Hi all,

 

Our architect asked us to choose a colour of the rendering for planning application. While we are thinking about it I wanted to check whether rendering is the only option available to us.

 

We have a standard brick and block ground floor which we are planning to extend at the back plus add a first floor. All new structures will be TF, hopefully, MBCs 300mm kind. As agreed with an architect we will need to add at least a 100mm of external wall insulation to the existing walls. 

1) My understanding is TF (at the ground floor level) has to be covered all the way to the ground and we should also try to bring the EWI all the way down and into the ground to decrease the cold bridging. At the same time, the brick wall - please correct me if I am wrong - should not have the rendering bridging DPC. We are on a slope so most of the side walls and the front wall have ground level well below DPC.

2) Does it make sense to even consider using plastic cladding for the first floor in this situation? Seems to be a cheaper option, but will probably make detailing of a joint between floors even more difficult.

 

Thanks in advance.

Edited October 8, 20179 yr by oldkettle
typo fixed

There may be issues with fire resistance of your external cladding material. Your architect should be able to advise, it's well documented in building regs.

I wanted to use brick-effect fibreglass at 5mm thick, rather than a 50mm cavity and 100mm brick wall  - thus gaining an extra 145mm internal room width. Unfortunately we're semi-detatched and therefore I would need to maintain 1hr fire resistance in both directions through my walls. This would have meant adding additional fireproof board under the caldding which made it prohibitively expensive.

Thank you @chrisb

 

We are detached so hopefully this is not going to be a problem, but I will check with the architect.