I've cured most of the rising+penetrating damp in my 100-yr old house
house by raking out the cavities to below DPC-level wherever there was
a problem. The original slate DPC seems to be in good condition.

However, in one place, there is a 2-ft wide pier which was possibly
added after the original build. It was built into the cavity. (It is
9" thick, and stands proud of the inside face of the inner sking by 2"
and proud of the inside face of the inner skin by the width of the
cavity, i.e., it actually fills the cavity. It supports an RSJ which
runs accross the room at that point, supporting a first floor outer
cavity wall. The ground floor was extended forwards at some stage.
Hence the addition of the pier and the RSJ.

The pier has had a damp problem all the time I've owned the place, and
the damness can be felt up to a higher point than the other places
that had dampness.

How can I cure the damp in the pier? Chemical injection? The outside
of the house has been painted with Dulux Weathershield for the past 15
years, so I guess it cannot be the penetrating damp. I suspect that
the DPC was omitted from the pier, or they filled the cavity with
brick and mortar at the point where the pier was built and neglected
to add DPC to bridge the filled cavity.

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) ?

I could just paint the wall with damp-seal, but I would like it to
pass a surveyor's dampness inspection when I come to sell the place
shortly.

Thank you,

Mike D

"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.

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

The message . com
from Chris George contains these words:

Rising damp is due to hygrosopic (yes that is spelt correctly) salts

Not in my dictionary.

OTOH hygroscopic is.

--
Roger Chapman

On Thu, 14 Jun 2007 09:59:42 -0700, Chris George
wrote:


In fact you could do that without the dpc and probably get away with
it but not recommended.
Good luck
Chris

Chris, Thanks for your input. All of what you said concurs with my own
understanding of the issue. The house was built with lime mortar, so
that prabably helped. Yes, the damp meter shows a higher reading near
ground level and in most places the walls are much drier above 1 mtr
above floor level. I agree that your remedy is the thorough approach,
but hacking the plaster off the walls and replastering is, of course,
extremely disruptive and messy, to say the least. And the plaster that
has been used is not easy to remove.

Cheers,

Mike

On Thu, 14 Jun 2007 13:44:57 +0100, "DIY" secret wrote:

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.

OK - thanks..

Mike

On 14 Jun, 13:31, Mike D wrote:
I've cured most of the rising+penetrating damp in my 100-yr old house
house by raking out the cavities to below DPC-level wherever there was
a problem. The original slate DPC seems to be in good condition.

However, in one place, there is a 2-ft wide pier which was possibly
added after the original build. It was built into the cavity. (It is
9" thick, and stands proud of the inside face of the inner sking by 2"
and proud of the inside face of the inner skin by the width of the
cavity, i.e., it actually fills the cavity. It supports an RSJ which
runs accross the room at that point, supporting a first floor outer
cavity wall. The ground floor was extended forwards at some stage.
Hence the addition of the pier and the RSJ.

The pier has had a damp problem all the time I've owned the place, and
the damness can be felt up to a higher point than the other places
that had dampness.

How can I cure the damp in the pier? Chemical injection? The outside
of the house has been painted with Dulux Weathershield for the past 15
years, so I guess it cannot be the penetrating damp. I suspect that
the DPC was omitted from the pier, or they filled the cavity with
brick and mortar at the point where the pier was built and neglected
to add DPC to bridge the filled cavity.

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) ?

I could just paint the wall with damp-seal, but I would like it to
pass a surveyor's dampness inspection when I come to sell the place
shortly.

Thank you,

Mike D

wrong diagnosis, wrong treatment. Ask the experts
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1


NT

On 14 Jun, 18:41, Roger wrote:
The message . com
from Chris George contains these words:

Rising damp is due to hygrosopic (yes that is spelt correctly) salts

Not in my dictionary.

OTOH hygroscopic is.

--
Roger Chapman

Mea culpa - missing "C" not to be confused with hydro....

On 15 Jun, 18:42, Mike D wrote:
On Thu, 14 Jun 2007 09:59:42 -0700, Chris George
wrote:

In fact you could do that without the dpc and probably get away with
it but not recommended.
Good luck
Chris

Chris, Thanks for your input. All of what you said concurs with my own
understanding of the issue. The house was built with lime mortar, so
that prabably helped. Yes, the damp meter shows a higher reading near
ground level and in most places the walls are much drier above 1 mtr
above floor level. I agree that your remedy is the thorough approach,
but hacking the plaster off the walls and replastering is, of course,
extremely disruptive and messy, to say the least. And the plaster that
has been used is not easy to remove.

Cheers,

Mike

IF and only if it is certain that the wall has hygroscopic salts in
it (and you can verify that by testing or as described earlier) then
you have no choice but to replaster or live with the damp.
The objection to re-plastering is often based on the fact that most
commercial companies, quite wrongly, recommend it - regardless of
whether or not it is necessary - to protect themselves. By all means
try to keep it if it is borderline - you may get away with it if the
prospective purchaser's surveyor comes after a dry period.
Chris

On Sat, 16 Jun 2007 00:01:18 -0700, Chris George
wrote:

IF and only if it is certain that the wall has hygroscopic salts in
it (and you can verify that by testing or as described earlier) then
you have no choice but to replaster or live with the damp.
The objection to re-plastering is often based on the fact that most
commercial companies, quite wrongly, recommend it - regardless of
whether or not it is necessary - to protect themselves. By all means
try to keep it if it is borderline - you may get away with it if the
prospective purchaser's surveyor comes after a dry period.

That's helpful - thanks again...

Mike D

On Fri, 15 Jun 2007 15:04:37 -0700, wrote:

Ask the experts
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1

Useful link - thank you.

Mike

On Thu, 14 Jun 2007 09:59:42 -0700, Chris George
wrote:

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!

The only problem with this method is that the fluid will just shoot
away into an abyss if there are any irregularities in the old mortar
(and there usually are), which I discoverd to my cost (and DPC fluid
isn't cheap). If I need to repeat the treatment (and the indications
are that I will) I will use those wax stick things that slowly melt
and permeate the bricks/mortar course much more effectively.

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

I wouldn't recommend using render - you could end up with condensation
problems instead. In my previous house I used Limelite Renovating
plaster, which worked a treat. I don't think they make it any more but
I think there are equivalents. I am busy tearing off the render off my
damp party wal and it is not going back on. The previous owners had
made doubly sure that the damp would remain in the wall by using vinyl
paint on top of the render!

Maris

On 18 Jun, 13:57, Maris wrote:
On Thu, 14 Jun 2007 09:59:42 -0700, Chris George
wrote:

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!

The only problem with this method is that the fluid will just shoot
away into an abyss if there are any irregularities in the old mortar
(and there usually are), which I discoverd to my cost (and DPC fluid
isn't cheap). If I need to repeat the treatment (and the indications
are that I will) I will use those wax stick things that slowly melt
and permeate the bricks/mortar course much more effectively.

DryZone operates on precisely the same principle! It is a gel-like
cream which disperses slowly over the next few days. It does not
operate like a fluid but clearly to be injected has fluid (albiet very
sluggish) properties. Its spread far exceed frozen sticks - (if that
is what you are referring to by "wax" sticks. If it is indeed wax the
melting point is such that at NRT it wont melt so I assume you are
referring to AQUEOUS sticks with "wax-like" ingredients. If I am
wrong, I would be interested in the trade name.



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

I wouldn't recommend using render - you could end up with condensation
problems instead.

Condensation occurs due to the dew point having been reached and I
have never found in the last 30 years of specifying both an example
where the difference in U value between Limelite Reovating (a
vermiculite-containg sand cement render) and a cement render has
tipped the balance to condensation forming. Limelite Renovating is a
great product (be careful not to be confused with other manufacturers
"renovating" plasters based on gypsum!)but there are plenty of
occasions where it is not suitable and this is one. It has practically
no capacity to prevent salt migration to the surface and efflorescene
is common. Its adhesion is questionable where you have variable
absorbent substrates - just try tapping it after and you will find
more "hollow" sounds than with render. Where there is limited risk of
salt contamination and no lateral penetration - go for it if you can
find it but don't fear appropriately specifed sand cement render. If
you really want a good product where limelite would be OK why not be a
purist and put on an original lime render using a lime putty (NOT
bagged lime!) but that is quite another post into which I have not
intention of further travel!


In my previous house I used Limelite Renovating
plaster, which worked a treat. I don't think they make it any more but
I think there are equivalents. I am busy tearing off the render off my
damp party wal and it is not going back on. The previous owners had
made doubly sure that the damp would remain in the wall by using vinyl
paint on top of the render!

Maris

On Tue, 19 Jun 2007 00:04:22 -0700, Chris George
wrote:

On 18 Jun, 13:57, Maris wrote:
On Thu, 14 Jun 2007 09:59:42 -0700, Chris George
wrote:

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!

The only problem with this method is that the fluid will just shoot
away into an abyss if there are any irregularities in the old mortar
(and there usually are), which I discoverd to my cost (and DPC fluid
isn't cheap). If I need to repeat the treatment (and the indications
are that I will) I will use those wax stick things that slowly melt
and permeate the bricks/mortar course much more effectively.

DryZone operates on precisely the same principle! It is a gel-like
cream which disperses slowly over the next few days. It does not
operate like a fluid but clearly to be injected has fluid (albiet very
sluggish) properties. Its spread far exceed frozen sticks - (if that
is what you are referring to by "wax" sticks. If it is indeed wax the
melting point is such that at NRT it wont melt so I assume you are
referring to AQUEOUS sticks with "wax-like" ingredients. If I am
wrong, I would be interested in the trade name.

We are probably talking about the same thing. I couldn't remember what
the contents of the sticks was but sticks they were.



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

I wouldn't recommend using render - you could end up with condensation
problems instead.

Condensation occurs due to the dew point having been reached and I
have never found in the last 30 years of specifying both an example
where the difference in U value between Limelite Reovating (a
vermiculite-containg sand cement render) and a cement render has
tipped the balance to condensation forming. Limelite Renovating is a
great product (be careful not to be confused with other manufacturers
"renovating" plasters based on gypsum!)but there are plenty of
occasions where it is not suitable and this is one. It has practically
no capacity to prevent salt migration to the surface and efflorescene
is common. Its adhesion is questionable where you have variable
absorbent substrates - just try tapping it after and you will find
more "hollow" sounds than with render. Where there is limited risk of
salt contamination and no lateral penetration - go for it if you can
find it but don't fear appropriately specifed sand cement render. If
you really want a good product where limelite would be OK why not be a
purist and put on an original lime render using a lime putty (NOT
bagged lime!) but that is quite another post into which I have not
intention of further travel!

Condensation does not depend so much on the U value of the
construction as on the conductivity of the surface. i.e certain
surfaces (e. granite, metals) will always feel cold to the touch (and
therefore likely to induce condensation) whilst others such as timber
will feel warm. The U value does, of course, play its part.
Limelite renovating plaster was developed for damp situations
(something also referred to in a forum about Limelite that I just
viewed) whilst standard Limelite backing plaster was for non-damp
locations. I will concede that it is sometimes a bit prone to losing
its adhesion. My main reason for using it (and Limelite backing) was
it insulation properties. Carlite has similar properties, of course,
but is as hygroscopic as they come.

Maris