Building Protection Advice

Building Protection & Rain Penetration Advice

Rain penetration

What is rain penetration and how does it differ from other forms of water penetration?

Rain penetration with regard to buildings, is penetration above ground, which can be at various points externally. It can be through windows, doors, roofs or chimneys and can also include spillage from rain water goods e.g. down pipes or guttering.

Rain penetration is different from other forms of dampness such as rising damp or condensation and therefore requires a different approach when looking for a solution. Rainwater can enter a building by various means, e.g. wind pressure, gravity or capillary action and the affected building will suffer as will the occupants whose living conditions will become increasingly unhealthy.

Is rain penetration common in older buildings?

It can be found in older buildings for a variety of reasons: through neglect, inappropriate works or poor maintenance, and poor access to areas such as chimneys, roofs or parapets.

Traditionally walls were offered protection from the rain through the use of lime renders, pentice boards, projecting cills and other good ‘weatherings’.
The removal of lime renders from buildings and/or inappropriate modern applications e.g. cement renders, will cause the building to be vulnerable to dampness.

In addition, poor drainage around paths, patios or walls will lead to soaking through inadequate drainage, particularly if laid right up to a wall.

Is visual observation the only detection method for diagnosing rainwater penetration?

A visual inspection is of course important as the use of electrical equipment without knowledge or experience can give false readings. The employment of an independent consultant or chartered surveyor is always advisable. Rainwater penetration can be observed externally as green staining particularly to walls, leaking down water pipes or guttering.

What methods can be used to control rainwater penetration?

Initially the cause of the dampness must be found and then the symptoms can be treated through various management strategies.

Carrying out basic maintenance prior to any extensive works should be the first step towards remedying the problem. Modifications can be justified but generally a ‘like for like’ approach is considered appropriate.

I would like to use a sealing method to stop rain penetration. Is that appropriate?

NO, as this can result in the entrapment of water within the building, causing further deterioration. As mentioned previously, older buildings that pre-date the mid-19th century ‘need to breathe’ and allow moisture to evaporate back out as opposed to modern buildings that use barrier methods to exclude water entry. Ideally, modern building technology e.g. cement point or render, water repellent treatments or plastic paints should be removed but this can cause further damage. We would be happy to discuss the right approach and appropriate workmanship with you.

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