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Damp Proofing

Rising damp & penetrating damp

What's the difference, how can I identify both, are there tell tale signs?

5 Answers from MyBuilder Damp Proofing Specialists

Best Answer

All properties are different which is why we offer a range of damp proofing solutions to suit different property types.

There are many sources of damp in buildings, rising damp, penetrating damp and condensation are the main types. It is important to get a reliable and properly trained surveyor to check out the problem fully before arriving at any conclusions.

Penetrating damp can be from driving rain, leaking gutters, defective adjoining roof coverings, defective seals to windows doors etc.

Rising damp is where dampness from the ground travels up the wall by a capillary action and there is either a defective, failed or no damp proof course installed to stop the progress of the moisture. An inexperienced or untrained surveyor may mistake condensation or penetrating damp or rising damp and recommend a course of action which will be unnecessarily disruptive and possibly expensive, worst of all it is also probably not required and will simply disguise the true cause of the problem.


Answered 19th Mar 2011

rising damp only reaches a max hieght of 1 metre ,any higher its penetrative


Answered 17th Feb 2011

There are ways of telling apart first visible signs for rising damp look for obvious staining low down on wall or salt crystals appearing check outside to see if damp course bridged ie driveway or new paths made higher. DPC should be 150mm above solid floor levels ie patios and drives. Penetraing damp sign are caused by problems on the outside and can be at any hieght so look outside for obvious signs ie gutter leaking, downpipes leaking or areas prone to wind where rain might drive into bricks allowing face of bricks to break down and become more porous if any of these problems are outside then check area inside the internal damp can move some times and come out somewhere else but it is usaully in the same area , Another problem you have to rule out is condensation which probably affects more properties than rising and penetrating damp put together this occurs mainly in winter if you want more information on condensation please ask
hope this helps steve


Answered 17th Feb 2011

corrrection to the 1st response rising damp will come up to 1.5 meters and is caused by a fault in the existing damp course or a non existent one. the buildings walls draw in moisture and suck it uo the walls. tell tell signs a tide mark up to and around 1.5 meters both pen and rise damp will cause salty marks and plaster failing. if its pen damp then u will usually have cracks or holes in render or pourous mortar or bricks letting it in.


Answered 23rd Feb 2011

the difference is that rising Damp occurs when a fault in the building’s basic structure lets in water from outside.
There are basically two types of damp:-
• Penetrating Damp
• Rising Damp
Penetrating damp occurs if water is coming in through the walls or roof, (e.g. under
a loose roof tile) or through cracks in the mortar bed or perished brick. Also, please ensure you check the outside of
your home after strong winds to ensure damage has not been caused.
Rising damp occurs if there is a problem with the damp proof course. This is a
barrier built into floors and walls to stop moisture rising through the house from the
ground. The usual evidence of rising damp is a ‘tide mark’ on the walls that show
how high it has risen. There can also be a musty smell.
Dampness can also be caused within your property if the external ground levels are
higher than the internal floor level. This will allow ground water to penetrate the
wall causing dampness internally. Please ensure that the levels of your garden are
kept at least 150mm below the internal ground floor level. Also, please do not store
items of furniture etc against the outside wall as this can lead to penetrating dampness
as well.
Damp can also appear due to a leak from a plumbing or heating pipe, washing
machine, dishwashers. Small leaks are often the cause of major repairs if left and not


Answered 17th Feb 2011

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