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Written by Warren Muschialli

Understanding The Causes of Penetrating Damp

Penetrating damp is most commonly caused by one of two scenarios:

  1. 1. Water entering the walls due to defects within the building fabric. Faulty rainwater goods are the main cause of penetrating damp. Loose or damaged tiles, blocked gutters, hoppers and drainpipes can cause problems. These should be fixed as soon as problems occur and should be kept in a state of good repair.
  2. 2. Wind driven rain. Properties near the sea or in exposed areas can suffer damp penetration from driving rain. Symptoms will usually only occur during wet weather.

How can I tell if there is penetrating damp?

Darker patches may appear on the outside of the wall. Internally, damp patches will show at the same point. If you live in an exposed location, the damp patches will usually be worse during bad weather or in the winter.

When there are building defects or poorly maintained rainwater goods, external darker patches are usually visible on the wall. Small plants will often take root where defects have allowed debris to accumulate.

Penetrating damp is far more common in older properties with solid walls. A new-build property with cavity walls offers more protection. New-builds are unlikely to suffer from this type of defect unless there is some form of bridging of the cavity.

Treating Penetrating Damp

Check the outside of the property

  • Inspect gutters, downpipes, flashing, rendering, window and door frames and the walls themselves in detail.
  • Make sure that gutters, hoppers and downpipes are unobstructed, and replace damaged goods.
  • The rendering may have cracked, letting in water, or it might be necessary to re-seal any gaps around window frames.
  • Check under the window sills to see if the drip groove is blocked with moss or dirt. If so, clean it thoroughly.
  • Ensure that flat roof membranes are in good condition.
  • If the building defects have been repaired and the walls are still damp due to wind driven rain, treat the walls with Newton 807-BKK eco, a clear coating that seals the walls with a vapour permeable treatment, preventing water from entering the walls.

Treating Penetrating Damp With Newton Damp Proof Membranes

When the cause of penetrating damp has been rectified, the internal walls will take some time dry out, typically at a rate of 1mm per day. With large, solid walls, this can mean that the walls are still damp for a year or more, damaging new internal finishes.

Installation of a Newton System 800 Damp Proof wall membrane will allow for internal finishes to be completed while the walls are drying out.

Newton damp proof membranes can be installed by a builder or DIY. Our damp proofing packs and other damp proofing products such Newton 806-CWC thermal paint and Newton 807-BKK eco external water repellent can be purchased here and ordered on next day delivery. Visit our Damp Proofing Shop

Alternatively we could send you a list of Newton Specialist Basement and Damp Proofing contractors in your area.

Please note that if your damp problems are below ground within cellars or basements, or there are earth retaining walls, a basement waterproofing solution would be required. Read More: Basement Waterproofing.

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