1. Look around your house

Are there defects, cracks or blockages through which water could be getting in?

This could be the cause of a penetrating damp problem. Penetrating damp is caused by defects within the building or rainwater goods, allowing water to pass through the roof or walls and into the property. A water mark on an internal wall would be a sign of penetrating damp, and will usually indicate the point of the defect, so check externally in the same area as the watermark for any obvious problems.

DIY solutions

Check the downpipes, hoppers and gutters for any blockages including moss, leaves, dead birds etc. Remove the blockage and you might find that this resolves the damp problem!

If the rainwater goods are old, they may need replacing

Ensure that any cracks or voids in the walls or around window or door frames are fixed.

Have a good look at the roof. Are there any loose slates? Problems with the roof are a common cause of penetrating damp

2. Are there any signs of damp mould on the internal walls? 

Are the walls cold and damp to the touch?

This could be a sign of condensation. Condensation occurs when there is excessive water vapour held within the air of the house. When water vapour cools due to contact with cold walls, surface condensation forms, which will make the walls damp and can lead to black spot mould forming which can be hazardous to health, as well as producing an unpleasant dank and musty smell.

DIY Solutions

Use extractor fans in the kitchen and bathrooms 

When using the kitchen or bathroom keep the doors shut and extractor fan on so that excessive water vapour does not go into other parts of the house

Consider installing humidistats within areas with high humidity

Ensure washing machines and dryers are adequately plumbed in according to the manufacturer's instructions. 

3. Do the ground floor walls exhibit damp patches and salt bands to about 1 metre from the floor?


The damp proof course (DPC) could be bridged by high external ground levels. Removing the high ground levels will stop further rising and penetrating damp, but ground salts are hydroscopic and although the wall will no longer be receiving moisture from the high ground, the walls may still be damp due to the moisture received by the salts that still remain in the wall. Advice should be sought from a damp-proofing specialist. 

Older properties may not have a damp proof course installed. If this is the case, we recommend installation of our Newtonite Damp Proofing System, which includes an injectable DPC, Newton 804-DPC, and a number of damp-proofing membranes such as Newton 805 Newlath, which will isolate the wall finishes from moisture still in the wall as the wall dries out post 804-DPC application.   

4. Is the property affected by damp in an exposed area, or is it older than a hundred years old?

Houses in exposed areas often suffer from penetrating damp problems due to the effects of driving rain. 


Newton 807-BKK eco is a clear coating seals the walls with a vapour permeable treatment that prevents water from entering the walls and so prevents further penetrating dampness, and allows the wall to dry out. Repairs to pointing and other defects need to be carried out in addition to this treatment. 

5. Find a good damp specialist

If you are unsure as to the cause of the dampness within your home, it is always best to consult a good, trustworthy damp proofing specialist. 

Please call Newton on 01732 360 095 or e-mail tech@newtonwaterproofing.co.uk and we will be happy to give you a list of damp proof specialists who cover your area free of charge. 

Newton’s Registered Installers are trained to offer you the best level of service and expertise, and always offer a reliable solution for your damp problem.

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