Lots of Efflorescence around stack.

[dishman]

Hello,

Just trying to solve a damp issue around a chimney stack.

In the loft, around the stack I am clearing some space around it and have notice that over the years a lot of efflorescence has piled over the year on the floor around the stack.

There is quite a lot of it. It is like a sandpit of white powdery material that has come off the chimney. I can't see it being anything else.

So, is it safe to just vacuum it all up?

I have a respiratory mask etc.

There is just an awful lot of it.

 

[^woody^]

Efflorescence is just salts. Not harmful, and you can vacuum it and the filter will hold it.

 

[dishman]

Thanks woody.

I knew it is just salts. It was just the sheer amount it made me a bit disconcerted. The bloody dyson did not seem to like the volume of it either. It has been there for so long it has broken down into a sandpit of fine white powder, so it seems to struggle, but it is the only way to quickly and easily clear it.

 

[KenGMac]

dishman, Hi

Should be no problem in simply using a Vacuum to get rid of your accumulated volume of white powder.

More of interest is why has this occurred?

From what you can see is the Lead flashing around the stack at roof line appear OK? Binoculars are good for this, as is a roof window / Velux to allow a peek at the lead flashing's, if present, if the junction between Stack and roof covering is cement then there may be a problem there?

Is the chimney flue in use?

If not? does the chimney pot have a vented cap? if there is no vented cap there is a high probability that rain water is entering the upper areas of the chimney Flue and causing the bricks in this area to be kept damp, excessive dampness caused Efflorescence and so the cycle progresses, more volumes of the white powder, which by the way is not harmful to health, it is a naturally occurring salt.

Bottom line is that there is a damp penetration problem, even the brickwork, which may be roughcast rendered on the exposed area of chimney stack that is allowing the rain to get into the Chimney Flue. OR/ there can be a problem with the Stacks flashing to the roof covering, OR? [Here we go again?]

If the Chimney Flue is not vented, that is an air brick in the fireplace [If it has been blocked up] and a vented Chimney pot Cap then Condensation WILL ! occur.

Now finally, if the blocked off fireplace has an air brick that was installed some several years ago, there is a possibility, stress possibility that the ventilator in the room may? again stress may? be blocked by debris falling down the internal flue, that will eventually accumulate and finally block off the room facing ventilator.

Sorry to bank on but it is OK to remove the accumulated white powder, but if you do not look at what is causing the Powder to form will not help you in the long term??

Ken.

 

[dishman]

I have made a post on this subject a while back I think, and a recent one in plastering.

It is a fully sealed chimney that runs through the back of the house. Not against an outside wall.

It was removed at ground level (it ran into the kitchen for the original arga). It still exists at first floor loft and roof level. At roof level it was fully capped with concrete slab. As far as I know it is fully sealed with no vent internally either.

I have an ongoing slight damp issue on the stack inside. It is most apparent in one of the bedrooms (the opposite side of the adjoining wall to the stack) but is only present at the top of the wall where the wall meets the ceiling.

The flashing around the stack looks to be in very good condition.

I thought that this was just a condensation issue with the stack sweating due to lack of ventilation. Feeling the stack inside, in the loft, it feels dry to the touch.

However after a recent downpour I noticed the wall seemed a tiny bit more damp, so is possible the cap is failing somewhere?.

I guess it could be the water is getting in and there is some sort of ledge in the stack internally where the damp is collecting?

Either way I think the solution is to un-cap and put a pot on. Then drill a hole into the stack inside and put an internal vent in.

Sound like the best solution to you?

I rang a roofer about to ask for a quote and he immediately tried to tell me over the phone that putting a pot and and a vent internally would not work and it was a waste of time. He said I needed a good plasterer.

Needless to say, I was unconvinced by his argument.

He then said that he had popped round when I was out and taken a look at the chimney from ground level and was even more convinced that the stack was fine and it was a good plasterer I needed.

Don't know what you guys think about that but I got the impression he felt the job was not worth his effort.

 

[theprinceofdarkness]

How old is the stack? If its Victorian is has 100 years worth of grot. If its 5 years old you have a problem.
P.S. Dysons are not suitable for picking up fine dust. Have you cleaned the foam filters and rattles a cane up the central hole in the machine with the dust container off?
Frank

 

[dishman]

Property is 85 + years old. The stack has been capped in the way I describe for the last 30 - 40 years at least.

Yes, the dyson is not great for fine dust. I am only using it for redecorating duties so I don't go through a dozen bags per day bags.

It is one of the older cyclone uprights which are poorly designed so the cyclones get blocked with dust over time. I end up having to open it all up one a year and clean it out, ironically, with another vacuum cleaner. In fact I end up jet washing it out.

 

[dishman]

Well, managed to squeeze into the eaves and hoover as much of the efflorescence as possible. There was a lot of it. I kept on goig until I could see the lath and plaster of the ceiling. It had partially solidified futher down. It required three/four emptys of a dyson cannister (1/3 to half full) to get rid of most of it. The new respirator I got worked great, my lungs are ok. The poor dyson just about survived though may need a filter transplant.

A closer inspeiction of the roof area around the stack revealed that there may be water ingress around the lead flashing. Although this does look good at roof level, on one side at lest.

On the underside however, the battens that meet the stack look discoloured (dark) and feel slightly damp. I can see the lead flashing on the underside and again it seems to look fine. Some does bend away from the tile so maybe water is dripping in that way i.e the lead is directing any water ingress in the wrong direction and it needs pressing up to be flush with the underside of the tile.

There was a lead tray behind the stack on roof level and this was filled with mortar and moss. I guess this could have been retainign enough water to back it up. I have now cleared this so maybe it will help.

I will post photos/video tomorrow.

 

[dishman]

Update...

Here are some pictures and a video of the chimney. Is there anything that looks amiss?



Edit: Link removed - sorry - I have pop up blockers and the upload site came up as safe on WOT. Did not realise it brought up inappropriate sites.

The video is a bit choppy in places.

There was a bit of rubble and moss on that ledge of lead behind the stack. Could this have been backing up water?