Help! Soaking chimney stack!?

[MissB26]

Hi I'm new to this site so please bear with me!

My partner and I have just got a house which needs quite a bit of work on it so have been unable to move in yet as we have 2 children. Stripping the walls and ceilings in the upstairs bedrooms we discovered a damp patch on the ceiling next to the breast wall. There is also a closet on the opposite side of the breast wall which has suddenly shown up a large brownish stain. Upon investigation, the wall under the stain is the consistency of damp sand.
Up in the loft there is a capped off chimney stack. It's soaking wet, the pointing too. Had a roofer out today as first assumption was a leak in the roof but he's ruled this out as the tiles are in good order and the felt on top of the stack is dry. He did however confirm that the stack was very wet and that the rafters it was touching were starting to become wet too. The plywood that the water tank is on is dry and the surrounding pipes do not seem to be leaking as they too are dry. We have a damp specialist coming on Monday with regards to the ground floor where there is damp in the walls and floor.
Surely the damp from the ground floor could not have risen all the way into the roof to the extent that the stack is soaking but yet the breast walls directly beneath on the ground floor and bedroom seem to be dry?

I was just hoping someone had an opinion or possible explanation as I'm stumped. I hope I've explained that clearly enough. I'm sure I'll find out what's going on on Monday but it's annoying me trying to think of an explanation. Thank you.

 

[mointainwalker]

The brown stain is very likely due to tar/soot deposits in the chimney.
These deposits absob water from the atmosphere , create a damp goo and the stain travels through mortar and plaster. You will probaly be able to smell something like tar if you put your nose close to the stain.

The chimney should have been ventilated with grilles at the bottom and an outlet at the top to maintain airflow. It should not just have been blocked off.

Just guessing that the sand you mention is the wall covering ( plaster or whatever ) that has disintegrated under continuing dampness.

This situation is not likely to cause your chimney to be "soaking wet " so you need to find the cause for that.

We have a damp specialist coming on Monday

Do bear in mind that unless you are paying for an independent survey, this is the equivalent of a sales-call and the "specialist" is more salesman than anything else. It is very unlikely that he will leave without diagnosing a problem that his company is "very experienced in solving ".

If it is that type of call, do not rely on one report, get others to compare findings.

If you do a search on here, you will find posts of people getting three reports, all with different findings.

 

[MissB26]

Thanks for your reply. The breast wall has one vent in on one side, the opposite side has none and is the back of the closet I've mentioned with the brown stain. I myself haven't been up in the loft but the roofer said the top had been capped off with felt - so this shouldn't have been done? Am I right in thinking the lack of air flow has caused condensation within the chimney? Quite rightly though this doesn't seem to explain the wet condition of the stack.

As for the person coming about the damp, I won't enlist any services until I've had more than one opinion. Thanks again.

 

[ibby]

Sounds like what 2nd poster has said.
No or very little ventlation is causing the soot to soak in the moisture.

 

[mointainwalker]

the roofer said the top had been capped off with felt - so this shouldn't have been done?

That sounds like a bodge using materials to hand. It would be normal to either fit a cowl or cement a curved tile across the pot to prevent rain in but allow air out. Lack of air-flow has certainly contributed to your problem as the air would take away some moisture.