Oblique / Tapered verges in slate

[mattgsxr]

Hi there,

I am attempting to install a slate roof on an oak framed garage that I have had built. Interestingly owing to the shape of the plot the roof is tapered with a width of 5.16m at the rear, 5.77m at the ridge and 6.13m at the front. The roof angle is 40deg. The structure is a double garage a bit like this one http://www.oakgarages.com/site/wp-content/uploads/2011/05/prices_2_bay.jpg but in my case although the front is full width, there is a symmetric taper from the front to the rear of the garage.

I have been reading and searching avidly, but I can't find out the best way to install the 20x10inch slates that I am planning to use. I do have access to 1.5x width slates. I can envisage lots of ways of doing this, but don't know which is the standard method.


My concerns are:
1) how I avoid having narrow slates on the edge of the roof, which my book says are a bad idea.
2) how I avoid water running off the sides of the roof (only a problem on the front section of the roof)
3) how to make it look right.


Any pointers would be appreciated.

Thanks,

Matt

 

[scottishslater]

overhang the slate 50mm on the verge start slating from the straight side first and use slate and a half on the verges

 

[noseall]

We used an angled roof trim to create a sort of hidden gutter along the verge of the narrow taper to collect any water run off.

I think the trim was black in colour, GRP and used by flatty installers.

 

[mattgsxr]

Thanks guys

That makes sense. Drawing it all out has helped me make sense of this. The smaller slates (some of them narrower than the regulated 150mm) will be covered by nice big ones, so I guess that means there is no problem.



Regarding hidden guttering, clever idea. I guess there are any number of dry verge solutions that would do this too. I'll find out what my local roofing guys stock.


Thanks again,

Matt

 

[datarebal]

Slate minimum does not have to be 150mm

easy way out is slate and halves or

You can set the roof out and trim more than one slate in a course

there are a couple of other methods too.

 

[scottishslater]

Slate min is 150mm you don't get the correct sidelap if you use a piece of slate narrower

 

[mattgsxr]

Thanks again.

"slate and a half" ordered.

 

[datarebal]

not all slates are 300 wide..... 150 is not minimum width of a half ... work it out

 

[mattgsxr]

not all slates are 300 wide..... 150 is not minimum width of a half ... work it out

Just something that I read in the nhbc document ( http://www.nhbc.co.uk/NHBCPublications/LiteratureLibrary/Technical/filedownload,45119,en.pdf )


"natural slate verges should be formed
with full slates and either slate and a
half or half slates that are a minimum
150mm wide."

So when I said regulated, that was all I meant. Sorry if I have caused confusion.

Matt

 

[datarebal]

no problem and no confusion...

a slate of say 225x450 can not have a cut of 150 mm it would need to be 112.5 ish and still have the correct side lap .
a 150 mm cut would push the bond ( side lap) to the extreme on the ajacent slate. simple..

 

[scottishslater]

Dosent matter what size the slates are the minimum width of slate clerk of works etc want you to use is 150mm wide they dont want people using inbands, Bachelor slates any more its bad practice ive seen may skipping hundreds of slate because of this on historic work or large sites 150mm is the rule.

 

[scottishslater]

so in other words you dont put in half cuts you get slate and half if your cuts are going below 150mm wide at abutments etc or generally anything you use a slate and a half

 

[datarebal]

I think your generalising a little to much., Firstly you were talking about correct side laps cannot be achieved with a half slate smaller than 150mm

A good example of this being incorrect would be A random slate in diminishing courses... first course could be say 30 inch long and 24 wide..top course could easily and often is 12 inch long 6 inch wide there by giving a 3 inch (75mm) side lap.

any cow saying this is wrong doesn't know their arse from their elbow.

Historically, slate and a halves were not always used.....as you should know.

Rules on large sites... umm looking around at the state of the slating on bigger sites I often wonder if there had been any rules applied at all.

However I would agree minimum width of a slate within the field slates 150mm on a random slated roof..

 

[catlad]

That 150mm rule is just a generalization for apprentises , an experienced slater will know when and were he can put what size slate.

 

[scottishslater]

Mate ive 19 years experience in roof slating and i can assure you when am doing historic slate work here in Scotland when using ballachulish slate i cant use any slate under 150mm if i do i have to take them out.In times gone by when we was doing random slate we could use inbands and then on course on top cover it with a wide slate dosent happen now if you do put in inbands your made to go up on your roof and cut them all out it actually wastes alot of good slate but thats how they want it done so when we size now anything 150mm is left on the ground to save us snagging the roof on finish.