Penetrating Damp Proofing Walls

What are the Causes of Penetrating Damp?

Typically, penetrating damp is either caused by issues with the plumbing of a building orby excess rainwater in regions with wet weather.Some common issues with penetrating damp are:

  • Poor roof maintenance;
  • Liabilities in the masonry such as missing or broken pointing.
  • Porous building material;
  • Defective insulation around window and door frames;
  • Missing or defective trays in cavity walls.

Especially in places like London, where precipitation is more frequent than usual, older properties are more prone to leakages, making penetrating damp can become a serious headache.

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Unlike rising damp, penetrating (or lateral) damp can happen in any level of a property and is formed horizontally. It is usually caused from a moisture excess on walls because of leaking gutters or downpipes, defective flashings, masonry and mortar defects and poor ventilation.

Moisture penetrates through walls when left unchecked and even though this may look harmless at first water, it can become one of the most destructive forces on your property. Even if it does not penetrate all the way through a wall it will often lead to condensation problems, mouldgrowth, increasedheatloss, and frostdamage into the masonry.


Penetrating Damp Symptoms

Identifying damp problems is quite easy, as a watermark will form on the affected area, pinpointing to the problematic spot. The longer a leakage stays untreated, this water patch will continue to grow, especially in periods of intense rain. Depending on the temperature and the ventilation of a room, mould might also appear on the wall. Generally, when trying to tell apart rising damp from penetrating damp, keep in mind that rising damp can only occur in ground floors and that there is no accumulation of minerals in cases of penetrating damp.


Apart from mould, penetrating damp can cause unpleasant odours, wet rot and undermine your property’s insulation.

Prevention of Penetrating Damp Proofing

A little bit of property care can go a long way to solving your penetrating damp problem:

  • Examine gutters, downpipes, flashing, rendering and window frames in detail;
  • Always make sure that downpipes are unobstructed;
  • If the guttering has seen better days, think about replacing it with new easy-to-fit plastic guttering;
  • Check the rendering to see if it's cracked, plus look at re-sealing any gaps around window frames;
  • Check underneath window sills as there should be a drip groove to shed rainwater, before it gets to the house wall. If this is blocked with moss, dirt or cement, clear it thoroughly.


Curing Penetrating Damp Proofing Step-by-Step

Damp can easily be spotted with the naked eye. The tricky part is diagnosing what caused it in the first place. This can be difficult and it is best if you involve qualified professionals with proper equipment, such as; electrical resistance meters, carbide meters, thermal imaging cameras and so on.

The process for treating and safeguarding against penetrating damp usually involves the removal of all plaster and backing coats to brick work in affected areas. Then the brick work receives a 3-1 waterproofed sand and cement render coat, followed by a multi plaster finish coat when render has been allowed to dry.



If you notice watermarks and/or mould developing on the walls of your property, contact Damp Proofing London Immediately for a free inspection. Alternatively, you can send us the details of your problem and we will respond as soon as possible. Our experience and professional equipment can make a difference when it comes to waterproofing issues.


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Contact us today on:        077 0908 4010

020 8378 0089

Unit 142 Culvert Court, Culvert Road, London, SW11 5AU