Red / brown dust in bathroom

MisterNick

TIW
Really - is it at an unusual level in this bathroom? Why can't it be normal household dust? In which case, it's coming in the door.

It is at an unusual level in the bathroom, and, I suppose, it could be household dust. The reason i am excluding the door at the moment is that there is a bookcase and chair just outside the door and they are not affected.

TIW
Do you have other bathrooms you can use? If so, could you close this door for a week or more, even applying masking tape around the door edge tobesure? Ditto not using the extractor, and taping plastic over the grill. Process of elimination.
As you say, there is no other suggestion of 'rot' existing anywhere, and that would be a highly unlikely event in any case. 

I have another shower room but not really practical to close this one off

TIW
Is your extractor a surface-mounted type, or in-line? Pic? When it's running, and you lift up a flat sheet of bogroll close to it, how close before it gets sucked against the grille? 

It's an in line one. I'll get some pics when i go up there later.
The paper test - it gets sucked up about 1-2 inches from the surface of the grill, so it does seem to have some pull.

TIW
A different issue here is what you say about your loft - adding more loft insulation on top of the house ceiling - which I presume is what you've had done - should reduce condensation up there, as less moisture should permeate the ceiling plasterboard to get up there in the first place. Are you sure this condensation isn't just a seasonal issue, it now being winter? 
Did you add the insulation, or did a pro do the job for you? Are you sure the eaves are kept unblocked?

The condensation only appears in very cold weather. I still need to do my loft hatch which I think is the source for a warm upward draft.
I do have a couple of posts on this forum from when I did the insulation as I did it myself. I took to all the old insulation out, put 100mm between the rafters and then 170mm  at 90 degrees. I also put in loft boards and boarded the entire loft. I didn't take it up to the eaves to ensure air flow.

MisterNick

Stuart
It might not be dry rot. It's just a possibility. Hopefully it isn't. Be a shame to have to take out some panelling.

Fingers crossed it isn't or that it is something worse

Stuart
Adding insulation increases condensation in the roof space.

Thanks, I thought this was the case.

Niv

Just a thought, you mentioned building work going on. Where is the building work in relation to the vent from your extractor? And, does your extractor have a (functioning) non return flap - they don't all have this feature. If its dust it could be coming in from the extractor when its not turned on and when building works are throwing lots of dust around?

stuart45

If you sprinkle the dust on a sheet of white paper it should give us a better idea of the true colour.

ThisIsWeird

stuart45 said:

Adding insulation increases condensation in the roof space.

I wasn't sure how this would pan out. 

On one hand, adding extra loft insulation should, I'd have thought, reduce the movement of moist warm air from the house to the loft - ergo less moisture up there to cause condie in the first place. On t'other, a reduction of heat to the loft from the house could make any existing condie less likely to be vented away = more?

I'm still inclined to think that it's more likely the former, but I have no definitive answer. I mean, surely the purpose of insulation is to reduce the passage of warm (= moist) air, so there should be less cond up there? A left-open loft hatch, for example, is known to create more loft cond.

Either way, some condie forming in the coldest and less windy spells is quite normal, and almost certainly nothing to be concerned about.

stuart45

Insulation is put inbetween the joists to stop heat escaping. It doesn't stop air going up. You need a VCL for that. Because the air entering the roof space is now much colder it's more likely to condense on the felt, or bottom of the tiles.
When houses weren't insulated, condensation wasn't an issue. The tiles were warm enough to melt snow. The main issue then was ice dams and icicles hanging down from the eaves.
When insulation first started being used, it wasn't realised that extra ventilation was required.

MisterNick

Right, I've been the loft - its not in a very accessible place.
I took the flexible tube from the shower grill to the pump off at the pump end, and it was very dirty. Cleaned it as best i could.
 I could not see a non return flap (non function or otherwise) as Niv describes, but this could be the problem. I'll answer Niv's post below.
Took the cowl off the pump which was very dirty and cleaned that and the blades. 
Checked the blades rotated when switched on and put it back together. 
The pipe from the pump to outside is less accessible.
Heres's some pictures.

MisterNick

Niv said:

Just a thought, you mentioned building work going on. Where is the building work in relation to the vent from your extractor? And, does your extractor have a (functioning) non return flap - they don't all have this feature. If its dust it could be coming in from the extractor when its not turned on and when building works are throwing lots of dust around?

Niv, Thanks for this thought.
There is no non return flap that I could see, although I suppose it could be on the vent. Can these be retro fitted? 
The vent is on the back of the house above where we had an extension built last year. we have also been having the garden done since last year. It is why we closed the window thinking this may have been the source.

MisterNick

stuart45 said:

If you sprinkle the dust on a sheet of white paper it should give us a better idea of the true colour.

Well, thats interesting - its looking grey now

stuart45

It doesn't look like dry rot spores in these latest photos.
Here's one of dry rot spores in a bathroom.