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We are nearing completion of a project to our house - a new sunroom extension and rendering the whole house (previously pebbledash and brickwork). The builder subcontracted the rendering to a tradesman. The front and back of the house which were pebble dash seem to be okay but the side elevation that was previously brickwork from an extension built about 15 years ago had large patches that were unstable and the render fell away. The tradesman said he thought this was as a result of a bad batch of materials and he has patched these areas but I am a) concerned that the rendering on this elevation is not as robust as the other walls of the house and b) that the patches will show through when we paint - and if this is likely - is there anything we can do about it prior to painting? Any advice would be very welcome. Thanks Kit

You can tap the rendering all over and listen for hollow sounds Kit. If it sounds hollow it may be a result of poor adhesion of the rendering to the wall. As for patchy painting you should leave the render until its all dried out to be the same colour. If it does not its the result of two different strengths of mix being used and the plasterer should be approached to find out why this is as it could affect the painting.