Moulds produce allergens, irritants and sometimes toxic substances. Inhaling or touching mould spores can cause allergic reactions, such as a runny nose, sneezing, red eyes and skin rash. Moulds can also cause asthma attacks and is therefore considered a health hazard. Dealing with mould in your property is a primary consideration, but the causes of mould and damp can be wide ranging.

If you notice damp or mould around windows, doors or ceilings this is likely to be caused by condensation. However there can be a number of other causes. A good way to track down the root cause of damp and mould growth is to locate a high capacity dehumidifier in the property for a few weeks after cleaning the mould and this should resolve the problem. If the mould persists then further remedial action is required and areas such as wall cavities, window seals, gutters, pointing and the roof need to be inspected.

Larger dark patches on ceilings or walls often indicate failures in roofing or rainwater goods. This in turn will lead to damp in the property and increase the risk of mould.

Flat roof felt will become cracked and porous over time leading to water ingress. This can also be caused by broken, slipped or missing tiles. Both issues require urgent treatment to avoid rot of sarking boards and other roof timbers. As these areas can be difficult or dangerous to reach and repair they should be inspected and repaired by a professional with the correct access platforms, tools, fixings and PPE.

Please note, slate roofing tiles should never be resited or repaired with silicon/mastic - this process leads to incorrect water flow under the tiles and can cause further water ingress that is very difficult to locate later. Furthermore natural slate is made of many layers and the slate is likely to simply "shed" the bottom-most layer and slip free no matter how strong the adhesive.