Flashing On Slate Roof Against Stone Wall

[purplechap]

Just come across this great forum. Wonder if anyone can advise me on installing flashing on a slate roof against a stone wall? I wish to re-weatherproof a 1940s extension against circa 1850 stone walls.

I have read plenty of advice on angle grinding between brick courses (and just looked through the good explanations on this forum). However is this still the method to be used on stone walls?

I ask for two reasons.

Firstly it looks like originally the lead flashing was mortared onto the wall and a 'quadrant' of mortar layered on top of it to direct the water on to the roof. I enclose a URL of the picture where a bit of mortar has crumbled off the leading.

Secondly, unfortunately we are on very bad terms with the neighbour and one of the walls (shown in the picture) is his gable end. I would very much like to avoid cutting into his wall, regardless of whether I have a right to under the Party Walls act. If there is an alternative method to installing flashing onto stone walls that meets with good practice (and regulations) then it would be great to hear about it.

Thanks a lot for listening.

 

[DAZB]

Probably the only other way without mechanically fixing a new flashing to the gable wall is to just recreate what has been there for years and re-flaunch the affected length of roof using a strong mortar mix of 3 parts sand to 1 part cement. If there is moss or other plant life growing you will have to remove it first , probably best with a wire brush and a spray of Round-up to kill it and then ensure it is dust free before you start.

 

[purplechap]

Thanks DAZB.

I'm a joiner not a roofer/builder though I didn't see any reason not to have a go at this myself.

I have an 'Understanding the Building Regs' book which talks about most things but doesn't mention standards for flashing. Elsewhere on this forum there has been advice given to people to insist on builders using 'deep flashing' (for brick walls?). This does suggest there are other ways (such as recreating the existing mortar joint as you concluded), though I just didn't know if they would satisfy current building regs.

Doing things "by the book" is my main concern here as I do not want to do anything substandard, especially as it involves working on a party wall.

Anyone else know anything about this subject, or is 'deep flashing' the only 'official' way to do it these days - even if that means grinding through solid stone!?

Cheers

 

[P.S.]

What about flashing tape ?

give it a good key, and paint on some primer

Does seem cheap and inferior solution to lead, but i used this as a tempory fix against a pebbledash wall/roof and 10 years later - no problems...

You could actually tuck lead under it, using the "tape" as the seal against the wall.

 

[masona]

Agreed with Dazb regarding strong mortar and maybe a hot pour bitumen to top of it as well.

 

[purplechap]

Thanks everyone. I will recreate what was there and add some bitumen on top for good measure.

 

[Tom.]

Isn't it better to use lime mortar, rather than cement?

 

[legs-akimbo]

No no no and no , a cement fillet to give it its proper term is quite simply a bodge, closely followed by ugly banjaxed after 12 months flashband and tar, if your gonna do it, do it right and its a done deal.!
Take a length of 4x2 or 6x2 depending on what width of lead you intend to use, and lay it up the stone wall on top of the slates and mark along the top for a straight line chalk for e.g.
Run an angle grinder with cutting blade along this line an inch and a half deep, if you think you might struggle to fix the lip of the lead into this groove go over with a stone grinding disk again to make it wider.
cut 1.5 mtr lengths of code 4 lead of 6"or 4" depending on what height your score mark is and laying this on a length of timber sat on tressles, the lead over hanging the edge of timber by over an inch dress down this edge at 90 degrees, cut enough of theese to reach the top with overhangs to each of 6".
Next create some soakers using 6" code 3 lead cut them long enough so that when you dress theese.... as with the flashing except along the length and through the centre,... they will slip beneath the edges of the abutment slate and overlap each other a good couple of inches when you work from the bottom to the top. Soakers done, place the first piece of flashing in place and take some four inch pieces of inch wide lead and fold them over till they are thick enough to wedge between the turned edge of the flashing and the ground out joint, taper one edge with the bash of the hammer insert into channell and tap in with the hammer and bolster chisell till tight, lead then wil never budge (3 per length) proceed in same fashion for next length of flashing till you reach the top. repoint the joint in 4;1 sand cement. Once done its a proper job if that is what you want, anything else particually a cement fillett will not satisfy any authorities and is a poor substitute that will need doing over and again.

Hope this helps

Regards

Robbo

 

[masona]

You're right Robbo but purplechap didn't want to cut into the wall.

Secondly, unfortunately we are on very bad terms with the neighbour and one of the walls (shown in the picture) is his gable end. I would very much like to avoid cutting into his wall, regardless of whether I have a right to under the Party Walls act.

 

[purplechap]

You're right Robbo but purplechap didn't want to cut into the wall.

Thanks masona and particularly Robbo for taking the time to give me those detailed instructions.

I do want to make a proper job, one that will last and meet the regs. Masona picked up on the heart of the question which was would replacing the existing 1940s cement fillet (i) make a proper job and (ii) meet regs. If it satisfied both of these then I would be able to avoid cutting into my neighbour's wall as he will give me grief as soon as I start.

If I need to cut into the stone wall to do a proper job as Robbo suggests, then so be it. This means I will have to cover myself with my neighbour by taking to the local authority to tell them this is what I intend to do (he'll phone them up, I just know he will).

Cheers guys.

 

[masona]

Why not pop down to your planning department and explains what you want to do and when your neighbour ring them up, they won't get anywhere. Can they see the area that need the work done ? if so do it when they are not there ! It best to do a proper job if you can as Robbo post.

 

[purplechap]

Thanks for your advice guys. This forum is great for having someone else to talk things through with.

I will do a proper job with deep flashing, but let the planners know first to pre-empt my neighbour kicking up a fuss.

 

[DAZB]

I'd agree with you Legs that it should be done like you say but also picked up on the fact that it was preferable not to cut into the gable wall . I became a Roofer myself after leaving school but now most of my work is Joinery and construction having a crew of six lads and a large Joinery workshop doing everything from manufacture of hardwood windows to Loft or Basement conversions. It keeps the rain off my back (ex roofer) and the wolf from the door , as they say.

 

[purplechap]

A phone call to the planning dept and they said I should serve notice to the neighbour under the Party Wall Act 1996, and that it was nothing to do with them.

I promptly did this in writing using a standard letter from gov.uk's website and popped it through his letterbox.

Neighbour put a ladder up against my courtyard wall at the back of my house and spitted venom over the top while I was working, saying he was not going to let me do anything. (Swear words were involved.)

It is a long story and this is not the place, though it involved me appearing as a witness against him in a criminal prosecution case that did not go his way. He really doesn't like me now

So from what I read about the Party Wall Act, while I have the right to install the flashing, if he ignores my letter (or writes back refusing permission), we have to resolve the "dispute" before I can do anything. This involves surveyors.

I just knew it would escalate which is why I was trying to get away without cutting into the wall in the first place

But now we have had this discussion, I kinda feel that anything less than cutting in the flashing is a bit of a bodge - and we don't want that!

 

[masona]

I do understand and at the same time it anger me why people are like this, they must be very sad people.

My mum's next door neighbour give me a hard time when I'm working there for building work, why why why, what is the matter with them and they never win !