Missing mortar in chimney perps

[sparer]

Hi,
I have a damp patch in a front bedroom and while trying to find the cause on the roof, I noticed that the chimney has missing mortar in the bottom perp above the flashing. Its the same on the left elevation too and looks deliberate (see photo). Any ideas why this might be or should I just fill them?

Thanks

 

[DAZB]

They will be weep vents from the internal cavity tray or lead liner so don't fill them in with mortar.

 

[sparer]

Thought it'd be something like that so thanks for the heads up

 

[^woody^]

They will be weep vents from the internal cavity tray or lead liner so don't fill them in with mortar.

Not in a two brick wide chimney!

 

[sparer]

Not in a two brick wide chimney!

Please explain Woody. Could this be the source of my damp?

 

[^woody^]

Chimneys don't, and even can't have cavity trays, so that can't be a weep hole. I can't think what purpose that open joint would serve.

There won't be much more, or any more water entering that open joint than would enter the brickwork anyway,
If that was the source of any damp, it would be damp from the day it was built, and if that's not the case you may be better off looking for other reasons for any damp.

 

[datarebal]

It's a weep hole , chimneys do have trays (these days actually usual two. Not actually cavity trays . But definitely trays as in this case

 

[Iwilldoit]

It's a weep hole , chimneys do have trays (these days actually usual two. Not actually cavity trays . But definitely trays as in this case

For how many years have the been fitted as that looks like a very old roof. But I do agree that does not look like the source of damp. Any photos showing the pots ?

 

[foxhole]

Parapet wall is a more likely source of damp.

 

[datarebal]

As I said , it's a weep hole for the lead tray . What appears to be the front apron flashing could also be the second tray which is standard good practice now .
With out close inspection one can't tell if it is or isn't.
I've a feeling the chimney has been rebuilt some time in the past . Hence fairly modern brick and flashing technique.
The step flashing needs pointing

 

[sparer]

The building was built in circa 1850 so its quite likely that the chimney has been rebuilt. It's certainly been repointed within the last 10 years. The leadwork on the parapet is in good condition and the pointing on the front elevation of the parapet is good and it's rendered on the back.

Thanks for the comments. I'm guessing that I'll have to look elsewhere for the damp. I have a small hatch into the eves in that corner so I'll take so damp readings on the internal gable and rafters to try to acertain whether its coming from the parapet or the roof.

 

[Deluks]

What about the chimney itself?
Is it capped off or cowled, or do you have a big unused hole on top of your house, above where you are having damp problems?

 

[datarebal]

Looking closer , the weep hole still has a bit of the brickwork bed blocking it . This can cause a dam effect and any build up of water could drip over the inside tray turn up . If it's low

 

[sparer]

What about the chimney itself?
Is it capped off or cowled, or do you have a big unused hole on top of your house, above where you are having damp problems?

It's capped with a flue ventilator

 

[sparer]

Looking closer , the weep hole still has a bit of the brickwork bed blocking it . This can cause a dam effect and any build up of water could drip over the inside tray turn up . If it's low

I see what you're saying. I'll drill a 10mm hole just above the lead and break out the bed below the weephole