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there is the danger of sealing all ventilation from a room (see Gas ).
    Condensation also occurs when a chimney has been closed off or removed without the insertion of an airbrick, or in the roof when loft insulation is carried too far into the breathing spaces round the eaves.

REMEMBER
     
    Just as we need fresh air to survive, good ventilation is vital to keep your home healthy. Airbricks—basically bricks with holes in—are used to vent the spaces under floors or in sealed chimney stacks. These prevent the build-up of moisture-laden air. Don’t block them!
    In rooms with high levels of condensation, such as kitchens and bathrooms, extractor fans should be employed—either on an outside wall or through a window. If neither is available it may be necessary to run ducting to a suitable escape point.
     

WARNING
     
    Don’t seal off every little draught from a room, particularly if it’s regularly occupied or contains a fuel-burning appliance. Moisture build-up from human breath and burning fuel will produce condensation. Most fuel-burning appliances also produce moisture, along with carbon monoxide and carbon dioxide—which are highly poisonous, especially in concentration.
     

ROT/INFESTATION
     
    All woodwork, especially softwoods (which comprise a large amount of the inner framework of most houses), should not be exposed to persistent wet conditions, whatever the cause. The occasional spillage of water is harmless, but constant wetting will lay the way open for wet rot or dry rot.

Rot
     
    Areas most likely to develop rot are roof timbers (either from damp penetration or condensation), bathrooms (round the bath, shower, toilet, bidet), kitchens (round the sink), window frames, door frames, floors and skirtings (particularly in the presence of rising damp).
    Dry rot is the more serious. It lives on timber, favouring damp unventilated spaces. Usually it goes undetected until it is well under way, the first sign often being a floorboard beginning to weaken. It gives off a distinctive mushroomy smell which should be noticeable in severe cases.
    The wood darkens in colour and cracks across and along the grain, producing an uneven network of squares, often with grey furry patches of mould. The wood becomes very light and crumbly. If the air is very moist round the fungus, it may produce larger fluffy whitish growths. After a year or so it produces thick bracket-like fruiting bodies with rust-red spores clearly visible.
    Dry rot is fast and deadly. It will travel across brickwork to reach unaffected timber. The spores travel well, and if they land on moist timber the whole process is accelerated.
    Wet rot needs damp wood to survive. The fungus usually only penetrates damp wood. It doesn’t spread in the same way—it’s unlikely to produce fruiting bodies indoors.
    It grows into the wet wood, softening it, and producing cracks along the grain. More than one fungus can produce wet rot, but the wood may appear lighter in colour and very fibrous, sometimes with brown strands on the surface.
    Wet rot tends to die if the wood dries out, but the path may be open for dry rot to develop.
    Any case of rot must be treated as a top priority. Affected timbers may need to be cut out and replaced. At any rate, whatever the scale of the emergency, expert help should be sought. All wood should be treated with chemicals to inhibit further mould growth, after all possible sources of damp have been eliminated. Any wood being cut out and removed should be in sealed polythene bags and disposed of finally by burning.

WARNING
     
    New timber used for skirting boards, window frames and door frames may be ‘green wood’. Traditionally timber was seasoned before use – left for a couple of years to expand, contract or warp and adjust to atmospheric moisture. With increased demand, wood is sometimes kiln-dried to speed up the process.
    Much new wood may still be ‘green’, containing a substantial amount of water. It is quite common for