Frequently, those first noticed are internal. Concentrated and prolonged wetting is likely to cause damp patches and plaster mould on walls and ceilings, and the decay of timber skirting boards, panelling etc. Investigation will often reveal rot in concealed timbers, such as roof truss bearings beneath parapet gutters.

Externally, masonry can suffer from algae growth and eroded mortar joints. Render may fail locally, particularly inappropriate cement-based coverings that draw in mortar through hairline cracks. External joinery can be attacked by wet rot where there are leaks above doors and windows. Blocked gullies may lead to a build-up of water and damage to foundations.

Good maintenance involves regularly clearing out rainwater fittings, particularly after the autumn leaf fall, and checking the system for defects. Periodic redecoration of ironwork is required to inhibit corrosion.

It can be advantageous to fit plastic leaf guards to gutters or wire balloons above downpipes. Leaf guards still admit pine needles and are sometimes easily dislodged, and material left to gather around wire balloons may cause blockages. Where visually acceptable, overflow pipes can be introduced above hopper heads.

Snow should be cleared from parapet and valley gutters with wooden or plastic shovels to prevent moisture seeping through joints. Alternatively, duckboards or electric heating tapes can be provided to keep gutters clear of snow.

Fittings are best checked for leaks in heavy rain. Proprietary adhesive tape is available for temporary repairs. Where poor access hinders maintenance, additional hatches or fixed ladders might be considered.

Absolutely, where feasible, to retain the maximum historic fabric. Lead, wrought iron and sometimes cast iron can be repaired with various welding techniques. Soldered dots or patches may be used for copper. Remember fire safety, though, when undertaking work of this kind.

Replacement, where unavoidable, should normally be on a like-for-like basis. Inappropriate substitute materials can erode the character of a building (for example, using PVCu instead of cast iron) or lead to premature failure (as with certain combinations of dissimilar metals).

Some changes may be justified. Substituting cast iron with painted cast aluminium might be acceptable where access for redecoration is exceptionally awkward. Such work may require listed building consent.