We are being quoted an extra £10 m2 to use the Baumit NanoporTop. The house is next to a moderately busy road. Any advice on whether it is worth paying the extra? thanks

I would be VERY cautious using any Baumit product in the UK.  If you search the forum you will find my posts detailing the problems I have had with my own render and the total lack of disinterest from the manufacturer to even come and have a look and suggest what might have been the cause of my problems.

 

When I installed mine, there was a BBA certificate for it.  That had been cancelled when I last looked.  Do some research and check there is once more a current BBA certificate for the product you are intending to use.  If not treat that as a big red flag and look for an alternative product.

Thanks @ProDave Is a BBA cert needed for building control or is it just something optional. Baumit give the impression of being a well established company and I have seen many references to their products being used so its disappointing to hear of your issues.

29 minutes ago, markharro said:

Thanks @ProDave Is a BBA cert needed for building control or is it just something optional. Baumit give the impression of being a well established company and I have seen many references to their products being used so its disappointing to hear of your issues.

I don't know if it is required, I don't have a mortgage and am not intending to sell so I don't have a structural warranty.  There was a BBA certificate when the design and drawings was submitted to building control, I don't know if that would have been an issue if there had not been.

 

It was when i was being given the run around by Baumit and their suppliers that it came to light that BBA certificate had been cancelled.  They would not answer why, but it was not a good sign that it was cancelled.  Baumit won't say why and BBA say they can't say.

 

 

For building control approval of anything at all, you just have to convince the bco that it is fit for purpose.

A certificate can help towards that.

 

I am wary of any additional coating. If this was necessary then it should be part of the product.

Similar to being offered an extra coating to a new car or sofa... if it needed it, they would do it at the factory.  Probably a very big markup.

So find a product that doesn't need it.

We have Baumit SilikonTop and it attracts dirt very easily and is a pain to clean: anything abrasive takes off more render than it takes off dirt. 

Can't comment on the dirt proof upsell but it does sound rather like sofa salesman tactics. 

If doing it again I'd definitely try and find out what the alternative options are. (we have pavatherm insulation system and they strongly recommend the Baumit)

I can confirm the SilikonTop is prone to "dirt".  In our case it is mostly the north facing wall, and after about 5 years it was looking grubby, upon closer inspection the "dirt" was mostly green in colour.  I concluded it was moss or similar algie growing, and I "cleaned" it by spraying with diluted bleach, diluted about 1 part bleach to 3 parts water and sprayed on with a squirty bottle.  Just left it for the next rain to rinse off and the wall is clean again. No abrasion needed.

 

So it looks like this is the "maintenance" needed every few years?