There are a number of reasons for damp proofing your garage, and the urgency of the situation may mean that you carry out the work during the winter months. A problem may have emerged affecting the building, or you could be considering creating an extra room in your home.
Garages are not designed as living spaces and are not built to the same rigorous standards as your house, so you may have to meet specific regulations if you are planning an extension to your home.
A damp proofing specialist will be a able to diagnose the problem and advise on remedial work that is needed.
A garage is often just one brick thick and damp can be created due to adverse weather conditions soaking the walls. If your garage is attached to your home the joining wall may be a source of damp. By inserting a cavity tray above the roofline of the garage you can solve this problem by directing any water onto the garage roof keeping the inside wall dry.
Now you can plaster or dry line inside walls. There may still be some damp, but there are a number of membranes and treatments which, when applied, will enable you to press ahead with remedial work.
Examples of sophisticated surface treatments can be found online at sites such as https://www.poeton.co.uk/treatments.
The cold outer walls or party wall can be fitted with a membrane and dry lined or plastered over. This creates an air gap and a dry surface to work on. The membrane also prevents salts seeping out once the plaster work has been carried out. At this point you can also opt to dot and dab fix a plasterboard or use battens and plasterboard.
If you opt for a sand and cement plaster this will create a damp barrier, and you will then need to finish with a thistle plaster multi-finish. A surface finish like this will, however, remains cold to the touch and may suffer condensation.
If you have an irregular surface such as stone, or where the surface is loose, a stud partition wall may offer the best solution. This will involve a timber frame arranged on the membrane. You will also be able to install insulation in the gap which is created with this solution.