Revealed: Building Material Breathability Experiment (surprising result)

Рет қаралды 48,522

Ай бұрын

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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Пікірлер: 342

@cypeman8037 Ай бұрын

Thought you were heading for a good night out on the town. The thumbnail looked like a row of dodgy lagers setup.

@RobNorman08 Ай бұрын

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 KZfaq channel videos.

@JT-si6bl Ай бұрын

golden rule!

@SkillBuilder Ай бұрын

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.

@JT-si6bl Ай бұрын

@@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!

@kieranmccreedy271 Ай бұрын

@@SkillBuildera problem in the trade you could address with your influence? Some seem to know 4.1 and that’s it! 🙈

@GraimearGaeilge Ай бұрын

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

@Begnis Ай бұрын

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

@alis49281 Ай бұрын

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.

@lksf9820 Ай бұрын

That'll be what we call hotlime or quicklime.

@alis49281 Ай бұрын

@@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.

@Birchall88 Ай бұрын

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.

@manicminer4573 Ай бұрын

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.

@David-td1tf Ай бұрын

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..

@ironimp1 21 күн бұрын

Spot on!

@yp77738yp77739 Ай бұрын

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.

@whitefields5595 Ай бұрын

Keep the experiments coming Roger, very interesting.

@SkillBuilder Ай бұрын

Thanks, will do! Just tell us what we should do next.

@ricos1497 Ай бұрын

@@SkillBuildertaste test?

@danielabrahams4061 Ай бұрын

@@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).

@whitefields5595 Ай бұрын

@@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

@0skar9193 Ай бұрын

@@SkillBuilder paint breathability ;) it is related to this test

@SteveHogarth-gn9wt Ай бұрын

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. 👍

@Birchall88 Ай бұрын

It would also be good to see an experiment of a wet wall drying with different mortars and renders in use.

@ricos1497 Ай бұрын

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.

@tikunani Ай бұрын

The building industry is full of people claiming to be experts, KZfaq 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.

@MJBott Ай бұрын

Really appreciate this Roger. Great content as always mate. Cheers

@Pete.Ty1 Ай бұрын

👍👍👍Great info. Thanks Roger

@RR-mt2wp Ай бұрын

Great long term test Roger.

@FiscalWoofer Ай бұрын

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!

@WindyJAMiller Ай бұрын

It continues to absorb carbon dioxide until it's turned to caulk, then crumbles.

@alec1113 Ай бұрын

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 👍

@SkillBuilder Ай бұрын

no just a 6.1.1

@alec1113 Ай бұрын

Thank you, Rog

@danielabrahams4061 Ай бұрын

@@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!!!

@Dagnostic Ай бұрын

In this ratio, what would be the most suitable sand to use? And would this be used as a mortar or a render?

@howardosborne8647 Ай бұрын

Nice one,Roger👌 A very useful demonstration of vapour permeability. I always add lime to render mixes.

@mdug7224 Ай бұрын

Really useful! Thanks.

@tobywebb6452 Ай бұрын

Brilliant, thank you

@patrickcolclough2423 Ай бұрын

Great stuff mate.

@willyoung8257 Ай бұрын

Nice video there Professor Bisby

@wimcruycke895 Ай бұрын

Fascinating 👍

@mattjohnson2848 Ай бұрын

Another great video, thank you 😊

@paullongley1221 Ай бұрын

Very interesting video, Roger, always informative😁

@TimCCambridge 22 күн бұрын

~ Hi. I did up a historic timber frame building with a small team for a year and a half. The nature of the house " breathing " relates to the way it sat on the ground. The cellar was always very damp and the whole base of the house needed to absorb and release efficiently. All traditional materials were used and an acceptance of good venting and a dehumidifier in the cellar was passed on to the owner. French drains were also recommended. We even got an article in a classic homes magazine with the comment "Restoration done properly ". Plus an awkward photo of me disregarding health and safety with my inventive use of a ladder ( terrible angle etc ).

@JohnStowers Ай бұрын

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

@madintheheid 27 күн бұрын

Simple though incontrovertible science. Thank you, SB.

@JD-mx2gv Ай бұрын

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.

@gingerelvis Ай бұрын

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...

@GCtrees Ай бұрын

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.

@SkillBuilder Ай бұрын

When did you ever see anyone using a hot lime putty? It is a health and safety nightmare.

@PaigeContracting Ай бұрын

@SkillBuilder anyone in conservation will use it nearly constantly.

@GCtrees Ай бұрын

@@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.

@lukenfoci Ай бұрын

@@SkillBuilderI used it for my Victorian house ;).

@jackmartin7098 Ай бұрын

Just did one last week. Got a pinhole in my gloves and burnt my fingers though.

@Tom-Lahaye Ай бұрын

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.

@wokelefty Ай бұрын

Awsome content lately Roger 👍

@SkillBuilder Ай бұрын

Thanks, we try to put out interesting stuff but it is a shot in the dark, you never know what works.

@davidcarter4454 16 күн бұрын

Use of lime in older properties without firm foundations is essential in order to accommodate gradual movement of the structure. If you use cementitious products then these will crack and fail. Lime has the ability to move as the structure moves. The fact that it is breathable is a bonus.

@SkillBuilder 16 күн бұрын

Yes you are right but often the NHL sets as hard as cement so you have to be clued up on which lime and get the mix right

@davidcarter4454 14 күн бұрын

@@SkillBuilder NHL 5.0 can take 5N / mm, concrete can take around 50 N/mm so is 10 times harder than lime. For stone/brick mortar you would want 3.5NHL lime (3.5 N/mm) to allow for movement, but even if someone did use NHL5 it would be much better than much harder concrete.

@funky_junkie Ай бұрын

I think what causes the most damage over time is wet brickwork being hit by a freeze.

@epikentertainment6214 29 күн бұрын

The freeze and thaw cycle over the years would be interesting to explore and see what holds up best.

@andyarchitect Ай бұрын

Good experiment 👍

@tikaanipippin Ай бұрын

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!

@sergiofernandez3725 Ай бұрын

Good stuff Roger. Worth sharing your findings with the BRE (Building Research Establishment)

@SkillBuilder Ай бұрын

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.

@smoath Ай бұрын

These experiments are brilliant. It's so good to get these ideas tested.

@stevenedwards9569 Ай бұрын

It’s also entirely flawed as it’s totally misudnerstood breathability and has failed to address set strengths for pointing mortars

@eurovisie2010 Ай бұрын

@@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 !

@eamonhannon1103 Ай бұрын

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

@Guvnor100 Ай бұрын

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.

@leepiper4621 Ай бұрын

Roger i love ur brilliance from US

@completepreservation Ай бұрын

I used the Dryzone Hi-lime on a wet wall, and it dried down beautifully 👍

@donaldmcintosh6940 Ай бұрын

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.

@jimhud134 Ай бұрын

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.

@justice4g Ай бұрын

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.

@SkillBuilder Ай бұрын

I completely agree which is why I said the 6.1.1 is better than a 3.1 NHL

@alis49281 Ай бұрын

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.

@oldboyuk Ай бұрын

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

@johnriggs4929 Ай бұрын

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.

@brianpilkington8925 Ай бұрын

Wish you'd done a hotmix gone cold too and a putty mix , which is all I use

@SkillBuilder Ай бұрын

Can we come and film you doing that? I hear a lot of people talk about it but they are rarely trades people.

@jessegoldswain5973 Ай бұрын

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

@laurenceturner9346 Ай бұрын

Fascinating video, Not a quick video to make. I would be really interested to compare vapour barriers, semi-permeable...

@alexanderhill4993 25 күн бұрын

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

@jamesowen1213 Ай бұрын

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.

@kevinwooldridge2127 Ай бұрын

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.

@geoffhunt6646 Ай бұрын

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.

@alis49281 Ай бұрын

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.

@skilloutsnf4814 Ай бұрын

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?

@jonathan.h 23 күн бұрын

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.

@DavidJohnson-yg8qm 16 күн бұрын

Suggestions. The best paint for outside of buildings. Lime wash or exterior quality paint

@user-xf2qt5il7n Ай бұрын

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.

@simoncelt5590 Ай бұрын

i appreciate the scientific methodology - good job

@emss66 Ай бұрын

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.

@TeddyBeers Ай бұрын

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

@SkillBuilder Ай бұрын

Good idea

@binmanblog Ай бұрын

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.

@ericrawson2909 26 күн бұрын

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.

@benchippy8039 Ай бұрын

Id be interested to see a similar experiment with breathable membranes

@ollie9709 18 күн бұрын

Great video Roger. Interesting to see 611 hydrated lime mix. Is there another alternative to skim interior than gypsum you would use for a smooth finish if you had a damp wall? What about paint?

@SkillBuilder 18 күн бұрын

You can use DryZone lime plaster, it will withstand moisture for years.

@ollie9709 18 күн бұрын

@@SkillBuilder thanks so much Roger, you’re a gent and a scholar

@jayseabie215 Ай бұрын

Water? More like a row of Heineken, Carlberg, and Stella Artois.

@danielabrahams4061 Ай бұрын

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.

@camheady235 Күн бұрын

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

@FSX3000 Ай бұрын

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"

@fjpavm Ай бұрын

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.

@freekhuisman1520 Ай бұрын

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!

@baldfeller 28 күн бұрын

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.

@ironimp1 21 күн бұрын

If it goes wrong will you blame yourself or Roger Bisby?

@SkillBuilder 20 күн бұрын

freejhusiman If you have soft rubber bricks I would buy a lime mortar that has been mixed. It is sold in tubs. If you have stocks or bricks which aren;t prone to spalling then the 6.1.1 mix is a good bet.

@lukemoxham2869 Ай бұрын

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.

@drmoonie Ай бұрын

Not debunked in my opinion following this - great vid, thank you 😊

@andyjackson3663 Ай бұрын

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"?

@0skar9193 Ай бұрын

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?

@SkillBuilder Ай бұрын

Good suggestion

@aafrics Ай бұрын

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?

@SkillBuilder Ай бұрын

Good suggestion

@philipsykes4413 Ай бұрын

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.

@aweexplore1328 Ай бұрын

Do the same experiment but coat with different water seal treatments. Stormdry, ronseal etc

@2BeefHair Ай бұрын

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.

@cyderryder Ай бұрын

Did you use graded sand for the NHL mixes? Correct sands play an important part in how mortars behave.

@SkillBuilder Ай бұрын

We used bagged rendering sand which is washed to remove salt.

@timstradling7764 Ай бұрын

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.

@user-ut5zo1cu8i Ай бұрын

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

@Hamishmcbeth Ай бұрын

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?

@brianmorrison3937 Ай бұрын

Does anyone know if adding something like a waterproof paste like stormdry to external bricks prevents the breath ability of the bricks many thanks

@HarryBates-xb6py Ай бұрын

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?

@boriss.861 Ай бұрын

Roger, Skill Builder Pixies & Elves great long term experiment!

@kadmow Ай бұрын

So the addition of polymers to the cement made it vapour impermeable??

@BacktoEarthLTD Ай бұрын

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.

@Paul-XS650 Ай бұрын

You should be querying more.

@stephenmurray2335 Ай бұрын

Very interesting as usual Roger, many thanks for posting this. I am planning to render my (brick) house this year. Would I be right to use 6:1:1 for both the scratch coat and skim coat? And what paint would you recommend - something breathable like say Sandtex?

@jinxit Ай бұрын

maybe it would be worth to weigh the cakes before and after, to see how much water had been trapped inside?

@SkillBuilder Ай бұрын

Good idea

@AlexGnok Ай бұрын

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 ?

@SkillBuilder Ай бұрын

They now sell a fast set plaster

@eliotmansfield Ай бұрын

Only comment i would make is that you should of added a “control” with a sealed lid

@elbuggo Ай бұрын

That's crucial!

@plummetplum Ай бұрын

Control ?

@elbuggo Ай бұрын

@@plummetplum You have to establish the number zero some way. Need something to compare these things to - it's always crucial.

@gdfggggg Ай бұрын

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?

@SkillBuilder Ай бұрын

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.

@tonysheerness2427 Ай бұрын

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?

@Fellinline Ай бұрын

What about non-hydrated lime (lime putty) and sand? That's the gold standard for breathable mortar?

@Mao.Loves.Zedong Ай бұрын

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.

@justbreakingballs 21 күн бұрын

You've just been proved wrong

@SteveAndAlexBuild Ай бұрын

I’ve just repointed a 60s bungalow gable end with 6 1 1 sand cement lime for the first time in 37 years 😬🧱👍🏽

@SkillBuilder Ай бұрын

Ho did it go? Have you got a video on your excellent channel?

@mawin5899 Ай бұрын

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?

@1978xs650D Ай бұрын

An air dried lime with a coarse, sharp aggregate.

@eddjordan2399 Ай бұрын

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.

@SkillBuilder Ай бұрын

That is spot on

@bilvis1985 Ай бұрын

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

@SkillBuilder Ай бұрын

We have a very nice electronic microscope and we can upload pictures. I will give it a go.

@bilvis1985 Ай бұрын

@@SkillBuilder I underestimated you Prof! My apologies

@tomclarkecc Ай бұрын

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.

@SkillBuilder Ай бұрын

you can buy a lime putty to repoint with. It will match what you have,

@tomclarkecc Ай бұрын

@@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.

@caterthun4853 Ай бұрын

What let down. Immediately clicked to listen to as thought you were reviewing beers.

@soupinabasket1 Ай бұрын

Cement is 60-70 % lime , will this effect the results ?

@markjewell911 22 күн бұрын

Feeling good about my 611 re pointing now 👍

@scotty6648 Ай бұрын

To technical for me Roger 😮 but love the channel and the videos.

@SuperHaptics Ай бұрын

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