How to find your original damp proof course

Did you know that properties built after 1875 were required by law to have a damp
proof course?

Before you contact a damp proofing company who may just inject a new chemical
damp proof course, consider locating the original DPC in your house – you may be
able to avoid unnecessary remedial works.

Where to start….

Typically, a damp proof course comprises of a layer of slate, bitumen felt, or plastic
membrane. The type of damp proof course is dependent on the age of the house.

Victorian houses will usually have a layer of slate bedded in mortar below the level of
the ground floor joists as shown in this photo taken from a late 19 th century house in
NW1 Camden North London …

Sometimes the damp proof course is formed by two or three layers of slates and is
hidden behind a thicker layer of mortar as seen in this early 1900s terraced house in
AL5 St. Albans Hertfordshire …

Houses built after 1930 were usually constructed with a bitumen damp proof course.
Hessian or burlap cloth soaked in a bituminous solution would serve well during this
period at preventing capillary moisture via rising damp. Bitumen is a very durable
material and will still perform well in houses which are nearly one hundred years old
such as this 1930s detached house in HA2 Harrow Middlesex …

 

Another example of bitumen felt DPC can be seen in this bungalow built in 1950 in
HP12 High Wycombe in Buckinghamshire …

Plastic damp proof membranes were almost exclusively used in buildings
constructed after 1960 and are still the preferred choice for a DPC today. Often
made from polypropylene they are manufactured in a way to provide a robust damp
proof barrier to prevent moisture rising up within the wall.

Here you can see the edge of the plastic damp proof course in this photo taken from
a late 20 th century semidetached house built in NW5 Highgate North London …

 

Once more here in this modern block of flats in N19 Archway near Islington you can
see the physical plastic membrane sandwiched in a low level mortar line:

 

Less commonly, blue engineering bricks were also used as to prevent dampness in
buildings due to their impervious nature. These bricks are stronger and less porous
than other types of brick and can look impressive when used to create an
inexpensive and effective DPC as shown in this turn of the century town house in
SL4 Windsor Berkshire …

If you need help identifying the damp proof course in your building, Avant
Garde Damp Solutions can help you.
Since 2003, we have expertly solved damp problems in homes and commercial
premises throughout North and West London,
including  Ealing  and Hammersmith
We rarely inject a new DPC as we believe that relieving the original damp proof
course offers a far more effective and long term solution.
Would you like to learn more? CONTACT US as soon as possible!