According to the Building Research Establishment, the most common damp problems are caused by plumbing leaks, which can happen at any time of the year. Leaks in the winter seem more serious, though - they might deprive you of life-preserving warmth and hot water, and any consequent dampness dries out slowly.
The most damaging leaks are caused by automatic washing machines. Their inlet and waste hoses are rubber, which perishes over time, and a machine- full of hot soapy water ejected under the kitchen units can cause an almighty mess, as well as taking weeks to dry out. So have a look at the condition of the hoses, and replace them if they look at all brittle or cracked.
Incidentally, washing machine engineers say you should never leave the washing machine running when you leave the house. It may be automatic, but it doesn't know how to turn itself off if it springs a leak. And it is a good idea to turn off the water supply to the machine when you go away on holiday.
The next most common cause of damp problems is condensation, and this does become more noticeable in the winter months. Many people have trouble understanding condensation in their homes, although they deal with it happily every day in their cars. Condensation occurs when warm, moist air encounters a cold surface. The way to prevent it is, first, to remove the warm, moist air by opening a window or turning on the extractor fan; and second, to keep surfaces warm by heating.
Many condensation problems are caused by people turning down the central heating room thermostat to try to save money, sometimes in response to government advice. This advice is misleading; whatever you save on your winter heating bill is chicken feed compared with the costs incurred in dealing with mould growth, staining and wood rot as a result of condensation. Better advice, in terms of both energy use and CO2 emissions, is to keep the central heating timer and room thermostat "on", but to turn down the exit temperature of the water leaving the boiler. This will maintain a low-level background heating effect, keeping walls above dew point temperature, and thus preventing condensation. On some domestic boilers the exit temperature control is hidden behind a panel, and it is usually only ever adjusted by a plumber.
The best way to deal with frozen pipes is not to let them happen in the first place. The "gushers" spouting from roads and pavements are not your problem. The water becomes your responsibility when it leaves the meter or stop valve under the pavement and enters the supply pipe under your front garden. The supply pipe should be at least 750mm underground, which is below frost level. However, frost "heave" of the frozen ground above can cause movement which may fracture old lead and steel pipes.
Minor leaks will not cause an immediate problem unless you are paying for your water - and your leaks - by meter. In this case you should have your supply pipe replaced with a length of new polybutylene pipe. In response to government pressure, many of the water companies are now undertaking to replace customers' leaking supply pipes free of charge.
Within the home, pipes freeze if they have water in them and the temperature is allowed to fall to 0C. Water, unlike other liquids, expands when it freezes, and this expansion causes the damage. Preventing pipes freezing is straightforward. If the building is going to be unoccupied over a period of freezing weather - if it's a holiday home, say, or a garage or workshop - you should consider turning off the water and draining the tanks and pipes. Otherwise, you must provide enough heat to keep the system above freezing point. Insulation will help, but remember, insulation doesn't warm things up, it only slows down heat loss. Insulation without heating will not work, so keep a low level of heating on throughout the cold weather.
The most common place for freezing pipes to occur is in the roof space. Here, paradoxically, insulation can sometimes do more harm than good. Insulation above the top-floor ceiling helps to keep the heat in the bedrooms, but means that the loft stays cold.
Insulation should never pass under pipes or tanks in the loft, but, wherever possible, should be diverted over them. That way, the plumbing system will be kept at the same temperature as the rooms below.