Mixing NHL lime mortar

Here we explore all the important mixing of the mortar. Vital that it is done correctly for a standard, high performance mix in your project.

[@ted2314]

I have an old brick and stucco home in the southern US (roughly 200 years old). In the rural south, older homes like this aren’t as common as the northeast, so there’s not much knowledge about properly preserving these old places where I am. Videos like this are invaluable to me, and I’m sure many others. My house has had concrete products used to repoint, or even stucco, much of it in the last 50 to 70 years, and that’s done some damage. The damage is not irreparable, but it just goes to show that the art and science of these old structures has been lost to time in many areas like mine. Videos like this are a HUGE help to me to know how to better preserve my old place. Thank your for sharing your knowledge and sending your video out into the world!

[@WrightM88]

Ditto. We’ll said. These videos are great!

[@kmcroes]

Thank you so much for this! I started a hempcrete company in the US and you can't imagine how hard it is to get information like this.

[@Justaskjoshpm]

Great videos mate well explained, I’m recently looking at offering lime pointing to my customers so this has helped me out a lot 👍🏼

[@tonyalways7174]

Really the most thorough explanation of mixing lime mortar I’ve ever seen on KZbin. Really impressive but not as impressive as the dreads 😂👍🏻

[@classifiedinformation6353]

You are spot on. I have learned a few more details with this video. Thank you. But, DON'T put your arm in a revolving mixer! It would do a number on your elbow and shoulder if it grabs and twists your arm. John C. Bielik Bethel, Missouri. USA

[@J.HarveyStonework]

Great video! Well explained, enjoyed that! 👍🏼

[@andrewclarkehomeimprovement]

Thank you for a comprehensive explanation. I've got some decorative brickwork to do in an 1880 town house and to be honest to the property, I'm doing it in lime, the bricks are soft handmades so Portland cement would be way too strong even with a weak mix. So thank you. 😊

[@sorbetingle]

Excellent, i learned alot, im now be able to rack out some old cement based cracked pointing, and point in a lime mix.

[@johnmelrose3109]

Very informative. Thank you. 👍🏻

[@Kajpaje]

Great to see a practical tradie explaining the process really clearly.

[@amyntas97jones29]

Great video. Many thanks.

[@brianoneill350]

Very knowledgeable, good video.

[@trailsportsuk3627]

Amazing thank you Mr P.

[@iestynjones5796]

Great information. Never knew you could keep NHL alive for so long.

[@michaeljamesdesign]

Reworking it makes it lose some of it's compressive strength but this isn't a bad thing as most NHL is too strong to begin with.

[@highgatehandyman6479]

@@michaeljamesdesign thats what i heard about nhl bring stronger than people assume And i find after knocking it up after gone off a bit that its greatly improved workability

[@michaeljamesdesign]

@@highgatehandyman6479 Nice and creamy.

[@hbpw857]

Broke that down perfect pal 👍

[@Westmoreland348]

Excellent and informative like all your videos. It was probably the only time when a face mask was useful in 2020😄

[@dportercontracting9974]

Ha I guffawed at that quip there @Westmoreland348 🤣

[@Westmoreland348]

Thanks, I learnt a lot from your videos, really appreciate them!!

[@chrisatkin7130]

Nice explanation, we are using NHL5 ( we are adding reinforcing fibres for binding strength) and topping off with NHL3.5 for internal walls. Our requirements are slightly different as we are renovating a cave house, that had been dug in sedimentary rocks. We are using crushed marble sand as our medium as its easier to get hold of in the area that we live.

[@michaeljamesdesign]

NHL5 is an incredibly strong lime with very limited flexibility and porosity.

[@chrisatkin7130]

@@michaeljamesdesign yes it is a little harder than we would like, unfortunately the 3.5 was not quite strong enough and cracked then separated in places. The other cave we must renovate is more stable on the walls, so plan to use either 3.5 or cal hidraulica, which we believe is hydrolic lime mixed with white marble sand 0-2mm. Any thoughts would be most welcome, if you have the time.

[@pamwalker7823]

Jonathan mentioned galletting stones or small flint pushed into the mortar as you go to prevent cracking. I tried it and I have no cracking issues whatsoever. Could use pea shingle, chipped brick or stone you have locally but the harder the better. the bigger the joint the bigger the size of the galleting stone

[@rogerthedodger5788]

@ michael Birchall .... I agree 100% with what you say. I find the way people mix so confusing. Mixing by weight, as done here, makes the most sense to me. The only caveat being how wet the sand might be, but that's probably miniscule in weight so irrelevant.

[@nicholasmisch5590]

I'm following your method for repointing the interior of an 1890s brick and stone foundation. Like you note in this video, there's a big difference between sand and lime by volume. I've done mixes both by volume and weight, when done by weight, It ends up being 2.25 containers to 3 masons sand (The sand I have is probably a little wet, which adds to the weight). I saw mentioned in another article to use as little lime as possible and should calculate the "void space ratio" of the sand you use. It would seem your use of pebbles on your deep mortar joints would support this theory. Any thoughts on this?

[@nicholasnicoloff873]

Hey man, so i want to build a stone house using local granite and would like to use lime mortar. What NHL lime would you use for this. Or would you do a hot mix with quicklime. I'll be apprenticing this year. Lots to learn

[@DanielOlivierArgyle]

Thanks man!

[@Jonathan-mk1ju]

Great explanation. Im guess the Lime putty is more for like tuckpointing, where its more of a decorative than structural.

[@dportercontracting9974]

Lime putty mixed mortar is more breathable than NHL mixed mortar. There are no clay particles in a standard lime putty mix, as in a hydrated lime mix. A lime putty mix won't cure as hard as an NHL mix of mortar. In my own work, I'd tend to use a lime putty mix for actual construction of a masonry unit, or lime plastering. I'd steer clear of any cut or tuck pointing when using lime mortar. Dressed mortar may look the part but water sits on the joints in the structure and the time taken for water to get to the ground is drastically increased. Thats just my personal opinion, Jonathan.

[@andyjm7100]

Very helpful

[@ProGamer-no8fm]

Great video, we are doing a full new-build with handmade clay bricks. Please help me with the questions below: 1. Do you recommend NHL 5 or 3.5 for mortar bed and pointing? 2. We are after a buff colour mortar, so using yellow building sand with lime, what ratio do you suggest? 3. Can we use mortar colour dye (like Bostik Cementone Cement & Mortar Dye) when using lime? 4. Do you recommend using any white cement in the mix for the mortar bed? Keep up the good work! Please reply.

[@dportercontracting9974]

Thanks buddy. For the actual construction side of using lime mortar, I would encourage you to use a lime putty as the binding agent. We only used an NHL 5 on this property, due to the exposed aspect. If you are in a sheltered site, an NHL 3.5 would be more than sufficient for the strength of the cured mortar. When using colouring additives, I would steer well clear of commercial dyes and colourings. They are made from synthetic constituents. These will have an impact on the functionality and breathability of the lime mortar. When colouring the lime mortars, you could experiment with some different coloured sands, or stick with natural pigments. Oxide based pigments work best with lime mortar. The ratio of aggregates to binder in the mortar will depend entirely on the substrate that you are bonding with the mortar, weather exposure, surface temperature of the finished structure and various other aspects. Never use any cement of any sort in a lime mortar as it removes the breathability and fuctionality of the lime mortar. Hope this helps? Hope this helps?

[@sebgreenfield8800]

Many thanks for this info. Could you help with some info on lime pointing internally? I have some inside walls to do on a 1830s Yorkshire gritstone building. Should I use NHL 3.5 and with what type of sand and aggregate and in what ratio? Also for large voids should I fill with larger stones and a bit of mortar and then let it go off a bit before pointing over the top?

[@dportercontracting9974]

Hi Seb, pointing internally is exactly the same process as external pointing. I use the same mix ratio as external pointing on random stone. On internal brickwork, depending on what the client's specification is, I tend to leave out the granite dust and use an extra sand to make up a 3:1 mix ratio. This results in a brighter coloured mortar that contrasts better against brick. This is my personal choice and obviously you could adjust the constituents of the mortar to your own preference. If you were to backpoint large voids, I would be tempted to leave the backpointing to carbonify for a few days, before the application of mortar. Keep in mind that the carbonification process is optimised at mortar depths of 25mm or less. Hope this helps?

[@sebgreenfield8800]

@@dportercontracting9974 Many thanks, that's great 👍

[@williamwilliam7100]

hello bit help please ,customer asked me to repoint existing house i think built 1950s.Existing many bricks cracked vertically in middle of bricks which i find abit odd.The existing mortar looks like hydraulic lime which looks like mixed with greyish bits added and hard as cement ..My question is some of the building is not being repointed so i have to match existing,which sand can i use would it be washed sharp sand .Thanks malcolm Devon

[@garethjones7334]

Didnt realise you were local to lancs. The brigs and duxbury bags gave it away 👍🏻

[@dportercontracting9974]

Barnoldswick matey. The home of the legendary and now defunct Briggs and Duxbury.

[@garethjones7334]

@dportercontracting9974 yeah Im from colne pal

[@steevew]

Great videos, very informative. Would you recommend mixing in a fine white mortar sand with the sharp sand to give a lighter finish? If so, what ratio do you suggest? I'm planning to use NHL 3.5 with a sharp washed sand. Any info appreciated, I'm new to this.

[@dportercontracting9974]

Hi there. Many thanks for the comment. I'd steer clear of any fine sand in your mix. There are several colours of lime that can affect the finish colour of mortar. You can find chalk white coloured lime or pure white. The chalk white gives the finish an off white colour. You can use various colours and kinds of sand in test mortar patches on the wall to see what finish colour your project will have.

[@steevew]

@@dportercontracting9974 Thank you for your reply, much appreciated. Damn I've now got 250kg of white fine sand if anyone is looking to buy some, haha! This weekend made my first mix to back point the wall I've virtually had to rebuild from bottom up, it's 200yr old. I've learnt everything I needed to know from watching your informative videos, without them I wouldn't have had any aggregate or sharp sand (all I bought originally was lime 3.5 and white sand). How long do you recommend leaving the wall after back pointing to finishing it with a lime render coat? TIA

[@EastyUK]

Im using a pozzolan (metakaolin) in my mix with hydrated lime, Sadly Hydraulic lime is impossible to find over here in California. Thanks for the vid.

[@michaeljamesdesign]

It's not impossible but it is out there.

[@EastyUK]

@@michaeljamesdesign I was thinking more at a feasible cost. Current price is $24 for 90lbs binder, plus driving fees, I'm just lucky the have metakaolin locally also.

[@michaeljamesdesign]

@@EastyUK That's a good price. Imported NHL is expensive in the States from what I can gather.

[@EastyUK]

@@michaeljamesdesign Yeah, there is a lot of love for hempcrete here and a many companies pushing it as the new thing with relaxed US hemp regulation. When the binder is pushing $90+ a 40lb bag delivered it really makes it not feasible for people. It's also very difficult to find good information on the various types of lime and what can be used as a binder. I'll do some videos on my path with metakaolin and hopefully it will open up some options for people in different locations.

[@user-zc7ko7jk1d]

You know your shit. Kudos.

[@imperialthreat]

Would love to hear elaboration about how lime allows moisture to wick through vs cement. In the states seems like portland is the standard i often here other countries say cement is a mistake and US always saying lime washes away. So confusing

[@dportercontracting9974]

I think the theory behind it, is that cement bonds the aggregate chemically into a solid, impeneterable structure. The cement bonds are so strong that the mortar won't allow for any form of movement, or expansion in the mortar bed/pointing. Lime mortar acts more like a cushion than a bonding agent. Mortar, ideally shouldn't bond the substrate. The mason should work towards making the stonework "hold" for want of a better word, itself together. Giving the structure strength, Instead of relying on the strength of the mortar to do so. Thats only my thoughts on it. I may be wrong.. Well mixed lime mortar won't wash out of the works. Just returned from a trip to the west coast of Scotland. Saw some 1000 year old, habitable, structures on an island. The lime mortars used, still look to be perfoming their job dutifully.

[@sophielaurie6510]

just about to start a pointing job on a brick house. I see the original pointing has specks of black - assuming char - any idea what this is for and whether I should add to the mix? makes for quite a nice effect and I have made some char this year that I could grind and add.

[@dportercontracting9974]

Hi Sophie, The black specks could be coal dust or mica. Depending on how faffy about the mix you want to be, you could send a sample of your original.mix off to the Scottish Lime Centre. They will do you a microscopic evaluation of the contents of your lime and mix up a batch of like for like mortar to match your original mortar. I expect that the black content of the mortar will be black ash. If the project is in the north of England, then there used to be bins on the end of most northern streets that the fire ash went into. The municipality then collected these coal, ash bins and the contents went into making lime mortar on local building sites. It makes for a very hard lime mortar when mixed right.

[@sophielaurie6510]

@@dportercontracting9974 thanks - this is in the South West near Glastonbury. Lots of mining around here so could have been coal dust as you say. I wondered about how it affected the property of the mix so might try a small sample and see what it looks like.

[@michaelbirchall2247]

Great video. I would think that measuring cement by weight would produce the same problem. I thought that's why it's all worked out in parts rather then in weight, so 1 part could be a spoon a bucket or a skip, as long as the sand and lime are all measured with the same item. 3:1 = 3 buckets sand and 1 (same) bucket lime. it even states this on the back of most lime and cement bags. But I'm not a builder. Great to see you gauging it out properly though, I cringe when I see people using shovels to measure, surely that's not consistent!

[@rogerthedodger5788]

You read my mind on this.

[@RockStockStar]

See page 29 regarding weighing - 'Measuring by volume can be inaccurate as this does not take account of the variations in RBD of different binders, which can affect binder:aggregate ratios. '

[@Chriscarper]

Great video, what ratio of sharp sand & NHL would you use of for repointing a standard brick 70's house please? I'm still trying to get my head around not needing cement lol, Thanks

[@dportercontracting9974]

Hi matey, thanks for the props! If you go for a 2.5 to 3:1 ratio of sharp sand to lime, you won't go far wrong. Itll look ace when ypu have lime pointed the original brickwork!

[@Chriscarper]

@@dportercontracting9974 great stuff, thanks 👍

[@mondayschild3493]

@@dportercontracting9974 Do use concreting sharp sand that is sold at builders merchants, normally heaped in large piles?

[@dportercontracting9974]

@@mondayschild3493 The local builders merchants is where I source my grit sand. Some call it "River sand." That will be a sharp enough aggregate to use in your mix.

[@mondayschild3493]

@@dportercontracting9974 OK thanks,i did a 3 to 1 mix with sharp sand and NHL5 when i cut some bricks out of a wall and replaced them i could not get the lime mix to stick to the brick, it was a case of forcing the mix into the joints to try and create a bond. I have some more to do i thinking of using 2 parts soft building sand and 1 sharp. The bricks were damp so this wasn't the cause of it. Can sharp sand be too sharp? as it just says "sharp sand" on the bag.

[@craigstyrin3453]

I bet that goes solid with grano dust in it? No building sand in it? Nice videos by the way!

[@RockStockStar]

Great educational videos. What mortar mix would you recommend for pointing up a granite property in Aberdeen? 1 part 3.5 nhl + 3 parts sharp sand? If you're ever short of work, head north. You'll have job for life re-pointing this city 😏

[@dportercontracting9974]

Thanks Smell my cheese. It completely depends on what kind of weather your property experiences, what aspect faces the sun, etc. You should get a decent mix with a 2.5 to 3: 1 sand to lime ratio. I'm guessing Aberdeen will be like most places now, cemented over the lime?

[@RockStockStar]

@@dportercontracting9974 Thanks for getting back to me👍. It's a south facing wall so I guess will have more temperature variances but less rain? I actually have a tub of lime putty and the old mortar is just sand now so in some places it's like 3" deep. Can I do it in 2 stages? An inch or so initially with larger aggregate then the final finished pointing in a few weeks when I have time? Yeah, we have a total mix up here. Patchwork white lime pointing and plenty of cemented for sure!

[@dportercontracting9974]

@@RockStockStar Sure thing to doing it in stages. If you back point the wall then it would be ideal to let it partially cure before you apply the finish pointing. I've a video on pointing a granite house up on Mull which would be a similar background to your property that you might get some help from.

[@RockStockStar]

@@dportercontracting9974 Super - many thanks. Yeah I've watched that video twice now so I think I'm ready! Thanks again👍

[@Offensiveword]

Can you use hydrated lime for pointing? I’m starting a job very soon and can only find hydrated????

[@dportercontracting9974]

You can use regular hydrated lime from the builder merchants but it will give you a weaker mortar upon final set. If you go to your local builders merchants and ask for a NHL 3.5, they will happily order you a bag or two in. The extra 10er a bag will be well worth the money.

[@Offensiveword]

@@dportercontracting9974 cheers , iv ordered some nhl 3.5 👍 … iff it goes wrong I’ll send them your way , 😆

[@maxtelero4904]

What ratio you use 1 lime to 2.5 with nhl 5?

[@dportercontracting9974]

Have a watch of the video and it will explain all, my friend.

[@gary24752]

What makes the mortar either a grey color or super white?

[@dportercontracting9974]

Various components of the mix will add colour or tone to a mix. NHL lime has clays in it which will add a darker or more grey colour to the cured mortar. Lime putty use, produces a brighter, whiter finish to the cured mortar. Various colours of sand are available, depending on where in the country you are. Each sand produces a different tone or colour to the mortar.

[@gary24752]

@@dportercontracting9974 Thanks

[@iangough7659]

Where you buy your granite dust from.

[@dportercontracting9974]

Your local builders merchants should have granite dust in stock. It can vary in colour from a greeny/blue to black colour.

[@jimhud134]

Would you say NHL 2 is suitable for internal re-pointing?

[@dportercontracting9974]

Definitely Jim. I would use a NHL2 for internal pointing, mixed to the same ratios.

[@jimhud134]

@@dportercontracting9974 Great, thanks for the reply.

[@cocoandrobin]

How can I contact you for a quote?

[@williamwilliam7100]

hello again,i think this house they used granite dust as the picture i took of the hse looks same when in your vid you used the churn brush on the wall to expose the motar between the stone.

[@davidcarr9563]

Can i use sand and hydrated lime 3:1

[@dportercontracting9974]

You sure can David.

[@philomena333]

Grano acts like pozzalan. I suggest instead grano put limestone dust n myre m1000 as pozzalon. Or u can use bilcanic ash if u have any

[@kategrey3068]

What neuton strength will the be at its strongest Does pozalin make it stronger Thank you

[@michaeljamesdesign]

It's difficult to say because NHL hardens over time. You shouldn't put pozzolan in NHL.

[@kategrey3068]

@@michaeljamesdesign OK great thanks why did you do the lime by weight other videos do it by volume Won't that make it even stronger

[@michaeljamesdesign]

@@kategrey3068 Not me.

[@kategrey3068]

@@michaeljamesdesign sorry is this not your page Thought it was as you're answering the questions I just checked as well its by volume with secil not weight

[@michaeljamesdesign]

@@kategrey3068 Always by volume.

[@euroasiabtlimited3208]

Portland should be used when solid brick or stone is the main wall. Lime mix must be used to allow the wall to breath and move in the way it does. A small amount of prtland added is sometimes used to mke the lime mix a 67% hardness . I like your use of granite dust. Nice one .

[@dportercontracting9974]

Thanks for your input. We don't use cementitious mortars as it stops the breathability of the wall and stops that active flow of moisture from the living space outwards. The harder the mortar, the more chance there is of cracks forming in it, allowing moisture ingress and damp forming . A lime based mortar acts as a cushion for the substrate, rather than a solid, fixture.

[@ericbibeau5631]

Hi the video show you out 2 buckets of sand and 1 bucket of granit dust. The video says 4 to 1. Can viewers assume you added an additional bucket of sand that is not shown in the video. Thanks.

[@dportercontracting9974]

Hi Eric, I'm not sure where the 4:1 is. We used a 3:1 mix on this project. 4:1 would be too weak for most outdoor, lime applications.

[@Mao.Loves.Zedong]

Nhl 5 is way to strong for repointing. 3.5 is more than adequate for any type of masonry.

[@richpurnell6520]

You don't measure by weight, you measure by volume.

[@MargotCottam]

11:41

[@michaeljamesdesign]

The reason it's that horrible grey colour is because Secil is from argillaceous limestone which is high in clay. That's why it's cheap in comparison to other decent brands. Traces of gypsum have also been found in it. The Secil quarry used to mine gypsum. NHL5 has very little free lime and is too hard even for chimneys. Your work is good but you need to up your game where your materials are concerned.

[@dportercontracting9974]

Thanks for your opinion.

[@michaeljamesdesign]

@@dportercontracting9974 It's a statement of fact Mr Porter. Roundtower NHL5 has a free lime content of nearly 25% whereas Secil NHL5 contains only 15%. So that's an 85% impurity content. I'm trying to persuade contractors to be more discerning where NHL is concerned as a lot of it is piss poor and sets really hard over time. Ideally you want to be looking at 40% available lime. There's not much difference in the price and you can use superior products to help you win better customers and more well paid work. Jus sayin

[@dportercontracting9974]

@@michaeljamesdesign Thanks

[@JR-yl2rm]

@@michaeljamesdesign Hi. I cant seem to source Roundtower locally. Could you recommend some other good hydraulic lime brands. Just Ionic and Hanson from our local builders merchants. Thanks

[@michaeljamesdesign]

@@JR-yl2rm Speak to Declan and Chalk Down Lime. Tell him about your project and that I've recommended you give him a call and that you want a decent NHL. He'll look after you.

[@jamesbyrne9292]

Fred Dibnah brought me here

[@greggharrison1128]

Can you tell me why you blocked my comment

[@dportercontracting9974]

I've been wandering round the wilderness of wild Scotland for the last 10 days. No signal, nor the want or inkling to go online bud... What was your question?

[@marcustschierschke3804]

Nhl5😫adding pozzolan to it are you fucking kidding me

[@rogerthedodger5788]

Further to my comment below I looked at the data sheet for the Tarmac Limelite NHL 3.5 that I'm using and on it it states "mortar mix proportions by volume" . So clearly weight or volume can be correct, you just need to check the data sheet.

[@johnchampion7819]

What's with the dreadlocks? Why and for how long have you had them?

[@Southpoint2019]

What would his hair style matter

[@johnchampion7819]

It's nothing to do with repointing which he's very good at, I'm just interested in why he chose that style. The problem with society today is that nobody can make a simple comment without somebody trying to put a nasty slant on the comment. By the tone of your question, I believe that you may be one of those people. His hairstyle does matter, especially to him, otherwise he wouldn't have gone to a lot of trouble to get that look. It's like the racist thing. It's gotten so far out of hand. It is destroying free speech. People nowadays have to be so careful about what words they choose before they speak. A sick society is being created by a minority.

[@Southpoint2019]

@@johnchampion7819 I admire your slippery ability to manipulate my reply into the inaugural negative I wasn’t remotely negative. Your question was which is likely why the chap with locks didn’t respond

[@Southpoint2019]

@@johnchampion7819 please don’t twist it into racism etc.

[@johnchampion7819]

@@Southpoint2019 Give the lad time to respond, he's probably busy repointing. I wasn't trying to lecture you. Your comment raises the question as to why you made it.

[@philomena333]

Thats too strong for wall. Shoudnt go above nhl 3.5 mate. Nhl5 was made for bridges etc😂🤣👍👌

[@dportercontracting9974]

Thanks for your opinion. The house has dried out beautifully, internally.

[@michaeljamesdesign]

Agreed. No need for NHL5.I'd only ever use this below ground.

[@markanderson6969]

@@michaeljamesdesign thats funny you've done a video using it above ground

[@michaeljamesdesign]

@@markanderson6969 And I did a couple of chimneys with it the other day.

[@andymagee6687]

It's not how you mix lime if you did this to my house I would take you to court False I formation t it's best

[@dportercontracting9974]

Thanks for your opinion Andy. Perhaps you could do a video yo show how you mix it? Keyboard warrior, faeces flinging at its best..

[@richardgoldsmith226]

@@dportercontracting9974 Great Vid, best not to reply to certain comments!

[@richardgoldsmith226]

I was wondering if you could do a video yourself? Show us all how its done.. I do suppose that if you were a master then you would do your own work so you wouldn’t take anyone to court, hey!