External Wall InsulationTo insulate a solid wall from the outside, a layer of insulation material is fixed to the walls with mechanical fixings and adhesive, then covered with protective layers of render or cladding. The finish can be smooth, textured or painted, tiled, panelled, pebble-dashed (for easy maintenance) or finished with brick slips to provide a real masonry brick finish. The finish will cover the whole of the outside of your property, including existing brickwork, and may change its appearance. So you must find out if you need planning permission: What about damp? Insulating the outside of your property, provided it is done properly, will give you a new weather proof layer that will protect you from penetrating damp for years to come, and should deal with any existing penetrating damp problems you may have had due to poor wall finish. The insulation will also increase the temperature of the internal surface of the wall, making it less likely that you will get condensation problems on your walls.
The main damp issue to be avoided with external wall insulation is rising damp. If you already have a problem with this, then it will have to be fixed before the insulation is fitted, otherwise you run the risk of trapping the damp inside the wall structure and so making the problem worse. It is also important to make sure that the new external insulation layer and cladding do not bridge the damp proof layer in the wall. The insulation should start above this, otherwise water may be able to use the insulation to climb above the damp proof membrane, causing rising damp where it wasn’t a problem before. An approved installer fitting a recognised external insulation system will ensure that there are no problems with rising damp and that the external surface is fully weatherproof throughout, so you should not see any new damp issues and you may see some benefit if condensation has been a problem in the past.