Architects and specifiers choose materials based on various factors such as structure, location, size, materials, and depreciation. Methods for evaluating building materials include structural analysis, analysis, and physical load testing. LCA evaluates the environmental impacts of construction materials throughout their life cycle, from extraction to disposal. Building evaluation work spans professions like architecture, services engineering, and facilities management.
This paper proposes a model to evaluate and select sustainable building materials based on sustainability, economic, and environmental parameters. It covers various parameters, acceptance criteria, and the ability to assess, evaluate, and improve future or current performance of buildings. Green products are evaluated and have attributes to reduce health and environmental impacts. Investing in high-quality materials not only ensures durability but also reduces the risk of damage.
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Labor cost estimation can be done through historical data and industry knowledge. Strength and durability assessment can be done through laboratory tests, such as compression testing for concrete. A list of materials can be made, and the crew’s time spent on each material can be estimated.
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📹 Revealed: Building Material Breathability Experiment (surprising result)
The ‘breathability of building materials’ experiment. Mixes From our test • 3.1 Sand and Cement • 5.1 Sand and Cement • 6.1.1 …
What are the five criteria for evaluating reference materials?
As a student, you will be utilizing various sources for your research projects, such as books, newspapers, magazines, databases, and websites. It is crucial to evaluate each source to determine its quality. Common evaluation criteria include purpose, intended audience, authority, credibility, accuracy, reliability, currency, timeliness, and objectivity. These criteria are used to determine the purpose, intended audience, authority, credibility, accuracy, reliability, currency, timeliness, and objectivity.
The sources you will use include newspaper articles, editorials, opinion pieces, viral videos, advertising, and textbooks. These sources are suitable for various audiences, including scholars, academic researchers, the general public, and students in high school, college, or university.
What are the 5 steps of evaluation?
The 5-Step approach is a systematic method for identifying and addressing a problem. It involves identifying the problem, reviewing evidence, drawing a logic model, identifying indicators, collecting monitoring data, and evaluating the model. This approach is crucial for service providers to understand the problem and its need for change. The evidence should guide the actions taken to achieve the desired behavior change, ensuring that the service is effective and efficient. The process of evaluating the model is crucial for ensuring the service’s effectiveness and achieving desired outcomes.
How to do an evaluation on a building?
As a facilities engineer, it is crucial to collect and analyze data on buildings using various tools and methods. This includes reviewing the building’s history, documentation, and performance records, and consulting with stakeholders like occupants, owners, and maintenance staff. To ensure the safety, functionality, and efficiency of the buildings, it is essential to evaluate their current condition and plan for improvements that meet the needs and expectations of these groups. This can be done through AI and the LinkedIn community.
How do I calculate how much material I need?
To determine the amount of material needed for a project, follow these steps:
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How do you analyze a building?
This article provides tips on how to analyze architecture, especially for those new to design or interested in buying a home. It emphasizes the importance of considering factors such as the building’s purpose, materials and facade, its usefulness, the surrounding area, light, human movement, and the overall aesthetic appeal. The article encourages readers to ask themselves questions about the building’s purpose, whether it’s a residential, office, cultural, or multi-functional space, and whether it’s a government building.
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How to calculate BoQ for building?
A bill of quantities (BOQ) is a crucial tool in the construction industry for accurate cost estimations and project management. It involves six basic steps: preparing a spreadsheet, breaking down materials, estimating labor, making an initial cost estimate, estimating time delivery, and making good use of the BOQ in the project. Labor and materials are the most crucial elements in a construction project, and without them, the plan and schedule for the project would be incomplete. Some argue that the BOQ should be used in all construction projects, and this article provides an explanation of how to build a BOQ for your next project.
How to quantify building materials?
The article provides three methods to improve the estimation of building materials. The first method involves calculating the total material costs for a specific job and dividing them by the total square footage of the job. This method is crucial for project planning, as it helps determine the average price per square foot for materials. The article also discusses three ways to streamline the estimating process and suggests a tool to save time while estimating.
How do I choose building materials?
The primary factors influencing the selection of construction materials are strength, durability, cost, local availability, ease of handling and storage, climate, required skills, availability, and sustainability.
What are the three steps in material evaluation?
In his 1999 study, Tomlinson proposes a three-tiered approach to material evaluation: pre-use, in-use, and post-use. However, he suggests that the procedures for each tier should be tailored to the specific characteristics of the material in question.
How do we evaluate materials?
Materials evaluation is a subjective process that is linked to the intended teaching and learning context of a coursebook. It can be pre-use, predictive, post-use, and retrospective, with the third phase of McGrath’s cycle in-use informing teaching practices and coursebook use. The pre-seminar task involved working in small groups to create an evaluation framework of one or two pages of chapter 4 from the ELT coursebook. However, the absence from the seminar may have resulted in a more subjective interpretation of evaluation materials.
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The more teaching experience an evaluator has, the more able they are to view a textbook with detachment and consider other users’ needs. The lack of English language teaching experience may have hindered or severely contrasted with the other group members’ contributions.
In conclusion, materials evaluation is a crucial aspect of teaching and learning, and the evaluation process depends on the context.
How to figure a building material list?
To calculate the required amount of products and coverage rates for a project, divide the total square footage by the coverage rate of the material. This can be calculated by dividing the square footage by the coverage rate. For instance, to stamp the total area using the ¼” Stamp Overlay System, the number of bags of S-1800 Super-Stamp Gray required is calculated by dividing the area by the coverage rate. This method ensures accurate and efficient coverage.
📹 How To Prepare Construction Cost Estimation Format In Excel For Projects
In this video, I explain how to prepare construction cost estimation format in Excel, including rate breakdown analysis for …
Im from Greece (a country significantly sunnier but still quite humid). In Greece the common practice at least the last 60-70 years is for plastering and rendering we use a mixture of 2 parts of sand(there are people going up to 4 parts but the majority use just 2), 1 part of slaked lime (im not sure if i use the correct terminology, but is lime melted in furnace added water and then left 6-12 months in open tanks/holes in the ground to mature) and 1 part of cement. We do use this not only in “modern” houses which are made from cemend blocks or bricks but also for stone wall houses(even on restorations) . It works really well, just lime mortar it doesnt work that good due to lack of strength and in a very seismogenic country strength is very crusial
We had a permanently damp conservatory wall for years, kept having to re skim the plaster.I stripped off the emulsion paint to bare plaster and put on a lime based paint instead. The water comes through and evaporates straight off, rather than being trapped by latex in the emulsion, the not been damp once in the last 3 years. Things need to breathe.
My understanding is that the lime mortar has a smaller pore structure than the brick and therefore causes water to be drawn from wet brick into the mortar joints allowing preferential drying. It is the capillary structure rather than the vapour permeability in lime that is preferential to sand and cement.
Why no lime putty/hotmix?. Also, in my experience, its not always about the permiability of the mortar but the strength. Water will always take the easiest path and if the mortars harder than the fabric of the building then the moisture will be pushed out through the fabric, causing damage, instead of through the mortar which is far easier to fix.
You’re not debunking anything because your experiment is flawed in so many ways (as others will confirm) that it would fail any examination or peer review. Experimental design means creating a set of procedures to systematically test a hypothesis – and you have not done this. You haven’t used a control sample for example, you haven’t specified the weight of each sample, whether they were cured to specifications and even whether the water was PH tested OR if the wet mixes were ph tested. You’ve just mixed some materials, created a few discs and sat them in cups of water plastic cups of water for a year. You’ve even titled your experiment “building material breathability” and your conclusion is nothing more than a subjective opinion.
Of course, breathability is not the only factor for using lime, like you say it can self heal the cracks, less so the 5.1NHLs but it can move with the building if needed. It also doesn’t bind to the stone in the same way as cement, so you can knock something down and easily reuse every stone…also for those looking to justify building sustainability it continues to absorb carbon overs its life, cement base alone doesn’t do any of that. Roger’s you are going from strength to strength! Love this one!
Roger methodology is perfectly fine to explain this problem. After 40 plus years I have seen many mix failures the most important thing is the cement lime sand ratio and have found six one and one the most reliable hydrated lime is perfect product, if time is available good idea to premix sourout lime and sand fully enclose in polythene and just add cement when ready to use
Good experiment, it confirmes what my opinion on this is. I already use the 6.1.1 sand-cement-hydrated lime mix for bricklaying and repointing, unless it is exposed to wet soil. Then I use cement only to get a bit more water resistance. That plaster doesn’t hold well on persistent moist brickwork was very clear in my house, but the old under plaster of a weak cement/lime mortar holds up quite well in these conditions. A lime skim also will hold better on moist walls, and lime does counter the growth of mold to some degree as it is alkaline.
The gold standard for breathability would be hot mix – also vapour permeability is only one element of (and possibly not the most important element) of breathability. I work repairing and conserving buildings using hot mix and would happily run this experiment with you with a few other mix options and maybe look at some different experiment designs to show why we’re advocating for lime. 👍
One thing that should be fairly obvious from this is using gypsum plaster on top of lime in an area subject to damp permeating in from outside will result in blown plaster as the moisture works through the lime but doesn’t get through the gypsum so easily. Something that I am experiencing currently with this relentless wet weather we are having…
It’s the strength of the mix that makes the difference. 3:1 contains twice as much cement as 6:1:1. The lower the cement content the more permeable the material. The lime products tested are the least permeable available, NHL 5 is practically cement. It would have been interesting to see lime putty included as it’s more permeable than any NHL. Hydrated lime is made from quicklime, as is lime putty, which may explain why 6:1:1 works well despite being a “cement” mix. Mortar should be softer and more permeable than the masonry to protect it. If you have hard bricks, cement is great, if you have soft stone, you need lime, and the mix is important. If you compare apples to apples i.e. 3:1 cement with 3:1 lime, the experiment proves that NHL lime is far more permeable than cement. The best result came from a form of quicklime which might have done even better without the cement, had that been tested. Not sure anything was debunked here because if you account for the different strength mixes and the types of lime used, the experiment shows that lime is more permeable than cement.
As a biologist, I would say that the test is flawed because for each of the test samples, the liquids had some things living in them, which caused the colour change and the scum as the organisms lived, breathed, metabolized and died during the year of the test. Heaven knows what the liquid originally was – tea perhaps? Then it would be slowly transformed to something like Kombucha, as a succession of microbes transformed whatever meager nutrients were present into something they could live on, getting some input from gases from the air passing through the disks. Water is not the only thing that was getting in and out through the samples of building materials in the disks. Nitrogen, carbon dioxide and other gases and volatiles from the air outside, some of which could be used as building blocks to allow the organisms to live, reproduce and produce the scum of their dead, and perhaps not-so-dead remains as the experiment progressed. Oxygen, nitrogen, carbon dioxide, hydrogen, methane, ammonia, nitrogen oxides, chlorine, hydrogen chloride, alcohol, hydrogen sulphide, sulphur dioxide, and more complicated organic and inorganic volatiles, produced as biological reactions took place, were either passing through the disks, and in some cases, being selectively absorbed by the disks. Some of these gases are acidic, and would be absorbed by lime, for instance, to react to make calcium salts, such as calcium carbonate, calcium sulphate, calcium nitrate, calcium chloride etc., to name but a few.
Where is clay mortar, e.g. Claytec? I use it in a bathroom (2 cm and more) and it buffers the humidity very well. We coloured it white with a lime paint. To be clear: it absorbs the high humidity and releases it slowly when the humidity is low. Only a minor amount actually passes through and is absorbed by our wood fiber.
Great test and article. We need more of these tests by people like you and also maybe from some “credible” statisticians and scientists to start making some sense of these religious like opinions that are causing us DIYers headaches and pocket aches. No self-respecting eco youtuber seems to dare to touching cement if they do not want to be abolished by the no cement cult
Anyone notice the colour of water and the mold that’s in the glasses. On old stone or brick buildings if sand and cement used on walls and gypsum plaster eventually you get damp problems. Old cathedrals when you see the damage done from Victorian cement repairs that’s being rectified by better methods of hot lime and lead. Certain paints and plasters are not meant for certain buildings and the truth is getting out there. And it’s quite easy to see from looking at buildings and windows which lets it breathe and which creates damp mold eventually or decay.
Would be interesting to see the finished mortars close up in a microscope, although I don’t suppose you’ve got one of those in your shed. I think you’re right about the air entraining due to the hydrated lime. Chucking a little bit of plasticiser in as well, plus a good long mix in a mixer will get it really ‘fluffy’. The big diesel mixers always do it best
The issue is not just permeability, but the excessive strength of the new mortar which puts excessive force on the old bricks and the lack of flexibility of the new mortar, which transfers movement to the old bricks, instead of having that movement dissipated in the soft mortar. We have old buildings where lime putty mortar was used with great success (for repairs). I don’t want to put a building at risk of destruction for the convenience (short curing time) of the work crew. Brick Saver LLC
What mix for repointing a typical 1930s semi please? The current mortar seems to be a crumbly mix internally, and then a ‘finishing’ pointing put on the outer show face. This outer pointing is now falling out in places. I had some of the outer mortar tested and was told it is ‘cementitious’. The inner mortar is lighter in colour and a bit crumbly.
With the amount of time it took for maybe a few hundred ml of water to pass through, surely the material you use has a trivial difference to the “breathability” of the building. I could remove as much liquid by opening the windows for ten minutes or running a dehumidifier for a couple hours as a “breathable” material would allow for in a month.
Oh Roger. You’ve totally and utterly misunderstood what breathability means in this context (and you’ve also misudnerstood the crush resistance of NHL). Addressing NHL first; NHL 5 just guarantees a certain crush strength – but an NHL2, whilst guaranteed to a lower value, can set higher than an NHL5. On “breathability”; water does not transfer in a vapour stage – it moves via capillary action in a liquid state. I don’t know why you’re so at war with the science: you could do so much good with your articles. It’s such a shame.
Interesting experiment, I’m not totally surprised by your results. It is now known that NHLs aren’t very good for building conservation, but this hasn’t filtered down to many people on the front-line and certainly not to the people commenting on your articles. The breathability of traditional building materials isn’t a ‘myth’ but it is poorly understood. Firstly, the term breathability is misleading. Moisture transport through mortar is mostly in the liquid phase, not vapour . Ie. liquid water is transported via capillary action. This is important because many manufacturers will claim a product is vapour permeable, but this is useless if it is capillary closed. Think of a gore-tex jacket, for example, you still get sweaty in them! Secondly, those of use with slightly deeper knowledge of technical conservation understand that the widespread use and adoption of natural hydraulic limes was a mistake. The vast majority of historic buildings, above ground, were built using quicklime mortars (sometimes called hot lime), which has only recently seen its own revival. Quicklime mortars are typically mixed at around 1:2 or 1:3 quicklime to sand, which produces a very lime-rich mortar (the lime expands as it slakes) which is very porous and effective at drying out buildings. Pozzalans can be added to aid setting. These mortars are also much more workable than NHLs. The heat produced by slaking the lime in the mortar mix is thought to produce a more effective mortar, even if subsequently used cold, although this is poorly understood.
Roger you’re bang on. We use a very similar mortar mix with the hydrated lime, we tend to use more hydrated lime in our mixes but it depends on the levels of exposure, etc but adding that extra lime really ups the plasticity I test by feel. And it is also self healing, thus any minor cracks will disappear. We have done countless jobs and never had any problems with the outcomes. Almost always gauged with white Portland, to varying degrees according to the requirements of the particular job. Great blog Roger, and yes gypsum is highly soluble in water. And as a footnote a lot of Paris, that’s the French version not the Texas variety is built on a significant deposit of gypsum, maybe the whole lot will float down the Seine in the future.
I was told that cement has microscopic and macroscopic cracks that allow the moisture through and then locks it tight within the bricks. Lime allows the moisture to leave the bricks, it shouldn’t be called breathing either, that’s the wrong way to think of it apparently. Lime does act as a plasticiser in a cement mix, but also apparently becomes inert after some time. The original methods used lime putty, lime putty and mud for the bedding mortar, lime putty and sand for render and pointing, fine sand and lime putty for the plaster and diluted lime putty for the paint. I’m thinking to get the full benefit of the system you need to encompass the lot? I’ve seen a lot of damaged walls that appear to have been damaged by the addition of concrete render. The bricks are at the lowest part eventually become sodden and crumble. Cheers for the info.
Never point a period property in a 6:1 sand and cement mix. Cement is rigid and will inevitably crack when the house inevitably moves. Lime os softer and moves and heals itself as the young man mentions. Please never point a house thats built in lime in cement it will stress the bricks and cause them to fracture
Sorry if i missed it, but you dont mention the aggregate you use. Sand for a cement mix, with or without hydrated lime is quite different to the aggregate used with lime. Lime putty sand tends to be coarser still than that used with NHL mixes. Im sure that you know that NHL is often frowned upon in many situations by knowledgeable heritage builders, so why not include lime putty with a sharp sand 0-4mm aggregate? Also, you assume that these materials may be used for plastering walls internally, but fail to mention the most vital aspect of a vapour permeable build-up, the decoration. If you employ a modern plastic paint on any surface it will seal it, locking in moisture. You shouldn’t be presenting your experiment as unbiased or fair, because it isnt. You have an agenda based on your ideas, just as i do, so you should have taken on board someone who understands traditional buildings to advise if you wanted meaningful results. But i guess that wasn’t the purpose of this exercise.
The lime mortar advocated for is non hydraulic lime, but you don’t test this. So not much point. Besides which many reputable organisations have monitored buildings for years and found cement wrecks old solid walled buildings, non hydraulic lime preserves them. They have also found NHLs as you use here also have their problems. With non hydraulic lime (which you don’t test), usually being what is needed.
I enjoyed this experiment and it would be ideal in a climate where the temperature doesn’t get much below 16’ but surely what has been missed here is the problem of “Interstitial condensation” which is common in our climate and which happens within the thickness of a wall where the warm air vapour passes through the surface and cools down within the wall, leading to condensation (droplets) which can result in the deterioration of the structure and fabric. This experiment is similar to saying that weathershield paint is “breathable”. It technically might be as it slowly lets vapour through but it can’t let droplets/condensation through and therefore is completely rubbish in many situations 🤦🏼♂️
In a country that can realistically rain nearly every week, where humidity can be between 40-60%, and that’s a good humidity. Recommending a material like gypsum because its quick is just misguided. Also gypsum has a neutral PH, so not only does it fall apart in the presence of persistent moisture, it is a perfect breeding ground for mould. And as others have stated, the main issue with cement is it is too hard. I don’t know exactly how you did the tests. but to tell the customers who have rotten timber frames behind the gypsum and cement that they are vapour permeable. And overall, this is just a silly thing, cement is a great material. For buildings the scale of the pantheon, a skyscraper, st pauls cathedral. But to us it for someones house because its “quick” is just lazy and poor time management. And furthermore, stop saying gysum is modern, its as old as lime and clay, it was readily used in countries like Egypt during the dynastic period, but we don’t live in a desert.
I appreciate an attempt to approach things scientifically but this experiment can’t possibly give anything resembling a complete picture, and it certainly doesn’t support the conclusion that it’s fine to use cement mixes in a conservation setting. I’m no conservation diehard (I find the totally uncompromising attitude frustrating at times), but it’s just not helpful advice.
Great experiment! As a building surveyor and retrofit coordinator this interests me greatly. I’d love to know if this experiment is a legit way of measuring its permeability. There must be a British Standard out there that provides the right test for this?! I’m going to look into this further. Thanks for providing the starting point for me to investigate.
I’d say this is more important when being used as an external render or internal wall covering. Once on, you treat them very differently. Cement based renders or plasters you would paint with a paint that is mostly plastic nowadays which is not particularly water permeable. Where as with a lime finished wall you wouldn’t go near it with a modern paint.
They need to Re-Instate Statite & Siraphite Plasters that used to BREATH as good ‘almost’ as Lime Finish 🤠 …. Remember when ALL Sand & Cement render on building sites were done using Sand delivered WITH the Lime already mixed in?? … It was Wet’n’Mucky but knocked-up a TREAT when most sites never had Mixers for us Spreads (Only the Brickies) ….
I think you are testing the wrong thing. Your experiment is for water vapor passing through the material. The key issue with the material is how water passes through it and evaporates from it. I would say you need to make a brick shape of each and then pour exacty the same amount of water in each brick frog. Then see how soon the brick weight returns to what it was. So it is the water escaping from the material and moving about within the material.
Interesting experiment, Roger. It would be really good to see an experiment on the effect of condensation on plaster as well as addressing the moisture from the walls. I think this experiment that you’ve done here, if I’m not wrong, shows why the chemical damp proof course, covered with sand and cement and plastered with gypsum, it’s such a failed solution. If we could get an experiment comparing a lime putty plaster to gypsum, and a mix of sand of cement with gypsum skim, we could nip this debate in the bud? What do you think?
Traditional building materials have used non hydraulic lime so your experiment is not a fair comparison. Anyone interested or involved in historical building repair/restoration will tell you the same thing and they would rarely use NHL unless underground or in constant exposure to water. Mix up some non hydraulic lime (air lime), preferably a hot mix and test again.
Very interesting as a stonemason for 48 years when I started the mix that we used was 7parts stonedust 5parts hydraulic lime 2 parts white cement it was a beautiful butter like mortar we now use 3 parts sand /stone dust to 1 part 3.5nhl which is not so easy to use but is suppose to breathe and allows water to come back out .Your testing questions the use nhl over hydrated.
Best article yet! Knocked a lot of Concrete off the inside of our home (inch thick) now lime rendered and warmer/ drier. I would still use lime on a period property but, great to see the options above and it really does show Lime is more breathable than cement unless the cement has hydrated lime in the mix. you did however miss natural lime/ hot lime 😀
Flawed experiment as hydraulic lime relies on a chemical reaction with water to dry, isn’t that breathable whereas non hydraulic lime relies on carbon to dry and significantly more breathable. In old building particularly ancient timber framed buildings one should use non hydraulic lime or face rot and decay. Non hydraulic lime can also help lower humidity in a building
Apparently not all NHL’s are built equally. They may have the same numbering like 2, 3.5 or 5.1 but are different due to the lime content and some can set less favourably more akin to concrete. I think Lafarge, St Astier are among the good ones. So its probably worth testing different brands of lime to account for these differences.
I live in a apartment in Portugal and above me there is the upstairs neighbors bathroom, there is no leaks but i asume that there is alot of vapor coming thru to my ceiling since in certain parts I can see bulges with the shape of a toilet for example. It takes years to form the bulge so thats why I asume there is no leaks… whats bulging is the plaster and paint coat (non plastic paint). I wanted to know what should I do, scrape all the old plaster and put a liquid vapor barrier and then plaster or should I use the lime (NHL) as a ” permeable plaster”
Hi guys – quick question. I have a shower downstairs that leaked (damp on otherwise of the “shower” wall). So I removed all the tiles and sure enough the shower tray wasnt fitter with any kind of water protection 🙄. Also, it seems the walls/corner are cleared suffering with the water ingress. So the question is – should I now remove the shower tray and leave a dehumidifier on to really attack it or am I best removing the tray and just allowing he moisture to leave the area “naturally”?
This is a great graphical representation of roughly what goes on in a building. The only result I query the validity of is the one with the gypsum skim on. Usually the finish is very fine/flat and so the surface area is as low as it can be, compared to the other biscuits which will inevitably have a rougher surface as they’re made with coarse sand. As this experiment shows the rate of evaporation, having a larger surface area would increase this and negatively impact smoother surfaces, even if they were not less vapour permeable. It would have been good to see a comparison with one finished with a very fine lime plaster for example, or even something like lime wash. Anyway, really useful easy to understand content though. Thanks.
One thing I would say is proven without doubt from these tests is that adding lime does make something more breathable. Coupled with the self repair aspect it shows what an amazing material it is. It would have been great if you had included either a hot lime mix or putty based mix as those are on the grapevine as being more vapour permeable. Great test here though, thanks.
Roger what are your thoughts in terms of breathability on Silicone Render? compared to lets say a traditional lime render, we have a very old Victorian boundary wall that’s having water ingress issues which needs re rendering and one of the surveyors who visited suggested using a modern silicone render (I believe it was EWI-075) I would of thought lime would of been more breathable and better suited to such an old wall? what are your thoughts?
I am an architect who works with old buildings and I found that both credible and embarrassing. What people are saying about hotmix and putty is true, but those will only harden if you keep them damp for weeks which means the building will be delivered late. So we specify NHL 3.5 iwhich goes surprisingly hard very quickly. I’m not surprised it wouldn’t be any more breathable than 1:1:6. NHLs big advantage is that you can tell the councils building conservation officer that you are using 100% natural lime if you specify NHL. For some reason hydrated lime doesn’t count. I believe that years ago it got a bad rep but nowadays it is sold in plastic lined bags and the co2 can’t get in to spoil it.
Wrong Roger! Why would you put out such a poorly conceived comparison test on your website and who exactly is giving you advice on testing? Frankly I am not sure where to start, but let’s take a few basic points 1. you missed out the most important breathable lime sample which is air lime. 2. you did not control the sand (soft, sharp, angular, spherical, particle distribution etc) water, or mixing method (by hand in a tub really!) 3. when carrying out wet cup permeability tests it should be in a control chamber and not on a shelf as this will give you a wide margin of error. 4. one sample of each is not at all acceptable as it would be good practice to take the average over 3 of each types of lime and or cement. I’ll stop there for now, but will add that this is not a breathability test that you have carried out, it is a permeability test which does not take account of hygroscopic or capillary activity which add very significantly to how a wall moves moisture in a solid wall and maintains a good equilibrium. If you want to report responsibly then speak to an independent and recognized testing centre (a University that specialises in this area such as Bath or Sheffield Hallam or the Scottish Lime Centre Trust), get your facts straight and then publish on your website. My advice is to take down this misleading article. And, if there is a critic out there who is thinking that these are the views of an academic well think again because I am a hands on craftsman who has bothered to educate himself and not be sucked into a world of misguided individuals such as yourself Roger, or into the world of the lime purists; I just look at the real science and then put it into practice.
Great experiment @SkillBuilder As we can see, some with cement seem to be as breathable as the lime ones. Is this maybe less about the material and more to do with the porosity? I’m intrigued to know because I am learning more about this type of stuff as my career progresses. How about a similar test with paints? Many paint manufacturers boast about breathability but in reality can we be so sure?
I love these real world experiments. It certainly dispells a lot of myths. Something I’d like to see is a brick wall sitting in water to see if rising damp is a real phenomenon. I’ve heard arguments that it’s a myth and rising damp is always a misdiagnosis of water permeating through the walls by other methods. It really would be interesting to see it demonstrated (if it really exists).
Shame you didn’t use “hot lime” or also known as “quick lime”. The typical NHL lime has long been known to act like modem sand cement in the vast majority sold out there and worthless. Adding hydrated lime is getting closer to a quick lime mix so not surprising you got good results using some. You should redo it by slaking your own quick lime with calbux 90 lime and do a lime putty mix for a skim coat test. Many real world examples out there of constant wet stone walls all dried up and stay dry with hot lime for pointing.
This experiment is subject to many, many variables in real life use.. I mean ‘Wild Weather..’ Assuming we are just discusing Bricks and Mortar then you have to look back at the Historical context as Construction methods and access to materials are not what they are now.. Hence the progression from stone build (Very expensive and may not be finished in your lifetime..) to ‘Peasant quality’ Wattle and daub which may slough off when it rains.. to Bricks & Mortar (Thank you Romans) including difficulty transporting these heavy materials any distance.. So, had to be local.. Then once we started using bricks we realised that they were mostly absorbent and it was a cycle between Rain.. Wind and Sun to keep us dry indoors.. Then.. Cavity walls.. (a logical advancement..) Then Render..etc etc We are on a trajectory where I believe Bricks and Mortar on on their last gasp.. There are far easier/cheaper ways to New Build.. But, I guess there is still lots of work maintaining the existing Housing stock..
I have a few questions. Regarding the NHL limes was it just NHL, or was it mixed with sand, and if so what was the ratio? I have a feeling that the more sand that is used the more breathable the material will be. Why didn’t you test a hydrated lime mortar? This for me is the real test. NHL is generally regarded as more breathable than cement, whether that’s true or not, but not by a huge margin. The higher the compression strength rating the less breathable. But in my experience most restoration experts will prefer using a pure hydrated lime mortar to an NHL. I’m a bit disappointed as this is what I was hoping to see. Interesting test though.
Poorly designed test ignoring most commonly used conservation limes like NHL2, 1, putty and hot lime. It’s long been known that NHL3.5 and 5 are too hard. No mention of aggregates used, relative substrate hardness and density. Ignorant conclusions which will perpetuate poor building practices being presented as fact by an amateur. If you want to hold forth on subjects like this at least get some education first.
It’s a shame you didn’t ask the viewers what materials to test in advance, I think a lot would have said hotlime or quicklime and maybe plasterboard & skim. There has been a big resurgence of hotlime in recent years and it would have been interesting to see how much utter bollocks there has been written about it – because I know there has. The other thing worthy of note is that some materials (OPC & NHL) continue to harden over time, not sure if that would have skewed your results or not (probably not).
Water is slightly acidic so will react with air (rain water slightly moreso) and there’s a closed system created here so would need to rule out chemical reactions and if le chatelier’s principal for maintaining equilibrium in a closed system comes into play. That said a conclusion that can be drawn is that they have different rates of absorption, and by looking at the samples it’s evident that a wall made from sample 3 which is in wet conditions will have absorbed moisture, and repointing that with sample 1 will reduce the rate at which any moisture could leave, so repointing should use a medium that has the same or higher absorbance than the existing medium.
Great experiment. Removes all doubt. On Last of The Summer Wine (UK tv series) one can often see limestone cottages which have been repointed with cement, causing the face of the limestone spall off. This leaves the pointing standing proud surface after a few years of weathering. Worse, is rendering a stone wall with cement. And far worse than even that, is not perusal this website.
Honestly, why do you bother to pander to idiots? In almost every instance the material that the “mortar” is used to glue together will be more vapour permeable than the mortar, with the exception of some granite stones and good engineering bricks. All modern blocks and most modern facing bricks are far less water resistant than the mortar, that was why cavity walls were introduced, and why a damp proof membrane is used at the base of the habitable areas. Make a brick sized block of mortar using a modern masonry cement, let it completely dry out as per manufacturer spec. Then take a modern face brick, make sure it is totally dry, weigh the dry brick and dry cement, then immerse both in a bucket of water for a week. After the week take out the brick and cement and re weigh them wet, allow them to dry in the same conditions, then weigh each one every day until whichever one returns to its dry weight first. It will be the brick every time because it allows moisture to pass through it easier than mortar.
Ah man I was hopeful for a min there, hear me out. NHL isnt the lime thats used in old buildings its air lime, so quick lime or hydrated lime only, add anything else and you kill it like if you add the wrong agreget to your pore and it messes the whole thing up. Very different material, cures differently and acts differently, that’s why more of the heritage groups don’t recommend nhl, roughly half of the water wicking vs air lime at the most. David wiggins did a really good lecture on it that describes how it works, you can find it on youtube, lots of science and history not marketing. Also hydrated lime will cure over time without a cement, just a lot longer if its cold or too damp. Ive used the same mix in my cold damp humid garage and to back point my roof, totally differnt results in time scale just because of the conditions. Takes a long time and the water needs time to get out slowly and curing actually happens due to co2 absorption not drying out, your looking at 1mm per month for it to really cure, rush it and it wont work right even in a cup. The reason I know is because ive repointed my wall with 2-1 hydrated lime and sharp sand with a touch of fine and its dried the wall out and dried like stone after a few weeks of good weather and looking after. Its also sucked the water out side by side with cement re pointing ive been removing. (1910 red brick terrace) Also worth noting dude “Breathability” is a marketing term from NHL adverts back in the day. Lime doesn’t move liquid as a gas it moves it as a liquid like a sponge, the windswept surface on the outside has a low humidity level so draws the water out of the wall.
Bottom line, none do really work compared to ventilation, dry air and heat because then the cup would have been empthy in 2 weeks! Nothing is worth the extra price compared to proper ventilation and proper blocking moister rising from the ground or penatrating in any other way. Have said that it is better to use sand and cement because it neither asorbs moiste and with good mechanised ventilation internal of the house, in every room, the result will be optimum.
As someone else has mentioned, there is a great deal of variation in breathability of modern bricks and blocks, so you simply have to use what is specified by architects, planners etc. However, Portland cement should never be used to repoint old lime rendered buildings. It is way too strong, and when the internal mortar shrinks and expands with a change of moisture content, often the old softer bricks will blow at the face. All too many instances where I live in Essex. But good luck in mixing the old quicklime mortar!
England & Historic Scotland is now banning the use of NHL’s in the restoration of listed properties apparently The more interesting comparison would be slaked hot lime (no NHLs or cement at all) Horses for courses though. A soft cob building wouldn’t stand NHLs whereas a NHL2 could be used on a Victorian brick. Some interesting discussions on building with lime on Facebook but probably better join under an alias 🙈😂 @SkillBuilder