Totally agree Roger. I've been involved in some new builds over the past 5 years where it's shameful the condition the render is in now. Even where external fan grills have been mounted on the render, you get the water marks either side of the grill. Today's architects love render, even if it's just a panel to break up the massing of brickwork. Same applies, water marks at the cills, boiler flues, basically anywhere that rainwater is allowed to be directed back against the render. I'd rather just see a traditional brick built property with some feature brick details or stone cills / lintels anyday.

The problem with Monocouche and it's brothers is the fact that it's really porous. My son does a lot of Monocouche, (because his customers prefer the look), but over 30 years ago now I was using 'Blue-Circle Hi-build' ... (The Pre-coloured exterior coatings) that were used to enhance the basic sand and cement render and required no maintenance. I recently went on a Nostalgia-Trip in my car (now that I'm long retired) and was very pleased to see that those with the Hi-Build still looked as good as the day they were finished (Well - Nearly ;-) A good hose-down every ten years is all they needed ... And NO - I'm not associated in any way with the Hi-Build products. Not even sure if you can still get it - it was dang expensive stuff, even back then :-)

Not a big fan of either .... looks fantastic when it first goes on then can only deteriorate from there . I may be biased but you can’t beat a beautiful, well built face brick wall 🧱🧱🧱🧱👍🏼

Well said Roger. Most of the new builds here in Bristol, UK are such bland, cheap designs and they invariably suffer from this. "Sinking the ship for a halfpenny of tar" is a phrase that comes to mind when looking at most modern buildings. Old buildings still look beautiful for a reason.

Great channel👍... We don't have that problem in the USA. On the east coast we mostly use red cedar shingles or clapboard. Lasts 30 yrs... Mostly Koma exterior trim ( a plastic , non shrinking type, never rots) ..

We stopped using theses systems years ago because of the problem you are describing, plus if the render cracks ( and it does ) its impossible to do an invisible repair on it. The open texture allows water and dirt to enter and even with cleaning some stains will remain. Plastic beads allow water to enter the render, and lets be honest they look crap. In the UK you cant beat the tried and tested systems. I agree with you that theses are not maintenance free as advertised in fact a whole industry has now come about just cleaning theses render systems. I have been involved in exterior wall finishes for some 50 years now theses are just a remake of the old Blue Circle Tyrolean / Alpine mix.

Monocouche, Monocouche, will you do the Fandango? (Sorry, couldn’t resist 😎) Roger ranting rounds off a perfect week!

Looks bloody brilliant when new. I’ve seen this staining all over and in different colours. Seems like a better background for organic mould build up too.

around here that stain also comes from vehicle smog filling the pores and then the occasional rain washing them down busy streets are the worst busy streets with many old diesel pos going thru even worse. thanks roger i picked up a thing or two today. in my experience if it has a texture sooner or later is going to cause problems. the owner of the house with the round window has another problem too... take care man. thanks again. pete

It's mantanence free in the colour black 😂😂😂😂 that's if there are no birds about 🤣🤣🤣🤣

Spot on Roger, basically poor detailing at the transitions will result in staining and this is the case whether it’s monocouche or a cement based render. Same outcome on boundary walls, the copes should have drips as in concrete or timber sills. Attention to detailing by an architect at design stage and quality, tight workmanship will prevent or mitigate against the problem.

Here in Latvia, new buildings are looking pretty shoddy after only a few years. I agree that it's down to the architects. Thanks for a great vid. 👍🏻

Good rant Roger! we had this problem with alpine render about 25yrs ago, that went out of fashion as will monocouche renders, this is now the dilemma we have with all these products in todays market ; they are not suitable for all locations but they are happy to sell you them, in the past they did not have a multitude of products to use so they became very proficient at what they did have. we all say they don't build them like they used to but I can assure you I have pulled out plenty of rotten windows, roofs & walls in old properties.

You can buy the sealer for monocouche but most renderers don’t offer it because its to expensive but all said and done you can’t beat sand/cement and cheaper

Great video Roger. We are just starting a major renovation and have to decide between a render or clad external finish. As we have a long north facing wall, there seems to be more of a risk for algae etc to stain a rendered finish. Neither our architect or any of the builders we hope to use have mentioned maintenance issues. Maybe we are now leaning towards composite cladding or even brick slips.

Hi Roger, good work!, having spent far too many years sorting out maintenance and repair issues on buildings of all shapes and sizes I have been observing the evidence of errors in design and construction leading to long term problems, the mantra I now preach to my clients is that there is no such thing as maintenance free!, anyone who offers such performance is mistaken or mendacious!. I have just watched two or three of your videos and am well impressed!. The dark staining that you are showing is most likely to be some carbon based material, maybe dead algae, which was pale green when alive and wet but once dried and dead remains as a sooty residue. You are of course correct in saying that the real problem is due to the water running over the surface, an issue aggravated by non-porous but textured surface applications. Porous surfaces like traditional clay brickwork absorb and distribute substantial amounts of water which will then evaporate slowly, and so do not support the same colonies of algae on the surface, we used to say that if you fill a bucket full of water with bricks after about an hour the bricks will have drunk all the water!. (of course quite a lot of the water will have overflowed as you put the bricks in!). The old methods of creating sailing courses and drips was of course very effective in reducing the surface water issues but because the industry that evolved those practices was not respected by the commercial interests and the craftsmen did not often know why things were done that way, no science was applied. One of the problems that re-occurs with some frequency nowadays is the appearance of damp patches on walls and ceilings caused by condensation, when most people see a wet patch they quite naturally suspect that there is a leak somewhere, because the water vapour that is the source of the wet is invisible, hanging in the air, the average modern house with central heating may have several gallons of water just hanging there until it can find a cold spot. This leads to the house-holder discovering a wet patch on the outside of the wall opposite the condensation patch on the inside, I now watch the clients' face very carefully as I describe how the evaporation of water from the outside lower the temperature of the masonry and heat comes through from inside, causing the cold spot for the condensation, the trick is to take it steady, step by step, and if I see the victims eyes start to glaze over, back off, clarify the missing bit, don't just carry on. These experiences have become familiar to me now, but in the early years I really did struggle because it has always been important to me to be able to put together a rational and logical account of what I observe and do, not just go and do as I was told just because the person telling me thought he was my boss. As you can imagine I was often not very popular with some of my employers, in fact I had to give them up and become self employed! Cheers Richard.

Overhang details are good to use but the joints in the stones need to be correctly jointed. If mortar bridges the drip on the underside where the stones butt up to each other then water , instead of dripping, will track back onto the render and leave streaks down the face of the property. And if the stones are say, 600mm wide, then you will have black streaks every 600 around the property. The mortar needs to be removed from the drip!

Totally agree my chimney spoils the whole look of the house and is too high for us to get the jet washer to it, previously was pebble dashed which had been painted, when we had the house renovated we were sold on the fact we wouldn't have to paint it it was done less than 4 years ago we live on a main road so pollution is obviously not helping.

Architects are building nemesis. Biggest cause of building failures.

Render like this needs to be sealed when its clean. Parex do Paraguard, Weber and K-Rend also do their own equivalents but they're are expensive compared to other sealers. They are also water based and sit on the top of the render to give the lotus effect. They remain breathable. Usually its two coats of the stuff. My garden wall is about 27m long so I'm looking at about 50sqm. The Paraguard stuff is over £220 for 25 litres which will cover that with two coats. I suppose you could use Thomsons water seal which is cheaper or go for solvent based nonsense stuff from screwfix which soaks in.

Nature is all powerful and it will eventually find a way to destroy anything we build given time. The idea that this type of surface finish will remain pristine for decades is just hype.

when I was on holiday in Cornwall I went through Nansleden which is a new model town that Prince Charles has been involved in, some of the houses are done out in nice pastel colours like pinks and blues (would probably look daft in Leeds but seems to work at the seaside!). I thought they had just painted them but I wonder if they have this stuff on, I didn't even know it existed.

Sand and cement for me👍

We K Rended just the lower part of the house that has overhangs that clear it, it's crazy to think it is maintenance-free, we give ours a quick dry brush over and it's as good as new if it had water runs it would stain like mad

This is without even getting onto the problem of the blockwork substrate settling and cracking and these cracks appearing in the face of the render. If this happens you can't even patch repair it as it will stick out like a sore thumb. Even if you paint it after. There's a reason why Monocouche is substantially cheaper than facing brickwork. Silicone render systems promise the world on a stick, but without careful detailed design fall victim to staining also. Plus they look like rice pudding /wood chip in anything over a 1.5mm grain size. Anything less and it shows up the basecoat shortcomings. "monocouche" translates as "one application". Nothing could be further from the truth really.

Great video apart from saying to use a jet washer to clean the building.

Sand cement has stood the test of time and will continue to

Most copings made today do not have drips on them,sand and cement render doesn’t breath which can cause a load of other problems if the building is not ventilated properly ,monocouche renders are far better looking and you can apply sealers but as some one else comments mentioned they are costly to buy,I always explain to customers to where they may have a problem if there is no drip for the water to run of and best ways to maintain them,also just to mention sand and cement painted renders suffer from the same problem of staining.

Always lime render, sand & cement is too hard and causes breathability issues in older properties. Lime render can be used over new blockwork, improves its patina with age and can self heal to a degree. Two pennyworth from an old duffer. !!! Have a great weekend. Regards Tim

Remove any loose and flakey. Soft wash with fungicidal. Rinse with hose. Paint with sandtex two coats.

Time for the Zinsser Allcoat 👌

This might have saved me thousands. Thanks for the heads up. I noticed K render seems to be a fashionable product and that got me concerned. Problem is new products do not get tested in real world environments over years of exposure. There are also other clips of people trying to clean these stains off and it looks a nightmare.

I want to take my old brown tiles off. Was going to render the whole house then,but just don’t know what to do now. It’s so 70s but want a modern look

I was thinking about using this stuff but I think I'll stick with the tried and tested sand / cement that I've used without any problems for the best part of 50 years. Plus it sounds a bit French so thats definitely done it for me !!!!!

K rendering as all still need’s drip edging,but totally agree it’s not a system you can put up and forget,every detail needs thinking about,stone course with a large over , and bang on rendering is so much better than.

I would hire roger for all my building work. He does a proper job.

Manufacturers like Parex, Krend, Weber recommend that you use pigment paint and sealant after rendering. E.g. Parex's DPR and Paraguard products. Which should prevent permanent staining.

We find hitting them with fungal wash then a pressure wash and apply a silicone paint. Also some of the issues in this video as well are from being applied to thin.

100% agree, my house is full of run offs and flat surfaces that attracts water and bird shit run off. My 5yr painted render is now looking a bit shabbym

Totally agree with you have being saying this for years, what did the builders of old know then that we don’t know now

Lot of apartments around marina here in portishead have this same product - so stained they now look really shabby.

I design buildings - I ALWAYS warn customers re this, especially on north facing walls. ANY protrusions - pipes, etc will do it, as will coping mortar joints which admit and release water. Not sure if its acid rain or just mould? Be v careful with a powerful jetwash on monocouche or you could damage it badly... You can repaint with a matching silicon/acrylic paint depending on which your monocouche is. Looks great, but bricks weather much better.

I clean this stuff for a living. Don't tell people to hit it with a jetwash. They will destroy the substrate and find it all over the floor.

The council did it on a row of houses in my village and it had algae growing on it within a year

Plasterer in the states and work with all these acrylic finishes and they all do this ,can't beat sand and cement 10 15 mm,paint looks great

Excellent video, Roger. Good information.

There basically doing everything right until the finish and haven’t KPRO’D the finished job , I use K,PRO about 3 weeks after I finish the rend (dependent on weather conditions) it’s another £80 a tub which has to go on the price of he job but we’ll worth it and it means the jobs finished properly,I wouldn’t dream of saying the JOBS FINISHED without K,PRO at the end

Very interesting. I learnt something today - thanks!!

Silicone render is the best solution. It could be applied over the top of other systems or ocr on block work primer then silicone render it's dead easy to use too!

Seen blocks of flats that look bloody awful with this problem, really horrible, looks like black mould.

0:48 You nearly sound like you know what your talking about Roger. The water run off areas are simply damp and a perfect environment for the Gloeocapsa magma algae to grow.

sand and cement defo

Umm very interesting one for me this one S.B. eventually i need to put some sort of external coating on my own home. It has made me decide if i go for a monocouche finish, i would prefer to use m9re of a smooth finish as opposed to textured (hopefully it will be better wearing). I don't fancy having to paint it though! Like you said what's the point in going to the expense of using it, if it needs to be painted the same as normal render. Great video as always 😘

Thanks for this video , I have to get my new garage / workshop rendered , was recommended K render but after this I think I might save my money and opt for a traditional render then Sandtex paintb , and repaint every 5 years with an airless sprayer I will buy with money I save .

Excellent info, Rog

I don’t think nicely pointed brickwork can be beaten.

Well said.. And a good Educational Rant worth listening to. Can you do a Rant on the WHITE STUFF that runs out of the brickwork on the new buildings? That's a total eyesore aswell Roger.

Ok that's it not using this render on my house, back to traditional sand and cement for me, Thanks Roger

You can paint over monocouche, in spain its on everything, its called monocapa. You just need to use a mix of PVA and water to seal the render and then you can paint,

Hi I was told this can’t happen if it’s treated with a paint on or spray on protector (I believe the protectors are water based). DONT believe them though.

What’s the best way of cleaning this product? Also, could we add a protector at the same time, to save doing it again?

Thanks

A plainface sand lime cement render with a good fined down finish painted with a good quality maisanry paint is far superior to these open textured renders I am a 76 year old retired plasterer speaking from my own experience I do take your point about the various corblings and overhangs and this needs some thought

Hi Roger, from what I see of your videos you are the perfect person to give an unbiased opinion. I am looking at having a spray-on exterior render applied to my house which was rebuilt about 20 years ago and the old traditional rendering which has been re-painted a couple of times has a few stress crack and marks whichI would like to cover/disguise. I have been looking at Corksol and Monocouch spray on type as being most likely to be appropriate. I think there is also one called Thermocork. I am based in Herfordshire and wonder what your thoughts would be?

Personally I think it's small bits of coal like parts that end up staining it alot of the times you dont seem to get this issue with k-rend ft scratch back I go past a house we done about 8 years ago it still looks clean I've seen some people have started businesses out of doing soft cleaning of this type of staining

Built house in busy part of town it got mono`d . 6 months and it look disgusting and needs jet wash 2x a year at least. Worked on house a few miles down coast, that`s on a windy cliff over looking sea. House has a big overhang roof, its hasnt needed jetting in 12 years. Both same colour. And it cracks.

Can I just say on the bag it actually says low maintenance not no maintenance... and with the right protection this can easily be washed away . I'm a expert ask me anything

Fellow ranter about This crap it is not compatible with the towns & cities we live in, it looks dirty within one winter. hopefully councils will start issuing some sort of cleaning orders on the building owners which in turn will make them reluctant to use the stuff.

So now you have upset all the architects and designers, I hope you have a quiet weekend. You are 100% right though, most of the pics you showed have capping and sills with with too little oversail and it doesn't look as though most of them had a capillary break underneath. I also notice a lot of the monocouche at the bottoms were finished off with the plastic corner profiles instead of a bell drip. I started in the '60s when all of that stuff was automatically part of building, it seems as though the hard won commonsense in construction has been discarded. We used to mfind one of the best 'self cleaning' finishes with a long life was the old Cementone oil based semi gloss, 7 tom 8 years between repaints if it was done well in the first place . Good rant, I look forward to the next one.

Thanks very much Roger for a very informative video. One question if I may please: you use the term 'monocouche' throughout, whereas some modern silicone renders are multi-layer (i.e. non monocouche). Do your comments apply to these multi-layer products too? We have a small single storey extension that currently has a sand/cement render. It was probably built in the 1970's and the render is still sound but has been patched up several times over the years. We are now considering stripping off the render and replacing it. Hence the need to understand whether to stick with sand/cement or use a silicone based system. Many thanks.

Nothing to do with acid rain. This is algae. Simple clean with a biocidal wash. Plus no monocouche render is no maintenance like you state it’s low maintenance. As for the silicon paint this is guaranteed for colour fast upto 25 years. If your unsure of anything just talk to manufacturer who could give you the correct advice.

Why we avoided mono, silicone thin coat is better

Lotus effect coating is what they need.. I forget the name of the product I've used, but I'm sure there's plenty of products on the market.

I have sprayed thousands of meters of this stuff, Roger is 100% correct

When I fist used it years ago I had egsactly the same opinion. People raving about it being trouble free but it's absolute nonsense. Do make good £ for applying it tho 😂

Didn’t know you can paint it very useful 👍🏼

Awesome rant Rog! However I don't think it's right to criticise the Architect, because clean lines are what they are trying to achieve on the buildings you showed. For example you can't go Modernist or Art Deco and have a bunch of overhangs conflicting with the smooth lines. As regards cleaning, I have adapted a £10 window cleaning pole by wedging some bamboo in the end. I have cleaned white gutters this way that are similarly stained. If the render can be sponged cleaned it might work. I have found with the gutters you need to have a few goes at it! I get your point re maintanence but I would rather have the clean lines myself :).

Sand and cement and lime mix all the way old school is the only school.

Stakker Humanoid prefers S&C.

I clean this stuff alot

I've had garden walls renderd in traditional sand and cement. They are pristine and smooth.. Thinking of boarding and rendering the house. What combination is best? Am I right in saying sand and cement traditional render can not be applied to cement boards. What type of modern render would. Get a smooth appearance the same as sand and cement

Hi Roger, thanks - that's a really informative video and a great rant :) I've just bought my first home and I think I have some k-rend on the outside. I'm seeing exactly what you show here - black marks on the render where water has been allowed to run. But I'm also seeing ghosting of the brick work in some places through the render. Should I be worried about water ingress due to this? It's my first home and I'm a bit concerned so any info / response is much appreciated! Thanks again for the video - great content!

Aren't these supposed to be sealed within 4 weeks? but nobody bothers and hence the dreaded black algae / mould? I have a 3000sqft house thats about to be done and can't decide what to use.. S&C or Mono and Seal? a lot of render and expensive to mess up.. arrrhhhh

The colours fade overtime too.

7 days after finishing. Paint with a clear silicone (special stuff) keeps it looking new for years and years

Any material which claims to be maintenance-free is a con: UPVC window frames become grotty unless you clean them with Jif or a solvent, fibreglass boats have blisters from osmosis or algae from rainwater, paving goes blotchy due to mould. The air is full of fungal spores, particles of dirt from pollution and water vapour, so of course a pristine surface will not stay clean. I didn't know this render was called monocouche, but I've seen it look like mouldy porridge just like in Roger's examples. Why not render plus masonry paint and then you can change the colour if you like?

The architects have used cappings instead of copings

9/10 if there is a problem with the render it is due to it being applied wrong or architect hasn’t prepared for it. Applying these renders needs special training with the people who created the renders, would solve a lot of issues down the line.

monocouche is dirt that sucks in the dirt and rain

hello Roger you should have a look at sto render its great...... self cleaning and the colours are amazing over 600 colours and the depth of the colour is amazing ...... i love it check it out mate

Like any thing , it all depends on the tradesman putting it on , that said a poor product can make a mug of a good tradesman , this material is not fit for purpose , i have a customer who approached me to look at her k render , badly stained , and in parts hollow , , supposed to be the bees knees , i think its the dogs bollocks ,Does not do what it says on the tin

found this video very informative and useful,

this or k rend are all the same it's going to stain after a few years that's why we use paint to tart it back up....

Could you show us some examples of good practice to avoid this problem?

"Monocouche!" That sounds like something one might see in a dodgy French porno movie. Not that I would know, I'm a good boy I am. Bloke down pub told me; so it must be true!

it would be maintenance free if the other trades done their job properly

Maintenance free monochucce companies sell paint,sealer and cracke repair kits even tho they all claim it needs none of them

Lol putting that render on like a pro.. Unreal

Sand cement render for me !!!!!

I’m from Leicester and have had 9 different quotes from plasterers/renderers and not one was willing to do classic sand/cement render on my property, on top of that none of them are willing to take the old render off before applying their chosen render either meaning I’m left trying to find labourers to do the job which is proving equally as hard. Is anyone out there that is willing to do the job? The property is roughly 150 sq meter