Rendering a timber frame extension

[jimbouk1978]

We have just had a two story extension built, the ground level built in block work & the first floor in timber frame.

The timber frame has been finished in render in the following way. Timber stud, then ply, a dpm, metal lath & finally render.
There is an internal air gap between the ply & the celotex insulation.

The building inspector is unhappy that water could get trapped within the structure. I do not understand how this could happen as the render has been waterproofed with additives & the dpm provides a waterproof barrier?

It would appear we have used an old fashioned method & now render is mounted on battens away from the ply.

Does anyone know where we can find documentation for this method being acceptable or suggestions on how to make it compliant?

Please any suggestions greatly appricated as he wants us to take it all down!

 

[DevilDamo]

Your best bet would be to contact a render company, e.g. STO...

http://www.sto.co.uk/

 

[^woody^]

Current industry recommendations ie from TRADA or BRE, state that all render cladding systems need ventilation and drainage

However, how is moisture going to get into the frame in the first place? Does it lack a internal vapour check or are there other voids in the frame?

Your existing air gap may suffice if there is drainage