An awful lot of unscientific, unsubtantiated assertions are made about
rising damp. You do not have to look further than the opinions
expressed above to get a feel of it.
As best I can I will give you a resume of what happens.
Rising damp is caused by the migration of a solution of inorganic
salts from the ground into the plaster and bricks of a wall over a
long period of time - decades. It is NOT water per se that is the
problem but the water that is abstracted from the atmosphere at times
of high RH.
The reason the BRE experiment did not work is probably because the
chaps doing it could not reproduce the conditions in a building over a
period of say 50 years. I happen to know most of them and they are not
the only ones to have tried the idea of putting brick columns in ponds
of water and testing dpcs this way. ~The University of the South Bank
did a similar experiment with similar lack of sucess and drew a
Rising damp does exist. It is not particularly rare. The problem is
the specialists do egg it a lot and class bridged dpcs and latereral
penetration as rising damp. That may account for more than 50% of the
houses treated - unnecessarily! Plastering is NOT always needed and
not necessarily for 1 m - the standard distance. That is normally to
protect the interests of the company rather than the client. When my
firm was contracting in this field (1979) we did it for 1 year and
decided that it was simply not worth doing because the profit margin
was too low and most of the houses we visited did not have true rising
damp needing treatment. We got calls out for condensation - pipe leaks
- bridge dpcs - you name it!
your friend needs to do several things
1) establish that there really is no dpc - they have been mandatory
since 1886 and could have been bridged by soil and concrete paths
2) IF NO dpc - then borrow or buy a damp meter and plot readings in
all walls on an isometric sketch of the affected areas over a period
of several months at times of high and low RH. Any variation in the
tide mark indicates RD. There should be a pattern of readings
starting from the top of no damp at say 1 m down to very damp at say
800 mm then slightly damp below that at the top of the skirting.
check the skirtings - are they wet (greater than say 14 w/w ) if so
you may have some form of dampness
3) get at least three free surveys - select using the following
criteria a) full members of the PCA (ex BWPDA) b) offering GPT back up
guarantee c) most importantly insist the surveyor has the CSRT
these three will not ensure you get a good survey but will cut out
an awful lot of crap
4) USE YOUR COMMONSENSE in intermpreting the results and dont take
them as Gospel - most firms have their intersts at heart
5) If there is dampness but the plaster is not visually damaged - take
a risk - put in the dpc but delay the replastering for a year and see
if it dries out - that saves a lot of money
6) understand that the rising damp does not occur in the bricks so
drilling the bricks is a waste of time- It occurs in the mortar. Ask
the firm if they drill the bricks (trick question) If they say "Yes"
show them the door and explain that you wanted someone who understood
they needed to drill the mortar not the brick to put the hydrophobic
layer in the mortar
7) the best dpc (in my opinion) is one using a silane based compound -
trade name "Dryzone" from Safeguard Chemicals - you can buy it and diy
See the website
Costs - these vary from firm to firm but a good diy can negotiate
reductions by taking off skirtings where needed for them and doing the
hacking off themselves
8) read up on the BWPDA (now PCA) code of practice for DPC s which is
similar to that of the BS which is also worth reading
Both are a bit out of date but show the principles.
Come back to me if you need further help
Thank you Pete for your kind explanation. I was a bit suprised at the
unfounded nature of the allegation and look forward to a reasoned
response with facts and/or supportive evidence to substantiate what
meow2 has said about my post. Absent that, readers will be able to
make their own judgements. As a scientist I am always willing to
listen to a reasoned argument and change my mind.
last time I wrote about this it took a couple of hours, so not
Theres a damp faq on http://periodpropertyshop.co.uk/phpBB2/viewforum.php?f=1
, but the sites down, and no idea if it'll resurrect or not. Some
just take more than a couple minutes to sum up.
On 30 Oct, 18:02, firstname.lastname@example.org wrote:
Not misinformation, per se, as you could actually do this and get the
right result for the building. Not the best in information either
though is it?
If you did this there is a very strong likelihood you would get 3
quotes for work. You are essentially recommending that if you think
you may have rising damp get an opinion from 3 commissioned sellers of
them to check. Now one may be honest, but thats a risk as big as
suggesting you get 3 doubleglazing salesmen to give you an honest
appraisal of your windows.
How about suggesting that the person pay for a destructive test to
confirm the wall is actually damp, rather than go through the whole:
resistance meter SUGGESTS it's damp,
put a cDPC in
wall is still showing signs of damp
attempt to claim on lovely GPT backed guarentee
CSRT qualified surveyor turns up again and this time does a
destructive test on the wall
destructive test DETERMINES its damp (...or not)
Surely that has to be better than relying on commissioned salesmen and
risking uneccessary works?
Disclaimer: I undertake the works described, am not currently a PCA
member because the company I work for is not. The PCA has independent
non-commissioned surveyors listed on their website. There are
excellent surveyors working for companies that make them sell on
commission, promoting free surveys perpetuates the problems described
in this thread, worse still: promoting companies that have a
commissioned sales business model perpetuates the poor public
perception of the industry as a whole.
My opinion, not necessarily that of the company I work for.
This really is the issue here. IME , you will be told that you have
rising damp and a chemical injection plus "specialist" re-plastering is
needed at xyz cost, plus an option to insure against further damp for 20
years. How good the guarantee would be remains to be tested if later
tests reveal that there was no rising damp and the damp problem was
attributable to other causes of damp remains to be seen.
This is what I was trying to suggest to the OP when I mentioned that a
proper *independent* damp survey be done. I wish I had worded my reply
more strongly and mentioned a destructive test now. To be fair though,
it is unlikely that a vendor would allow such a test if they have been
living with a damp problem, and even tried to disguise it for the sale.
Fair enough and I agree with that totally.
FWIW, you have made some good points here but so has Chris who also,
obviously, has a wealth of experience in this field.
These might be of use if there is reason to believe there is a damp
problem, but doing one simply because a surveyor wants to offload
responsibility and a salesman says they want to do some work
isnt appropriate imho. Unless theres a realistic reason to believe
otherwise, the problem normally isnt damp, its the damp game.
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