Penetrating damp in Doncaster: gutters, brickwork and render

Not every damp wall is rising damp or condensation. In Doncaster’s Victorian terraces and inter-war semis, a large share of damp comes from rain finding its way in. That is penetrating damp, and the cause is usually visible from outside. This guide shows what to look for on the outside of your home, in the order that tends to find the cause. It is general information, not a diagnosis. For the other two types of damp, see our condensation vs rising damp guide.

Signs of penetrating damp

• A damp patch that appears or gets bigger after rain, and dries in dry weather.
• Staining or bubbling on a wall or ceiling near a window, chimney, gutter or roofline.
• Damp that is not confined to the base of the wall, and that does not need cooking, showering or drying washing to set it off.
• Patches on a wall that gets driving rain, often the side facing west or south-west.

Check the outside, in this order

1. Gutters and downpipes. Are they blocked, cracked, sagging or dripping at joints? A leaking gutter can soak one patch of wall.
2. Roof edges, flashings and chimneys. Slipped tiles, failed flashing and cracked chimney pots or flaunching let water in at the top.
3. Pointing and brickwork. Eroded mortar joints and cracked or spalling bricks can let water through a solid wall.
4. Render and cladding. Cracks and gaps, especially at the base and around windows, can soak up water.
5. Windows and doors. Failed sealant and cracked cills can leak into the reveals.
6. Ground and drains. Raised ground, paths, flower beds or a blocked gully against the wall bridge the damp-proof course.

Victorian terraces: brickwork and chimneys

In areas such as Hyde Park and Wheatley Hills, solid brick terraces often have old soft lime mortar, exposed chimney stacks and shared gutters. Weathered pointing is a common route for water. Repointing with a suitable mortar, rather than a harder one than the brick, helps the wall last.

Inter-war semis and cavity walls

Houses in places such as Balby and Bentley often have rendered or pebbledashed walls and cavities. Cracked render lets water in behind it. In a cavity wall, debris, mortar droppings or poorly fitted insulation can bridge the gap and carry water to the inner leaf. Damp that appears on one wall after heavy rain, often near a corner or window, is worth checking for these.

What to do first

• Clear gutters and check for leaks while it is raining, if it is safe to do so from the ground.
• Take dated photos of the outside and inside of the same wall.
• Do not paint the outside with a sealant or the inside with damp-proof paint before you know the cause.
• If the problem is at height, use a qualified roofer or a safe access method. Do not climb on a roof or use a ladder alone.

When to ask for a survey

If you have fixed the obvious things and the damp is still there, or you cannot find the cause, ask for a written damp survey; see what a damp survey costs and includes. A good survey checks the outside before recommending any treatment. If it keeps causing mould, see black mould removal and causes.

If you rent

Leaking gutters, roofs and walls are building defects. Tell your landlord or agent in writing with photos. See damp and mould in rented homes in Doncaster.

Next step

If you would like help, tell us what you can see through the enquiry form. With your consent, we will pass it to a local damp and mould professional who covers your area.

Sources and further reading

GOV.UK guidance on damp and mould.

Related guides

• Rising damp and damp proof courses
• Doncaster areas and DN postcodes
• Damp after flooding
• Condensation vs rising damp
• Damp survey cost in Doncaster
• Cellar damp and tanking in Doncaster

Frequently asked questions

What is penetrating damp?

Rain or water getting into a wall or roof through a defect such as a leaking gutter, failed pointing, cracked render, a poor window seal or a bridged cavity. It typically shows as a patch that grows after rain.

How can I tell penetrating damp from condensation?

Penetrating damp usually follows rain and shows near a defect on the outside, such as under a gutter or window. Condensation usually shows on cold surfaces and corners and is worse in winter and in rooms with cooking and showering.

Can blocked gutters cause damp inside the house?

Yes. An overflowing or leaking gutter or downpipe can saturate one section of wall, and the damp can show on the inside face. Clearing and repairing gutters is a sensible first check.

Can cavity wall insulation cause damp?

In some cases, if the cavity was unsuitable or the wall is exposed to driving rain, moisture can cross to the inner leaf. If damp appeared after insulation was installed, contact the installer and check any guarantee.