Torching - anyone done it?

[Athers1971]

I’ve decided to remove the failing/failed bitumen felt in my attic rooms. I'm going to replace it with lime torching (parging).

Anyone done this? Is the idea to fill the space between the batten and the slate, so that it is as thick as the batten? Or should I just be giving the slates a scratch coat a few mm thick up to the battens?

 

[stuart45]

If the battens are close like yours fill in between them with a haired lime mortar. Most lime suppliers will sell it ready mixed.

 

[Cubist]

Coo, you had me going there for a moment. Thought you meant Torching as in the technique of 'Flaming' a timber, as some of our American Cousins do, to water-proof the outer face and inhibit pest infestation.

I'll go back to sleep now.

 

[Feltwell]

Haven't done it, but it had certainly all long since failed here. How long that took - no idea!

Breathable roofing membrane is remarkable stuff, it was our only roof covering for 3 months in winter, you could feel breeze through it, see straight through it, but not a drop of water came in. I guess you're trying to avoid taking the slates off though.

 

[Athers1971]

Haven't done it, but it had certainly all long since failed here. How long that took - no idea!

Breathable roofing membrane is remarkable stuff, it was our only roof covering for 3 months in winter, you could feel breeze through it, see straight through it, but not a drop of water came in. I guess you're trying to avoid taking the slates off though.

Yeah the slates are in relatively good order as well as the battens etc and so reluctant to re-roof.

 

[malcolm]

What's the problem you are trying to solve following removal of the nasty bitumen? Is it leaking now?

 

[Athers1971]

What's the problem you are trying to solve following removal of the nasty bitumen? Is it leaking now?

I’ve got some large rips / holes in places which is providing too much ventilation let’s say. I’m going to be insulating under the rafters and so need to do something now before I lose access to the underside of the roof covering.

The slates doing its job, i.e. no leaks so I’m hoping that removing the felt and torching with lime will help prolong the life of the roof.

 

[malcolm]

Too much ventilation can be a good thing to have above insulation. I insulated a garage roof once and any warm air that made it's way past my perfect sealing condensed on the cold surface above the insulation and dripped back down onto my work bench.

 

[Stevers]

There was a time when roofs weren't felted. The resulting extreme air movement left lofts very dirty, with the chance that snow could be blown into the loft. In Scotland at least this risk was presumably mitigated by the use of sarking boards, and torching should also reduce that risk. Snow (and in the right conditions there could be a lot of it), could make a terrible mess if it wasn't laboriously shovelled out before it melted!

 

[Kearn]

Ideally, you’re looking to fill the laps, to minimise water ingress and reduce and lifting due to high winds getting under tiles. I’m not too versed in slates, we have unicorn triple romans on our roofs, which when torched basically covered the last few inches of the head lap, so between the underside lower section of the upper tile and the top, upper face of the tile below.

So from the underside of the roof, you’d be pushing up the higher tile and getting some muck between it and the lower tile so it gets squished in between both.

I think you’ll struggle to fill the whole gap between battens on the underside of the slates as there’s nothing for the lime to physically hang on to, so it would simply be suction to the slate. It also doesn’t really have a role on the underside of a tile, it’s for where one meets the next and there’s the chance of a gap.

It’s worth doing a thorough job and possibly monitoring once done in some miserable weather to check for any ingress. The last thing you want is the insulate from underneath and not be able to see any possible leaks slowly doing damage invisibly.

 

[Flyfisher]

Coo, you had me going there for a moment. Thought you meant Torching as in the technique of 'Flaming' a timber, as some of our American Cousins do, to water-proof the outer face and inhibit pest infestation.

I'll go back to sleep now.

At the risk of digression, I thought the same thing from the thread title. We have a large outbuilding that had a very poor condition pantile roof when we first moved in. Subsequent stripping of the pantiles, so we could repair the underlying structure, revealed many burnt timbers that looked as if they'd been in a fire but the burning was not consistently in one area as I'd have expected if they had experienced an actual fire. It looked as if someone had used a blow torch on them.

So it might not only be our American cousins who do such things!

Anyway, apologies for the digression (but Cubist started it ). Carry on . . .

 

[Cubist]

Anyway, apologies for the digression (but Cubist started it ). Carry on . . .

Ohhh.. don't mind me, my shoulders are broad enough. They need to be to support this often thick head.

And thank you; I had suspected for a long time that this novel technique did not originate in the wilds of the USA and, like so many other innovative ideas, had been filched from jolly Old Blighty. Confirmation much appreciated Flyfisher, ta much.

 

[stuart45]

I thought it was the Japanese who first used it. Shou sugi ban.

 

[Cubist]

I thought it was the Japanese who first used it. Shou sugi ban.

Nah, surely not. We would never do such a thing and anyway they shut the doors for donkeys years to keep us out....... ohhhh, maybe that why...

 

[Flyfisher]

And thank you; I had suspected for a long time that this novel technique did not originate in the wilds of the USA and, like so many other innovative ideas, had been filched from jolly Old Blighty. Confirmation much appreciated Flyfisher, ta much.

Just to wrap this up, I found my original post on the subject, just in case anyone is interested (go on, you know you want to ):
https://www.periodproperty.co.uk/forum/threads/rot-or-fire.13303/#post-181042

 

[Cubist]

And I would never have put you down as just another 'tease'. But there you go, appearances can be so deceptive.

 

[Athers1971]

This is a photo of how I imagine is not ‘right’. I imagined it was a full covering of the visible tile or slate. But what do I know.

Photo courtesy of Mike Wye website!

 

[Athers1971]

Something like this one

 

[stuart45]

It can be done either way. It really depends on the batten spacing.

 

[CliffordPope]

Coo, you had me going there for a moment. Thought you meant Torching as in the technique of 'Flaming' a timber, as some of our American Cousins do, to water-proof the outer face and inhibit pest infestation.

I thought it meant "torching" as in the listed building insurance thread.