Re-pointing question

[TeaTime]

Sorry for the rookie question but I am just checking to make sure I will get rid of a problem.

The stairway to my first floor has quite a high roof (not sure what the space above my stairs is called) and I have noticed on one corner that there has been some black mould building up there recently. On the corresponding outler leaf of the house I have noticed a few areas that are in need of re-pointing.

I am going to get it repointed as soon as my guy gets back to me, but I am just wondering if I am right in thinking that if the damp is able to penetrate the outer leaf and cause the inner leaf to get damp, it will be the cause of the black mould build up on the inner surface of the wall?

This is quite a recent problem, but should I look to be doing anything else apart from repointing the brickwork?

Thanks in advance of your comments

TT

 

[kazuya]

it could be causing it but it depends on a few things, how much mortar there is left in the joints, if its a cavity wall or not and what condition is your roof in? as its in the top corner it could be a cracked tile or something, why not post some pictures

 

[TeaTime]

I will be getting some pictures and post them here.

I am trying to get hold of a bloody big ladder so I can see the full extent of the damage.

I know I have to get some roof work done soon because the lead flashing on the chimney has come away in one area, I will try and get a good photo for you guys of inside and out.

I am not adverse to paying to get a job done by a good tradesman, I just like to get a good idea of what needs to be done first, so I know what is being done to my property.

I have cavity walls, not solid. Ihaven't checked my roof tiles yet, I will do so and post back.

 

[Joe Malone]

I'm assuming from your comments that you're 100% that its a cavity wall? If so penetrating damp to the inner leaf would be unusual but can occur due to poorly installed wall ties or wet blown fibre wall insulation. The area in question by the way is the stairwell bulkhead. To prove penetrating damp you would need to check for moisture at depth in the masonry using deep wall probes or calcium carbide. Very few will have this diagnostic equipment.

If there are no obvious damp patches visible then it is more likely that you have an issue with cold surface condensation. So you will need to improve the walls insulative value to raise its temperature above dew point or improve ventilation and heating to the property. You would ordinarily start with the most cost effective option first which to my mind would be to install a continuous running extractor fan in the bathroom. Make sure it's a silent running centrifugal fan with boost speed wired to the bathroom lighting circuit. Of course, you should check that you have cavity wall insulation and if not then this could be a quick fix... simply get blown poly beads installed in the cavity. Avoid blown fibre like the plague, it is not inherently waterproof and sinks to the bottom of the cavity once its wet. I do a lot of damp investigation and building defect analysis work so I speak from experience.