Learn
from the UK's top Expert: become your own expert - save money. Quick
DIY Master Class in Dampness and Condensation - become your own Expert in
1 hour! Buy our "Dampness in Buildings" reprinted book by the great
expert Graham Coleman. A great read, short and to the point. Click
here to buy the reprint.
A
'damp meter', surface thermometer and memory hygrometer (see www.dampness-info.co.uk/meters.htm)are
useful tools for this diagnosis - if not available use the back of your hand to
assess the relative dampness of one affected area to another unaffected area.. Check
for yourself using this quick summary 1.
Can you see any 'black spot' mold? Yes
= Condensation (use our Condensation Test
kit to confirm). Check ventilation and heating - redecorate with our Anti
Mold Emulsion. If you have a cavity wall (check the brickwork pattern on the
outside - longwise only bricks indicate a cavity construction) you might have
some dirty wall ties, giving rise to 'cold spots'. These can be cleaned by taking
out individual bricks. Severe black mold stains can be covered, after treatment,
with Stain and Damp Seal Paint, to prevent
the marks from 'grinning' through your final paint colour. No
= Probably not condensation although 'salts' from rising dampness can kill off
mould, masking part of the problem - is their any patchy mould? Try using an illuminated
map reading magnifier to view the wall surface. What can you see - strands of
fungus? Give us a ring for free advice on 01626 331351.
2.
Can you see a 'tide' line or damp stain above the skirting board up to a height
of about 6" - 18" (150mm - 450mm). Are the skirting boards damp or rotten? Yes
= may be rising dampness - check exterior ground levels are at least 6 inches
(150mm) below the Damp Proof Course level, check that the wall plaster does not
'bridge' the DPC or go down to a solid floor. Install a DPC and Replaster to our
Specification - use Renderproof Waterproofing
Additive. Also, check your neighbouring properties - are their floor levels above
yours? Have they replaced any timber floors with concrete of filled in a basement?
Councils often raise the level of the roads and pavements over the years, people
often raise the level of their gardens, or build things (like steps) against the
house wall. No =
if the damp is higher up the wall or patchy, more likely to be penetrating dampness
- check the exterior walls for defects, check gutters and downpipes, check the
pointing in the joints, treat with Ultra Proof
waterproofer.
3.
Can you see fluffy white 'salts' on the wall or are they crunchy beneath flaking
paint or lifting wallpaper? Yes
= you probably have penetrating dampness - the 'salts' indicate that wetting has
occurred and drying out is taking place - treat with Salt
Neutraliser, if the plaster is not too damaged. Check the exterior walls for
defects, check gutters and downpipes, check the pointing in the joints, treat
with Ultra Proof waterproofer. No
= your dampness may be due to 'hygroscopic salts' deposited in the wall from chimney
deposits (after burning coal or wood), or from a previous use of the building
(e.g. coal shed, animal food store, butchers shop). Treat with Salt Neutraliser
and replaster to our 'tanking' specification using BondAcryl.
In severe cases it is best to use the Mesh
Membrane wall lining system, rather than 'tank' or replaster - chimney salts
can burn back through even the best render backing coats sometimes.
4.
Have you got isolated damp patches that come and go, particularly on or next to
chimney breasts? Yes
= you may have 'hygroscopic' (means "attracts moisture from the air")
salts and chemicals from burning wood and coal, which have bled through the plaster.
Sometimes they show up as brown or yellow stains, particularly in wallpaper. Treat
with Salt Neutraliser and replaster
to our 'tanking' specification using BondAcryl.
In severe cases it is best to use the Mesh Membrane wall lining system, rather
than 'tank' or replaster - chimney salts can burn back through even the best render
backing coats sometimes. No
= map out the areas of dampness and look for the highest concentration - does
this area connect to a feature - like a radiator, boiler or sewerage pipe cover?
Have any recent changes been made to the building?
5.
None of the above - are the walls and floor visibly damp? Yes
= you may have a water leak topping up your soil under your property - follow
the water leak testing routine in the left hand column. No
= we give up - call us on 01626 331351 for a chat and we'll see if we can
help.
Testing
to find the water source If
you have a Water Meter turn off all your water using appliances for a few hours
and check to see if the meter dial moves. A.
Ask your local water Authority to test your Water Mains pipe for leaks. Particularly
ask them to test your neighbour's supplies on both sides: if you live on a hill
with properties above you check all those on the high side of your house. This
service should be free of charge. B.
If you have liquid water in your building (on a solid floor, or in a basement)
ask the Water Authority for an analysis - this will tell you where the water comes
from - mains, sewerage or spring/ground water. C.
Test your own drains - test the foul water by finding the man hole cover, lifting
it and running a tap to see which hole your water flows from. Block this hole
with a rubber bung (Hire Shop or Builders Merchant - 4 inch or 6 inch). Then fill
up a ground floor sink or loo with water and mark the level. Leave over night
- if not at the same level next day you need a Drains Company with a camera to
investigate. Don't forget to remove the bung! D.
Test the surface water drains - place a Dye Bag or granules of drains testing
dye (Builders Merchant) into the drain and fill up with water. Using a torch,
at night, look for signs of the coloured dye - it glows in the dark.
Replastering
old walls - You
may only have contaminated plaster and the original source of the moisture may
have been successfully tackled (e.g. new damp proof course, water leak solved).
Many, many Builders and Plasterers do not use this method of replastering and
in most cases the symptoms, of 'salt' contamination, will reappear if they have
used modern lightweight plasters, like 'bonding' or 'browning'. 1.
Hack off all old plaster to at least 300mm clear of all signs of damp or salt
and at least 1 metre above ground floor level - use a meter to test the walls
and remove plaster at least 300mm above the highest level that readings can be
obtained. Reason
- This is to ensure that the residual 'salts' do not climb above the new plaster
in the future. 2.
Brush the walls to remove all plaster residue, particularly around angle beads. Reason
- old plaster will have 'salt' in it and will cause damp spots to appear in time.
3. Repair any holes or poor joints with sand and cement (4:1) using washed, sharp
(means slightly gritty) plastering sand (sometimes called screeding or rendering
sand). Do not use fine, unwashed sands. Reason
- fine, unwashed sands often contain salt and the fine particles are too numerous
to find enough cement particles to bond together tightly - these two problems
make for a weak render, prone to the easy passage of 'salts'.
4. Special Note - walls made with non-porous stone or brick, like granite or blue
brick, will require an adhesive to help stick the render coat to the wall - use
BondAcryl concentrate) Reason
- normal renders and plasters stick to the wall by suction - the surfaces need
to absorb some water. Without this suction the render or plaster will not grab
the wall and may become loose and hollow as it dries. 5.
Damp the walls lightly (to reduce 'suction', which can cause excessive drying
and cracking) and apply a thin coat (maximum 1/2 inch, 12.5mm) of render consisting
of 3 parts sand - dry, washed, sharp (means slightly gritty) plastering sand (sometimes
called screeding or rendering sand) with 1 part of fresh (free flowing - no lumps)
Portland Cement. Reason
- thick coats are more likely to slump down the wall during application and crack
during drying out. 6.
Scratch the render surface liberally all over with a nail board, trowel, metal
float or similar object. Reason
- without these scratches the natural drying shrinkage will cause cracking, crazing
and hollowness to develop - the next coat will probably pull the first coat off
as it dries. 7.
Use only Renderproof water proofer/plasticiser in the water that the render is
mixed with, at the rate of 1 part Renderproof to 40 parts of water. Do not use
fine, unwashed or wet sands. Reasons
- Renderproof binds the sand to the cement and prevents liquid water passing through.
It also makes the mix stickier (plasticising) which help to hold the render together.
Wet sand weighs more than dry, so it will make your mix weak. Fine sands produce
a weak, powdery render, which will not resist 'salts'. Do not allow the plasterer
to add plaster (usually 'browning') or washing up liquid to the mix. 8.
When the render surface is firm enough (but not bone dry, or it will need re-wetting)
apply a second coat to exactly the same specification - if further coats will
be needed to reach the desired thickness don't forget to scratch liberally. In
hot weather spray the render surface with water to slow the drying process. Reasons
- excessive drying out increases the suction and can prevent one coat sticking
to another. Rapid drying always increases shrinkage, which gives rise to cracking
of the render or finish plaster. 9.
Whilst still damp (or re-wet again) apply a skim coat of Universal or Board Finish.
Do not polish or add water. Reason
- this will produce
a shiny, glazed finish which looks good, but is prone to condensation, black mould
growth and poor drying. 10..
Delay any decoration for at least one month and then only apply a thin coat of
breathable emulsion paint (not a heavy vinyl). Do not repaint or wallpaper for
at least three months. Reason
- the paint or paper will fall off the wall due to the water vapour that will
be trapped underneath in the new render.
For
Meters, Damp Proofing and Mold Products go to the: DAMP
SHOP A Calibrated Damp
Meter is a useful tool,
for checking your walls and floors. 
Then
consider a Home Condensation Meter also
known as a Hygrometer. This
shows you how much moisture is in the Air. This
one has the Jumbo Sized Display. 
This
one has the Standard Sized Display. 
To
kill Salts you can use Salt Neutraliser - to
buy Salt Neutraliser - go to our Shop
Anti-Mold
Paint Additive and
Ultra Mold Cleaner
would solve this problem with a 5 Year Guarantee. 
Ask
us about the answer to Black Spot Mould - Anti-Mould
Cleaner and Anti-Mould
Paint Additive with
a 5 Year Written Guarantee  BondAcryl
special Bonding Agent - go
to our Shop for Damp Products. BondAcryl
can be added to Renders and Screeds to make then Waterproof. 
Render
Additive - waterproofer,
salt inhibitor, plasticiser. This
is used to make Render (sand and cement plaster) into a 'salts' barrier but
it still allows the passage of vapour, so allowing the walls to dry. 
Or,
you can use an Air Gap Membrane on the wall. This
provides Insulation and a nice new surface for
plaster or plasterboard This
one is the Standard Mesh Membrane, 7mm thick.. 
This
one is the Slim Mesh Membrane - only 3mm thick. 
Learn
from the Expert: become your own expert - save money. Quick
DIY Master Class in Dampness and Condensation - become your own Expert in
1 hour! Buy our "Dampness in Buildings" reprinted book by the great
expert Graham Coleman. A great read, short and to the point. Click
here to buy the reprint.
FURTHER
READING - click to see: Damp
Proof Courses - what are they? Damp
Proofing Methods - different types. Damp
Proofing Efficacy - does it work?
Want
to become Qualified in Dampness and Timber Decay? Contact
us for details of Professional Courses Call
David or Angela on: 01626 331351 | 
