Damp or Condensation on new plaster

[Bugwug]

Hi

I had my lime plaster re-skimmed with modern plaster and since then i have noticed a damp patch up near the ceiling (in the pic)

I have lived here some 14 years, that section had lining paper on it previously and a big mirror hanging there so it’s possible this was occurring out of site or was not a problem because of the original plaster.

I noticed it within days of the new plaster in April/May.

It comes and goes, never goes fully but seems worse in mornings than evenings so likely condensation.

Doesnt seem damp in the attic.

I have drilled air holes in the wood barrier that has sealed the chimney all this time.

Chimney is open at the top as i have a wood burner in living room.

How should i resolve this? It hasnt rained for some weeks yet is still there, waxing and waning.

Thank you

 

[blup]

The new plaster is the location of the damp but probably not its cause, so it likely pre dates the plastering.

The damp is towards the right hand side of the chimney breast - is this where the flue from the wood stove is located? Smoke pellets will confirm the location of the flues relative to the fireplaces. The smoke from burning wood can damage the inside of the chimney and allow damp to form.

If the damp is on the unused - bedroom - flue, it probably needs more ventilation than a few drilled holes.

Is the flashing on your chimney in good order - that might be letting in moisture. Likewise missing mortar or damaged brickwork.

Have you thoroughly checked the condition of the timbers around the chimney in the loft, they may be affected as well?

Just some pointers.

Blup

 

[JohnD]

are there water pipes and tanks in the loft?

 

[bobasd]

just wodering if you realise youve got at least two flues and stack pots/terminals in that chimney breast and that all flues are seperate and must be kept separate by the brick feather.

the odds are that salts from an unswept flue or flues have penetrated the chimney breast and are attracting moisture from the air.

you will have to have both flues swept.
to sweep the bedroom flue youl have to open up where the wood is boarding up the fire opening.
afterwards, if you block off the opening again then youl need to insert a proper vent.

youl then need to hack off the plaster and render back up with a sand and lime render.dont use gypsum plaster.skim with limelite finish, although some use multifinish or board finish.

you should have a SS flue liner for the wood burner and the liner needs a proper terminal on the chimney stack.

 

[Bugwug]

Hi

is this where the flue from the wood stove is located?

Hmmm, hard to say. Certainly the living room is beneath this room and the stack is in a similar place

The smoke from burning wood can damage the inside of the chimney and allow damp to form.

I have only had the wood burner for 2 winters (2016/17, 2017/18) but can imagine how the flue could be up against that wall.

If the damp is on the unused - bedroom - flue, it probably needs more ventilation than a few drilled holes.

Do you think i should try and remove the wooden barrier from the bedroom end of the chimney? I never put it there. I could drill more holes, would that be better?

Is the flashing on your chimney in good order - that might be letting in moisture. Likewise missing mortar or damaged brickwork.

The flashing looks ok, i dont see damp bricks when i am in the attic and above the bedroom but the water/damp could be on the otherside/inside of the chimney

Have you thoroughly checked the condition of the timbers around the chimney in the loft, they may be affected as well?

I did not notice anything looking damp (as above) and it hasnt rained for many weeks. I shall have another dig around up there ta.

are there water pipes and tanks in the loft?

No, nothing, all gravity fed around here.

you should have a SS flue liner for the wood burner

Yes, it is a stainless steel flue liner for the woodburner located in the livingroom. Apologies if i had misled anyone by my use of flue, i understood this to only mean stainless steel.

the liner needs a proper terminal on the chimney stack.

I believe it was but would have to confirm with the installer


Thank you guys

 

[JohnD]

all gravity fed around here.

what do you mean? Where are the water pipes for taps and radiators? Does your boiler have a pressure gauge? Is there a hot water cylinder?

 

[Bugwug]

Hi

All water pipes are down stairs, the water pressure is very good around here so there are no pipes in the loft space (it wasnt even accessible until 2 years ago when i had a hatch made.

Ta

 

[bobasd]

how would you sweep the bedroom flue without the wood barrier being removed?

 

[Bugwug]

how would you sweep the bedroom flue without the wood barrier being removed?

Hi

Yes I understand, apologies, my misuse of flue spun this off a bit.

You are suggesting that their may be historical salts in the bedroom brick flue that perhaps my use of the living room stainless steel flue may have exacerbated.

One of your great suggestions has included removing the barrier and then sweeping the bedroom brick flue which has not been used for at least 30 years (i know the previous owner in the pub).

I shall go up (to the loft! Pub is later) shortly

 

[bobasd]

no, im not suggesting that the ss liner is making conditions in the other flue worse.
why are you going up in the loft, youve already been up there and looked for staining or leaks?

 

[Bugwug]

no, im not suggesting that the ss liner is making conditions in the other flue worse.
why are you going up in the loft, youve already been up there and looked for staining or leaks?

To have another poke around to see if i can see anything else

 

[blup]

Do you think i should try and remove the wooden barrier from the bedroom end of the chimney? I never put it there. I could drill more holes, would that be better?

Yes, remove the whole thing initially, especially if this is the flue subject to the damp but be careful as there could be an accumulation of soot, dead birds and their nests behind it.

Blup

 

[Bugwug]

Do you think i should try and remove the wooden barrier from the bedroom end of the chimney? I never put it there. I could drill more holes, would that be better?

Yes, remove the whole thing initially, especially if this is the flue subject to the damp but be careful as there could be an accumulation of soot, dead birds and their nests behind it.

Blup

Hi,

My neighbour called in today to check on my projects and i showed him the damp patch.

He went on the roof and advised that the Y shaped cap on top of the
Chimney looks fine as does the pointing and flashing.

His belief is that this will dry out over months.

I am not as optimistic as i dont know when this started, only when I noticed it.

I will remove the barrier tomorrow (Sunday)