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There used to be plumbing rules in years past for a reason Why things work the way they shuold. Nobody gives a fk anymore . and don't know why When was the last time any of us saw a water officer?.Eberyone is a black belt in all trades these days but no one knows basics! Leading to bad times for the future

Ok so why do all these old buildings, that have wood built into the walls using lime last hundreds of years, then get some sand and cement put in and rot away within 40 years. Building design has had to change to allow for the amount of moisture that sand & cement retain.

Polymers and plastics are permeable and their properties may impact their suitability for a specific purpose. Roger, I suggest you do the experiment again using glass beakers!!

I love how poor they are...A radiator is a heat emitter...NO radiant heating.... Ask them what radiant heating is...... I have never heard such nonsence.... They really don't have a clue.....What I love is listening to how they intend to change the laws of physics....They sound convincing... But it's just lies....I am sorry but no wonder every can't trust HVAC engineers. Fit a micro CHP and you will get combined heat and power.... He has not mentioned how you get DHW that needs to be at 60 degree's C to avoid legionnaires disease

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 HVAC Engineer and someone who has worked in the industry for 27 years.... Don't bother with heat pumps. As now a controls engineer in the commercial sector.... We have heat pumps with heat meters on the secondary side and an electrical meter on the primary side... We are getting massive negative coefficients... Don't bother with air to water heat pumps...If you want a heat pump...use recycle air conditioning units... What a load of rubbish they are talking a 7kw car charger will use more than a 12kw heat pump... Really... How is 7 greater than 12..... 12 kw will use 4 x 12 =48amps... What planet are these boys on... Don't waste your money or time... Fit a boiler and bin the heat pump

Clay plaster/mortar is best! The oldest building material known to man.

Awsome content lately Roger 👍

Roger, I love you but I don't want to be this close to your face.

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.

The issue is, like most renewables, they don’t work when really needed on the existing housing stock. People don’t have £20k to spend - on top of insulation, glazing, solar etc, doubly so with the number of chancers setting themselves up as grant installers on social media.

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.

please repeat the test

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!

Unfortunately the eu wants to ban people from repairing their "old bangers"

Amazing idea. I would love to see how a kick of vinyl or hard wearing paint affects it. Also Pva/Sbr on a top of it would be great

Another great video, thank you 😊

Hi Roger, quick question, how long before you can rub up the base coat with a float, great video as always, thanks

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

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?

An ounce of evidence trumps a ton of eminence.

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.

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).

You ever use an R W Rose ? The R W Rose and the Marshaltown, the beat

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.

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.

Heat pumps are great to pair with a whole house solar system.

Am I right in saying this is only for heating the house. How do you heat your domestic hot water for washing, baths, showers etc ? One of the reasons a combi boiler is so popular is its relatively small and compact, can be sited almost anywhere, and heats domestic hot water or heating water as and when required.

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

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?

Very interesting video, Roger, always informative😁

Buddy. 6.1.1 is only one coat. To weak. Sand and cement is at least a two coat job. Be carful u don’t send people down the wrong road.

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

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.

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

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

This experiment is completely wrong, for old buildings you should use non-hydraulic lime without any cement, it is also not necessary for water vapour but liquid as well. In short this guy has no idea what he is talking about, please take your advice from RICS and SPAB not him.

Skill, in what country do you live?

Not a perfect test by any means. Repeat the test with two samples, one with storm dry and another without, checking the chamber to see if there is any difference. All experiments need a control, and the intreated brick provides that. Then end you take a cross section of both samples so you can see how far the moisture penetrates each one. Is obviously going into the treated brick because there are bubbles, so some moisture is forcing the air out, but how much? To make it even more scientific, before you cut a cross section, check the underside of each sample at the end with a moisture meter.

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.

Hi Roger. I been watching your videos few years now, you are my go to channel every job I do. . I have removed my bath and going to install a shower tray. Question for you , on one of your videos you say never stick tray down with tile adhesive as it might crack the tray with movement. Then on this video you are using tile adhesive for wood. Please give me your thought. Regards Brian

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.

Lime self heals concrete Id always found that fascinating Since the Roman empire used It so much in their construction That still stand today and into the future

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.

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.

Wonder what effect paint has on the results.

brilliant video... great information .. thanks to you all

When I was a lad I worked with my Father as a central heating engineer. That meant learning plumbing, electronics, joinery, plastering, brickwork, tiling flooring, painting and decorating if the customer wanted us from start to finish which they usually did.

variation due to sealing at the edge will be greater than the cement layers methinks

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?