DIY Doctor UK DIY Forums

I am at my wits end with this because i cant figure out where its coming from.WE have had a number of jobs done on the wall where the window is situated including replacing the window itself ,because of a constant issue with damp penetrating from the a outside ,The wall itself is brick double skinned with a cavity which has been filled with insulating polystyrene beads although the damp issue was there well before they were put in.
The outer skin of the wall has been painted which doesn't seem to act a s barrier to driving rain.
When we first moved into the house we had the areas around three windows on the wall replastered because it was literally falling off.We also had the trays over the windows replaced and new weep holes installed.Now that has worked for two windows but not the other.Any holes or gaps that we could find in the brickwork we had filled in and checked the guttering to see if that was blocked and it wasn't.
Had two building surveyors round who could not enlighten me the builder I used has obviously not cured the problem so i really don't know where to turn to.Another builder, structural engineer or damp proof consultant? Can anyone suggest what i can do?

You write, that it is a brick cavity, wall that
the wall was damp when you moved in.

Have you stood outside in the pouring rain and
watched what happens to the wall?

Have you checked the roof, guttering and any down
pipes for leaks?

Is the wall exposed to strong winds and driving
rain? If it is, the wind may well be forcing the
rain through the wall. The reason we have cavity
walls is that this used to happen a lot with
solid walls,(it still does) the cavity is
supposed to be empty! The government issued
guidance on this years ago! Homes in the west of
the UK, in exposed positions or houses anywhere
ditto, should not have their walls filled! The
filling enables the rain to cross the cavity and
make the inner wall wet. The solution is to remove
the polystyrene balls.

You write, the wall has been painted. Paint isn't
necessarily rain/waterproof. However, Thompson’s
make a transparent/invisible wall paint, that
seals bricks and more importantly the mortar
enabling the water to run off, it is also
breathable.

Are you sure the damp isn't condensation? The
wall would have been cold and wet when you had it
re-plastered. Being cold, all the water vapour in
the room, will automatically condense into the
wall keeping it damp.

Perry525 wrote:You write, that it is a brick cavity, wall that
the wall was damp when you moved in.

Have you stood outside in the pouring rain and
watched what happens to the wall?

Have you checked the roof, guttering and any down
pipes for leaks?

Is the wall exposed to strong winds and driving
rain? If it is, the wind may well be forcing the
rain through the wall. The reason we have cavity
walls is that this used to happen a lot with
solid walls,(it still does) the cavity is
supposed to be empty! The government issued
guidance on this years ago! Homes in the west of
the UK, in exposed positions or houses anywhere
ditto, should not have their walls filled! The
filling enables the rain to cross the cavity and
make the inner wall wet. The solution is to remove
the polystyrene balls.

You write, the wall has been painted. Paint isn't
necessarily rain/waterproof. However, Thompson’s
make a transparent/invisible wall paint, that
seals bricks and more importantly the mortar
enabling the water to run off, it is also
breathable.

Are you sure the damp isn't condensation? The
wall would have been cold and wet when you had it
re-plastered. Being cold, all the water vapour in
the room, will automatically condense into the
wall keeping it damp.

The wall just looks very shiny and wet when it rains

I have had the roof checked , once by a roofer and once by a surveyor .The latter suggested I should have some metal straps attached to ceiling joists and to the part the adjoining wall I am referring to because he felt the wall had move slightly causing the tiles to displace somewhat. This obviously would have been an internal fitting.

The roofer thought such displacement normal for a house of this age but felt the wall should be repointed entirely We had already had some of that done because the pointing had become very soft on the first metre or so from the gound

So far we have had 3 surveyors each giving different advice.The first suggested having new wall ties to the wall, which we have had done.

The second suggested we had new window trays fitted because when we moved in we noticed the plaster was hanging off the top recess of two windows on that wall and water dripped in when it rained.

The third suggested the steel wall straps.

We had to have the insulation pumped in to comply with building regs when we had a new build at the back of the property.Its interesting you mentioned government guidelines because the building inspector was adamant that the insulation would not cause a problem.It clearly seems to be doing so although as we had thee problem before I originally thought it was not the cause, in fact there could also be debris in the cavity acting as a bridge.

I have not looked at the guttering myself but was assured by the builder who filled various crack on the wall (especially those which formed when we had new windows fitted) that the guttering was clear .The lintels are brick soldiers and a gap formed which we had to have filled .

I did think condensation might be an issue as there was considerable mould in the window recesses.I have since been running a dehumidifier constantly and slightly opened the fan lights .I cleared the mould although the recess does still feel damp.

Having said there is an area on the wall to the top right corner of one window where the paint is simply bubbling and flaking off.
There is a similar area further down on the same wall to the bottom left corner of the second window.

We have pretty much decided to have the insulation removed but not at all sure that would cure the problem.Using Thompson or some other similar product, maybe well the best extra option.I did think about having an inspection done as well by removing a few external bricks around where the dampness is worst.
We have spent a lot of money on this house and we are now very keen to make sure that any extra we do spend will cure this problem we have.
Many thanks for all your advice, its very much appreciated

I always feel that I cannot trust builders and surveyors to do a good job. I am only satisfied when I have looked myself.

May I suggest that you go up into the loft yourself, armed with a bright light, and take a careful look at the roof. This involves laying on the floor and getting as close as possible to each rafter and joist and looking from both sides, look for water marks.

Note: On one occasion I had an internal wall that was damp, on careful inspection I found there was a handful of fiberglass laying on the loft floor, it had been carefully placed to disguise a roof leak.The rain was running through the fiber glass into the top of the internal wall.

While you are there check where the pipes from the water tanks go, are any near the wet wall?

If you have a long enough ladder get up to the roof and check the tiles, guttering and downpipes.

Once you have cleared the above mentioned items, there only remains the wall as the problem.

You write that you have had new ties fitted and that the wall is (full?) of polystyrene balls.

Before the wall was insulated, the installers were supposed to check the cavity for obstructions and cement bridging the cavity. Did they do that?
Did they confirm it is clear?

At this point, having checked all the above, then its time to waterproof the wall with Thompson's or some similar breathable product.

Running a dehumidifier with a window open is a waste of money. While the air outside is nearly always colder and drier than the air inside your home, it does nevertheless contain water vapour (especially during our recent bad weather) this water vapour is entering your home through the open window and condensing on the cold plate inside the dehumidifier. Close the window and run the dehumidifier or open the window and turn off the dehumidifier.

Mould only grows where there is food and water, what have you got on the wall that the mould is feeding on? It is getting its water from the wall or the air.

The bubbling paint is a sure sign of condensation. Probably the wall is the coldest part of the room.

How did they fit the windows? Did they fit them inside the outer wall opening? Or in the cavity? Did they fit closers in the cavity? Or fill with polystyrene or foam.To prevent cold bridging. It would appear that the inner wall is cold.

I wish you luck with your research.

Perry525 wrote:I always feel that I cannot trust builders and surveyors to do a good job. I am only satisfied when I have looked myself.

May I suggest that you go up into the loft yourself, armed with a bright light, and take a careful look at the roof. This involves laying on the floor and getting as close as possible to each rafter and joist and looking from both sides, look for water marks.

Note: On one occasion I had an internal wall that was damp, on careful inspection I found there was a handful of fiberglass laying on the loft floor, it had been carefully placed to disguise a roof leak.The rain was running through the fiber glass into the top of the internal wall.

While you are there check where the pipes from the water tanks go, are any near the wet wall?

If you have a long enough ladder get up to the roof and check the tiles, guttering and downpipes.

Once you have cleared the above mentioned items, there only remains the wall as the problem.

You write that you have had new ties fitted and that the wall is (full?) of polystyrene balls.

Before the wall was insulated, the installers were supposed to check the cavity for obstructions and cement bridging the cavity. Did they do that?
Did they confirm it is clear?

At this point, having checked all the above, then its time to waterproof the wall with Thompson's or some similar breathable product.

Running a dehumidifier with a window open is a waste of money. While the air outside is nearly always colder and drier than the air inside your home, it does nevertheless contain water vapour (especially during our recent bad weather) this water vapour is entering your home through the open window and condensing on the cold plate inside the dehumidifier. Close the window and run the dehumidifier or open the window and turn off the dehumidifier.

Mould only grows where there is food and water, what have you got on the wall that the mould is feeding on? It is getting its water from the wall or the air.

The bubbling paint is a sure sign of condensation. Probably the wall is the coldest part of the room.

How did they fit the windows? Did they fit them inside the outer wall opening? Or in the cavity? Did they fit closers in the cavity? Or fill with polystyrene or foam.To prevent cold bridging. It would appear that the inner wall is cold.

I wish you luck with your research.

Yes well i know what you mean, its very hard to find professional people one can fully trust .I dont wish to elaborate too much except to say that with the two surveyors I dealt with I couldnt help but feel their services added up to " money for old rope". Now you mention about looking at the roof space and at the joists and rafters in particular, that is something they certainly didnt do.Quite happy to use a damp metre and make grand statements.
This weekend i shall make a point of getting into the roof space .As i live in a a chalet bungalow , the main loft is situated inside one of the slopes of the roof Mind you it has been boarded so it could be a bit tricky checking the where the rafter meets the joists.It is, though, on the side of the house where most of the problem lie so i will have to look into it .I know the wall above the joists looks pretty dry from the inside but I think I might invest in a damp metre just to satisfy myself.
We have no header tanks or pipes to worry about in the roof space above as they were removed or disconnected when a combi boiler was fitted
I have a pair of long ladders so can check guttering , downpipes and tiles although I once builder, used seemed to think they were ok
Unfortunately the insulation people did not check for any obstructions , they were working indirectly for a local council which had given us a grant so they were just eager to get the job done and move on.Seems a naive to say but it would never have occurred to me that in an ideal world they would check for any possible obstructions.I just thought they drilled holes in wall and pumped the stuff straight in
I take your advice re dehumidifier and leaving any windows open.I noticed there was small amount of water on the window sill inside and thwtas when the winodw was slightly open ,With the humidfiier on it has dried
I am not sure what you mean by "what the mould could be feeding on" .Its just painted surface thats all.The mould is entirely on the underside of the plaster covered oak lintel in the recess. On the outside the lintel is made from brick and some of the paint on that is also bubbling up or flaking off. I made a point of running a skewer into the weep holes above the trays to free up any blockages.

We did have a problem with the window fitters because when they took the old ones out, the lintel shifted slightly downwards, they panicked and filled the gap with silicone.The silicone was subsequently removed and replaced with mortar but the lintels do look a bit bowed.
I am not sure what you mean by how they fitted them .They are sited towards the outer edge of the cavity, about an inch from it.If by closers you mean the one and half inch strip of plastic which runs round the inside edge of the window, then I would l say yes they have fitted that.The windows seems to sit on it and I cant see any foam or polystyrene.

Today i spoke to my neighbour whose house was built at the same time as mine and is also a bungalow .The same kind of rather porous bricks were used in its construction and yet she has no problem at all with damp.Her walls were not painted like mine were but she did have some sealant applied and my guess is that was done because she had insulation installed as well.It seems to me that sealant might be the key.
Once again i must thank you very much for your advice, its very much apprecaited

further update:
had a builder call round , who checked guttering and roof and found nothing wrong there .No water pipes running in the vecinity either.He thinks the problem I have is caused by driving rain going through the painted brickwork via defective pointing which needs to be replaced .He also thinks the cavity trays above each window may have been dislodged when the new windows were fitted and suggested the fitters should have used akros when they fitted them.

He will carry out an inspection in the worst affected ares by removing a few bricks because he thinks there maybe some debris gathered there which acts as a bridge.
I agreed to the repointing but what i not sure about is his suggestion that the existing cavity trays should be replaced by new pre formed one that runs the length of the wall and above the three windows and with weep holes every 600mm.I see his logic but i thought such cavity trays only ran above each window,i.e. they are not like regular DPCs.Could someone advise me please? Thanks

for a cheaper option, than trying to renew cavity trays etc try spraying the wall with a clear silicone sealant, that will repel the rain and stop any problems £17.99 in screwfix no nonsense silicone sealant 5Ltr

welsh brickie wrote:for a cheaper option, than trying to renew cavity trays etc try spraying the wall with a clear silicone sealant, that will repel the rain and stop any problems £17.99 in screwfix no nonsense silicone sealant 5Ltr

`i spoke to Thompsons, who produce one of the best known ones, and they said it would not work because the surface has been painted , in other words it needs to sink into the brickwork which it obviously cant

Lets go back to the beginning.
Did [u]you[/u] examine the joists, rafters and tiles in the loft?
Why did you not check the gutter yourself?
The wall was wet before the polystyrene balls were (poured in) how were they installed?
Welsh brickie, agrees a cheaper (much) solution is to paint the wall with Thompson's silicone (or similar) after it has been re pointed. Or even before!
Taking the wall to pieces will cost a fortune.
I wonder if you are being ripped off.

I agree with perry525 I think your being ripped off, if the wall is painted then paint a pva solution on the wall,its inexpensive
then when its dry hose the wall down, to see if its worked

Perry525 wrote:Lets go back to the beginning.
Did you examine the joists, rafters and tiles in the loft?
Why did you not check the gutter yourself?
The wall was wet before the polystyrene balls were (poured in) how were they installed?
Welsh brickie, agrees a cheaper (much) solution is to paint the wall with Thompson's silicone (or similar) after it has been re pointed. Or even before!
Taking the wall to pieces will cost a fortune.
I wonder if you are being ripped off.

not the whole wall, just a few bricks where the damp patches are thats all. It shouldnt take long.Repointing I have agreed to because it look pretty poor.Then i would need paint over again.I am quite willing to use Thompsons but when i phoned them to ask for their advice they suggested it wouldnt work because it wouldnt be able to to sink into the brickwork.I also phoned Safeguard ,who make a similar product, and they told me the same thing as in
"Good Afternoon Don

Thank you for your enquiry.

Unfortunately we do not manufacture anything that can be applied to painted surfaces.

Stormdry, our Masonry protection cream can only be applied directly to an unpainted/untreated surface.

I am sorry we can not be of any assistance.

Kind Regards,
For and on behalf of Safeguard Europe Ltd

I looked in the loft space which is directly above the worst area and the inner leaf looks bone dry which suggests to me there is no blockage there.I'll check the gutter myself today

Hi, did you ever get to the bottom of the issue? I have a very similar scenario apart mine is on a westerly facing brick built gable end. There is a small window and it's only above this that the problem seems to exist!