Damp and mould

In the colder months, condensation can be a major problem in many homes.

It's caused when warm, moist air hits a cold surface like a window or external wall and condenses. This leads to water droplets running down the cold surface. Sometimes condensation occurs in hidden areas like roof voids and under flooring.

The more water vapour (moist air) generated in your home, the more likely you are to get condensation. The main causes of water vapour are steam from cooking and boiling kettles, baths and showers, drying clothes inside, and poorly-vented tumble dryers.

If left, condensation can become black mould, which can cause health problems. It also looks and smells bad, and damages wallpaper, clothes, furniture, and other possessions.

There are several things to consider when dealing with condensation.

Heating

Condensation is most likely to occur in homes which are not well heated. Try to keep room temperatures above 15°C.

Ventilation

You'll get less condensation if you allow air to circulate freely. Make sure vents and airbricks are not covered or obstructed, and allow fresh air into rooms whenever possible.

Insulation

Good insulation helps to keep surfaces warm, improves energy efficiency, and reduces your heating bills. Lofts should have insulation which is at least 270mm in depth. If you rent your property, its Energy Performance Certificate rating should be no less than an E.

Reducing moisture

Condensation is caused by moist air, so reduce moisture levels by:

• opening windows for at least 10 minutes a day, or opening window trickle vents during the day
• closing internal doors and opening the kitchen window while cooking
• using lids on pans while cooking to reduce boiling time (which reduces the amount of steam)
• only boiling as much water as you need in the kettle - this reduces the amount of steam, and saves you money
• opening the window while you're in the bath or shower, and leaving it open for about 20 minutes afterwards
• put cold water in first when you're running a bath - this makes significantly less condensation
• drying surfaces in your kitchen and bathroom after using them, and wiping down windows which have condensation on every day
• not leaving wet towels lying around
• leaving a gap between furniture and walls to allow the air to flow

Rising damp is caused by a failed or 'bridged' damp-proof course. This allows moisture in the ground to rise up through the walls of your home, sometimes up to a height of 1m.

The typical sign of rising damp is a tide-mark at the top of the area of damp, which is caused by salt deposits.

Black mould does not grow where there are salt deposits, which means the damp is likely to be rising damp.

Penetrating damp is water which finds its way into your home from the outside. It can occur at all levels of the building and is usually higher up.

It's caused by:

• overflowing gutters
• missing roof tiles
• leaking pipes and downspouts
• badly fitting windows or doors
• damaged pointing, cladding, flashing, or rendering
• covered air bricks

Signs of penetrating damp include:

• blotchy patches
• wet and crumbly plaster
• swollen and soft plasterboard
• lifted paint and wallpaper
• mould and mildew
• drips and puddles
• wet rot on wood

If a problem with the property is causing the damp, your landlord is responsible for dealing with it. This includes penetrating damp, rising damp, and damp caused by faulty plumbing. If the plumbing problem is caused by something you've done (like flushing the wrong things down the toilet), you'll have to pay to have it fixed.

Your landlord is legally required to provide you with a way to ventilate your home, as well as a suitable fixed form of heating. This means a radiator or something similar, which you do not need to move from room to room to heat your home.

Ideally, bathrooms and kitchens should have mechanical ventilation with a humidity sensor.

Common problems your landlord must fix include:

• faulty guttering and drainpipes
• leaking pipes, for example a leaking bathroom waste pipe
• broken heating systems
• missing roof tiles
• broken window locks or windows which are painted shut

Once the problem is fixed, your landlord should replace any damaged plaster, skirting boards, or flooring, and redecorate if needed.

Landlords are also responsible for making sure their properties meet minimum energy efficiency standards. Properties which do not meet these standards are likely to experience damp and excessive cold.

You're responsible for using your property in a tenant-like manner. This includes heating and ventilating the property to avoid condensation, which causes mould.

Condensation can occur if you:

• do not open windows or use mechanical ventilation systems (like extractor fans) during or after showering
• not ventilating the property enough (for example, not opening windows)
• covering up warm radiators with damp or wet towels or clothing
• regularly drying clothes indoors

Anything you do in your house which creates moisture, or does not remove moisture, increases the risk of damp and mould.

If the damp or mould is caused by something you've done, you must deal with it and redecorate if needed (unless you have an agreement with your landlord). You must speak to your landlord before you do any work.