Hi,

I have a problem with mould on a single skin wall in a bedroom.

It's a 1930's 3-bed semi with bay windows. Downstairs, in common with
the rest of the house, the lower part of the bay is cavity-wall
brickwork.

The problem is that upstairs, in the front bedroom, the lower part of
the bay is actually a 4-panel single-skin affair. Limited investigation
show that it's a wooden framework filled with a mixture of broken brick
and mortar, pebbledash-rendered on the outside and plastered on the
inside.

The inside surface of this bay gets quickly covered with large patches
of black mould. In winter, the surface is visibly damp.

I initially sealed the outside with waterproofer (Thompson's Rainseal or
similar) to ensure that no water was coming through from the outside
and then covered the inside with a double layer of 2mm polystyrene
sheeting to try prevent condensation.

Alas, in a few months, the PVA glue failed and the sheeting peeled away
from the wall because it was being lifted off by efflorescence. And, of
course, it is all now covered in mould again.

Is it possible to /ever/ treat a wall like this to prevent mould
occurring or should I simply do what I suspect is the 'proper thing' and
erect some kind of inner skin to turn it into a cavity wall?

If I do have to turn it into a cavity wall, what's the best material
(and method) to use?

TIA

--
-blj-

On Sat, 17 Feb 2007 08:40:28 +0000, Brian L Johnson wrote:

Hi,

I have a problem with mould on a single skin wall in a bedroom.

It's a 1930's 3-bed semi with bay windows. Downstairs, in common with
the rest of the house, the lower part of the bay is cavity-wall
brickwork.

The problem is that upstairs, in the front bedroom, the lower part of
the bay is actually a 4-panel single-skin affair. Limited investigation
show that it's a wooden framework filled with a mixture of broken brick
and mortar, pebbledash-rendered on the outside and plastered on the
inside.

The inside surface of this bay gets quickly covered with large patches
of black mould. In winter, the surface is visibly damp.

I initially sealed the outside with waterproofer (Thompson's Rainseal or
similar) to ensure that no water was coming through from the outside and
then covered the inside with a double layer of 2mm polystyrene sheeting
to try prevent condensation.

Alas, in a few months, the PVA glue failed and the sheeting peeled away
from the wall because it was being lifted off by efflorescence. And, of
course, it is all now covered in mould again.

Is it possible to /ever/ treat a wall like this to prevent mould
occurring or should I simply do what I suspect is the 'proper thing' and
erect some kind of inner skin to turn it into a cavity wall?

If I do have to turn it into a cavity wall, what's the best material
(and method) to use?

TIA

====================================
It depends on how much work you're prepared to do and the general
condition of the bay. If the outer skin is in reasonable condition then
the best thing to do is to remove the inner skin, (lath and plaster??)
clear out all the rubble, assuming that it's loose enough to remove.
Having done this then a membrane can be fitted and the void left by the
removed rubble can be filled with insulation. Complete the job with
flexible plasterboard.

Before doing any of the above check the state of the 'mixture of broken
brick and mortar' infill. It's possible that this is intended to be there
as some kind of supporting wall or it may just be builder's rubble. Check
to see if it's loose enough to remove by hand or whether it's
intentionally mortared together.

Cic.

--
================================
Testing UBUNTU Linux
Everything working so far
================================

On 17 Feb, 08:40, Brian L Johnson wrote:

Hi,

I have a problem with mould on a single skin wall in a bedroom.

It's a 1930's 3-bed semi with bay windows. Downstairs, in common with
the rest of the house, the lower part of the bay is cavity-wall
brickwork.

The problem is that upstairs, in the front bedroom, the lower part of
the bay is actually a 4-panel single-skin affair. Limited investigation
show that it's a wooden framework filled with a mixture of broken brick
and mortar, pebbledash-rendered on the outside and plastered on the
inside.

The inside surface of this bay gets quickly covered with large patches
of black mould. In winter, the surface is visibly damp.

I initially sealed the outside with waterproofer (Thompson's Rainseal or
similar) to ensure that no water was coming through from the outside
and then covered the inside with a double layer of 2mm polystyrene
sheeting to try prevent condensation.

Alas, in a few months, the PVA glue failed and the sheeting peeled away
from the wall because it was being lifted off by efflorescence. And, of
course, it is all now covered in mould again.

Is it possible to /ever/ treat a wall like this to prevent mould
occurring or should I simply do what I suspect is the 'proper thing' and
erect some kind of inner skin to turn it into a cavity wall?

If I do have to turn it into a cavity wall, what's the best material
(and method) to use?

TIA

Sounds like youre going the wrong way about this,
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1

Whatever you do, batten/insulate is surely needed with 4" walls,
theyre expensively conductive.


NT

Cicero wrote

snip

It depends on how much work you're prepared to do and the general
condition of the bay.

It looks awful. I'll end up doing quite a bit to it, I think.

If the outer skin is in reasonable condition then
the best thing to do is to remove the inner skin, (lath and plaster??)
clear out all the rubble, assuming that it's loose enough to remove.
Having done this then a membrane can be fitted and the void left by the
removed rubble can be filled with insulation. Complete the job with
flexible plasterboard.

I've had a dig around in one corner. g

The outer rendering looks to be in good condition (and, as I said, I've
liberally doused it in waterproofing liquid -- whether or not it's
effective is anybody's guess) with no pinholes or cracks.

The bay wall itself is made up of 5 fairly flat sections. Each section
is a rectangular box of 3" x 3" timber with a single diagonal. Inside
this framework is piled a mix of broken brick and mortar. The outside is
then mortar rendered and the inside is plastered. (The curved skirting
board, instead of being kerfed wood, is actually a moulded plaster sweep
across the entire bay!)

I don't think I could remove the bricks etc without disturbing the
render on the outside. In reality, I think the infill and the outside
render are probably one and the same!

You mention membrane -- what sort of membrane? PVC sheeting? Butyl?

Before doing any of the above check the state of the 'mixture of broken
brick and mortar' infill. It's possible that this is intended to be there
as some kind of supporting wall or it may just be builder's rubble. Check
to see if it's loose enough to remove by hand or whether it's
intentionally mortared together.

--
-blj-

"" wrote


Sounds like youre going the wrong way about this,
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1

I can't quite find a topic there that directly pertains to my problem.
Is there something there that I missed?

Whatever you do, batten/insulate is surely needed with 4" walls,
theyre expensively conductive.

Very true!

My worry, though, is that battening on to this wall will just rot
because it will get soaked. Is that not the case?

--
-blj-

On 17 Feb, 23:40, Brian L Johnson wrote:
"" wrote

Sounds like youre going the wrong way about this,
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1

I can't quite find a topic there that directly pertains to my problem.
Is there something there that I missed?

First read would be the damp FAQ, search for that thread. Then
describe and ask them about your situation.


Whatever you do, batten/insulate is surely needed with 4" walls,
theyre expensively conductive.

Very true!

My worry, though, is that battening on to this wall will just rot
because it will get soaked. Is that not the case?

You've got 2 prolems to solve. Of course the damp issue needs solving
as well, otherwise as you say it'd rot. Insulation needs to be part of
the eventual solution though, otherwise condensation is going to be
hard to stop, and you'll be wasting much money on heating.


NT

"" wrote

On 17 Feb, 23:40, Brian L Johnson wrote:
"" wrote

Sounds like youre going the wrong way about this,
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1

I can't quite find a topic there that directly pertains to my problem.
Is there something there that I missed?

First read would be the damp FAQ, search for that thread. Then
describe and ask them about your situation.

Okay, so there're not in favour of tanking, and it looks like I should
be stripping off the outside rendering and replacing it with a lime-
based render to allow the water to escape.

That'll be tricky because taking off the existing render will expose the
broken brick and mortar-mix interior and, in that case, I may as well
rebuild the wall entirely.

Which may not be a bad idea.

Whatever you do, batten/insulate is surely needed with 4" walls,
theyre expensively conductive.

Very true!

My worry, though, is that battening on to this wall will just rot
because it will get soaked. Is that not the case?

You've got 2 prolems to solve. Of course the damp issue needs solving
as well, otherwise as you say it'd rot. Insulation needs to be part of
the eventual solution though, otherwise condensation is going to be
hard to stop, and you'll be wasting much money on heating.

I suppose that until I've sorted the problem, it's hard to tell how much
money I was wasting on heating!

Anyway, until winter has finished, I think I've just improve ventilation
around the wall and tackle the job during the summer months.

--
-blj-

On 18 Feb, 09:54, Brian L Johnson wrote:
"" wrote
On 17 Feb, 23:40, Brian L Johnson wrote:
"" wrote

Okay, so there're not in favour of tanking, and it looks like I should
be stripping off the outside rendering and replacing it with a lime-
based render to allow the water to escape.

its one option anyway

That'll be tricky because taking off the existing render will expose the
broken brick and mortar-mix interior and, in that case, I may as well
rebuild the wall entirely.

Which may not be a bad idea.

I suppose that until I've sorted the problem, it's hard to tell how much
money I was wasting on heating!

might help to calculate it & multiply by how many years you'll be
there.

Anyway, until winter has finished, I think I've just improve ventilation
around the wall and tackle the job during the summer months.


NT

On Sat, 17 Feb 2007 23:32:35 +0000, Brian L Johnson wrote:

Cicero wrote

snip

It depends on how much work you're prepared to do and the general
condition of the bay.

It looks awful. I'll end up doing quite a bit to it, I think.

If the outer skin is in reasonable condition then the best thing to do
is to remove the inner skin, (lath and plaster??) clear out all the
rubble, assuming that it's loose enough to remove. Having done this
then a membrane can be fitted and the void left by the removed rubble
can be filled with insulation. Complete the job with flexible
plasterboard.

I've had a dig around in one corner. g

The outer rendering looks to be in good condition (and, as I said, I've
liberally doused it in waterproofing liquid -- whether or not it's
effective is anybody's guess) with no pinholes or cracks.

The bay wall itself is made up of 5 fairly flat sections. Each section
is a rectangular box of 3" x 3" timber with a single diagonal. Inside
this framework is piled a mix of broken brick and mortar. The outside is
then mortar rendered and the inside is plastered. (The curved skirting
board, instead of being kerfed wood, is actually a moulded plaster sweep
across the entire bay!)

I don't think I could remove the bricks etc without disturbing the
render on the outside. In reality, I think the infill and the outside
render are probably one and the same!

You mention membrane -- what sort of membrane? PVC sheeting? Butyl?

Before doing any of the above check the state of the 'mixture of broken
brick and mortar' infill. It's possible that this is intended to be
there as some kind of supporting wall or it may just be builder's
rubble. Check to see if it's loose enough to remove by hand or whether
it's intentionally mortared together.

================================
I think you've established that it isn't just rubble filling the void so
the next step is to discover what exactly this hybrid wall (timber / rough
brickwork) is supporting. Obviously it's supporting the window frame but
you really need to discover how much support it's giving to the roof of
the bay. It would be sensible to ask a local builder for an inspection to
decide this. Depending on what you find it may be a quite straightforward
job (but messy) of removing the whole of the existing wall and replacing
with a new wooden structure (with insulating infill) covered on the
outward side with a membrane.

This kind of replacement can be done piecemeal without disturbing either
upper or lower window frame provided that adequate support can be provided
whilst the job is in progress. The structure of the bay roof is the
important thing to be sure about.

As far as the membrane is concerned heavy duty polythene sheet is used but
a visit to your local builders' merchant should show you if there's
anything more modern.

Cic.

Cicero wrote

I think you've established that it isn't just rubble filling the void so
the next step is to discover what exactly this hybrid wall (timber / rough
brickwork) is supporting. Obviously it's supporting the window frame but
you really need to discover how much support it's giving to the roof of
the bay. It would be sensible to ask a local builder for an inspection to
decide this. Depending on what you find it may be a quite straightforward
job (but messy) of removing the whole of the existing wall and replacing
with a new wooden structure (with insulating infill) covered on the
outward side with a membrane.

This kind of replacement can be done piecemeal without disturbing either
upper or lower window frame provided that adequate support can be provided
whilst the job is in progress. The structure of the bay roof is the
important thing to be sure about.

Good points. I'll have one of the local builders (my brother-in-law has
just used a good one) to check out the situation with the bay roof.

Apparently the old wooden windows were replaced with the current PVC
ones about 8 years ago. I imagine that they're much heavier than the
originals -- which means that it's more important than ever to determine
the state of the wall's internal wooden framework.

As far as the membrane is concerned heavy duty polythene sheet is used but
a visit to your local builders' merchant should show you if there's
anything more modern.

Ah, I see now where you're meaning the membrane to be used. Yes, I'll
have a look to see what's available.

Thanks for the advice.

--
-blj-

On Mon, 19 Feb 2007 08:13:40 +0000, Brian L Johnson wrote:

Cicero wrote

I think you've established that it isn't just rubble filling the void so
the next step is to discover what exactly this hybrid wall (timber /
rough brickwork) is supporting. Obviously it's supporting the window
frame but you really need to discover how much support it's giving to
the roof of the bay. It would be sensible to ask a local builder for an
inspection to decide this. Depending on what you find it may be a quite
straightforward job (but messy) of removing the whole of the existing
wall and replacing with a new wooden structure (with insulating infill)
covered on the outward side with a membrane.

This kind of replacement can be done piecemeal without disturbing either
upper or lower window frame provided that adequate support can be
provided whilst the job is in progress. The structure of the bay roof is
the important thing to be sure about.

Good points. I'll have one of the local builders (my brother-in-law has
just used a good one) to check out the situation with the bay roof.

Apparently the old wooden windows were replaced with the current PVC ones
about 8 years ago. I imagine that they're much heavier than the originals
-- which means that it's more important than ever to determine the state
of the wall's internal wooden framework.

As far as the membrane is concerned heavy duty polythene sheet is used
but a visit to your local builders' merchant should show you if there's
anything more modern.

Ah, I see now where you're meaning the membrane to be used. Yes, I'll
have a look to see what's available.

Thanks for the advice.

===============================
Just a small but obvious point; if you do replace the wall you can use
almost any kind of exterior cladding as an outer shell. Tiles are
commonplace, uPVC is clean and durable - the possibilities are
almost endless.

Cic.

--
================================
Testing UBUNTU Linux
Everything working so far
================================

On Mon, 19 Feb 2007 08:13:40 -0000, Brian L Johnson
wrote:


Apparently the old wooden windows were replaced with the current PVC
ones about 8 years ago. I imagine that they're much heavier than the
originals -- which means that it's more important than ever to determine
the state of the wall's internal wooden framework.


PVC windows need to have the cills carefully sealed where they touch
the wall reveals. There also needs to be an expansion gap there. If
these gaps are not sealed then water could enter the fabric of the
building. Possibly any screws used to attach the cill to the bay could
allow water through.

Maybe go up a ladder and see if there is anything that looks like it
could do with sealing with frame sealant.

Another thing , look under the cill and see how it is sealed. Look at
your neigbours houses maybe there should there be flashings there and
the fitters didn't bother refitting them?