On 14 Jun, 13:44, "DIY" secret wrote:
"Mike D" wrote:
If chemical injection might be the answer, can anyone advise where I
can obtain a DIY-er's kit - (preferably from a well-known DIY chain) ?

You can hire damp proof injection equipment and buy the fluid from most tool
hire firms and from some builders merchants such as Jewsons. I haven't seen
this stuff in Been & Queued or Homebase.

Dear Mike
Firstly lets identify and separate penetrating damp from rising damp.
The former is most unlikely to be the cause of your problem unless the
pointing is bad, the brick porous and you live in a part of the
country that has horizontal driving rain commonly. The cure is NOT an
external paint of whatever sort as sooner or later that will micro
crack and let in water but not let it out! so if there is penetrating
damp due use the cavity not a paint!
Rising damp is due to hygrosopic (yes that is spelt correctly) salts
absorbing water from the atmosphere. It is caused by decades of
migration and evaporation of salt solutions from the ground in the
MORTAR of the wall to the surface plaster where water only evaporates
off leaving salts behind. Clorides and nitrattes etc. The cure is two
fold.
1) stop the salt solution rising
2) if NECESSARY hack off the contaminated plaster (which cannot be
cured) and replaster in a cementation - non gypsum plaster
A word of warning
you need to inject not the bricks but the mortar layer with a
continuous layer of hydrophobic material to make the mortar water
resistant
I have used in my house DryZone from Safeguard Chemicals. It workeed.
It only requires a bit of commonsense to follow the instructions and a
dirty great big applicator gun with lance on the end. You could rig up
your own system with aluminium or steel tube and a LARGE mastic gun.
Test the plaster as follows with a damp meter (hire or borrow) every
few cycles of humidity high and low and see if it alters the readings.
Test the pattern of existing readings - If there is a "high tide" mark
somewhere 300 to 1000 above the ground with lower readings above and
below - that is probably rising damp!
If you replaster use a 3:1 render with Sika No 1 water proofer and you
wont go far wrong
In fact you could do that without the dpc and probably get away with
it but not recommended.
Good luck
Chris