Roof Problem - Damp, Bats, Broken Mortar - See Photos...

[johncrowther]

Ok, I've taken a load of pictures. I've started to have a different impression about what the problem is, having climbed into the attic and taken a load of photos of the house. Haven't been up there since I moved in nearly 3 years ago.

I started out thinking there was a leak in the roof causing a damp patch in the spare room ceiling and water to get in down spare room (outer) wall. I also thought the wall aspect could be due to pointing. But I'm now starting to think it is a condensation problem as the radiator in that room doesn't work (it will do from tomorrow) and we dry a lot of clothes in doors at this time of the year (so I think maybe a lot of moisture in the house migrates to that cold room.)

I would be grateful if people could look through these pics and my comments and offer some advice if possible (the story involves the sub plot of bats in the attic and a s**t load of broken off mortar stuff....)

1) So here is the suspiciously regular shape of the ceiling's damp patch.

2) And here is the damp on the wall of the same room. Some patches near to the top of the wall, just under the cornice result in small dribbles emanating from them that run down.

3) Here is a pic of the outside of the house (the spare room relates to the window on the left). There is the odd wonky slate here and there but nothing too horrific.

4) Now inside the attic I can see the reason for the bizarrely regular rectangle shape of the damp patch. The insulation has been rolled back from that area. I have since rolled it back over.

5) Here is a general view of that part of the roof followed by a pic of the front side of the roof (which doesn't seem to have any problems.)

6) Here is the corner near to where the main damp patch appears on the wall - seems to involve droppings, straw and a s**t load of mortar stuff that has dropped off. As well as some hanging things that look bat related.

7) Some kind of toilet tissue looking stuff (?)

8 ) Some kind of white little spores on the wood.

9) The underside of the slates, missing the mortar stuff that has all fallen on to the top of the insulation.

I'm assuming the insulation has been in for 25 years or less (that's a guess), so it seems odd that all of the mortar stuff has fallen down since that time. - seeing as it is mostly on top of the insulation. Could this have been caused by bats?

CONCLUSIONS

So, I noticed that the top of the plaster where the damp patch is and where the insulation was rolled back was bone dry! And no clear evidence of roof leakage. Also, it hasn't been raining today or yesterday (bit of snow) so it seemed odd that the back wall of the spare room was really drenched. So am I right in thinking that it is condensation from drying clothes all day and there being no working heat source in that isolated room? The moisture would have migrated to that rectangle patch on the ceiling which would be especially cold (because no insulation above it) and to the back wall (and window) as there is no radiator on in there. CORRECT?

So I don't think there is necessarily a roof or pointing problem causing damp patches in spare room.

Also....

Why has all the mortar stuff fallen off (seemingly in recent times in roof that is over 100 years old) - is it because of bat activity. And should I be worried about this? It seems to in most of the attic.

THANKS IN ADVANCE!

[verne]

firstly, the white pot hanging thing is an aerial insulator. i have several. old radios needed a good dipole aerial for decent reception over a large part of the country and you have found a remnant of one of those.

i reckon you have about hit the nail on the head with your theory about condensation. most houses have some big air currents - do cooking smells roam around the house? if they do you can guarantee everything else does too. gas ovens produce huge quantities of water vapour and people produce gallons. if you have a limited number of open chimneys/fireplaces and not much alternative ventilation you are asking for troubles (black mould, chest infections,etc). indoor drying is likely to be only aggravating an existing problem.

the straw like stuff looks like the reeds that used to bed my tiles before we had it stripped. our top floor ceilings also used reed and plaster instead of lath and plaster. the floors of our top storey is also reed and plaster. i am wondering why you have these in your attic - maybe the slated roof is not original?

such a tiled roof has a lot of mortar. as the reed bundles fail and the tiles begin to sag dabs of mortar and oddments of brick, etc. are used to prop them up and fillets of mortar are used to stabilise damaged tiles to prevent them sliding.

difficult to see from the photo but the amount of scrap slate and the way it is gathered in one or two confined areas leads me to believe they are roofer's trimmings rather than what has dropped through deterioration of the slates... further evidence your roof is not original comes from the picture showing a definite line or change between your roof and your neighbour's.

your roof appears to be fairly dry but as it is not felted there will be times when some water will find its way in. the combination of moss and frost will damage the slates and make them porous. wind and other vibration will eventually loosen an odd slate and allow it to slide... the white stuff looks like efforvesence which is evidence of some water ingress at some time.

first time it rains hard i suggest you make another pilgrimage upstairs.

the white spores might be nothing or might be dormant dry rot waiting for moisture to allow them to get going. dry rot is fascinating stuff and a ripe fruit is quite attractive. it is probably nothing but we must be vigilant about such things, especially as the weather becomes milder and damper.

[johncrowther]

Verne,

You are a font of knowledge; thanks for replying!

The mortar stuff seems to be all over the top of the insulation, and there are bits hanging from the inside of the roof, waiting to drop. So my impression is that the inside of the roof used to be covered in this mortar stuff, presumably to hold the tiles on to the batons. It would appear, as things stand, that the roof is doing ok without this mortar stuff in place, but I don't want to tempt fate. I'm not sure why there is so much of it in that corner; perhaps the same person who rolled back the insulation from that rectangular strip chucked it all there as it was in his way?

I would be very surprised if that roof isn't original. The house is just over 100 years old and the roof looks like others in the street (apart from those that have been re-roofed with concrete tiles.) The house to the left of mine has some sort of black grease spread all over its roof so that might give a misleading impression - I can see what you mean; their black grease makes their roof look different. If those white things are for old aerials then presumably the wooden frame has been in situ since the house was built.

The straw stuff is only in one corner and near to it, on the brick (the top of the external wall) there is what looks like bird droppings, hence my presumption that it could be bats. I agree.. I need to have a nose round up there when it is pouring down outside.

Radiator is working in the spare room now and I had it on full blast yesterday with the dehumidifer on. The wall looks a hell of a lot drier with only stain indicating where there was previously water. The ceiling has also dried. So my plan now is to repaint the room and continue keeping it warm with dehumidifier on every other day, and window on the latch when ever somebody spends any time in there. If the damp patches re-appear then I think I may need some pointing doing, or roof work.

Thanks again

[Rich]

Hey John

I'd put money on it that your roof is NOT the original roof. I was trained as a slater/tiler at college when i was 18 and have worked on many many re-roof's where we would carefully take off as many slates as possible, chuck out all the cracked ones and replace them, then re-roof the entire building and once finished, it looks old, but nice and tidy...

You look at most slate roofs, 30+ years old and you can see they are in need of re-roofing as slates crack, slide out of place and generally fall off over the years.

You can tell a good slate from a bad one by tapping it with a hammer and a bad slate makes a distinctive thud sound, very dull, and sounds like it will break if you hit it again whereas a good slate makes a nice clean "doink" kinda noise.

Also, the mortar in your loft has been applied from the inside, hence its shape and might have been done when the roof was re-roofed...

Given that you seem to have zero felt under your slates, it may have been re-roofed a VERY long time ago, either that or the roofers didnt know anything about felt at the time, as its the norm to lay felt over the battens before putting the slates on, although not essential, it does ensure that should a slate dislodge, you dont suddenly have a gaping hole in your roof letting water and wind, and wildlife into your loft space...