Weatherproofing rosemary tile verge (undercloak?)

[paulb33]

Hi All,

The sun is shining at last and our joiners have started work on the roof line. Just 5 minutes in and they have raised a question. How should this roof verge be treated?

Water has been penetrating the verge and will likely continue to do so in the absence of weather protection on the exposed edge. The good news is that we're using linseed oil paint, which should help wick dampness away.

But, should we be treating the tile edge (a black gloop was previously used....)? Our roofer will be coming onsite after the roof timbers have been repaired/reinstated. The joiners have suggested we install a fibre undercloak, in readiness for the roofer..

(Looking at the damp timber hitting the scaffold, I'm thinking perhaps uPVC isn't so bad after all...... :lol: )

Thanks in advance,

Paul

 

[DJH]

Always a problem Paul, with these small tiles as you can't achieve an overhang in order to weather the barge board below. I would use some pressure treated timber for the barge and paint it with several good coats of paint.

Have you abandoned your blog?

Doug

 

[paulb33]

Thanks Doug. So, no under cloak, tile bed or gloopy black paint treatment?

Yeah: the blog is on hold, due to time pressures.... Have lots of photos of windows, linseed oil paint etc. that I have to upload when I get the chance.

Paul

 

[DJH]

An undercl0ak is good but it will only extend out as far as is possible to fix the tile onto the battens. I have seen slate used as an undercloak but you have to consider the effect of strong winds at this point of the roof.

Doug

 

[paulb33]

There's remnants of a black bitumen(?) further up the apex, suggesting a felt was originally turned over the bargeboard. I wonder if we should be replicating this?

(The photos show bargeboard with fascia board removed)

 

[plasticpigeon]

That's not too bad for 110 years or so! Are the tiles at the verge actually nailed to the bargeboard or just set in mortar? Wouldn't an undercloak raise the height of the tiles at the verge? i'd have thought an undercloak would need the wood on the board to be reduced in height, if so then it doesn't sound a great solution

 

[paulb33]

That's not too bad for 110 years or so! Are the tiles at the verge actually nailed to the bargeboard or just set in mortar? Wouldn't an undercloak raise the height of the tiles at the verge? i'd have thought an undercloak would need the wood on the board to be reduced in height, if so then it doesn't sound a great solution

Yeah. I worried about raising the tile too. What about a thin layer of felt turned over?

The tiles are nailed into the bargeboard and set in mortar. There is a large overhang (see below).

 

[paulb33]

This has also surfaced an important talking point. Namely, when a timber should be replaced (rather than filler used). Does anyone have a philosophy on this?
Paul

 

[plasticpigeon]

My philosophy is to only replace if structurally unsound, otherwise repair/fill. This is only my own thought, not any standard way. I think your wood looks easily good enough to save, but obviously i can only see pictures, and I have only an informed amateur point of view. Is there another board nailed to the one in the pic? If so the rotten bit won't even be seen! don't know about felt tuned over, but it is important not to get water between 2 pieces of wood if there is another board over the top.

 

[paulb33]

My philosophy is to only replace if structurally unsound, otherwise repair/fill. This is only my own thought, not any standard way. I think your wood looks easily good enough to save, but obviously i can only see pictures, and I have only an informed amateur point of view. Is there another board nailed to the one in the pic? If so the rotten bit won't even be seen! don't know about felt tuned over, but it is important not to get water between 2 pieces of wood if there is another board over the top.

We're replacing a few sections of the more rotted out bargeboards. The timber in the photo goes into the wall cavity and the rot here was keeping me up at night. We've agreed that the rotted bit can be cut out, much to my relief...
Paul

 

[paulb33]

Is there another board nailed to the one in the pic? If so the rotten bit won't even be seen! don't know about felt tuned over, but it is important not to get water between 2 pieces of wood if there is another board over the top.

Yes, PP. The fascia board will be fixed on this bargeboard (butting up to the tiles and hiding a multitude of sins...).

Interestingly, the roof has tongue and groove boards under the battens. And very wide battens. Its this structural solidity that reassured the joiners we can cut out the rotted structural timber. 'Its built like a church roof' said the joiner. No surprise: the architect and original owner (John Coates Carter) was a specialist ecclesiastical architect, in practice with JP Seddon.

 

[agbagb]

The edges of my pan tiles on the dormers have a thin cement bound asbestos sheet (6" wide) under them. The edge is then mortared up from that so the timber is separated from the roof covering. If yours hasn't got an over-hang and doesn't need the mechanical support maybe a strip of DPC under the lats would do the job.

 

[88v8]

In our 1920 house there was an undercloak of flat tiles.
It tipped up the verge a little so that less water ran off the edge.
Nevertheless when we bought the house in 1980 one side of the south verge was rotted, and its lower support. But that was all.
The timber had always been creosoted, I redid it every few years.
Subsequently I had to replace the bottom of the fillet on the same side, as you see below, and repoint the verge. Perhaps this was because of the new verge timber shrinking a little.
I think with lime mortar a degree of maintenance is inevitable, which becomes problematic when it's not ladder-accessible as in your case.

We reproduced the roof arrangement, including the creosoting, in our 1991 extension, and neither timber nor tiles needed attention in the twenty years we continued to live there.

I'm inclined to think that an undercloak is better than none, due to the tipping effect and the better support for the verge.

Ivor

 

[paulb33]

I'm inclined to think that an undercloak is better than none, due to the tipping effect and the better support for the verge.

Ivor

This is v helpful, Ivor. Great photos too. I love your unpainted render, by the way...

 

[88v8]

I love your unpainted render, by the way...

Haha, the original was all hacked off and renewed in 1980. Originally one coat, it had all but vanished in places, revealing the heterogenity of second-hand bricks which the impoverished builder and only previous owner had perforce to use.
The new two-coat render (pebbledash) I had done with soft sand so that although using cement - knew no better m'lud - it would assume a pleasant brahhn hue.
And too right, I never painted it. I think only a complete masochist paints roughcast render, especially in the burbs where it will be grubby in a trice.

Ivor

 

[Feltwell]

I'd use a fibre undercloak personally, then point the verge, which doesn't need to be in lime. Not historically accurate, but it does work. The undercloak looks rather like asbestos board - I can take a picture of what was done here if you like.

You can use tiles which can look quite good, like Ivor shows. This may be of interest:-

http://www.clayroof.co.uk/design-details-eaves-and-verges.htm

 

[paulb33]

I'd use a fibre undercloak personally, then point the verge, which doesn't need to be in lime. Not historically accurate, but it does work. The undercloak looks rather like asbestos board - I can take a picture of what was done here if you like.

You can use tiles which can look quite good, like Ivor shows. This may be of interest:-

http://www.clayroof.co.uk/design-details-eaves-and-verges.htm

It would be good to see your work, Feltwell. I'm less concerned about historic accuracy in this hidden location. But, I don't think tiles would suit the very simple roofline here and it would raise the lip of a very large roof, exposing it to wind damage.

Paul

 

[Zebra]

Will it be possible to add an undercloak retrospectively, if you're not taking the roof tiles off? Are the tile battens not attached to the bargeboard? What else would they be attached to, given the overhang you have there?
I have a slate undercloak, and very nice it is too. It's new, I had the roof retiled three years ago. The previous people had cement rendered up and over the bargeboard, right up to the underside of the tiles... :roll:

 

[paulb33]

Will it be possible to add an undercloak retrospectively, if you're not taking the roof tiles off? Are the tile battens not attached to the bargeboard? What else would they be attached to, given the overhang you have there?
I have a slate undercloak, and very nice it is too. It's new, I had the roof retiled three years ago. The previous people had cement rendered up and over the bargeboard, right up to the underside of the tiles... :roll:

We'll probably pull the tiles back on the verge, giving access to the bargeboard and allowing us to rebed them.

 

[Zebra]

I see. In which case I probably agree with Feltwell that a fibre undercloak would do. It's thin enough not to raise the line of the tiles, and if you're not too concerned with historical accuracy in this location, then the fact that it's a single strip rather than individual tiles will probably offer more support to the verge, structurally.