Jump to content

rendering over crepe


Angie
 Share

Recommended Posts

We had an extension built about 5 years ago and almost from the start the crepe has developed some horrible black marks, some from where the gutters drain but now generally all over. The new walls originally matched our house but now they look dirty and horrible despite spraying with a chemical, gentle power washing or just with a brush on smaller areas. Can we cement render over this crepe? We are thinking of using a cement colourant to save painting but leave a smooth finish rather than the bumpy surface we have now. In fact anything is better than its current look. Just wondered if this would work or whether cement would stop the breezeblocks from breathing (as someone has mentioned) or whether that's a load of rubbish? Thank you
Link to comment
Share on other sites

Breeze blocks covered in crepi stopped breathing some time back. If indeed they were porous enough to breath in the first place, some are some are not, depends on the density.  Natural limestone is what we usually refer to as breathing but some concrete blocks do have a vapour permeability.

You might with a resin de anchorage (SBR) get a good bond but that black is I believe a mold that grows very well on crepi.  Now if Chancer were here he might be able to help.

You might be better with a self coloured Webber render, these are a silicon render which stays and is easy to clean but a swine to patch if damaged.

Link to comment
Share on other sites

Would not painting it be best?

We had a house built, with crépi on the exterior, and after a few years it developed sort of "weeping" black and brown marks and looked most depressing. I subsequently noticed other houses with the same problem. It was as if the crépi contained tiny "colour bombs" that burst.

Once it was repainted, the problem stopped.
Link to comment
Share on other sites

[quote user="Loiseau"]Would not painting it be best? [/quote]

Yep, not painting it would be best [:D] Only teasing [;-)]

Just don't paint it with crepi!  I wonder if the colour bombs are in the grit pieces?  seen a fair bit of purple staining. there was some on a section of garden wall at ours that looked like mold spots (grey to black sploges) 

Link to comment
Share on other sites

  • 3 weeks later...
Thank you for all your responses. We have just come back from the house and in a local builders mechants they sold a product call Bidon Nettoyage Rapide, quite expensive at 32 euros for 5 litres but it claims to instantly remove this type of mould/dirt/fungus (whatever it is) almost instantly and without rinsing. Anyone had experience of this product as if it does work it would be a lot cheaper and less hassle than re-rendering. Thank you
Link to comment
Share on other sites

Would be very interested to hear how theproduct worked out. Would it damage plants? The bits I want to clean all have niceplants growing at the base, and the only time I tried one of those guys who comes round with a lorry (ho hum, yes, I know) I ended up with lovely clean walls and a long bed of dead plants.

Chrissie (81)
Link to comment
Share on other sites

[quote user="Lehaut"]Don't worry about it, if you post anything on any forum, you will always get people who like to roast.[/quote]

Just as you get people turning up with their wooden spoons to make something from nothing.

[quote user="Angie"]Sorry if I've missed something, what am I supposed to be blaming anyone for?[/quote]

Yes you missed the LOL because there are no emojis available on phone replies. [:D]

Simply

to say Angie, you asked about rendering over crepis but really you

wanted just remove the marks/mold whatever. Unusually that's what I

answered.  No roasting anybody. [:D]

[quote user="Chrissie"]Would be very interested to hear how theproduct

worked out. Would it damage plants? The bits I want to clean all have

niceplants growing at the base, and the only time I tried one of those

guys who comes round with a lorry (ho hum, yes, I know) I ended up with

lovely clean walls and a long bed of dead plants.

Chrissie (81)[/quote]

Depending what the label actually says on

the back, it maybe Quaternary Ammonium Chloride, or anti algae as it's

known in the pool world. So yes it is likely to be harmful to some

plants.

If it is another compound we will have to wait and see. 

Link to comment
Share on other sites

  • 1 year later...
Sorry for the really late reply! We purchased a product in the UK called "Wet and Forget", its expensive (think we paid about £60 for 5ltrs of which I have about a third left) but they do deliver to France (P&P). The fungus/mold/algae had got even worse over the spring and summer and nothing we bought in France worked (and yes, like you Chrissie) we even paid for the services of the man with a lorry who showed us an expensive product but guess once we were out of sight he just used normal bleach (judging by the smell and white patches) and charged us a fortune. Well I used Wet & Forget, spraying it on more liberally than the instructions because our end wall is so bad. It needs to stay dry for a day and then any rain etc. actually makes the product work and it continues to do so. It did take, as stated by the company, a good 3 months to see any noticeable difference but the transformation over the past six months has been dramatic, to the point that it has completely gone. Only one long dark strip remains and that was because I couldn't reach it properly. If I knew how to upload the before and after photos I would!! Will be applying a second application when we go over in June to get rid of the final bit of this horrid black stuff and then an annual spray should be all that's needed to keep the wall clean - its just one side of our house so doesn't take more than an hour. PS - totally harmless to animals, birds and plants!! The other advantage is that it doesn't stain crepi or render. It did darken the wall for a few days but once fully dry it returned to its normal colour which is quite light - something that isn't guaranteed with the French products containing bleach.
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...