Don’t Be Tempted to Pressure-Wash a Roof, NFRC Warns

The NFRC is warning householders not to be tempted to pressure-wash moss or lichen off their roofs.

Providing autumn maintenance tips for homeowners, NFRC’s Head of Technical and Training, Bob Richardson said: “NFRC would never recommend the use of pressure washers to clean moss, lichen or algae off a roof as the high pressures can damage the tiles or reduce their overall service life.”

Advice

Many roof tiles are finished with a lamination which helps extend their lifespan by protecting the tile from the weather. Pressure-washing roof tiles can remove this protective layer.

Moss or lichen growth on roofs is not uncommon in the UK and can often be seen on both roof tiles and roof slates. However, this may not be something to worry about.

Bob explains: “A small amount of moss or lichen growth will not be harmful to the roof covering. Only in extreme cases, it may affect the flow of water off the roof and thus increase the risk of leaks or damage.”

Moss or lichen build up is likely to be an increased problem where roofs are overhung by trees or are shaded by other buildings. It can also occur where pigeons and other birds congregate leaving droppings that act as fertiliser to the plant’s growth.

Roof covered in moss

When moss or lichen builds up between a roof’s tiles or slates then it can interrupt the flow of rainwater down the roof’s slopes. It can also be washed into gutters, particularly if a heavy rainfall follows a very dry period. This shrinks the plants helping them detach from the roof. If moss and lichen start to cause problems, householders can consider applying a treatment. Look for treatments that inhibit the plant growth, or brushing or scraping the plants away.

Working at Height

However, accessing the roof can pose dangers to householders who do not possess the training to work safely at height.

Bob cautions: “The preferred method would be the use of a system from ground floor to eliminate any working at height.”

Autumn Maintenance

It’s not only moss and lichen that householders should be looking out for on their roofs. Other regular roof maintenance should be thought about, particularly as we approach winter to avoid unforeseen costly bills.

Bob Richardson, NFRC Head of Technical and Training

NFRC’s Bob Richardson continues: “It’s coming to that time of year when homeowners should consider checking their roofs. Look for any noticeable damage or missing slates and tiles before winter arrives.

“Undertaking proactive maintenance of your roof should help to mitigate the risk of expensive reactive maintenance. It will help avoid any unforeseen expenditure due to water damage that may occur. This especially important in light of the economic climate and rising costs.

“This check should be visual and undertaken from ground level. NFRC does not endorse any work at height being undertaken by individuals without the correct skills, knowledge and experience and using the correct access equipment.”

Checklist for Roof Inspections

Signs that a roof may need the professional attention of a roofer to look out for are:

Missing slates or tiles
Damaged slates or tiles
Slates or tiles that are out of line and not facing in the same direction as the others
Mortar missing from any ridge, verge or abutment
Loose or defective flashings around any penetrations through the roof like a chimney stack, or in a valley
Overflowing gutters or vegetation growing out of the gutters, which can lead to potential roof plumbing issues such as water backing up into downpipes or pipes

The roof could also be viewed from inside by going into the loft space.

Bob advises that there are signs to look out for here. Bob points to, “the presence of daylight through the roof coverings or dampness in the loft”. He says these could be signs that the roof requires maintenance.

Insulation to Keep the Bills Down

Bob adds: “Whilst within the loft it would also be prudent to check the insulation. Predominately this will be above the ceiling level and would be a fibre roll insulation installed between the joists tightly fitted without any gaps.

“As hot air rises, 25 per cent of your home’s heat can be lost from a poorly insulated loft. So if additional insulation can be fitted, this could help further reduce heat loss through the roof ensuring that the house stays warmer longer. The UK government recommends a minimum insulation thickness of 270 mm.

“Installing more insulation will keep your house warmer but will also make the roof space above the insulation colder. As such care should be taken to ensure any water tanks or pipework above the level of the insulation are also adequately insulated. This will prevent them freezing.”