Damp chimney breast, survey?

[bobo29]

Hi all, not sure if this is the right forum or not, hopefully a Moderator could move if not.

In September last year prior to purchasing our property we had a Homebuyers report completed which mentioned that there was some penetrating dampness on the chimney breast caused by various issues within the chimney stack.

Because of this, we took the decision to completely remove the chimney stack to below the roofline and have the roof "made good" and tiled over in that area. This work was completed at the end of July, however the damp spots largely still have not cleared away and after periods of rain are probably about 80% as bad as they were before the stack was removed. The damp spots are limited solely to the chimney breast on the upper floor.

I do not believe that there is any issue with the workmanship of the new roof as I have placed sheets of cardboard at the top of the chimney in the loft for a couple of days where it opens into the loft area, and they are dry even after rain, and the wall getting worse.

Could anyone recommend what type of firm would be best to identify what exactly is my problem? Is a standard RICS surveyor likely to be able to help or do I need a buildings engineer?

 

[jj4091]

Because of this, we took the decision to completely remove the chimney stack to below the roofline and have the roof "made good" and tiled over in that area. This work was completed at the end of July, however the damp spots largely still have not cleared away and after periods of rain are probably about 80% as bad as they were before the stack was removed. The damp spots are limited solely to the chimney breast on the upper floor.

So are you saying it begins to dry out & then shows damp again after rain? If so then the rain has to be getting in somewhere or other, personally I would be asking the builder to come back & check his work.

 

[bobo29]

It never fully dries out, even in the summer when we had three weeks of no rain, it was still appearing as if it was still damp when it was cold.

There may be water coming in, but it is not coming in through the roof, and it is that what I want to have checked out.

 

[jj4091]

I would still ask your builders opinion first, he will probably do it a lot cheaper than any other profession & should be able to identify the problem just as well.

 

[martin hill]

Is your chimney back to back with nextdoors.

 

[bobo29]

Is your chimney back to back with nextdoors.

Nope I’m end terrace, the chimney breast is on the outside wall and not attached to any other building.

 

[martin hill]

Right. If the roof area sound and no leaks you may have an issue with the gable wall pointing on the chimney breast that has always been there. Dont cover the hole in the loft as now you have an added issue of no airflow into the chimney breast from outside. Are you going to remove all the chimney breasts ?

 

[bobo29]

Right. If the roof area sound and no leaks you may have an issue with the gable wall pointing on the chimney breast that has always been there. Dont cover the hole in the loft as now you have an added issue of no airflow into the chimney breast from outside. Are you going to remove all the chimney breasts ?

Hi, thanks for the reply.
I was wondering if it was perhaps an issue in the wall, when I look up the chimney from the ground floor I can see water droplets on the (inside of the outside) wall. They are tiny and look sort of dirty if that makes any sense.
The chimney breast opens into the loft, I only covered the top with card for a couple of days just to see if any water was coming in. wasn’t planning on removing the chimney breast fully due to cost and the fact it doesn’t lose me that much space.

 

[foxhole]

Sounds like you have penetrating damp through the flank wall .

 

[martin hill]

Hi, thanks for the reply.
I was wondering if it was perhaps an issue in the wall, when I look up the chimney from the ground floor I can see water droplets on the (inside of the outside) wall. They are tiny and look sort of dirty if that makes any sense.
The chimney breast opens into the loft, I only covered the top with card for a couple of days just to see if any water was coming in. wasn’t planning on removing the chimney breast fully due to cost and the fact it doesn’t lose me that much space.

Hi there. Well you have paid to have it capped off from the roof so it makes sense to take them down now. You will be surprised at the space you'll gain. It's a dirty job but can be done by you.

Check in loft if any ceiling joists resting on the breast. If not it possible to do.I did mine with the help of the missus and son. If possible clear the room. If not cheap throw away dust sheets taped over everything. 4 or 5 cheap buckets hammer and bolster chisel. I found it easier to take all the plaster off first. Get some help on hand. Fill a few buckets and get them to take down and outside while you fill a couple more. Slow and steady. Once the first few rows of the brick out at the top its a case of going down row by row. The ones that are into the outside wall leave till last. As you work your way down keep spraying on the breast with one of those plant mister bottles to keep dust down. I used all the bricks and plaster from the breast for hardcore for new path. Most chimney's in old houses the mortar perished so not to hard to do.

 

[sircerebus666]

It also sounds as if the initial survey was wrong too or does it mention there might be an issue with the gable?

 

[RichT1979]

I would hazard a guess that the salt contaminated plasterwork has not been properly removed from the chimney breast and a sulphate resistant finish has not been applied ?

If not there is a risk that any moisture inside the property will be drawn to it and look very much like a damp penetration problem.

A very common problem and sometimes difficult for a surveyor to differentiate between.

Good luck.

 

[bobo29]

Thank you.

I managed to find a proper (i.e. non-Property Care Association) surveyor this week who visited and suggested that it may be a ventilation problem and suggested I install a vent in the bedroom to the chimney breast and an air-brick on the external wall going into the chimney breast.

My property has a cavity wall, however the chimney is partly in the cavity so the external wall goes straight into the chimney.

 

[bobasd]

lack of through ventilation in the chimney flues, and subsequent chemical penetration of the chimney breast plaster (as touched on by RichT1979) by these chemicals will require the replacement of the contaminated plaster with a 4:1 sand and lime render, and having all your flues swept.
the back wall of your flues might indeed be a single brick thick but why not post pics of the outside of the gable.

i dont understand the need for an external air brick if you already have access to the chimney breasts inside the property, and all and any flues are now wide open in the loft?

fwiw: i suspect the elimination of the chimney stack was an expensive, worthless exercise.

 

[bobo29]

i dont understand the need for an external air brick if you already have access to the chimney breasts inside the property, and all and any flues are now wide open in the loft?

Can’t answer that I’m afraid. By wide open, there’s a gap of about 1cm before the roofline starts.

I wouldn’t say it’s wasted, the stack was very ugly and unsightly and would have required sealing if I’d have retained it. You could hear rainwater coming in when it rained!