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 Sand, Cement and Hydrated Lime
• 3.1 Natural Hydraulic Lime (NHL)
• 5.1 Natural Hydraulic Lime (NHL)
• Dryzone Hi-Lime
• Rapid Set Plaster
• 6.1.1 with Skim
_________________________________
Breathability of Building Materials
Breathability in building materials refers to their ability to allow moisture vapour to pass through them without transmitting liquid water.
This characteristic is crucial in maintaining healthy indoor air quality and preserving the longevity of building structures by preventing moisture accumulation that can lead to mould growth and structural damage.
Why Breathability Matters
In buildings, moisture is generated daily from cooking, bathing, and breathing.
Breathable materials help manage this moisture by allowing it to pass through walls and evaporate away, thus preventing the buildup of dampness and reducing the risk of mould and mildew.
This natural regulation of indoor humidity levels contributes to a comfortable and healthy living environment.
Common Breathable Materials
1. Lime-based Mortar and Plaster: Unlike standard cement, lime is highly breathable and can accommodate fluctuations in humidity by absorbing and releasing moisture.
This makes lime-based products excellent for use in older buildings, where flexibility and breathability are essential to withstand natural settling and movement over time without cracking.
2. Natural Hydraulic Lime (NHL): NHL is preferred in restoration and conservation projects for its moderate set time and high breathability.
It works well in damp environments, providing durability without sacrificing the traditional aesthetic of historic buildings.
3. Clay Plaster: Clay is another highly breathable material with excellent moisture regulation.
It helps create a healthy indoor climate by buffering moisture levels and purifying the air, which makes it ideal for eco-friendly constructions.
4. Gypsum Plaster: While gypsum plaster is less breathable than lime or clay, it provides some moisture permeability, which is often sufficient for modern construction needs. It's also fast-setting, making it a popular choice for quick renovations.
Measuring Breathability
The breathability of building materials is often measured by their permeance, commonly referred to as the "perms" rating.
This measurement indicates how much moisture vapour can pass through a material. The higher the perms value, the more breathable the material.
Choosing the Right Material
Selecting the right breathable material depends on several factors, including the climate, the building's existing materials, and the space's specific needs.
For instance, more breathable materials might be necessary in areas with high humidity to manage indoor moisture effectively.
The Impact of Breathability on Building Longevity
Using breathable materials can significantly impact a building's longevity. Allowing walls to dry out naturally prevents structural damage caused by trapped moisture, such as rot and deterioration of building fabric. This not only ensures the structural integrity of the building but also maintains its aesthetic and functional value over time.
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#building #construction #experiments
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Thought you were heading for a good night out on the town. The thumbnail looked like a row of dodgy lagers setup.
One of the main reasons for using lime with both re-pointing and laying bricks is to ensure the mortar is never stronger than the bricks themselves. Rob Songer...who most certainly knows his stuff when it comes to brickwork has mentioned this a few times on his KZhead channel videos.
golden rule!
We have also mentioned it in many videos. Sadly when you see how much lime is sold by builders merchants you know that there are more people talking about it than actually doing it. They use plasticiser.
@@SkillBuilder I'm always asking the folks I see with lime if thats add mix, even if it looks like they want to punch my teeth out. But it's really up to the brand to read non-binder... but it still depends if the builder even reads it. I surveyed a job 140k roof job where the architect wrote 'lime mortar', and i saw chalk white powder in the pointing. Yup - just bagged hydrated lime. Keep up the excellent work!
@@SkillBuildera problem in the trade you could address with your influence? Some seem to know 4.1 and that’s it! 🙈
Roger you're a legend, you make, think, question and re-design and do the sort of stuff I'd love to but will never have time or skill either that you have. 10 out of 10 on this one, your latest and greatest new 'old' one ha ha. I owe a coupla drinks if you're ever in Dublin. When they talk about the benchmark, you're it pal
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
Actually clay (German: Lehm) is very common, even more in traditional houses of Africa. Often it is just called 'dirt' in USA. The incredible thing about clay and anything made with it, is the humidity regulation. Clay mortar covering the inside of a room with at least 2 cm thickness, covered in lime color, can roughly absorb 100 ml water per m² . It functions as a buffer and is a great material for bathrooms.
That'll be what we call hotlime or quicklime.
@@lksf9820 I saw the application of hotlime in a documentary about restoration of an old house with old techniques. Amazing stuff how it expands and fills the gap between wood frame and foundation. I found remains of it in our 400 y.o. house and hurt my skin, because I didn't recognize it at first.
Keep the experiments coming Roger, very interesting.
Thanks, will do! Just tell us what we should do next.
@@SkillBuildertaste test?
@@SkillBuilder Maybe do a rising damp test, build several small columns with mixtures of mortar (if you can please include a hot lime or putty based lime as well as NHL) plus various cement mixes. Keep the bottom of the columns in water and see if the water rises. Maybe even include a dirt only mortar (just soil).
@@SkillBuilder Roger a previous comment of mine (last month?) outlined a 'Rising Damp' test on a series of materials. There is a comment in this reply thread seeking a similar thing
@@SkillBuilder paint breathability ;) it is related to this test
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.
Perhaps Roger could repeat the same test with the cups upside-down or on their side which would test this aspect. Would not need to run for 12 months, maybe 12 weeks.
looks like the same volume at mix at the end as the beginning... just that each mix has absorbed into the mix and expanded... ? Which reveils only how week the mix is in constant absorption situation....! Were the discs allowed to fully set before this test was conducted...? Need to be re-done don't think this is that reflective of there porosity..
Really appreciate this Roger. Great content as always mate. Cheers
Great long term test Roger.
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. 👍
It would also be good to see an experiment of a wet wall drying with different mortars and renders in use.
I'd love to see this type of collaboration on the channel Roger if you're reading. Similar to the heat pump one with Adam, where you got the "other side's" point of view and turned it into one of your best series of videos.
The building industry is full of people claiming to be experts, KZhead is full of people teaching others the wrong information. From what I see Roger is an amateur holding forth on subjects he knows little about. classic Dunning-kruger effect.
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.
👍👍👍Great info. Thanks Roger
Nice one,Roger👌 A very useful demonstration of vapour permeability. I always add lime to render mixes.
Great stuff mate.
Posted this in a couple of renovation groups on Facebook. You are a cat amongst the pigeons! People hate being corrected on the sanctity of Lime Plaster
Excellent content, Rog . Thanks to you and your team for doing this experiment, also your 6-1-1 mix. Was there anything else added to the mix. Great stuff Rog , keep it coming 👍
no just a 6.1.1
Thank you, Rog
@@SkillBuilder Can you please add to the description the size of glass, size of petri dish and initial volume of water used in the experiments? Thanks!!!
In this ratio, what would be the most suitable sand to use? And would this be used as a mortar or a render?
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!
It continues to absorb carbon dioxide until it's turned to caulk, then crumbles.
Very interesting video, Roger, always informative😁
Simple though incontrovertible science. Thank you, SB.
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.
When did you ever see anyone using a hot lime putty? It is a health and safety nightmare.
@SkillBuilder anyone in conservation will use it nearly constantly.
@@SkillBuilder All the time in heritage building conservation and have used a putty mortar my self for plastering internally. Yes there are additional considerations but its a practice used very frequently in building conservation.
@@SkillBuilderI used it for my Victorian house ;).
Just did one last week. Got a pinhole in my gloves and burnt my fingers though.
Nice video there Professor Bisby
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.
Fascinating 👍
Awsome content lately Roger 👍
Thanks, we try to put out interesting stuff but it is a shot in the dark, you never know what works.
I used the Dryzone Hi-lime on a wet wall, and it dried down beautifully 👍
Brilliant, thank you
Another great video, thank you 😊
Really useful! Thanks.
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...
Good stuff Roger. Worth sharing your findings with the BRE (Building Research Establishment)
They have done these experiments but, like the British Standards they have to sell you the findings to pay their bills. I subcribed to the BRE for years.
Thank you, really useful because i am renovating an old house and i do this with an cement sand mix. People tell me constantly not to do that but now i have proof that its not bad!
It depends on the old bricks you are repointing, if they are soft, cement will cause problems, if they are hard and dense, probably not a problem.
Interesting video, using hydrated lime in the cement gave a good result. I’ve recently started repairing an old building using lime putty (which is quite expensive), good to know there could be a cheaper alternative.
These experiments are brilliant. It's so good to get these ideas tested.
It’s also entirely flawed as it’s totally misudnerstood breathability and has failed to address set strengths for pointing mortars
@@stevenedwards9569 I don't understand this video.. I read in the text below the video that this breathablity is to let vapor through and liquid not passing. BUT,.. Isn't it the problem that the vapor is passing the mortar from warm inside to the outside that it will condensate inside the wall.. I would prefer only air to go out. But I think that it would be impossible to only let air through and keep the damp out !
Roger , can you prepare a video on chimney’s that have a poor draw ? What is the analysis of common symptoms , the root causes and the solutions
Very commendable exercise which has created so great debate allowing a broad spectrum of debate. The " all lime good " all cement bad" trope needs taming and this video goes some way to champion curious thinking.
Each material has its strengths and weaknesses. The 'cement everything' was an error of the 70s. Here we have a huge comeback of a large variety of building materials, the biggest one is clay (Lehm) and hemp fibers. And what some companies make with wood scraps or straw is just amazing. Cement is good for foundations and wherever you need something very hard and strong. Lime is strong where you need a softer mortar and protection against invading water or fungi. Clay is the best choice for internal walls and mortar or protected outer walls. Out of the three, cement is also very heavy and the hardest to use. Clay is the easiest.
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.
Roger i love ur brilliance from US
Great demonstration of breathability, I would be interested in a depth scientific study, with greater depth: incorporating variables and repetition. Another demonstration I would be glad to see are the thermal properties in relation to condensation/dew point.
Fascinating video, Not a quick video to make. I would be really interested to compare vapour barriers, semi-permeable...
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.
Hi Roger, All very interesting. I have a 200+ year old house needing pointed and have been wondeing what waybto go. Could you test the comparative strengths of all these mortars? Also what mix did you use for the two nhl? Cheers.
Good experiment 👍
Great video. Would love to see you make one on PIR backed plasterboard. Just fitted it to a room and noticed a big difference already but seeing lots of 'breathability' controversy about using it
Don't take any notice of the doomsayers. PIR backed plasterboard will save you a fortune on your heating bills and make for a much more comfortable living space. The majority of this 'breathability' b/s is about as fact based as the 'climate change' con.
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.
i appreciate the scientific methodology - good job
I think going with the most breathable option as a render still has merit, it's likely the source of the moisture is a constant so the quicker it can be rid of the better.. a softer mix is needed to preserve the old bricks too.
I completely agree which is why I said the 6.1.1 is better than a 3.1 NHL
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?
Not debunked in my opinion following this - great vid, thank you 😊
Best video 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 :D
I repointed our 1860's stone house with the 6:1:1 mix 20 years ago and have had no problems with damp or anything else.
Nice experiment. It looks a small amount when it's in a glass but over the area the size of a wall that would be many liters per week. The mistake I see is OPC used to point stone walls and this looks awful and the cement cracks the stones.
Agree, cement pointing repairs look awful. I am just an amateur, but have built a few stone retaining walls in my large garden. 6.1.1 with hydrated lime looks good and is nice to work with. I like to mix smallish batches with a plasterer's mixer. No time pressure on using it before it goes off. Random natural stone is very time consuming if you want it to look good. Too many stone walls are thrown up as fast as possible by builders working to a price, and it shows.
Wish you'd done a hotmix gone cold too and a putty mix , which is all I use
Can we come and film you doing that? I hear a lot of people talk about it but they are rarely trades people.
I've got an old stone house from 1800s. About 40 years ago it was rendered with cement (unpainted). The render is cracking over lintels. I've removed 60cm from the wainscoat and replaced with NHL 3.5 3:1 mix. I've bought lime stone veneer I want to put as wainscoat. The question is so I remove the rest of the cement or patch the cracks? And do I use NHL 3.5 or lime putty as the render? Cheers
Water? More like a row of Heineken, Carlberg, and Stella Artois.
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.
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"
Did you use graded sand for the NHL mixes? Correct sands play an important part in how mortars behave.
We used bagged rendering sand which is washed to remove salt.
Certainly a well graded sand with a good range of grain sizes will give best results. Equally the finished pointing or rendering using NHL gauges will be tapped to level with a brush or floated to give a coarse open surface texture which will add evaporation. I noticed that the test biscuits were tap compacted and trowelled level giving a closed surface restricting evaporation.
Amazing idea. I would love to see how a lick of vinyl or hard wearing paint affects it. Also Pva/Sbr on a top of it would be great
Good idea
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?
Good suggestion
Id be interested to see a similar experiment with breathable membranes
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, Skill Builder Pixies & Elves great long term experiment!
Do the same experiment but coat with different water seal treatments. Stormdry, ronseal etc
To technical for me Roger 😮 but love the channel and the videos.
Would have been interesting to see hot mix (quicklime) mortar in the lineup. NHLs have now been rejected by many lime practitioners in favour of it as the degree to which it hardens over time is more predictable and the vapour permeability is said to be considerably greater.
Nhl isn't that breathable. Some of the nhl brands go off like cement dont listen to this guy never repoint/repair something that was built in lime with any kind of cement.
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
My understanding was that NHL was mostly to be used in foundations (for it's ability to set in wet conditions) and regular lime (hydrated lime a.k.a. slated quick lime) for above ground work for breathability and anti-mold properties.
I think what causes the most damage over time is wet brickwork being hit by a freeze.
The freeze and thaw cycle over the years would be interesting to explore and see what holds up best.
when i was taught how to render internal 9" brick work i was told 6.1.1 with multi over the top never had a problem i guess thats why. we used to use it for external render as well on wet medium dens block or old brick work wetted right down. 3 coats and wiggle lines as keys.
That is spot on
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.
Thank you Roger. Surprising result I must admit. I also believe the aggregate can have a significant effect. Fancy running a test on sands with different particle sizes for us?
Good suggestion
It be great to do a test on the ewi systems. They all say its a breathable system which i doubt is
Surely the house breathing is best from good ventilation management,
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?
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"?
Do the same experiment again to rule out the moaners. So, should I do a 5.1.1 scratch, then a 6.1.1 for top coat external render?
We will always have the moaners. Your render treatment is spot on. You can use the same mix on both coats because the top coat is thinner.
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.
you can buy a lime putty to repoint with. It will match what you have,
@@SkillBuilder Thanks, I really appreciate your help! I was told the outer 'show face' pointing is cementitious though, which I assume means it is not lime.
Does anyone know if adding something like a waterproof paste like stormdry to external bricks prevents the breath ability of the bricks many thanks
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
We have a very nice electronic microscope and we can upload pictures. I will give it a go.
@@SkillBuilder I underestimated you Prof! My apologies
Really interesting - although you risk having all the crazy heritage “experts”! They really love their lime and hemp 😂
I am expecting those guys to jump in with their quills, they will be hot lime and horse hair for sure.
But that's the whole problem with this test. It hasn't tested the materials that the heritage guys actually use. It's all good and well testing NHL against cement, but we already know that NHL is somewhat comparable to cement. I'm not sure why Roger didn't test hydrated lime putty, mixed with sand. That's what the heritage guys use. It's VERY different from NHL. It sets with exposure to CO2, not to water like NHL. I would never use NHL as any kind of render. I use it for screeds, and any application where I want greater strength and it doesn't matter in terms of breathability. For all masonry and repointing, and all plaster and render applications I'll use hydrated lime putty (in old buildings that need it that is, otherwise I'll just use cement and gypsum).
I thought you'd got a round of drinks in at the bar lol
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.
You should be querying more.
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.
If you still have the experiment running could you weigh the remaining water (without the biscuit of base material) to put some numbers to the differences.
Roger, could you recommend a good quality shower tray manufacturer, and where to buy it. Thanks 👍🏻
Kudos from plumber's merchant
@@SkillBuilderit's all very good praising him for his comment, but he asked for the name of a shower tray!
When you say "Rapid Set Plaster" are we talking about a Multifinish (red stuff) which is not very rapid (I mean depending on what are you comparing to) - or is it something of the likes Gyproc Easifill 20 ?
They now sell a fast set plaster
So the addition of polymers to the cement made it vapour impermeable??
what's the best thing for repointing external walls on old buildings? Is it still hydrated lime or was that a recommendation for interior walls?
An air dried lime with a coarse, sharp aggregate.
Interesting experiment on water vapour, but vapour is not the only thing as concrete can wick up water to 4 feet, does lime also wick up water to 4ft?
I`ve seen some Lime at BnQ. I might get some. Big bags tho. My house is 200 years old and has plaster popping off the walk everywhere with Slat Peter.
No. Don't do that. The lime sold at B&Q is what's called a builder's lime, and is added to cement to plasticise it. It's not suitable for any proper work on an old house, as it is too low in calcium. What you want is lime putty, in a mortar. My advice is to call and talk to a proper lime company like Mike Wye or Ty Mawr. They sell mortars made with sands local to your area that are likely to match your existing pointing.
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. So I'd suggest if you repeat it, start with a controlled clean solution of boiled distilled water with something biocidal in it, like a dilute copper sulphate solution, which would prevent almost all growth, yet colour the water without breaking down to make any reactive gases, you might get a fairer test. It might give the exact same levels you got above, and validate your original test conditions, for which you can tell me off for being a know-nothing-know-it-all, and I'd have to agree with you!
Would have love to see how tanking slurry performed
Interesting experiment. The results are about what I would expect. NHL3.5 or NHL5 have very free lime. You would not use NHLs to make a building breathable, they are more like cement. You should use hot mixed lime with sand in a 2:1 or 3:1 ratio for real breathability.
If the risk with 6.1.1 is making it too strong with sand/cement then why not just use the 3.1 NHL or 5.1 NHL that had similar results, but without the sand/cement risk? Or are there other risks with NHL mix?
variation due to sealing at the edge will be greater than the cement layers methinks
Only comment i would make is that you should of added a “control” with a sealed lid
That's crucial!
Control ?
@@plummetplum You have to establish the number zero some way. Need something to compare these things to - it's always crucial.
Great test and video. 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
Did you try slaked lime and sand (not 6:1:1)
Do this test with wall insulation materials.
What let down. Immediately clicked to listen to as thought you were reviewing beers.
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).
This has dispelled nothing as it is flawed. Probably around 12yrs ago, Plymouth Uni did exactly this, set up a brick wall laid with lime putty mortar mix at 3/1 in a bath of water. They phoned to ask why the water wouldn't rise, I pointed out that it wasn't sealed in cement and plastic paint so is able to evaporate.
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 watching this channel.
There are no limestone cottages in Holmfirth - they're made of millstone grit (siliceous sandstone.) As for the 'spalling off' effect you mention ...The 'strapped' pointing you see in this area was is shaped with a pointing iron and is intended to stand proud of the stone at the outset. It doesn't cause damage to the stone - the damage would have been caused by weathering before it was pointed.
@@johnriggs4929 Whether is Yorkshire sandstone or siltstone or limestone all three contain forms of calcium carbonate as a binding matrix. Over time, strap pointing with cement damages them - period. Google this whole line for examples of what I am talking about: heritage-house, stuff-about-old-buildings, raking-and-re-pointing, examples-of-strap-pointing Could it be that you spent 20 years repeating other peoples mistakes?
@@Nuts-Bolts I've been in the building trade for 50 years, and no matter what you"ve found on Google - I can tell you you're talking out of your backside. But you just stick to your pet theories...