We have a nice pastel pink coloured pebbledash coating over the side of
our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in diagnosis,
I need to rule off some other causes like guttering leaks and cracks in
brickwork, but as a treatment is the following expenditure generally
effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html

To preserve the finish, I need something transparent ...

--
Adrian C

Adrian C wrote:
We have a nice pastel pink coloured pebbledash coating over the side of
our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in diagnosis,
I need to rule off some other causes like guttering leaks and cracks in
brickwork, but as a treatment is the following expenditure generally
effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html


To preserve the finish, I need something transparent ...


I doubt it will be effective over paint

Adrian C wrote:
We have a nice pastel pink coloured pebbledash coating over the side
of our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in
diagnosis, I need to rule off some other causes like guttering leaks
and cracks in brickwork, but as a treatment is the following
expenditure generally effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html

To preserve the finish, I need something transparent ...

Dunno about that one but I can heartily recommend Liquid Plastics K501 for
what you want to do. It really is the dog's whatsits for that job
http://www.liquidplastics.co.uk/product.asp?id=163

Pete

Adrian C wrote:
We have a nice pastel pink coloured pebbledash coating over the side of
our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in diagnosis,
I need to rule off some other causes like guttering leaks and cracks in
brickwork, but as a treatment is the following expenditure generally
effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html

To preserve the finish, I need something transparent ...


Its quite the opposite. What many people dont seem to realise is that
water content in a wall is an equilibrium between water entry and
evaporation. Waterproofing products reduce water entry, but they
reduce water evaporation even more, so the wall gradually ends up
wetter.

The standard advice a la SPAB etc is to replace cement render with
lime, which allows much more evaporation. However its best to only do
such work when the cement render can be removed without damaging the
bricks.

This is one of those topics there is much argument about. If in doubt
check out SPAB's info on the topic, or ask on the periodpropertyuk
forum.

Having said all that, obviously you need to check the rainwater goods
etc before deciding bigger work is needed.


NT

Its quite the opposite. What many people dont seem to realise is that
water content in a wall is an equilibrium between water entry and
evaporation. Waterproofing products reduce water entry, but they
reduce water evaporation even more, so the wall gradually ends up
wetter.

Crazy logic. I have a SW facing gable end wall that was permanently damp
until it was sealed 10 years or so ago. Now it doesn't get wet
internally, so it doesn't need to dry. I really don't see the problem.

Stuart Noble wrote:
Its quite the opposite. What many people dont seem to realise is that
water content in a wall is an equilibrium between water entry and
evaporation. Waterproofing products reduce water entry, but they
reduce water evaporation even more, so the wall gradually ends up
wetter.

Crazy logic. I have a SW facing gable end wall that was permanently damp
until it was sealed 10 years or so ago. Now it doesn't get wet
internally, so it doesn't need to dry. I really don't see the problem.

i knew youd be along, thats why I said where to get the info from the
experts


NT

Adrian C wrote:
We have a nice pastel pink coloured pebbledash coating over the side of
our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in diagnosis,
I need to rule off some other causes like guttering leaks and cracks in
brickwork, but as a treatment is the following expenditure generally
effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html


To preserve the finish, I need something transparent ...

pebbledash is more or less water proof. I strongly suggest you look
elsewhere..like higher up a wall with a cavity. .g. I had water dripping
out of a window lintel, due to failed bargeboards about 15 ft higher..it
ran down the cavity..

wrote:
Adrian C wrote:
We have a nice pastel pink coloured pebbledash coating over the side of
our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in diagnosis,
I need to rule off some other causes like guttering leaks and cracks in
brickwork, but as a treatment is the following expenditure generally
effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html

To preserve the finish, I need something transparent ...


Its quite the opposite.

oh god, sermon time.


In modern houses, (post the ark basically) there should be a waterproof
outer coating, and the indside breaths to lower any moisture, and you
have ventilation to exhaust it from

wrote:
Stuart Noble wrote:
Its quite the opposite. What many people dont seem to realise is that
water content in a wall is an equilibrium between water entry and
evaporation. Waterproofing products reduce water entry, but they
reduce water evaporation even more, so the wall gradually ends up
wetter.
Crazy logic. I have a SW facing gable end wall that was permanently damp
until it was sealed 10 years or so ago. Now it doesn't get wet
internally, so it doesn't need to dry. I really don't see the problem.

i knew youd be along, thats why I said where to get the info from the
experts


which you aint.


NT

The Natural Philosopher wrote:
pebbledash is more or less water proof. I strongly suggest you look
elsewhere..like higher up a wall with a cavity. .g. I had water dripping
out of a window lintel, due to failed bargeboards about 15 ft higher..it
ran down the cavity..

Thanks, will do. We had the guttering and the roof replaced a year ago,
and it's a bit uncertain wether the damp had got in and damaged the wall
before or after that operation (it's a dimly lit room).

Though, where the water is coming in is the exposed gable end and there
is brickwork for two chimneys that I suspect will need looking at. A
fellow popped his head through the door and reckoned some sprayed on
sealer on the render would do the job - which to me looked a bit doubtful.

I'm more interested in the cause of it and am now heading for a cheap
'prongs in the wall' damp meter (screwfix? ebay?) and a closer look,
once I get access.

--
Adrian C

The Natural Philosopher wrote:
wrote:
Adrian C wrote:
We have a nice pastel pink coloured pebbledash coating over the side of
our 1930's (solid brick - no cavity) house, and water seems to be
getting in to stain some of wallpaper inside. A bit early in diagnosis,
I need to rule off some other causes like guttering leaks and cracks in
brickwork, but as a treatment is the following expenditure generally
effective?

http://www.i-sells.co.uk/enviroseal-external-water-repellent-concentrate-ltrs-p-4048.html

To preserve the finish, I need something transparent ...


Its quite the opposite.

oh god, sermon time.


In modern houses, (post the ark basically) there should be a waterproof
outer coating, and the indside breaths to lower any moisture, and you
have ventilation to exhaust it from

Adrian wrote:
our 1930's (solid brick - no cavity) house

SPAB advice:
http://tinyurl.com/ak5dbn


NT

wrote:
Stuart Noble wrote:
Its quite the opposite. What many people dont seem to realise is that
water content in a wall is an equilibrium between water entry and
evaporation. Waterproofing products reduce water entry, but they
reduce water evaporation even more, so the wall gradually ends up
wetter.
Crazy logic. I have a SW facing gable end wall that was permanently damp
until it was sealed 10 years or so ago. Now it doesn't get wet
internally, so it doesn't need to dry. I really don't see the problem.

i knew youd be along, thats why I said where to get the info from the
experts


You can depend on me

pebbledash is more or less water proof.

But often the render supporting the pebbledash is crazed. Not always
easy to see

On 8 Mar, 16:33, wrote:

Its quite the opposite. What many people dont seem to realise is that
water content in a wall is an equilibrium between water entry and
evaporation. Waterproofing products reduce water entry, but they
reduce water evaporation even more, so the wall gradually ends up
wetter.

Although I'd agree your general point, you can't extend this to, "all
walls will become wetter if their outer face is sealed" without
knowing more about the wall and the weather.

How much water exposure does the wall suffer?

Where does the evaporation take place, inside or outside face?
(mainly an issue for sheds, but it's significant for single-skin rear
wings in Victorian terraces too).

Can you reduce the water exposure on the outer face or top surface by
fixing some other problem, such as guttering or inadequate
waterproofing around the eaves?

We've got a big Victorian pile with a damp problem that's almost
certainly caused by a leaking roof valley. Yet the previous owners
spent money on having a "coating" applied to everything outside. It's
a "coating" rather than mere "paint", because paint doesn't cost over
£11 thousand! No fix, a lot of money, and yes it's probably going to
make that specific problem worse rather than better. However the
coated section of the house (apart from this small area) _is_
distinctly drier inside than the unpainted section to the rear, which
has the same wall construction and is actually more sheltered from the
weather.

I also like the colour, although I wouldn't have spent £11k for it!
8-)

SPAB, and the Scottish equivalent, are largely talking about large-
scale buildings with very thick walls. Their obsession with lime
renders as a panacea works fine on those, but it's not the solution
when you're a cheaply-built fisherman's cottage facing the worst of
the sea's weather.

On 8 Mar, 21:34, The Natural Philosopher wrote:

In modern houses, (post the ark basically) there should be a waterproof
outer coating, and the indside breaths to lower any moisture, and you
have ventilation to exhaust it from

If we were talking about "modern" houses, we either wouldn't be having
this conversation, or we'd be asking how to sue the builder for
getting it wrong. "Modern" in this sense is really quite modern, and
much newer than where many (most?) of us live. It's certainly far more
recent than the Ark.

Andy Dingley wrote:
On 8 Mar, 21:34, The Natural Philosopher wrote:

In modern houses, (post the ark basically) there should be a waterproof
outer coating, and the indside breaths to lower any moisture, and you
have ventilation to exhaust it from

If we were talking about "modern" houses, we either wouldn't be having
this conversation, or we'd be asking how to sue the builder for
getting it wrong. "Modern" in this sense is really quite modern, and
much newer than where many (most?) of us live. It's certainly far more
recent than the Ark.

When I said post the Ark, I sort of had a reason.

Meows stuff applies to soft brick or timber houses with lime mortar and
no DPC.

Once you move to portland cement, the mortar is more or less waterproof
compared with lime, and the bricks have to be strong enough to be used
with it.

It was about the same time that relatively hard brick and portland
cement came in that DPC's were also becoming used, and tee design of
houses shifted from allowing water to get out, to stopping it getting in.

Use of open fires also tended to remove internal moisture adequately.


Given a proper overhanging roof and drip boards around windows, such
houses are perfectly dry in the absence of strong driving rain or other
persistent soaking.

Us of a impermeable coating on such a house is either decorative, there
to act as a barrier in the presence of driving rain, or possibly to
prevent spalling when frost hits a slightly prmeapble surface of poor
brick. Its often applied where frost damage has already happened.

Needless to say if the ingress of water is elsewhere than via the
coating or cracks in it, the coating merely makes the symptoms worse.

Hence th myth that applying such coatings makes the PROBLEM worse. It
doesn't. Its simply makes it more obvious.

I repeat, in a post 1900 style house, control of damp by structural
breathing is the wrong approach. The structure isn't permeable enough
with or without coating.

You need to fix the leaks in the impermeable surfaces..and generally
those are failed guttering, timberwork, lead valleys and the like. Or
bridged DPC's.

Condensation inside is curd by ventilation, insulation, and heating.

The Natural Philosopher wrote:
Andy Dingley wrote:
On 8 Mar, 21:34, The Natural Philosopher wrote:

In modern houses, (post the ark basically) there should be a waterproof
outer coating, and the indside breaths to lower any moisture, and you
have ventilation to exhaust it from

If we were talking about "modern" houses, we either wouldn't be having
this conversation, or we'd be asking how to sue the builder for
getting it wrong. "Modern" in this sense is really quite modern, and
much newer than where many (most?) of us live. It's certainly far more
recent than the Ark.

When I said post the Ark, I sort of had a reason.

Meows stuff applies to soft brick or timber houses with lime mortar and
no DPC.

Once you move to portland cement, the mortar is more or less waterproof
compared with lime, and the bricks have to be strong enough to be used
with it.

It was about the same time that relatively hard brick and portland
cement came in that DPC's were also becoming used, and tee design of
houses shifted from allowing water to get out, to stopping it getting in.

Use of open fires also tended to remove internal moisture adequately.


Given a proper overhanging roof and drip boards around windows, such
houses are perfectly dry in the absence of strong driving rain or other
persistent soaking.

Us of a impermeable coating on such a house is either decorative, there
to act as a barrier in the presence of driving rain, or possibly to
prevent spalling when frost hits a slightly prmeapble surface of poor
brick. Its often applied where frost damage has already happened.

Needless to say if the ingress of water is elsewhere than via the
coating or cracks in it, the coating merely makes the symptoms worse.

Hence th myth that applying such coatings makes the PROBLEM worse. It
doesn't. Its simply makes it more obvious.

I repeat, in a post 1900 style house, control of damp by structural
breathing is the wrong approach. The structure isn't permeable enough
with or without coating.

You need to fix the leaks in the impermeable surfaces..and generally
those are failed guttering, timberwork, lead valleys and the like. Or
bridged DPC's.

Condensation inside is curd by ventilation, insulation, and heating.


Even modern bricks are not impermeable, and cement mortar used in
brickwork ditto.

The house wall being discussed is non-cavity, so the wall:
a) conducts water/damp through it
b) has no cavity surface from which to evaporate damp
c) is much more likely to experience transient surface condensation
d) due to all the above has a much higher risk of water problems than
a modern cavity wall
e) Has warm humid air on the inside and often cold air outside, which
routinely is _below_ the dew point of the interior air.

And now, its being proposed to add a vapour barrier *on the outside*
of this wall. That simply isnt an effective solution. To use that
approach is to misunderstand how water is handled by such a wall.

SPAB's advice re avoiding impermeable coatings is not aimed at huge
rambling residences, its aimed at walls that dont conform to modern
construction standards, ie dpc & cavity. SPAB's advice re lime is a
different topic aimed at not exactly the same types of wall.

And far from SPAB's advice being 'obsession', they actually are the
experts on this, and have learnt this stuff from both a huge amount of
experience and understanding the theory behind it. For someone to
claim they know better than spab simply because thats how it used to
be popularly done and they dont see what the problem is, is dubious at
best.


NT

e) Has warm humid air on the inside and often cold air outside, which
routinely is _below_ the dew point of the interior air.

I would venture to suggest that, with central heating, most homes have
warm, dry air on the inside, especially in winter.

And now, its being proposed to add a vapour barrier *on the outside*
of this wall. That simply isnt an effective solution. To use that
approach is to misunderstand how water is handled by such a wall.

No surface treatment is ever a "vapour" barrier. It isn't like covering
your house in cling film, it simply acts as a barrier to water droplets,
which is a completely different issue. Take a piece of new wood and
allow the rain to pour down on it for a couple of weeks. On planing you
will find that only the surface is wet. However, that doesn't mean
moisture isn't going in and out in the form of vapour, and there is no
way to prevent that. There are figures somewhere detailing the vapour
permeability of various surface coatings, and IIRC they are way up the
scale.

SPAB's advice re avoiding impermeable coatings is not aimed at huge
rambling residences, its aimed at walls that dont conform to modern
construction standards, ie dpc & cavity. SPAB's advice re lime is a
different topic aimed at not exactly the same types of wall.

It might help if SPAB defined "impermeable" in terms of coatings. AFAIK
there is no such thing short of full scale encapsulation. The siloxane
type products outlined earlier in this thread don't form a film at all,
so describing them as a "coating" is very wide of the mark.

And far from SPAB's advice being 'obsession', they actually are the
experts on this, and have learnt this stuff from both a huge amount of
experience and understanding the theory behind it. For someone to
claim they know better than spab simply because thats how it used to
be popularly done and they dont see what the problem is, is dubious at
best.

I don't mind listening to experts, even the self-appointed ones, but I
stop when their arguments cease to make sense.

Stuart Noble wrote:

e) Has warm humid air on the inside and often cold air outside, which
routinely is _below_ the dew point of the interior air.

I would venture to suggest that, with central heating, most homes have
warm, dry air on the inside, especially in winter.

40% RH is fairly normal for an old house.
As air is reduced in temperature, it can hold much less water vapour,
so cooling 40% 20C air to outdoor temp results in condensation on a
cold winter's day. One way old non-cavity walls handle this in winter
is by evaporation from the outside surface. If that evaporation is
heavily reduced, damp problems sometimes occur.


And now, its being proposed to add a vapour barrier *on the outside*
of this wall. That simply isnt an effective solution. To use that
approach is to misunderstand how water is handled by such a wall.

No surface treatment is ever a "vapour" barrier. It isn't like covering
your house in cling film,

Exterior coatings of many kinds greatly reduce rate of evaporation.
Its not necessary to prevent it completely to run into trouble.

it simply acts as a barrier to water droplets,
which is a completely different issue. Take a piece of new wood and
allow the rain to pour down on it for a couple of weeks. On planing you
will find that only the surface is wet. However, that doesn't mean
moisture isn't going in and out in the form of vapour, and there is no
way to prevent that. There are figures somewhere detailing the vapour
permeability of various surface coatings, and IIRC they are way up the
scale.

SPAB's advice re avoiding impermeable coatings is not aimed at huge
rambling residences, its aimed at walls that dont conform to modern
construction standards, ie dpc & cavity. SPAB's advice re lime is a
different topic aimed at not exactly the same types of wall.

It might help if SPAB defined "impermeable" in terms of coatings. AFAIK
there is no such thing short of full scale encapsulation. The siloxane
type products outlined earlier in this thread don't form a film at all,
so describing them as a "coating" is very wide of the mark.

Even those reduce evaporation. After repeated application over time,
they heavily reduce evaporation. It isnt the solution.

And far from SPAB's advice being 'obsession', they actually are the
experts on this, and have learnt this stuff from both a huge amount of
experience and understanding the theory behind it. For someone to
claim they know better than spab simply because thats how it used to
be popularly done and they dont see what the problem is, is dubious at
best.

I don't mind listening to experts, even the self-appointed ones, but I
stop when their arguments cease to make sense.

They make sense just fine, but naturally one needs to study and
understand them properly. The understanding of how old buildings
handle water has moved forward in the last 2 decades, and
unfortunately not everyone is willing to learn what they thought they
knew all about.


NT

wrote:
Stuart Noble wrote:

e) Has warm humid air on the inside and often cold air outside, which
routinely is _below_ the dew point of the interior air.
I would venture to suggest that, with central heating, most homes have
warm, dry air on the inside, especially in winter.

40% RH is fairly normal for an old house.
As air is reduced in temperature, it can hold much less water vapour,
so cooling 40% 20C air to outdoor temp results in condensation on a
cold winter's day. One way old non-cavity walls handle this in winter
is by evaporation from the outside surface. If that evaporation is
heavily reduced, damp problems sometimes occur.

Condensation shouldn't be a problem in a properly heated and ventilated
house. The usual problem in winter is that cold air coming into the
house contains too little moisture, is heated to 20degs or whatever, and
is then much too dry for comfort. In other words, there is generally a
shortage of moisture, not an excess.
However, even if you discount that, you have to balance vapour going out
against rain ****ing in. I am simply not prepared to have wet walls so
that a minute amount of possible condensation can go in the opposite
direction.

And now, its being proposed to add a vapour barrier *on the outside*
of this wall. That simply isnt an effective solution. To use that
approach is to misunderstand how water is handled by such a wall.

No surface treatment is ever a "vapour" barrier. It isn't like covering
your house in cling film,

Exterior coatings of many kinds greatly reduce rate of evaporation.
Its not necessary to prevent it completely to run into trouble.

I'm not sure they reduce it at all. Water vapour is air, and it just
isn't that easy to stop. What can be a problem with surface coatings is
when rainwater, not vapour, gets behind it.

it simply acts as a barrier to water droplets,
which is a completely different issue. Take a piece of new wood and
allow the rain to pour down on it for a couple of weeks. On planing you
will find that only the surface is wet. However, that doesn't mean
moisture isn't going in and out in the form of vapour, and there is no
way to prevent that. There are figures somewhere detailing the vapour
permeability of various surface coatings, and IIRC they are way up the
scale.
SPAB's advice re avoiding impermeable coatings is not aimed at huge
rambling residences, its aimed at walls that dont conform to modern
construction standards, ie dpc & cavity. SPAB's advice re lime is a
different topic aimed at not exactly the same types of wall.
It might help if SPAB defined "impermeable" in terms of coatings. AFAIK
there is no such thing short of full scale encapsulation. The siloxane
type products outlined earlier in this thread don't form a film at all,
so describing them as a "coating" is very wide of the mark.

Even those reduce evaporation. After repeated application over time,
they heavily reduce evaporation. It isnt the solution.

And far from SPAB's advice being 'obsession', they actually are the
experts on this, and have learnt this stuff from both a huge amount of
experience and understanding the theory behind it. For someone to
claim they know better than spab simply because thats how it used to
be popularly done and they dont see what the problem is, is dubious at
best.
I don't mind listening to experts, even the self-appointed ones, but I
stop when their arguments cease to make sense.

They make sense just fine, but naturally one needs to study and
understand them properly. The understanding of how old buildings
handle water has moved forward in the last 2 decades, and
unfortunately not everyone is willing to learn what they thought they
knew all about.


NT