Remnant chimney stack in the attic / loft

I have a problem on chopped chimney stack in the attic / loft - there is only a remnant of the internal stack left in the attic / loft. For over 30 years it was like this together with it being capped externally.

As seen in the recent attached photo there are some damp or condensation looking patches and lines on the remnant stack in the attic / loft.

It was not there before September 2018 when the remnant internal stack was slurry-cemented and the timber-blocks on the ceiling joists which supported the remnant stack were removed and the remnant stack put on lintels and gallow brackets. The builder who did this unfortunately blocked two unbricked ventilation gaps in the remnant stack. There was also chipboard flooring boards installed.

Roofers either say it is

  1. condensation and suggest roof vent tiles, or they say its
  2. chimney outside or ridge tile and flashing.

Is it - condensation or rain ingress? chemical: hygroscopic or cavity: interstitial?

What is the diagnosis and solution?

Too many unknowns, this is not a DIY forum.

Too many scattered and different solutions without guarantees by
“experts” in roofing and dampness trade who have visited site.

Could it be that whilst also some roofing work got done in November
2018 - for example, chasing external chimney stack above roof line in
order to install flashing, the chasing between brick rows “punctured”
some key areas in the mortar that was holding out against rain

Thank God it’s not a Witches Bend. LOL!
Don’t want to go down that rabbit hole again.

Good LINK Jeffery.

We are not there, it could be many different things. You need someone to perform a leak test if everything looks right. By parging the brick you stopped drying out to the outside. So it’s either leaking and or sucking up moisture during rain which then travels below roof’s deck via capillary effect and cannot dry as it did in the past because of the parging coat. You need to get an expert roofer, not a $20 an hour laborer. As an option, I would remove the chimney altogether and properly close the roof.

1 Like

whaaaa ???

Since you brought it up…

Lol. As if I care.

Thanks. Dont know about leak test.

Should I purchase a humidity tester to find out if its condensation and the remnant stack in the attic / loft is acting like a freezer producing the dew point temperature for water vapour to condense on it?

Should I also buy a moisture meter that has probes and then measure the rate whether the rate increases at high level to differentiate between condensation and slow rainwater ingress?

If its slow rainwater ingress should the portland cement be removed using acids and the bricks re-pointed using waterproofer and liquid damp-proofers?

Before you buy any gadgets, you need to ensure the roof covering and flashing are installed correctly. Based on what you wrote, you need someone with experience to help you. Good luck.

A roofer climbed up there and said flashing looks good and also chimney. As the chimney at roof level is capped he said if he uncaps and puts hooded pot then ventilation should help. Though after asking if it was alright to use heavy tools on remnant chimney supported only with lintels and gallow brackets as its cut off at the floors he pulled out from the work saying it was beyond his knowledge and to get guidance from dampness / ventilation experts.

The dampness / ventilation experts do not work at attic / loft level as they concern themselves only with rising damp from ground zero.

Some other roofer said change half the flashing around chimney and sone ridge tiles but he cannot be bothered to send a written estimate or quote.

Another roofer did not climb up but said the chimney capping needs to be re-done.

Some other roofers roofers suggest roof tile vents.

Another older roofer said he cannot see any problem.

Do you have pictures of what the roof and chimney looks like above the roof? and something we can see well? There is something in what you say that does not add up. Where are you located? Where are you finding these “experts” in a pennysaver? (no, im not joking!) are they licensed? how long have they been in business? How come the chimney was not decommissioned by complete removal?

Do you have pictures of what the roof and chimney looks like above the roof? and something we can see well?

Not close up ones - though I have asked one of the roofers to email it
to me but he has not sent a quote / estimate

Where are you located?

England in a terraced house

Where are you finding these “experts” in a pennysaver? (no, im not joking!)

Google local has review rating and Check a trade has review rating

are they licensed?

Roofers and builders do not normally say much about licensing, rarely
you find “City & Guilds” qualifications mentioned on vehicles. Those
from Check a trade are researched by them for insurance and reviews

how long have they been in business?

Check a trade has profile e-pages

How come the chimney was not decommissioned by complete removal?

It is a terraced property, most of the properties in England are
terraced and usually front chimneys are shared ones. These properties
are usually 100 years or more old now and chimneys are not normally
completely removed.

This particular chimney is independent and if its removed totally
there will be a big gap in the roof and also in neighbour’s roof.

The chimney in question

Parapet wall and some roof (please don’t confuse tv aerial laden chimneys in the background as they are neighboring terraced houses)

Could these products be any good:

Easy solution as brush on and some mortar patching - Microshield Ultra
3L - Masonry Waterproofing Cream

Tough solution because taking out all the render, removing pointing
mortar between bricks, drilling, injecting chemical, re-pointing
bricks and then metal beading and rendering all the chimney -
Ultracure Damp Proofing Course

The parging of your chimney above the roof is old, worn out with cracking in multiple places, and will easily let rain water through. The flashing is also questionable, cannot tell what’s going on from the limited pic. There is no proper crown, any cracking on top will let water through. Parging the chimney inside the attic was a bad idea but least of the concern until the part above the roof is fixed. Get a good chimney repair contractor to fix all cracking, reparge, and install a proper crown if you want it to last longer.

You honestly expect anyone to take your opinions with any modicum of authority when you can’t even use proper terminology???

Maybe this will help…