is 25.5° pitch enough?

[DH202020]

I have recently been afflicted with the current concrete roofing tile shortage!

 

To finish the garage roof I have sourced a Sandtoft Concrete Lindum Interlocking sandfaced/granular tile

(the supplier ordered them last year)

 

The specifications say the lowest pitch is 30°mine is 25.5°

Originally I had allowed for Redland which allowed a lower pitch.

BIG question will they still function OK?

 

P.s if anyone has 340 double roman in brown granulated spare let me know

Thanks David.

[Ian]

@DH202020

unfortnately I think the answer is no as that's too much of a difference.

 

One possible solution which I've used successfully in similar situations is to use a profiled fibre roof sheet under the clay/concrete tile.

 

something like this that is BBA certified for use at the low pitch you need:

https://onduline.co.uk/downloads/ee7f03ac-55c2-42f5-9b6c-06d6f6495100.pdf

Edited May 24, 2017 by Ian

[DH202020]

Hi Ian, Not thought of that, adds about £260 to the job though, Mmmmmm wonder why Redland/Marley with same shape/ style, can go so low?

Now you've got me thinking...would timber firing pieces be more reasonable? 

Any idea the difference between 22.5 and 30 expressed in measurement?

[Ian]

26 minutes ago, DH202020 said:

 

Now you've got me thinking...would timber firing pieces be more reasonable? 

Any idea the difference between 22.5 and 30 expressed in measurement?

Too much height difference to make up with firring pieces.

 

In order to work the measurement difference for the 2 different pitches you need to know the width of your garage measured between the outside faces of the walls

 

If your garage was say 6 metres wide then the 30 deg pitch roof would need a ridge height that was about 500mm higher than the 22.5 pitch.

 

ian

[DH202020]

Ok...

Width is 3.4 (length of of one side is 2m to facia board)...so going by what you said...it's too much

 

Back to square one...any double roman out there??

 

Thanks again Ian.

[Onoff]

9 hours ago, DH202020 said:

Hi Ian, Not thought of that, adds about £260 to the job though, Mmmmmm wonder why Redland/Marley with same shape/ style, can go so low?

Now you've got me thinking...would timber firing pieces be more reasonable? 

Any idea the difference between 22.5 and 30 expressed in measurement?

 

Rough & ready CAD sketch, this is what you're looking at dimension wise. Up slope goes from 2000 to 2134mm and ridge height increases by 301mm:

 

 

EDIT: Not sure if these are double roman or not but only 210:

 

https://www.gumtree.com/p/roofing-ventilation/second-hand-marley-roof-tiles/1238249683

 

EDIT 2: Pretty sure the glaze influences the allowed slope. "Shiny" surface tiles can go lower as water sheds easier and moss finds it harder to get a hold, rough glaze tiles need a higher pitch. Certainly the case for my tiles when I enquired about some replacements there were two glazes available. (I just took one down to B A Miles in Sutton at Hone). These are mine on the SW slope, about 30 years old (actually are these double roman?). I managed to get a copy of the original plans (bad microfiche copy) from the council from when it was re-roofed and it says Redland 49 but I don't think they are?

 

 

 

Edited May 25, 2017 by Onoff

[DH202020]

Thanks onoff

 

They are double roman Redland 50s or Marley

 

I've now gone back to the conservation and planing officers, asking for a meeting on site (they seem to like that sort of thing)

I'm not happy about second hand tiles, am going to suggest a different covering altogether!! Me thinks