Roof leak

[fathersymes]

I'm restoring a 19th C. farmhouse with slate roof. There are signs of leaking on the upstairs chimney breasts, there is a tar type deposit on the ceiling and some of this has also stained the ceiling downstairs near the chimney breast.

I need to get a roofer to look at it, but would like a bit of knowledge so as he doesn't rip me off. Does anyone have any idea as to the likely cause of the leak?

There is no access to the attic space, should I make a trapdoor here?
Also should this be insulated with something like sheeps wool?

 

[Raylea]

Is there any flashing around the chimney on the roof, if so what sort lead or concrete. If lead, goody goody maybe where it joins brickwork needs repointing back in, concrete not so good does not allow for movement. Hack of replace with LEAD. Or is there none is so LEAD.

Hope this helps
Raylea

 

[Nemesis]

I certainly would make some access - and ensure the place is insulated.

Are the fireplaces open or blocked?

And agree - check the flashing!

 

[Lime]

I agree about both cement/lead and access.

If the tiles/slates look ok almost certaintly the join between the chimney stack and the roof is letting in water.

However my attention was drawn to your remark, "tar type deposit" which is not what I would expect from a simple leak through the roof/chimney join.
It suggests to me that water is picking up soot or tar from somewhere or the tar is directly coming through the chimney brickwork.
If the chimney flue leaks smoke into the loft or a substantial downdraught causing soot to enter the roof it is possible that there is a layer of soot above the ceiling that has caused the discolouration.
Or it could also be caused by water coming down through the chimney flue or brickwork and picking up soot/tar on the way then staining the ceiling.
Or it could be that previous occupants have burnt a lot of wood in the fireplace below and the tar and condensed moisture from the smoke has seeped through the brickwork directly.
In any event you would do well to inspect the chimney brickwork both inside the loft and the stack above the roof as it may need repair or repointing.

 

[Pford75]

Agree...we had leaks recently with similar deposits...ours was a combination of slipped slates, cracked lead flashing and some dodgy cement pointing which had failed....flashing repaired, slates replaced and repointed in lime and leak has stopped

 

[citizensmith]

How big is the chimney stack? We had a similar problem and similar tarry deposits. Roofers found flashing was bad, but also found large zig zag crack through brickwork and 15 feet of stack rocked when nudged from the top!!
The whole lot had to be rebuilt but at least staining and leak is now banished for my lifetime (I hope).

 

[Penners]

Of course the flashing around the chimney should be checked. But I do think Lime's comments should be noted. The most likely source of tars is the interior of the chimney. So it's possible that these are coming through some porous area of the chimney, from its interior.

 

[Nemesis]

An unventilated blocked up chimney can cause these sort of problems too - condensation occurs.

Opening up the loft area is something I'd certainly make a priority - that way you can check on roofing timbers, check the stack, and put in insulation.

You could also have a leaking chimney of course - a favourite place is where the flue passes through a ceiling/floor void.

 

[fathersymes]

many thanks to all for comments, one of the fireplaces is semi bricked up, this is also full of twigs from nests.

The roof was briefly inspected (externally) by a conservationist who said it just needed repair. My concern is that if a roof leaks it can be very difficult to find the leak as water can travel from the hole and enter building somewhere else.

What is best practice for roof repairs? Is it best to strip roof and put back all slates. Should there be some sort of felt underlay?

 

[Penners]

What is best practice for roof repairs? Is it best to strip roof and put back all slates. Should there be some sort of felt underlay?

To answer that question first:

If the roof really needs a complete repair/renewal, that means stripping off all the slates (carefully, to preserve as many as possible), then removing the battens.

The timber structure needs checking and repairing where necessary, then cover with a breathable membrane (Tyvek for example), re-batten and rehang the slates. You'll need a proportion of new slates, to replace any that have been damaged in stripping.

But why would you need a complete strip and re-roof just for a leak in the chimney area?

If the current roof has no felt, that's not in itself anything to worry about. Many old roofs have none. The critical question is - does it keep the water out?