Dealing with damp and mould is not a sign of a neglected home, but is a universal struggle for most UK households due to the wet climate, older housing and high humidity levels. 

Daily routines can release litres of water vapour into the air every day, and rainfall can also test the outer shell of a home. Water will look for the path of least resistance, so if it cannot flow off a roof and down the drains, it will eventually seep inwards.

Tackling mould does not need to mean that you have to spend thousands on damp-proofing or structural overhauls. Controlling moisture is instead a matter of guided entry and clear exit. 

Managing Rainwater at the Roofline

Guttering and downpipes, which are the main elements responsible for protecting your home, are in good working order. Because a standard UK roof can collect tens of thousands of litres of water each year if it is not safely channelled away, it cannot only cause damage to your roof. It’s not stopped there; it will fall down the walls, raining down on the brickwork, pooling around your foundations and seeping up your outer walls. There is also the problem of penetrating damp. When an external brick or render is being consistently saturated from overflowing rainwater, that moisture will eventually travel across cavities and make an appearance on your internal walls in the form of peeling wallpaper, cold patches and black mould.

You can tell when there are problems with the guttering without having to get out the ladder. When the rain is coming down, go outdoors and look up at your roof to see if there are water streams pouring over the front of the guttering or if there is water leaking from joints. You can also keep an eye out for some static clues—tide marks on brickwork, green algae stains on outer walls beneath the roofline, or gutter brackets bowing from the weight of held water. On the ground, look for soil erosion or mud splashes directly beneath the line of the guttering, as this may indicate that water is missing the downpipe.

In order to keep water moving freely, there are several steps every homeowner should be taking:

• Every so often, you need to clear guttering out of autumn leaves, moss and silt. A single handful of debris can block your downpipe, turning a slight drizzle into an overflow.
• Slopes and seals need to be fixed, as old gutters can lose their pitch over time, causing water to sit stagnant, rust metal joints or degrade rubber seals in uPVC systems.
• UK rainfall has become heavier and more intense, so you will need to replace outdated or narrow profile gutters with more modern, high-capacity deep-flow systems to help your roof cope with a sudden, heavy downpour.

Where water goes matters just as much as how it leaves the roof. Downspouts need to drop neatly into a gulley grid or soakaway instead of spilling out onto the ground. French drains and linear channel drainage around driveways and paved areas of your home will also prevent water from pooling around lower damp-proof coursing, stopping rising damp before it can start.

Tackling Damp at the Highest Point

The roof of your home is the surface exposed to the most severe environmental factors – including direct impact rain, high winds, temperatures below freezing and regular expansion and contraction. Even a break in the roofline, such as a skylight, can create a potential vulnerability. Water penetrating from the top floor is not always a gushing leak from the ceiling. It is more often a stealth trickle strimming down internal rafters, soaking ceiling insulation or generating mould up in the loft or roof-space over bedrooms well before it breaks out through the plasterboard.

Several things help to keep roof windows watertight on the outside. For example, flashing is the purpose-built metallic or flexible apron surrounding a roof window that channels rainwater over and around the window frame, safely guiding it onto the tiles below and into the gutters. Homeowners should look out for cracked rubber seals, degraded sealant or weather damaged flashing aprons. Moss build-up behind window flashing is another common culprit, as it acts like a sponge by holding water against timber frames. Modern, integrated flashing kits are engineered specifically for different roofing materials in order to create a seamless, weather-hardened barrier against wind-driven rain.

The upper levels are affected the most as the warm, moist air in the house naturally rises and accumulates at the top of the home, just under roof windows. As this warm, moist air strikes a cold window surface, it will cool down quickly, and the moisture in the air will condense into liquid water. Over time, this standing water on internal window sills can become a breeding ground for black mould and rot timber window frames. Replacing old, single-glazed rooflights or damaged double-glazing with new, insulated glass units can make all the difference. Thermally efficient glazing is warmer on the inside, so the interior air is less likely to reach its dew point, and condensation is prevented before it forms.

Ventilation & Letting Your Home Breathe

In a drive to stop draughts and in pursuit of energy-saving, many British homes have become ever more sealed, which means moisture is sequestered inside. Daily living moisture from activities can accumulate enough moisture from everyday activities such as leisure to produce up to ten to fifteen litres of moisture per household. This allows for ideal conditions for mould spores, as mould loves moisture and will not grow in moving air. In the absence of welcoming breezes, moist air clings to the nooks and crannies of the house.

Like a hot air balloon, warm moist air will rise to the roof. But they say they can generate a natural chimney effect by combining ground-floor windows with roof windows at the high level. To the rhythm of opening a lower window a crack and a roof window at the top to let in cool, fresh air at the bottom, and push out stale, warm air through the top. Just ten minutes of window-opening per day can help dissipate the moisture-laden air indoors without bringing down the indoor temperature too much. Many modern windows also come with trickle vents – a small, adjustable slat that’s built into the top of the window frame. These small points allow a small quantity of fresh air to flow in at all times, even when the windows are firmly locked shut; for this reason, they are perfect for a tough winter when you want to have as many windows unbarred as possible.

Controlling moisture comes down to two simple jobs: guiding rainwater safely away from the exterior with proper drainage, and letting trapped internal moisture escape with effective roof ventilation. Before the next rainy spell, it is best to check the exterior and loft of your home to ensure that this is something you can do yourself.