Low Pitch... Should I Slate?

Bluscreendream

Hi guys,

I've have been told that a newly built lean to roof we had done is 15 degrees (please see attached diagram showing dimensions). I was planning on having this slated with 12"X24" Barona Capco slates, I'm concerned about the low pitch though, would I be crazy to go ahead with this, at a pitch of 15 degrees would there be a danger of strong winds removing some slates or driving rain going up under the slates? Many thanks.

AckwelFoley

1890400600

capcos technical department



I wouldnt be happy withy a pitch less than 20 - 25 degree using slates

ronan45

I did a similar job, The driving wind rain blows back up under the roof tiles and you get damp patches on your internal roof plaster. I would advise you dont.

mp22

If you really want a slate finish sheet in the roof with 1/2 osb board,then a single layer of torch on felt,batten and slate as per normal.

antiskeptic

Bluscreendream wrote: »

Hi guys,

I've have been told that a newly built lean to roof we had done is 15 degrees (please see attached diagram showing dimensions). I was planning on having this slated with 12"X24" Barona Capco slates, I'm concerned about the low pitch though, would I be crazy to go ahead with this, at a pitch of 15 degrees would there be a danger of strong winds removing some slates or driving rain going up under the slates? Many thanks.

I've a 400 sqft extension with a slated roof at that pitch (with Velux's in there too - contra the standard spec) and haven't had a problem in ten years. It's unsheltered and on the rainy/windy side of the house.

CBYR1983

Finally a use for trigonometry! If only I could remember it...

You have to slate it for the aesthetics

ronaldo84

what about these slates i think there a great job on low pitches http://www.jjroofingsupplies.co.uk/shop/Roof-Slates/Interlocking-Slate/Cambrian/prod_5046.html

Carlow52

all the trig is here

http://www.visualtrig.com/
from within
here
http://www.blocklayer.com/Default.aspx

[Thanks to snyper for this link]

PeteHeat

Hi,

Even low pitch tiles would be a problem at 15 degrees, slates at that pitch are a leak waiting to show.

The reason some appear to get away with such low slopes is the new type underlay's (breather membranes) last longer than the old bitumen based types.

There are roof sheets pressed to look like slate that may suit your needs better.

.

Merch

Does the low angle cause rain to blow up into the space?
I though the overlap just had to be increased?

Is a low angle affected more by wind too?

PeteHeat

Wind is one of the problems.

Light / misty rain with a light breeze is a bigger problem.

The main problem with slate is called capillary attraction, to experiment stand two panes of glass together in a basin with water in the bottom and the water will rise between the panes of glass.

With concrete tiles as the pitch gets lower they will tilt back, at best sitting flat on the roof.

I know there are specifications in the UK like the link above, what they don't tell you is they are part of a system which depends on the breather membrane (underlay) with a list of other accessories.

If you check out the specifications for the very same products supplied by Irish manufacturers / suppliers the specifications change to the realistic slopes (pitches).

A good slate or tile roof does need any underlay to be waterproof, obviously not recommended today but I have renewed roofs two hundred years old that never had underlays (it hadn't been invented).

.

Paul.C

Less than 10 degrees has to be felted. But adhere to manufacturers instructions. Its the only way your insurance will cover

1chippy

done a roof at16 degrees in slate for a client who was adament on slate. doubled the membrane. ended up going back two years later and putting torch on on and slating over. wouldnt agree with slating anything below 25 degrees

Paul.C

Yep, not surprised while working for a boss about 8 years ago the same thing happened. Dont remember the pitch....all I remember was looking at him and saying "that needs to be torched on ye" He didnt even answer, he just looked and walked away. He then proceeded to slate away as I was having nothing to do with it. Later he pulled me aside and told me not to speak "out of turn again" The next day he handed me red rawl plugs to fix 8 solid white oak frames in opes that had at least 2 inches between frame and brick either side. I laughed and told him to stick his job where the sun dont shine. Bloody scam artist.

This roof he was doing was a back garden extension with highpoint under the external sill and the low point about 30 foot down the garden, so I id imagine it was about 10 degrees. As well as that he covered the manhole with laminate flooring instead of moving it outside the extension.

I heard he had to go back less than a month later as the tiler poured grout down the jacks and it blocked everything. And Id imagine he had to go back and fix the doors and roof.

I think the lady that hired him really got unlucky when she opened the golden pages.

Sorry for going off topic a bit, just reminded me that if sounds wrong....... then its more than likely gonna be wrong. So id look into it via manufacturers as its a lot easier to do it right once than regretting not going with your gut

ronan45

My roof pitch is 11 degrees and slated, I have stains on the ceiling in about 12 different locations. What would be the most Economical way to put this right Its about 600 aquare foot extension with Velux windows.
I have seen someone selling a metal type roofing like a fancy galvanise. The pockets are empty. If it rains for any extended period you can see damp patches appear on the plaster. I had a structural engineer look at it and he said there is no way the builder should have used slates on an 11 degree roof? Any advice

paddy147

snyper wrote: »

1890400600

capcos technical department



I wouldnt be happy withy a pitch less than 20 - 25 degree using slates

+1 here,this is the issue I had when we were looking at different roof designs and angles for the kitchen roof.

I believe Nordman tiles can be put on low pitch,but they dont half make a racket when its raining.:eek:

I had the roof done with a 23 degree pitch and propper roof tiles,in the end,as that is what the structural engineer suggested and determined.:)

Paul.C

You have a few options but removing the slates is in all of them.

You can get metal roof covers that look like roof tiles. Last time I checked they came in 10ftx 5ft segments. Also there are other types like strips of metal that crimps together at the join. These to me would be your best option and are designed for this purpose.

You should be covered insurance wise so It shouldnt be to bad. Just make sure when the slates come off you check the timber for rot/moisture etc.

Quite unfortunate situation but its definitely your builders fault, he must have at least had a feeling that this may happen and went ahead with it anyway. I wouldnt use or recommend him again.

Best of luck with it

ronan45

Hmmm would insurance cover the builder putting on the wrong tiles though leading to leaks. Ill get a few quotes around. Cheers Mate

ronan45

Just came across this peeps if anyone interested


http://www.gumtree.ie/dublin/90/66198090.html

Paul.C

ronan45 wrote: »

Just came across this peeps if anyone interested


http://www.gumtree.ie/dublin/90/66198090.html

Yep thats the exact stuff I was talking about:D

I know they sell it in supermikes blanch but its widely available.

Also Insurancewise I can only speculate on it as ive never been down that road TBH. I hope for your sake it is:)

padjocollins

i've a 10 degree slant on my roof, my previous builder told me it would be fine. the timber and membrane are up. what are good options . Felting and this http://www.tapcoroofingproducts.com/product/tapcometal-roman/ for example ? thanks