What should I check on my house each season to keep it dry?

The expensive failures in a house are almost all water failures, and nearly all of them were visible for years before they became expensive. What makes them invisible is that people inspect at the wrong time — a dry Saturday in June tells you nothing about a gutter that overflows in a downpour, and an afternoon in the loft in July tells you nothing about condensation.

Safety

What you'll need

• Binoculars
• Head torch
• Waterproof coat
• Gutter scoop and a stable ladder (optional)
• Hygrometer (optional)
• Camera

Step by step

1. Late autumn — clear the rainwater route end to end.Gutters, hoppers, downpipes, the shoe at the bottom, and the gully it discharges into. A silted gully backs water up against the wall just as effectively as a blocked gutter overflows onto it.
2. Late autumn — clear the ground.Leaves off airbricks and gullies, planting cut back off the walls, and anything stacked against the house moved away. A wall needs air on it to dry.
3. First heavy driving rain — go outside and watch.This is the single most useful inspection of the year and it can only be done in the wet. Overflowing gutters, a joint dripping down a wall, water sheeting off a sill rather than dripping clear, a splashing downpipe, water pooling against the brickwork. All invisible on a dry day.
4. First heavy rain — check inside at the same time.Walk the rooms during and just after. A patch that darkens now and fades in a week is penetrating damp and you have just proved it.
5. Cold winter morning — read the cold surfaces before the curtains open.Window glass, reveals, corners of external walls, behind wardrobes, the ceiling line at the eaves. This is condensation at its most visible, and the pattern tells you which rooms need attention.
6. Cold winter morning — check the loft.On a cold still morning with a torch, look for beads or frost on the underside of the roof and on nail points, and for damp insulation. This is when loft condensation shows itself.
7. Early spring — walk the outside with binoculars.Slipped tiles, cracked or missing ridge mortar, lifted flashings, vegetation in a gutter, cracks in render, failed pointing on the weather elevation. Winter's driving rain is what finds these, and spring is when you see the result.
8. Early spring — check the ground level again.It creeps up every time anything is landscaped, delivered or stacked. Measure the clearance below the damp course on each elevation and photograph it with a tape in shot.
9. Summer — do the work.This is the dry season and therefore the working season. Repointing, rendering, external painting, roof work, gutter replacement and any wall that needs to dry all belong here.
10. Summer — service the ventilation.Clean the extract fans and their grilles, check the ducts are still connected and falling correctly, clear the trickle vents, and clear the airbricks. Do it now so it is right in October.
11. Keep a one-page record.Date, what you checked, what you found, photograph references. Next year's comparison is what turns a check into a diagnosis.

Tips

• Set two calendar reminders: one for late October, and one that simply says 'go outside next time it really rains'. The second is the one that finds things.
• Photograph the same four corners of the house each spring from the same spots. Changes are obvious in comparison and invisible in isolation.
• If you are buying a house, the driving-rain walk and the cold-morning walk are worth arranging before exchange if you possibly can.

Common mistakes

• Only inspecting in good weather — Every water-related defect in a building is easiest to find while water is running through it. A dry-day inspection finds the consequences months later instead of the cause immediately.
• Clearing gutters but never the gully or the downpipe — The route is only as good as its worst point. A clean gutter feeding a blocked gully still puts water against the wall, and the wall is the thing you were protecting.

Checklist

• Gutters, hoppers, downpipes and gullies clear
• Ground level at least 150mm below the damp course on every elevation
• Airbricks and underfloor vents open and unobstructed
• No planting or stacked material touching the walls
• Sills projecting with intact drip grooves
• Pointing and render sound on the weather elevation
• Ridge, verges, flashings and valleys intact from the ground
• Loft dry on a cold morning, eaves ventilation clear, hatch sealed
• Extract fans moving air, ducts connected, trickle vents open
• Photographs taken and dated for comparison next year

Questions people ask