Roof leak - any advice?

[Another John]

I just happened to look up at the globe light in our bathroom last night, and noticed that it was half-full

Outside ======= From outside this morning, with the aid of binoculars, I cannot see any tiles missing or slipped.

It's *conceivable* that the water got in yonks ago, and I've only just noticed it: about 6 months ago I did notice a tile that had slipped, on this line in the roof; I shoved it back into place with a long pole, and it's still properly aligned with all other tiles.

Prognosis? ========== I don't yet know how bad this is: next time it rains heavily I'll be up in the loft looking. The water in the light may have been there for -- ooh - weeks? months?

However the rafter concerned is damp and has a slight case of wet rot where the wood meets the roof felting -- mostly it feels sound, if damp.

Remedies? =========

I'm proposing to spray the rafter with Thompson's Water Seal: it's all I can think of doing so far! Apart from looking for a leak, next time it rains heavily.

History =======

This is a 1962-built house, far from being a Rolls-Royce build, but not jerry-built either. The tiles are concrete. The roof is orientated exactly East-West, and the leak is on the North side, which is quite heavily mossed.

Any general advice, or experiences, that anyone can offer?

Cheers John

[RobertL]

i'd cut away the sasrking felt in the wet areas so I could see the underside of the tiles all the way from top to bottom. The sarking is probably a crumbling mess by now anyway if it is the bitumen soaked sort. .

In our 1960s house we found one of those concrete tiles had corroded a hole right through it. Without the sarking there you can change the tiles from inside.

Robert

[Another John]

Thanks Robert: how did you then replace that piece of sarking felt so that the joints would remain intact? Seems a bit difficult to me, though there's always a knack to these things once you find out what it is!

While I'm on the topic: what are the pros and cons of drilling vent holes in the soffits(?) of this roof? These are solid pieces of timber in the 1960s part of the house, but I noticed that when we had an extension put on in the 1990s, the soffits are basically continuous open plastic grilles: a complete contrast!

John

[Another John]

[Bloody hell! This is a bodge and a half!]

Sorry: just noticed that some of my original post is missing! "half full of water" is what I'd said originally, and (naturally!) I also described the conditions INSIDE the roof as well.

[george [dicegeorge]]

Wont that just seal the damp in the wood?

I would: Put plastic paint trays in the loft to catch the drips. Then find the leak. Then fix it. Then let the wood dry out. Then scrape off the rot and treat it wet WetRot hardner fom those green tins. [g]

[george [dicegeorge]]

I believe that the felt is only a secondary line of defence, no water should get past the tiles, so you can cut away the felt from inside and find out where the leak is. You should be able to replace the felt later from the inside.

[g]

[Another John]

Thanks for the input George. No - the Thompson's tin implies that it can be applied to wet wood, and it's completely breathable (it seems to be just some kind of colourless oil-based stuff, very thin; I've had a 5 litre tin for about 20 years (by the look of it). Used for both brick and wood.

Mind you: treating this rafter with Thompson's is purely treating symptoms: I'm well aware I need to identify and cure the cause!

Cheers John