Options for 'too shallow' for tile choice

[Post and beam]

The tiles that i had chosen are 40 degree tiles, apparently. Part of my roof, the single storey dining room extension is at 35 degrees.  A tiler has told me about something that fits under the tiles that will allow 40 degree tiles to be laid as shallow as 11 degrees. 

Is this cosher? and if so what is it or is it BS

Thanks in advance as always

[nod]

Probably a bi more info 

40 seems an odd size to go down to 

Most roofs are 30-50 

11would be nearly flat 

[Post and beam]

The tiles are from Lifestiles in Halstead. They rate their tiles as suitable down to 40 degrees. The main roof of our proposed house is steeper than this so they are suitable.

But, the dining room has a shallower roof and they are not suitable for that.

So, if what my tiler has said to me is true i can use these tiles.

Yes, 11 degrees is almost flat.

[Big Jimbo]

If your roofer is talking about a double layer of underfelt, it's a bodge, and it will leak. You are going to struggle to get a tile down to 11 degrees. As @nod said that is almost flat. You are going to need a hell of a headlap, and i would still expect it to leak.

[Temp]

 

3 hours ago, Post and beam said:

Part of my roof, the single storey dining room extension is at 35 degrees.  A tiler has told me about something that fits under the tiles that will allow 40 degree tiles to be laid as shallow as 11 degrees

 

35 degrees is possibly OK for some tiles.

 

But see here for options. Not all would recommend them...

 

https://www.dreadnought-tiles.co.uk/Pitches-below-35-degrees

 

 

 

 

[Post and beam]

17 minutes ago, Big Jimbo said:

You are going to struggle to get a tile down to 11 degrees.

Thats not what i need or what i said. I need tiles suitable for the 35 degrees of our single storey dining room.

[Temp]

Is it very exposed? Have you already purchased them?

 

Some Marley and Weinererger are rated down to 35 degrees. 

 

https://www.burtonroofing.co.uk/blog/the-versatility-of-clay-plain-tiles-burton-roofing/

 

Quote

Although the British Standard for Slating and tiling; BS 5534, recommends a minimum roof pitch of 35 degrees for double lapped plain tiles that comply with the geometric characteristics of EN 1024, the Edilians Phalempin Plain tile range is one of the few double lapped plain tiles on the UK market that can be used on roof pitches as low as 30 degrees.  

 

[Post and beam]

7 minutes ago, Temp said:

Have you already purchased them?

No. But i know what i want to use and am trying to understand if what i was told is true or BS. This will determine whether i do buy them or look for something else.

[makie]

https://www.permavent.co.uk/products/easy-slate/

https://uk.onduline.com/en/professionals/tools/news/product/low-pitch-roofing-solution-thats-right-light-and-watertight

 

It can be done. I've installed Rosemarys on a extremely low pitch with the bitumen sheets in the second link. 12 years and no leaks.

[Temp]

30 minutes ago, makie said:

https://www.permavent.co.uk/products/easy-slate/

https://uk.onduline.com/en/professionals/tools/news/product/low-pitch-roofing-solution-thats-right-light-and-watertight

 

It can be done. I've installed Rosemarys on a extremely low pitch with the bitumen sheets in the second link. 12 years and no leaks.

 

Presumably if you use a bitumen based product it has to be a ventilated cold roof structure (50mm ventilated void) or is a warm roof structure with insulation above the rafters possible?

[makie]

20 minutes ago, Temp said:

 

Presumably if you use a bitumen based product it has to be a ventilated cold roof structure (50mm ventilated void) or is a warm roof structure with insulation above the rafters possible?

Genuinely couldn't tell you, all of this was installed for us by the builder with the architect overseeing it. We just had to batten on top of them.

[Nickfromwales]

Isn't the norm to just increase the overlap slightly to run with the slightly lessened pitch? From 40 to 35 is nothing afaik, so I'd say this is fine. Just go with the increased overlap for belt and braces?

[Temp]

4 hours ago, Post and beam said:

The tiles are from Lifestiles in Halstead. They rate their tiles as suitable down to 40 degrees. The main roof of our proposed house is steeper than this so they are suitable.

 

I had a quick look at their web site. They have  some rated down to 40 and others 35. Think I would tell them which ones you like and see if they can recommend a similar tile that's OK at 35 degrees. Or perhaps see if they will contact the manufacturer and ask if increasing the overlap and by how much would allow them to be used at 35 degrees. Make them work for your order. 

 

 

 

[makie]

19 hours ago, Nickfromwales said:

Isn't the norm to just increase the overlap slightly to run with the slightly lessened pitch? From 40 to 35 is nothing afaik, so I'd say this is fine. Just go with the increased overlap for belt and braces?

Can be done but voids any warranty.

[Mike]

Permavent also have a product for plain tiles down to 17.5° : https://www.permavent.co.uk/products/plain-easy/

[Post and beam]

Update:

The supplier of these tiles have stated that they will certify them at 35 degrees. They are content that the location does not represent an exposure to adverse weather.

Sorted.