cleaning up work which is what I'm on with just now. You're right about climate benefits - the mortar absorbs carbon as it sets. Best wishes...
Well done. Great to see and I apprreciate the heads up regarding thw gloves. How did you remove the cement render at the start of the project?
Hi Joel - I used an sds hammer action chisel and broke the cement render off in plate size chunks - in some places the render had blown and was easy to remove but on the modern block work it was well stuck on so more difficult to bring off. Thanks for watching …👍
ah, does the Belle mixer knock the lime mortar up well enough, or is a roller pan mixer much better or Baron pan mixer ? Your darling demo is very rare to find these days, but its how the old Irish cottage owners protection their external walls. They had very high porous renders which assist evaporation of moisture, the porosity is assisted by the use of very large aggregate articles
I am a diy’er so used the mixer I already have. The hotlime mix was already to use from the supplier - a gritty lime rich mix. Just needed knocking up with some water and bigger aggregate (up to 8mm I recall) added to make the harl mixture.
As mentioned in my reply to your other comment, I understand that ‘hot lime’ is preferred over bagged lime as it has greater porosity. If you check out my other videos I used exactly the same stuff internally to plaster my bedroom wall. In addition using a finer mix which came in buckets to do the finish coat. All the materials came from a guy called Tim at Eden Hotlime Mortars in Cumbria edenhotlimemortar.co.uk
Thanks for watching and commenting…very encouraging
what is the hot lime mixture ? How did you mix it in bulk volume ? great introductory video on hot lime harling.
Hi - I found a local supplier of hotlime mortar and it came in a dumpy bag on the back of a lorry (Eden Hotlime, Kirkby Stephen, Cumbria). All I had to do was add my aggregate of choice and artificial hair. Then mix in my small mixer - deposit into a garden trig and add water to make the Harlingen slurry. I hope that helps. I am not an expert in these matters but read about the properties of ‘hot lime’ as opposed to bagged lime and the supplier sent me what I needed…
Hi, I wonder if anybody could help me know what I need to do? I have an internal brick wall that has lime rendering before being plastered. The walls of the house are 1930s 9 inch solid. Some areas of the render came away from the walls and needs repair. I'm not a builder and it seems really difficult to find someone to even advise on this let alone to repair it. So many rogue builders who are not true tradesmen out there these days. Anyway, I need to know what specific materials and the correct mixture for rendering internal brick walls with a lime mortar. Looking online there is so much on offer and not sure what to buy. Any advice would be very helpful. Thank you and thanks for te video.
Hi Jimmy - apologies for not responding sooner. There are very few builders with ‘lime’ experience as most properties are built or repaired with gypsum plaster/cement. I’m not an expert either but got the impression that NHL lime is not ideal and that lime putty mixed with an aggregate/sand or already mixed as in my case was the best most ‘breathable’ option in older properties where there is no damp course. It might be an idea to speak directly with a lime supplier who can offer advice and a product if you are considering doing the work yourself. Just do an internet search. For a base coat you don’t need a ‘fine’ aggregate but a washed coarse sand, then use a finish coat with a finer sandier aggregate. These can be bought premixed and delivered to you. It is a bit trickier to get a flawless finish (as I found) but that is probably why so few people offer a lime option. Hope that helps
@@solway17carlisle Thanks fer the information. I should be able to get on with the work. All the best. X
Whats the finished look
It’s pretty good on the whole though a bit rustic in parts. I will also film the process of lime washing in due course so I’ll show the harl cover then. On the whole, it’s stuck well and I’m happy with it. Thanks for watching and possibly subscribe to see the next part 👍
you'll bugger your back doing this...
Ha ha! It’s heavy work for sure but my back survived ok - more worried about the lime burn on my wrist ….