What is growing on your house, and why

Symptoms we get asked about most

• Why render turns green - and how to clear it for good

  Homeowner sees green film spreading across render and wants the cause and fix.

• Black streaks running down walls: what causes them

  Owner has vertical dark staining under sills, gutters or copings.

• Moss on roof tiles: when it matters and when it does not

  Owner has visible roof moss and wants to know if it is urgent.

• Lichen on roofs and copings: the slow damage nobody sees

  Owner has crusty grey or orange growth on tiles and stonework.

• Seven signs your gutters are blocked before the ceiling tells you

  Owner suspects gutter blockage and wants to confirm without a ladder.

• Gutters overflowing only in heavy rain - what that means

  Gutters cope in drizzle but flood in downpours.

• Slippery patios: why they get dangerous and what fixes it

  Owner worried about slip risk on a green or black patio.

• Red and orange staining on block paving

  Owner sees pink or rust-coloured bloom on paving.

• Salt and sea air: what it does to coastal exteriors

  Coastal owner wants to know how sea air changes cleaning needs.

• Why only one side of the house goes green

  Owner puzzled that one elevation is filthy and another is clean.

• Conservatory roofs: green gutters, grimy panels and cold spots

  Owner with a dirty conservatory roof and box gutter.

• Water spots that will not come off glass

  Owner has cloudy or spotted glass after cleaning.

• Damp patch on an upstairs wall - roof, gutter or wall?

  Owner has interior damp and wants to identify the external cause.

• Bird droppings, nesting debris and blocked outlets

  Owner with gull or pigeon fouling on roof, gutters or render.

• White powder on brickwork: efflorescence explained

  Owner sees white bloom on brick or block and thinks it is mould.

• Cracked render: what to fix before cleaning

  Owner wants a wall clean but has visible render cracks.

• Weeds and moss in driveway joints

  Owner with growth between blocks or slabs.

• Oil and tyre marks on driveways

  Owner with vehicle staining on paving or concrete.

• After a storm: what to check outside the house

  Owner doing a post-storm exterior check.

• Preparing the outside of a house for sale

  Seller wants maximum kerb appeal before photography.

• Green tarmac and concrete: cleaning without damage

  Owner with a green tarmac drive or concrete path.

• Slippery decking: cleaning timber and composite

  Owner with green, slippery decking.