Penetrating Damp Problems
A) Penetrating damp is caused by block cavities when there is a lot of debris such as sand and mortar and parts
of bricks and wood left over from the original build bad building
practices today. This material gets wet and penetrates on to the
internal wall this damp then rises up onto the internal plasterwork and
looks like rising damp and which makes it look like the Dpc has failed.
B) Other courses of low level penetrating damp are heavy soils
raised up and touching the property’s external walls causing this
constant wetting and with blocked cavities this damp transfers across on
to the inner wall and timbers.
These properties have climbing plants, these types of plants grow by
sending their root system into the mortar which causes the bed joints to
open and force out the sand and lime mortar. This will leave your wall
open to driving rain and damp patches high up on the wall. And with this
much foliage the wall cannot evaporate any excess moisture. Wall ties
will also be exposed to the elements and will start to rust away.
D) Penetrating damp is also caused due to new raised ground levels and
the Damp Proof Course (DPC) being breached also the render is touching
the ground drawing moisture. The render being cement is cracking and it
has been render to the ground this is causing moisture behind it and
forcing it to detach from the wall. This will bypass the current DPC.
E) Remember a Dpc is a physical barrier
to stop moisture traveling upwards you would be very unlucky to have
one fail completely. A dpc will not stop anything, if things are going
under it or over it.
F) If Rising damp is suspected in vast cases it will really be penetrating damp which transfers across a wall and not up through the Dpc.
If the DPC has been broken or removed due to building work then another can be inserted and over lapped to make a new DPC.
Defective Guttering and Downpipes
wetting in the same area will allow water to soak through the walls
this will be due to lack of maintenance in many cases.
Defects liked blocked or broken gutters, broken downpipes and blocked
drains are some of the common faults which cause internal damp by
Blocked Air Vents and Cavity Walls
When air vents and cavities are blocked this will stop air circulating
under the floor and will increase the dampness in timbers. As this
moisture increases the right conditions for wood rotting fungi will
increase and create the right conditions for wood boring insect.
It is quite common in old houses to have blocked cavities due to poor building practices of the time.
These large amounts of building materials are carelessly left in there because early Victorian builders didn’t fully understand the cavities purpose.
Also when older houses had there sash windows replaced with new
plastic PVC the old sash weights and wood were left in the cavity
causing damp to transfer to the inner wall.
Some cavities have vast amounts of material in them causing damp to
penetrate onto the internal walls making it look like rising damp and a
If a property has had its old sand and lime plaster replaced or has
been skimmed over with pink gypsum plaster which isn’t breathable and
the property suffers from high humidity. This will make the plaster damp
and were this material holds a natural amount of natural salts such as
nitrates, chlorides and sulphates they can be carried within the
Some of these salts are hydroscopic (attract and hold water vapour
from its surroundings) and can make a wall appear to have rising damp or
some kind of damp penetration, when in fact it is damp humid air in a
room attracting moisture from the atmosphere.
A cement plinth with some of the render removed shows how when the
plinth cracks and shrinks how it traps damp behind it at a lower level.
This is made much worse by higher ground levels keeping the plinth
constantly wet and now bridging the DPC this has allowed plant roots to
also make the area worse by retaining more moisture.
cement plinths where originally put there as decoration to hide the
DPC. These days when they fail all they do is let water in at a lower
level and not let it out this trapped damp will appear on the internal plasterwork at a lower level along the skirting board.
French drain is simply a shallow gravel ditch excavated near the base
of the wall. This helps disperse damp that would otherwise collect and
soak into and up a brick wall, by allowing the moisture to evaporate
away first. If the ground is considered to be too wet a perforated pipe
can also be used to divert water further away from the house. This is
done by digging an extended trench into the garden, before back filling
with 20mm – 40mm gravel.
One of the most common damp problems is caused by defective plumbing
these leaks can go unnoticed for months or years causing serious damage
to sub floor areas. Copper pipes can develop miniscule holes caused by
corrosion and this is a particular problem with unprotected copper pipes
laid in concrete floors.
Older houses are affected by this problem more every year, soft sand and lime mortars are washed away by weathering and allowing rain penetration.
As well as preventing rain penetration and protecting wall ties from corrosion good pointing makes the house look better again.
Building Cracks in External/Internal Brickwork
buildings move and most will show some signs of cracking at some stage,
many cracks have been there for decades such as historic structural
movement which has now stabilised and mean very little. Sometimes these
cracks are danger signs such expanding corroding wall ties but mostly
it’s just your house adjusting to the seasonal weather changes during
Any minor cracking may simply be your old house shuffling about on
very shallow foundations like it always has and with general maintenance
these cracks can be refilled. Always call for advice if you have any
concerns about these problems.
Houses which suffer from this problem are caused
when the old sand and lime mortar has been eroded away with time as it
was supposed to, this protected the soft handmade bricks and aloud the
mortar to expel moisture. Spalling is caused when the old sand and lime
mortar is replaced with much harder sand and cement which is tougher
than the old bricks and doesn’t allow moisture to be expelled through
the mortar bed.
What happens now is that that trapped
moisture cannot pass through this harder mortar and forces it way out
through the face of the brick causing it to blow the face of the brick.
Woodworm Infestations Treatment
Most of our woodworm treatment takes place in the lofts of houses as
that is where most seem to start because these little beetles fly into
them and start there life cycle. But any long term woodworm infestation
in a house with softwood such as pine in its construction can and does
seem to spread. They do like the ground floor area this probably due to
sub floor timbers attracting slightly more moisture and making the wood
more easily attacked.
They will spread along the floor joist and underneath the floorboards
into other rooms in the sub floor areas and when the grubs are ready
emerge from there flight holes as adult beetles. The woodworm treatment
we off will quickly stop the infestation and the woodworm life cycle as
the product soaks into the wood.
The woodworm treatments we offer can easily stop the wood boring
insect infestation which is alive in your house and causing damage to
your construction timbers. A woodworm treatment is applied to prevent
the further damage caused by the woodworm grub
Beetle infestations like the common furniture beetle are common today
because much of the timber used in construction is softwoods such a
pine. Everything in your home from the roof joists to the floorboards is
made from it and they like to infest damp timber.
Properties from the 16th, 17th and 18th Century
tend to have much more hard wood in there construction like oak and
suffer attack from the Deathwatch beetle in damp conditions.
Common Furniture Beetle
The common furniture beetle is the everyday name given to the insect
which de Geer called Anobium punctatum in 1774. The common furniture
beetle belongs to the family ANOBIIDAE which contains about twenty two
different species found in Britain.
The adult beetle varies in size from 2.5 mm to nearly 4.5 mm in
length and is usually chocolate brown in colour. All are covered with
fine yellowish down which does not however hide the longitudinal rows of
punctures or small pits on the elytra or wing cases.
The Deathwatch beetle is an indigenous British insect which due to
its habits has been well known for several hundred years. It was given
the name Xestbbium rufovillosum by De Geer in 1774 which is the name now
commonly used although in older text the name tessellatum was used
The Death Watch Beetle is a wood boring beetle, typically sized
between 6mm – 9mm, the females slightly larger than the males and larvae
growing up to 11mm long. It is dark greyish brown in colour with a
pattern of yellowish scale like hairs on the pronotum and wing cases.
The wing cases however often become rubbed when the colour may be more
reddish and shining. The longitudinal rows of small pits on the wing
cases, present in Anobium punctatum are absent in Deathwatch.
old cob cottages were built on stone plinths, the effects of rising
damp should never become a problem as long as there is adequate external
land drainage. Specific attention should be paid to the build-up of soil that surrounds the stone plinth. As overtime this can build up leading to water penetration.
Wall tie failure
old Victorian and Edwardian homes early wall ties were large fish tail
items made from galvanized steel because this was the best product of
its time. But there was an understanding that due to the material used
that sometime in the future they would probably have to be replaced due to corrosion.
When these large wall ties do start to corrode seriously, they expand
under the bricks and can cause horizontal and vertical cracking.
Raised Ground Levels
properties over time have had the ground around them raised to install
new paths and driveways this has had a negative impact on the house its
In some cases it has blocked air bricks and in others it has gone
above the properties Dpc which prevents rising damp affecting you and
your internal timbers. In others if you have a rendered property it will
allow moisture to travel up the render and pass your Dpc and cause
Damp Proofing and Woodworm Treatment Surveys
Once you have a fault and it takes affect long term then damp problems
start to appear they manifest themselves into one of several common
types of damp; rising damp, penetrating damp, salt damage or
condensation due to excessive internal humidity.
Any one of these damp issues can then lead to secondary problems such
as wet and stained walls, woodworm infestation, wet and dry rot
outbreaks and wall tie replacement due to corrosion or spalling
You may need a professional damp, woodworm, waterproofing or building
survey report because you are buying or selling a property. Or have had
a Home buyers report and need questions answered fast and reports
Free Sales Quotations for Property Faults
A sale quote allows a prospective buyer of our
services to see what costs would be involved for the work they would
like to have done without the need for a detailed survey report.
Don’t be damp Be Dri call us today and let us help you with any of
your damp proofing, woodworm treatments, wall tie replacement,
repointing brickwork and wet and dry rot issues.
It’s free to call and costs nothing to ask your questions.