Roof and gutter maintenance in Costa Rica

A roof here deals with close to four metres of rain in an average year, strong sun, salt air and a steady fall of leaves. It rarely fails all at once. It fails at one screw, one joint or one blocked gutter, and it gives notice to anyone who looks.

Metal roofs: the fixings go first

Many roofs on this coast are coated steel sheets held down with exposed screws. Each screw seals with a small rubber washer. Years of sun harden and crack the washer, the sheet moves as it heats and cools, and the screw works loose. Water then follows the screw into the timber or steel below.

Manufacturers' maintenance guides say to inspect a metal roof once or twice a year and after severe weather, and to replace loose or rusted fixings with corrosion-resistant ones. Here the sensible time is the end of the dry season, before the roof is tested.

Leaves and branches matter more than they look. Debris holds moisture against the coating and starts rust, so valleys and the areas around vents and skylights are kept clear. Scratches through the paint are touched up before they spread.

Two more things shorten a metal roof's life. One is contact between different metals, which sets up corrosion where they meet: the wrong screws, or a copper pipe resting on the sheet, is enough. The other is salt. Warranties on coated steel roofing commonly exclude or limit roofs within a few hundred metres of breaking surf, which says what the makers expect salt to do. Rinsing the roof with fresh water in the dry season helps.

Tile and flat roofs

On a clay tile roof the tiles shed most of the water, but the waterproofing is the layer underneath them. A cracked or slipped tile exposes that layer to sun and rain, and plants rooting between tiles hold water where it should run off. Tiles break under careless feet, so inspection is a job for someone who knows where to step.

A flat concrete roof or terrace depends on its membrane and its drains. A drain blocked with leaves turns the roof into a pond, and standing water finds any weakness in the membrane. Drains are cleared on the same schedule as gutters.

Gutters are part of the roof

A gutter full of leaves does not fail quietly. Water backs up under the roof edge, runs down the wall and soaks the ground at the foot of the house. Gutters and downpipes are cleared before the rains and repeatedly during them, and tested with a hose: the water should leave the downpipe and keep going, away from the building.

Read the ceiling

A new stain on a ceiling is a leak until proven otherwise, and it should be traced the same week. Not every stain is the roof: blocked condensate lines from air conditioners cause plenty. Either way the United States Environmental Protection Agency's guidance applies: materials dried within 24 to 48 hours of getting wet will, in most cases, not grow mold. Left longer, they may.

When to do the work

Repairs and repainting belong in the dry months, when coatings cure and nobody is walking a wet roof. During the rains the job is to keep water moving and to notice change.