Penetrating Damp - not sure where the water is coming from

[Endofmytethers]

I am wondering if anyone can assist with a problem I have. After the driving rain that we had in mid Feb, I have noticed wet patches on the wall of my middle bedroom (end terraced house, gable end wall). The wet patches are on the wall, coming down from the roof, between the chimney and the wall and also a bit in the middle of the chimney breast and some spots on the left hand side wall between the chimney and the other wall of the bedroom.

Initially I thought it was due to missing pointing outside on the gable wall, so got that re-pointed (after hiring scaffolding etc.), but after it rained, I noticed that the wet patches got darker, which can only mean that water is still getting in. The roof is new, there are no gutters nearby and apart from the side wall (which has been re-pointed), I cannot understand where the water is coming in from. There are some hairline cracks in the bricks and it may be that the bricks are quite porous, so after the re-pointing was done, I was advised to use Thompsons water seal on it. I applied the thomsons water seal, but this clearly hasnt solved the issue and Im lost as to what to do next. Someone suggested I used facade cream, or to apply a couple of coats of sandtex masonry paint, but im not sure if I can use either of these two options now that the thompsons water seal has been applied? Any ideas as to what to do?

 

[DamoB]

As it all seems to centred around the chimney, and you've just had a new roof, I can't help but wonder if the flashing around the chimney has been installed incorrectly.

Seems a bit suspect assuming you didn't have problems before the roof was replaced.

 

[Endofmytethers]

The new roof was actually replaced a couple of months before I moved into the property (approx 5 years ago). The lead flashing around the chimney has also been checked recently - looks fine. The chimney has now been "covered" to stop water coming through the dis-used chimney and the mortar between the bricks on the chimney stack has been filled in where necessary.

 

[DamoB]

I'm not sure then, but more often than not damp that seems to be penetrating from the roofline is connected to a problem with the roof...sagging felt under the eaves course is a common one.

But if the roof and flashing are both sound then it must be a problem with the masonary. Maybe a phonecall to Thompsons would confirm whether you can paint on top of it? I've never used the stuff so can't help on that one.

 

[Endofmytethers]

Thanks for the reply anyway, appreciated.

I did give thompsons a call, apparently you can paint over the old solvent based stuff, but not the 'new improved formula' water based one, which has silicone in it - I shouldve paid more attention before I sprayed the stuff on. But in any case, I kinda expected it to stop letting the water into the porous bricks (if that is indeed the problem).

 

[ree]

What do you mean by the "chimney" has now been "covered"? --- A chimney stack or a chimney breast has been rendered?

You would help yourself if you posted pics.

Is the gable wall a solid wall?

Have you had a look in the loft area?

Your directions for locating the damp spots are confusing - use one reference point eg. the chimney breast on the gable wall, and work from that reference.

 

[Endofmytethers]

In answer to your questions:

The chimney 'pot' has been covered to stop water coming into the chimney pot itself - it is a disused chimney.

I will post some pics up shortly - I am at work at the moment, but will do so.

Yes, gable wall is a solid wall.

I have looked in the loft - no obvious signs of wetness on the wall in the loft.

Essentially water is on both sides of the wall on either side of the chimney breast - on one side its at the top of the wall - patches coming down from bedroom ceiling. There is a patch of water on the centre of the chimney breast next to the ceiling. There are also water patches on the other side of the chimney breast on the wall in the middle of the wall - circular patches.

 

[Endofmytethers]

Hi,

I have now uploaded a photo album of the damage and some outside pics .. apologies for the delay in posting these.

Any help would be appreciated.

Thanks

 

[roy c]

If you look at your last picture there doesn't seem like there is much over hang of lead on the corner of the stepped lead flashing from the lead work at the back of the chimney. There may be rain getting down in between the gap of the lead that is overhanging the corner. Also have you checked the "flaunching" on the top of the chimney ? This is the mortar that is benched up to run water off the flat part of the top of the chimney and also holds the pots on. This sometimes cracks and water gets in and runs down the inside of the chimney and appears on the inside walls. If you have a look in one of my albums called "Cracks" you will see what I mean ,even tho the chimney we repaired was a stone built one the problem we had to sort out was caused by cracks in the "flaunching " and cracks in the render..

 

[Endofmytethers]

Thanks for the reply - I will get someone to check both of these although the last guy that checked said that the lead flaunching and mortar holding the chimney bit were both ok.

Do you think it's more likely to be the chimney letting in water rather than the brickwork on the gable end wall? (I'm due to try and paint the gable end wall again just in case)

 

[roy c]

I cannot say for certain where it is coming from all I can do is give a few suggestions, If it is a solid construction then if there are a few cracks in some of the bricks then it may track back to the inside also if the pointing hasn't been done with a consistent gauged mix then there may be a problem there, you mentioned "lead flaunching" the flaunching is the banked up cement mortar that holds the pots on and lets the water run off the top of the chimney like I said in the last post, If there are cracks in this flaunching then it will let water in!! I would get someone who can dress lead and knows what to look for on a chimney with lead flashings and stepped lead work like yours to have a look at it and give you his opinion,, Lead-beating and forming lead aprons for chimneys was a plumbers job years ago and also traditional roofers who did their own lead-work, Now it seems that anyone can call themselves "roofers" and are "experts" at dressing lead. This is fine till they get their money disappear and the rain comes down!! But old trades men now are now getting scarcer as they die off and their skills die with them. The new generation are coming along and basically making it up as they go along, This is only my opinion but I am now within a few years of retiring so I am now getting into the "cynical ole man" syndrome ,,Sorry for the rant,,

 

[ree]

Painting brickwork is useless, and you will only be making more work for yourself now and in the future. It can also give you further difficulties.

A past attempt was made to re-point the gable, unfortunately the beds were not raked out properly before a "strip" of S&C was applied, and neatly struck off.
The re-pointing mix was too cement heavy, and is cracking and expanding and falling out.
Raking out should be to about 18mm to 25mm deep, not 3mm or 4mm.

Another attempt has been recently tried to point up bits here and there - smearing of the brick facework is the only result.

The whole gable and both stacks should be properly raked out to 22mm, and pointed with a soft mix.

The stack flaunching shows indications of vegetation growing on the surface. A couple of stack bricks need replacing , and there is a suspicious dark area which might be moist soot working its way to the surface of the stack brickwork (when was the flue last swept?).

I'll return to this post in while.

 

[ree]

The back gutters on both stacks should divert the water round the stacks and down into the guttering on the front and rear elevations. At the moment, you have gable chute arrangements discharging into space.

The one piece stepped cover flashing is wrong for fibre cement slate (or any other slate). There should be individual slate soakers covered with stepped flashing. Moisture could be creeping under the one piece lead.

There is no fibre cement undercloak at the verge - the v. thick pointing is cracking and showing damp stains.

Any work on the fragile cement slate roof must be done responsibly from roof ladders.

The loft interior pic shows moisture stains below the purlin.
Is the purlin going/bedding into the chimney breast?

Why has scaffold been erected? Why to that height?

Any further professional work should provide pics of the finished job.

 

[Flyboytim]

Sound advice there from ree, but does not really address the internal damp.

The actual position of the dampness suggests condensation:

- the ceiling of an upstairs room - bedroom? - where the warmest, most humid air meets a cold external wall

- the coving implies that there may be a plasterboard ceiling which may have edge gaps and cracks which lead to the loft space, chilling the small void behind the cove.

Check that loft insulation adequately covers right to the edge and over the ceiling joists, and that the painted wall above in the loft is not getting condensation on its surface that is running down - if so, insulate that wall too, and seal any vapour leaks from the rooms below into the loft space.

As well as maintaining trickle ventilation, and reducing the bedroom temperature, make sure there is air movement in the room especially during the winter months to prevent warm air stagnating near the ceiling. A simple oscillating fan will do, or a ceiling fan switched to move the air downwards.

 

[JohnD]

a disused chimney needs to be ventilated top and bottom, or it will get condensation inside. This usually causes yellow or even brown staining on the plaster as it carries tar from the old fire deposits.

however the amount of water you show looks like rain or plumbing. Can you see the wet in the loft on a rainy day? Are there any water pipes up there?

I see the person who pointed the chimney and part of the wall used a teaspoon. A small pointing trowel would have been better. Perhaps he's never done it before, which is not a good sign.