How to treat damp walls

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X L34
Rev 5.1 September 2009
(c) John Newton & Co. Ltd.
The Guide To Diagnosing And
Treating Damp, Permanently

John Newton & Company is a leading supplier of damp proofing membranes, the permanent
solution for treating damp problems. We have a wide range of damp proofing products and a
full technical team available to advise you on the best solution. We are also market leaders
in basement waterproofing, pumping and drainage solutions. For further information ring
01732 360 095 or visit

X L34
Rev 5.1 September 2009
The Guide To Diagnosing And Treating Damp, Permanently
(c) John Newton & Co. Ltd.
What are the Causes of Damp?
Damp causes many problems in properties. With the high level of
rainfall in the UK, the average home has to deal with thousands of litres
of rainwater, so it is no surprise that damp can become a big problem
for many. Damp on walls can look very unsightly, often causes a bad
smell in the house, and can cause permanent damage to plaster, paint
and finishes. It can also be bad for our health, aggravating respiratory
problems and encouraging the emergence of mites and mould. In many
cases, damp can be made worse due to poor maintenance. Damp
problems can be found all over the house - in or around the roof, walls,
High levels of rainfall in the UK
floors, windows, doors or pipework on any building. Often, if there is a
causes many damp problems
damp patch visible inside the home, the cause can be identified from an
issue on the exterior. A wet patch in the ceiling, for example, might be a
sign of a leaky roof
Let's start by looking at the main types of damp:
Rising Damp
Rising damp is caused by water soaking up through porous materials
into the floors and walls of the property, and usually occurs in houses
which haven't got a damp proof course, or the course has failed to work
properly. In these cases, the walls feel damp and cold to the touch, and
there is sometimes an unsightly mark on the walls. Internal decorations
often become stained and damaged, and plaster can become loose.
Any wall in contact with the ground can suffer from rising damp, thus
Clear water marks rising from the
affecting walls both inside and out - however it rarely comes up further
floor are evidence of rising damp
than one metre in height.
Penetrating Damp
Penetrating damp is caused by issues with the building or plumbing,
where a problem has allowed water to enter the property. Properties
near the sea or in exposed areas can suffer damp penetration from
driving rain. Symptoms will usually only occur during wet weather, but
it can affect roofs and ceilings, along with walls. A watermark might
appear on the interior wall, and grow if the water continues to enter.
When there are problems with the roof or gutter, rainwater is in regular
contact with the wall and causes saturation. Penetrating damp is far
more common in older properties, which have solid walls. A new
build property with cavity walls offers more protection and is unlikely
to suffer from this type of defect. Penetrating damp can be tricky to
diagnose, and often may require expert help.
Penetrating damp is often caused
by problems with the plumbing
John Newton & Company
Tel: 01732 360 095 Page 2

X L34
Rev 5.1 September 2009
The Guide To Diagnosing And Treating Damp, Permanently
(c) John Newton & Co. Ltd.
Condensation damp is caused by excessive moisture that cannot escape
from the property - as opposed to water coming in, in the cases of rising
and penetrating damp. If there isn't sufficient ventilation, condensation
will arise and moisture will be in the air, even if you cannot see it. There
can be a number of causes, for example poor heating, not opening
windows and using radiators to constantly dry clothes. Mould may
appear on walls, ceilings and fixtures and fittings within the house. In
addition, there is usually a strong musty smell present. Unlike rising
Mould is often present when damp
and penetrating damp, which is caused by problems within the building
is caused by condensation
condensation is largely caused by the inhabitants of the property.
How To Prevent and Treat Damp
There are several simple measures that might help damp, so it is worth
looking over your property thoroughly as the problem may be something
you can fix quickly. In addition, preventative measures, will also prove
extremely beneficial in keeping your property warm and dry.
If the cause of your damp is hard to identify, a damp meter can help you
pinpoint the source.

Treating Rising Damp
Classic rising damp is usually worse at the bottom of a wall than at the
Earth butting against a wall can
top. Common causes are blocked airbricks and `bridging' - when earth
cause rising damp
from the garden butts up directly on to the house wall, trapping moisture.
This is a common problem, but can be remedied by simply digging away
all the soil to see if it makes a difference.
If digging the external soil away doesn't work, you may need to look at
installing a dimpled damp proof membrane to the interior walls. This is
installed to the existing building substrate with fixing plugs, then plaster
is applied to the membrane. The membrane acts as an impermeable
separation barrier between the old surface and the new finish. This
significantly prolongs the longevity of the internal finishes whilst allowing
the damp wall to dry. The dimples of the membrane form an air gap
between the membrane and the wall, which ventilates the damp wall
and allows it to dry out naturally. Newton membranes generally require
minimal preparation, are quick to install, and are considered to be most
Newton Damp Proofing Membranes
sympathetic to the structure.
are a permanent damp proofing
John Newton & Company
Tel: 01732 360 095
Page 3

X L34
Rev 5.1 September 2009
The Guide To Diagnosing And Treating Damp, Permanently
(c) John Newton & Co. Ltd.
Treating Penetrating Damp
Penetrating damp forms when water gets in from the outside, so the first
step is to check everything in and around the property. Look at gutters,
downpipes, flashing, rendering and window frames in detail. Always
make sure that downpipes are unobstructed, and if required think about
replacing the guttering. The rendering may have cracked, letting in water,
or it might be necessary to re-seal any gaps around window frames. Also
check under the window sills to see if the drop groove is blocked with
moss or dirt. If so, clear it thoroughly, the blockage might be causing
A blocked gutter can cause
water to seep in to the property. A badly fitting roofing felt on a flat roof
penetrating damp
will also cause damp, as will a cracked wall so these would need to be
Treating Condensation
Condensation forms when warm air trapped inside the house meets cold
walls. Under these circumstances, mould quickly spreads. A portable
humidifier, which will suck up moisture in the air, can help, as will
maintaining regular heating, and adequate insulation - thus drying out
the room. Humidity-controlled extractor fans can be a great help too.
The mould and mildew can be removed by scrubbing well using bleach
diluted with hot water. Leave it on the surface for ten minutes then clean
What Is A Damp Proof Course?
Modern homes, built over the last 100 years, normally have cavity walls
Old houses often do not have damp
- two layers of bricks with a space between - and this can help prevent
proof courses
damp. And at the base of the walls, a damp proof course (DPC) is usually
installed, which comprises a waterproof covering, such as slate or felt
to prevent damp rising through the porous wall from the foundations.
Houses built before 1870 were not obliged to include this protection,
and it may well be lacking.
Chemical damp proof courses are often costly, and if not properly
installed and maintained, won't be much use. The installation of damp
proofing membranes negates the need for a damp proof course, and is
a simpler method of damp proofing. Part of the process of installing an
injected damp proof course is usually hacking off the existing plaster - an
extremely disruptive and messy process. Drilling and injecting a DPC is
also an exact science. Newton Damp Proofing Membranes, in contrast,
can be applied over most existing wall finishes without the need to
Newton 805 Newlath has been
remove them, providing an impervious barrier to protect the internal
used to treat damp in many
finishes without changing the status quo of the wall.
Grade II Listed buildings
John Newton & Company
Tel: 01732 360 095 Page 4

X L34
Rev 5.1 September 2009
The Guide To Diagnosing And Treating Damp, Permanently
(c) John Newton & Co. Ltd.
Frequently Asked Questions
What Is Newton 805 Newlath?
Newton 805 Newlath is a BBA certified 5mm high density polypropylene
studded membrane which has a heat welded mesh to the front face of
the product. With the 5mm studs facing the damp substrate, an air gap
is achieved so as to not trap moisture within the walls. The mesh on the
front side is a direct key for applying a render, plaster or a plasterboard
dot and dabbed. The material is opaque so the original substrate can be
Newton 805 Newlath is the original
seen behind for ease of application. It is the original and best meshed
and best meshed damp proofing
damp proofing membrane, with millions of metres now installed in the
UK and Ireland.
How Can I Find A Good Damp Proofing Specialist?
Just ring John Newton & Company on 01732 360 095 and we will put
you in touch with a damp proofing expert in your area, free of charge.
Newton Registered Installers are trained and monitored by John Newton
& Company so that we have not just the best damp proofing systems but
the best contractors to diagnose your problem, design your system and
then install Newton membranes to the very highest standards.
Can I Install Newton Damp Proofing Membranes?
Our Damp Proofing Membranes come with detailed fixing instructions
and can be installed by a skilled builder. If in any doubt, John Newton
Newton Damp Proofing Membranes
can be installed by a skilled builder
& Company can recommend professional installers who are highly
or professional damp proofing company
experienced at fitting the material quickly, and thus cost effectively.
Can I use Newton Damp Proofing Membranes in a below ground situation?
No. Our damp proofing membranes are suitable for dealing with all forms
of damp conditions above the ground but the fixing plugs do not deal
with the potential of running water. If you have basement waterproofing
then our Newton System 500 would be ideal. Call us or visit www.newton- for further information.
Are Newton Damp Proofing Membranes Guaranteed?
Yes. John Newton & Company are the holders of BBA certificate 00/3716
for Newlath, and all Newton membranes are guaranteed against
Newton Membranes can be used to
deterioration for 30 years, and have a life expectancy of at least 50 years.
deal with all types of damp including
rising and penetrating damp
John Newton & Company
Tel: 01732 360 095
Page 5

X L34
Rev 5.1 September 2009
The Guide To Diagnosing And Treating Damp, Permanently
(c) John Newton & Co. Ltd.
About John Newton & Company
Independent, family run and with a proud heritage spanning over 160
years, John Newton & Company is a market leader in the manufacture
of top quality, innovative and highly reliable waterproofing and damp
proofing solutions. Whether a damp wall needs treating, or a full basement
waterproofing system is needed, we can put you in touch with the best
damp proofing or waterproofing company in your area
John Newton & Company Is:
John Newton & Company was
Independent - we are not tied to any one supplier. This enables us to
established in 1848 by the current
source the very best products available globally from a range of reputable
chairman's great grandfather
Innovative - John Newton & Company was the first to introduce a ventilated
damp proof membrane in 1937 with their unique product Newtonite,
used extensively for renovation of buildings in the United Kingdom up
until 1983. The Newlath product was introduced to the market in 1984
together with its polypropylene fixing plugs. John Newton & Company was
also the first to develop and introduce a meshed membrane to accept
renders or plasters, Newton 805 Newlath. This remains the original
meshed membrane, and its success is measured by the fact that over 2
million metres have been used nationally since its introduction.
Outstanding products - Our wide range of water control and drainage
products have been developed through our unparalleled expertise and
proven in the widest applications. From church vaults and flooded cellars
Newton 805 Newlath was the first
to leaking tunnels, railway arches and wet basements, our BBA certified
meshed membrane on the market
products continue to provide, effective, lasting and economic solutions
to the problems of unwanted water.
Technical expertise and personal service - Our customers know they can
count on us to provide outstanding levels of personal, friendly service,
in-depth specialist knowledge and full technical support. Our technical
team is always on hand to advise you about any project, big or small.
We can also put you in touch with a reliable and trained damp proofing
expert in your area free of charge.
The name you can trust - As specialists in the damp proofing industry
since 1848, we have built an enviable reputation for quality, service
and reliability. Whether it's a new-build construction, renovation or
refurbishment project, you can rely on our products to ensure your
commercial or domestic buildings remain dry, protected and safe at all
Newton Damp Proofing Membranes
have revitalised many previously
uninhabitable properties
John Newton & Company
Tel: 01732 360 095
Page 6