Plaster not drying around chimney area?

[zenonithus]

Hi all,

I had my kitchen walls and ceiling skimmed about two weeks ago. Everything is bone dry except for the old stove chimney area in the corner. It still seems a little damp. It has been raining pretty heavily recently. I am on the top floor flat, so does this appear to be some sort of damp issue with the roof? What do you guys think?

When I stripped of the old wallpaper I did notice bit of mold on the ceiling next to the chimney and much of the plaster had blown on the chimney, so this damp issue has probably been there a while.

 

[KenGMac]

zenonithus, good evening.

Instant considerations are

1/. A leak around the old stoves chimney head, a lead flashing? or missing mortar in the brick work of the Chimney head? or a failed Chimney head cap?? allowing driving rain to saturate the Chimney head brickwork? or missing cracked / damaged roughcast render??

2/. A missing chimney pot? or a chimney pot without a ventilated cap?

3/. Is the old chimney flue vented? that is is there a ventilation grill on the wall inside the room? and is there a ventilated chimney cap?

Sorry for all the questions but some / many / one of the above could be your problem??

Ken.

 

[roughcaster]

Certainly looks like damp to me.

 

[bobasd]

i agree.definitly damp. it must have shown damp before skimming.
can you go into the loft above or is it a flat roof.
can you get on the roof or off a ladder an photo the stack an roof area?
how many flues are in that chimney breast.

that dont look like a first class skimming job, to much water an whats the white bits here an there?is that bits of old painted skim that was left on?

 

[zenonithus]

Hey guys! Thanks for your feedback, really helps me get to the bottom of this as I can't really move on with the kitchen until this damp issue is ressolved.

KenGMac: Great questions! I will forward these to the building management as I don't have access to the loft hatch (they just put a new padlock on it) There is no flu going into the chimney. When I took off the blown plaster I could see where the old flu hole had been bricked up before putting bonding on it.

bobasd: I will go out on my fire escape balcony and try to take pictures of the chimney and post them up tomorrow. Maybe you guys can spot anything wrong with it? Those white patches are areas I filled after

Here is a clearer picture of the chimney. All blocked off, no vents or anything on it.

 

[darrington]

To be honest, even the bottom part of the wall looks suspect. There is nothing like Gypsum plaster for showing up damp areas.

 

[zenonithus]

Good point! I'll check the bottom tomorrow, though it might just be some patchy shading in skim.

 

[roy c]

Might be worth putting in an air-brick in. Or make a hole in the top part of chimney and a vent at bottom and the air flow might help it dry out a bit quicker..It seems like a bit of a rough job on the plastering, He didn't use bonding as the backing coat did he? If he did that's why it's not drying out very quickly...

 

[zenonithus]

I did patch up the blown out plaster with bonding over the exposed brick, though those areas are bone dry. The dark patch at the bottom is bonding and not damp

So I got some pictures of the chimney earlier. Not sure if there is anything visibly wrong with the lead seal. Though I did notice the other flats flu chimneys have chimney pots sticking out at the top and I can't really see one on mine, not even the top of the pot. Could this be the issue?

 

[roy c]

If you have an open chimney then you are going to get water in when it rains.. So you need to put cowls on your chimney or hoods to stop water going down it...imagine how much water will go down your chimney with the rain we are getting, its got to show on the chimney as the bricks will act as a sponge...

 

[zenonithus]

Hey roy, cheers for the reply. Yes true! I'm not sure what is on top of that chimney. I'm going to take a look at the other flats to see if theirs are the same. My neighbour next to me appears to not have a cowl either. I wonder if they have just cemented over the holes or something?

 

[KenGMac]

zenonithus, good evening again.

The image posted is of interest, in that one flue does not have any "protection" against rain penetration, that is a chimney pot and or a flue cap. result is that rain will enter that "unprotected flue" which is not in use so as above posts the brickwork acts as a sponge, which in turn once saturated over time and in heavy rain will and probably has percolated down to the inside of the property, after all this situation has been on-going for years??

In my original post my note of 2/. has this as a prime suspect, might well be the source of your problem?

You need to get the flue capped with a ventilated cap, then fit a ventilator grill into the base of the flue inside the room.

Ken.

 

[zenonithus]

Hey Ken, thanks for the feedback, yes it definitely looks that way. They are sending a guy to have a look soon. I'm not sure if those two cylinders are open exposing the chimney to the elements (and god knows what else) or if they are filled in perhaps with concrete? Do you think it's possible to cap this off without having to put a vent at the bottom? As it would mean having to smash a hole in the newly plastered chimney plus it wouldn't look too good. I bricked up the fireplace and didn't leave an air vent as there was a closed cowl on the chimney and it seems fine and dry.

 

[KenGMac]

zenonithus good evening.

Managed to have a look at the image posted, original dark but?

What appears to be going on is that there is an open flue to the outside [ the left hand terminal in the image posted] and a gas terminal on the other chimney pot, the latter will probably prevent rain water entering the chimney flue, but? the open [left hand] terminal does not appear to have any vented cap thus rain water will be able to enter.

As for fitting an internal vent? if you do not want to do that it is possible to install a ven grill or indeed an air brick externally? just a consideration.

Ken.

 

[zenonithus]

Hey Ken, Thanks for the observation. That is actually my neighbours chimney, just to show they have something covering (gas terminal) they actually still have an old asbestos flu running into the chimney in the kitchen, so must still be in use. Here is an image of my one. As you can see both terminals have nothing on them, so I am thinking these are big holes letting in water. I'm not sure I can put an air brick on the outside as it's classed as part of the building and not mine? What would it mean if there is no air vent? Wouldn't the cowl have vent openings to let the air escape?