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#1
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What's the shallowest allowable slope for a slate roof?
My architect has specified slate on a roof with a slope of 16.8
degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? Thanks. |
#2
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What's the shallowest allowable slope for a slate roof?
hulk hogan wrote:
My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. I've never used/lived with it but I was once told that slates (natural and artificial) can be used on lower pitches with a waterproof sub-roof - design to depend on exposure, area etc. And that seems to be the case from eg http://www.marleyeternit.co.uk/produ...les+%26+Slates and http://www.hayday-construction.co.uk...ow%20Pitch.pdf. I offer this only to help you search on. It is to be hoped that someone with real knowledge will be along shortly. -- Robin |
#3
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What's the shallowest allowable slope for a slate roof?
hulk hogan wrote:
My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? Thanks. I gather its too shallow to be watertight, but you can put a watertight layer underneath the slate to allow its use at any angle. Fibre cement sheet makes a good durable sarking. NT |
#4
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What's the shallowest allowable slope for a slate roof?
"hulk hogan" wrote in message ... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? Check your local library website - you may find that library membership includes online subscriptions. For example, miine includes the online OED, Times Digital Archive, Groves music and art online and BSI reports. The relevant part of BS 5534 is 5.3.4.3 Roof pitch The recommended roof pitch and minimum head-laps for double-lap, natural, fibre-cement and other artificial slates, nail-fixed or hook-fixed, should be obtained from Table 4 and Table 5. The roof pitch should be not less than 20°. |
#5
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What's the shallowest allowable slope for a slate roof?
"hulk hogan" wrote in message
... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. We had a low angle slate roof on a bit of our house. Didn't work, people couldn't make it work. Gave up, had the entire thing rebuilt with a proper roof. |
#6
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What's the shallowest allowable slope for a slate roof?
Clive George wrote:
"hulk hogan" wrote in message ... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. We had a low angle slate roof on a bit of our house. Didn't work, people couldn't make it work. Gave up, had the entire thing rebuilt with a proper roof. Indeed. I had similar problems with IIRC pantiles. Slope (30 dgress IIRC)too shallow to b reliable in heavy weather. If at all possible go for a more sensible angle. This is asking for trouble (though it CAN work) |
#7
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What's the shallowest allowable slope for a slate roof?
On 17 Mar, 12:23, "neverwas" wrote:
hulk hogan wrote: My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. I've never used/lived with it but I was once told that slates (natural and artificial) can be used on lower pitches with a waterproof sub-roof - design to depend on exposure, area etc. *And that seems to be the case from eghttp://www.marleyeternit.co.uk/products/TechnicalServices/FAQs.aspx?p... and *http://www.hayday-construction.co.uk...ow%20Pitch.pdf. *I offer this only to help you search on. *It is to be hoped that someone with real knowledge will be along shortly. -- Robin Hmmm. That doesn't sound like what he's specified. The spec mentions an underlay of 'Tyvek Supro'. |
#8
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What's the shallowest allowable slope for a slate roof?
On 17 Mar, 12:40, "OG" wrote:
"hulk hogan" wrote in message ... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? Check your local library website - you may find that library membership includes online subscriptions. *For example, miine includes the online OED, Times Digital Archive, Groves music and art online and BSI reports. The relevant part of BS 5534 is 5.3.4.3 Roof pitch The recommended roof pitch and minimum head-laps for double-lap, natural, fibre-cement and other artificial slates, nail-fixed or hook-fixed, should be obtained from Table 4 and Table 5. The roof pitch should be not less than 20°. You're lucky! My council libraries dont provide them at all - you have to go to the National Library. They have to retrieve the hard copy from off-site location. I'm trapped in the stone-age apparently. |
#9
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What's the shallowest allowable slope for a slate roof?
On 17 Mar, 14:04, The Natural Philosopher wrote:
Clive George wrote: "hulk hogan" wrote in message ... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. We had a low angle slate roof on a bit of our house. Didn't work, people couldn't make it work. Gave up, had the entire thing rebuilt with a proper roof. Indeed. I had similar problems with IIRC pantiles. Slope (30 dgress IIRC)too shallow to b reliable in heavy weather. If at all possible go for a more sensible angle. This is asking for trouble (though it CAN work) Problem is it is an extension of an existing roof - the existing is a cruddy felt construction and will get replaced. I the pitch of the roof could be steepened by taking one or two rows of bricks off the top of the wall to at least achieve 20degs... |
#10
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What's the shallowest allowable slope for a slate roof?
"hulk hogan" wrote in message ... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? If it were my roof and I couldn't make it more than 16.8deg I would increase the overlap of the slates. mark |
#11
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What's the shallowest allowable slope for a slate roof?
After serious thinking neverwas wrote :
hulk hogan wrote: My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. I've never used/lived with it but I was once told that slates (natural and artificial) can be used on lower pitches with a waterproof sub-roof - design to depend on exposure, area etc. And that seems to be the case from eg http://www.marleyeternit.co.uk/produ...les+%26+Slates and http://www.hayday-construction.co.uk...ow%20Pitch.pdf. I offer this only to help you search on. It is to be hoped that someone with real knowledge will be along shortly. Surely, within limits, what matters is the overlap? The greater the overlap the more shallow the roof can be made. -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.co.uk |
#12
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What's the shallowest allowable slope for a slate roof?
mark wrote:
"hulk hogan" wrote in message ... My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? If it were my roof and I couldn't make it more than 16.8deg I would increase the overlap of the slates. mark Do you not think fibre cement sarking would be cheaper than 50% more slate? It would also look conventional. The other problem with adjusting slates from 2 layers to 3 (cant think how better to explain it) is that it changes their angle for the worse. NT |
#13
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What's the shallowest allowable slope for a slate roof?
Harry Bloomfield wrote:
Surely, within limits, what matters is the overlap? The greater the overlap the more shallow the roof can be made. They words here are "within limits". Even with greater than 50% overlap, you won't get a watertight slate roof shallower than 20 degrees. |
#14
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What's the shallowest allowable slope for a slate roof?
Harry Bloomfield wrote:
After serious thinking neverwas wrote : hulk hogan wrote: My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. I've never used/lived with it but I was once told that slates (natural and artificial) can be used on lower pitches with a waterproof sub-roof - design to depend on exposure, area etc. And that seems to be the case from eg http://www.marleyeternit.co.uk/produ...les+%26+Slates and http://www.hayday-construction.co.uk...ow%20Pitch.pdf. I offer this only to help you search on. It is to be hoped that someone with real knowledge will be along shortly. Surely, within limits, what matters is the overlap? The greater the overlap the more shallow the roof can be made. I am not so sure Given a certain windspeed, what matters is how high the water can be driven. if its more than the rise of a tile, it will climb up the tile. The uber flat roof stuff is laid with interlocking joints I seem to remember |
#15
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What's the shallowest allowable slope for a slate roof?
On 18 Mar, 08:02, The Natural Philosopher wrote:
Harry Bloomfield wrote: After serious thinking neverwas wrote : hulk hogan wrote: My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. I've never used/lived with it but I was once told that slates (natural and artificial) can be used on lower pitches with a waterproof sub-roof - design to depend on exposure, area etc. And that seems to be the case from eg http://www.marleyeternit.co.uk/produ...es/FAQs.aspx?p... and http://www.hayday-construction.co.uk...ow%20Pitch.pdf. I offer this only to help you search on. It is to be hoped that someone with real knowledge will be along shortly. Surely, within limits, what matters is the overlap? The greater the overlap the more shallow the roof can be made. I am not so sure Given a certain windspeed, what matters is how high the water can be driven. if its more than the rise of a tile, it will climb up the tile. The uber flat roof stuff is laid with interlocking joints I seem to remember I think I'll be ensuring that the pitch is at least 20degrees by raising the high end of the roof further up the wall of the main building (it's a lean-to). At that pitch at least there will be specified acceptable head-laps etc given in BS5534. You'd think it specifies a minimum pitch for a reason, and upping the headlap by a 'finger in the air' amount at lower pitches has no guarantee of success. I looked at the interlocking 'slates' such as Redlands Cambrian, but if plain real slate is possible, it'd be preferable, since it looks better. Apparently the interlocking joints on these single-lap systems work like miniature gutters which direct water down onto the lower course of slates. The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? |
#16
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What's the shallowest allowable slope for a slate roof?
hulk hogan wrote:
The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? This thread is quite interesting since we've just been having an exactly similar conversation with our architect, who has drawn a roof at 22 degrees inclination and has specified it as a flat roof with slates for decoration. I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. |
#17
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What's the shallowest allowable slope for a slate roof?
In uk.d-i-y, Jim wrote:
hulk hogan wrote: The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? This thread is quite interesting since we've just been having an exactly similar conversation with our architect, who has drawn a roof at 22 degrees inclination and has specified it as a flat roof with slates for decoration. I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. We had a new single-storey extension roofed with slate at 20 degrees about ten years ago, and despite being in an exposed location in a wet part of the country, it hasn't given any trouble at all. We were constrained by the height of the first-floor windowsills, and in order to get as much as 20 degrees slope and still have adequate headroom at the low end of the roof, we sloped the floor. It's about three inches lower at the far end, which in practice is virtually unnoticeable. -- Mike Barnes |
#18
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What's the shallowest allowable slope for a slate roof?
hulk hogan wrote:
On 18 Mar, 08:02, The Natural Philosopher wrote: Harry Bloomfield wrote: After serious thinking neverwas wrote : hulk hogan wrote: My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. I've never used/lived with it but I was once told that slates (natural and artificial) can be used on lower pitches with a waterproof sub-roof - design to depend on exposure, area etc. And that seems to be the case from eg http://www.marleyeternit.co.uk/produ...es/FAQs.aspx?p... and http://www.hayday-construction.co.uk...ow%20Pitch.pdf. I offer this only to help you search on. It is to be hoped that someone with real knowledge will be along shortly. Surely, within limits, what matters is the overlap? The greater the overlap the more shallow the roof can be made. I am not so sure Given a certain windspeed, what matters is how high the water can be driven. if its more than the rise of a tile, it will climb up the tile. The uber flat roof stuff is laid with interlocking joints I seem to remember I think I'll be ensuring that the pitch is at least 20degrees by raising the high end of the roof further up the wall of the main building (it's a lean-to). At that pitch at least there will be specified acceptable head-laps etc given in BS5534. You'd think it specifies a minimum pitch for a reason, and upping the headlap by a 'finger in the air' amount at lower pitches has no guarantee of success. I looked at the interlocking 'slates' such as Redlands Cambrian, but if plain real slate is possible, it'd be preferable, since it looks better. Apparently the interlocking joints on these single-lap systems work like miniature gutters which direct water down onto the lower course of slates. The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? Yes. The slate also has one more function: its the robust layer, it stops falling objects breaking the fibre cement. So it takes both layers working together to provide all the required functions for a long lived functional roof. NT |
#19
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What's the shallowest allowable slope for a slate roof?
Jim wrote:
I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. I'm not a roofing contractor but that roofing system is clearly designed to makes the slates, or tiles, redundant. |
#20
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What's the shallowest allowable slope for a slate roof?
On 19 Mar, 00:00, Mike Barnes wrote:
We had a new single-storey extension roofed with slate at 20 degrees about ten years ago, and despite being in an exposed location in a wet part of the country, it hasn't given any trouble at all. Good to know. |
#21
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What's the shallowest allowable slope for a slate roof?
Jim wrote:
hulk hogan wrote: The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? This thread is quite interesting since we've just been having an exactly similar conversation with our architect, who has drawn a roof at 22 degrees inclination and has specified it as a flat roof with slates for decoration. I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. My experience of that was that after a while the felt goes. And a costly strip and redo is in order. |
#22
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What's the shallowest allowable slope for a slate roof?
The Natural Philosopher wrote:
I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. My experience of that was that after a while the felt goes. And a costly strip and redo is in order. The other option seems to be to use a modern plastic tanking membrane, hot welded at the joints, rather than felt. But it's unclear whether most contractors would be familiar with this approach, or what the cost implications are. |
#23
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What's the shallowest allowable slope for a slate roof?
Mike Barnes wrote:
In uk.d-i-y, Jim wrote: hulk hogan wrote: The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? This thread is quite interesting since we've just been having an exactly similar conversation with our architect, who has drawn a roof at 22 degrees inclination and has specified it as a flat roof with slates for decoration. I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. We had a new single-storey extension roofed with slate at 20 degrees about ten years ago, and despite being in an exposed location in a wet part of the country, it hasn't given any trouble at all. I think the crappy extension I had failed after about 15-18 years. It was really the last straw that broke the camels back. With water coming in in several places, the overhead cable that stopped the roof pitch being decent was undergrounded, the house was demolished, and proper angles used.. ;-) We were constrained by the height of the first-floor windowsills, and in order to get as much as 20 degrees slope and still have adequate headroom at the low end of the roof, we sloped the floor. It's about three inches lower at the far end, which in practice is virtually unnoticeable. Thats generally why this is done. I have to say I had a bloody valley join with an existing roof, and they are buggers. If its a leanto or bow window type thing, there isn't the huge volume of water in on spot. If you have interlocking machine made tiles, then its not so bad. The water can't drive around the interlock easily. But I still say unless there are overriding reasons to have a low pitch, don't. And know what you are getting into. |
#24
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What's the shallowest allowable slope for a slate roof?
On Mar 19, 7:47*am, Bruce wrote:
Jim wrote: I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. I'm not a roofing contractor but that roofing system is clearly designed to makes the slates, or tiles, redundant. The slate would provide pretty good UV protection for the felt though, so the felt should last longer. |
#25
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What's the shallowest allowable slope for a slate roof?
Martin Bonner wrote:
On Mar 19, 7:47*am, Bruce wrote: Jim wrote: I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. I'm not a roofing contractor but that roofing system is clearly designed to makes the slates, or tiles, redundant. The slate would provide pretty good UV protection for the felt though, so the felt should last longer. Oh, absolutely. But a slate roof at the right pitch should last much longer. |
#26
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What's the shallowest allowable slope for a slate roof?
The Natural Philosopher wrote:
Jim wrote: hulk hogan wrote: The architect has been saying things like 'I think 17 is within the tolerances' and 'remember the underlay membrane is a second line of defence' both of which I think are... well, he's not a roofing contractor. I couldnt find anything about using fibre cement sarking on the internet - is the idea that the roof would be waterproof even with no slates, making the slate decorative? This thread is quite interesting since we've just been having an exactly similar conversation with our architect, who has drawn a roof at 22 degrees inclination and has specified it as a flat roof with slates for decoration. I emailed Marley and they sent me a "Below Pitch" spec which describes laying sarking, two layers of felt, and a membrane under a normal slate roof at these kinds of angles. It's a bit belt-and-braces but sounds like the correct thing to be doing. I haven't had a roofing contractor's opinion yet on it. My experience of that was that after a while the felt goes. And a costly strip and redo is in order. Sounds like someone did it wrong. If you use fibre cement sarking, overlapping at any joints, the felt etc isn't even needed. The slates act as a windbreak, so there is much less tendency for water to be driven up the sarking overlaps than occurs with the slates. I've experience of such a roof with no felt or membrane, and no trouble at all. NT |
#27
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What's the shallowest allowable slope for a slate roof?
Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel 👹
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#28
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What's the shallowest allowable slope for a slate roof?
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#29
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What's the shallowest allowable slope for a slate roof?
On Tuesday, 25 July 2017 18:35:10 UTC+1, wrote:
Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel 👹 Not sure why you bring this up now, but fwiw my one very shallow roof has been doing fine for a long time. NT |
#30
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What's the shallowest allowable slope for a slate roof?
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#31
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What's the shallowest allowable slope for a slate roof?
On Tuesday, 25 July 2017 20:08:07 UTC+1, mechanic wrote:
On Tue, 25 Jul 2017 11:54:03 -0700 (PDT), tabbypurr wrote: On Tuesday, 25 July 2017 18:35:10 UTC+1, wrote: Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel �� Not sure why you bring this up now, but fwiw my one very shallow roof has been doing fine for a long time. No probs with snow where you live? Snow load is not a problem for properly designed roofs. NT |
#32
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What's the shallowest allowable slope for a slate roof?
On 7/25/2017 8:08 PM, mechanic wrote:
On Tue, 25 Jul 2017 11:54:03 -0700 (PDT), wrote: On Tuesday, 25 July 2017 18:35:10 UTC+1, wrote: Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel ������ Not sure why you bring this up now, but fwiw my one very shallow roof has been doing fine for a long time. NT No probs with snow where you live? It does depend entirely on where you live. Also wind loads, and driving rain. |
#33
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What's the shallowest allowable slope for a slate roof?
Phil L wrote:
wrote: Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel ?? Cheers for the ancient info. Roof tiles can go as low as 22 degrees Some of mine are 17.5. |
#34
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What's the shallowest allowable slope for a slate roof?
On 26/07/2017 09:51, Capitol wrote:
Phil L wrote: wrote: Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel ?? Cheers for the ancient info. Roof tiles can go as low as 22 degrees Some of mine are 17.5. If clay pantiles are too shallow they stay damp for too long in winter and freeze thaw will shorten their life. This typically only shows up as a problem after many decades and on paths that have also been weakened by walking on - notably the path up to the TV aerial on a chimney. There are special tiles for low slope roofs with a second underside ripple on them to make them more weather proof against bad weather. -- Regards, Martin Brown |
#35
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What's the shallowest allowable slope for a slate roof?
On 25/07/2017 19:07, Phil L wrote:
Roof tiles can go as low as 22 degrees I just happen to know that Marley do some good for 15, and look like slates. Andy |
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What's the shallowest allowable slope for a slate roof?
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What's the shallowest allowable slope for a slate roof?
In article ,
Capitol writes: Phil L wrote: wrote: Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel ?? Cheers for the ancient info. Roof tiles can go as low as 22 degrees Some of mine are 17.5. My parents have one roof which is shallower than the tiles allow. This is done by having the waterproof layer under the tiles (I think it's glass fibre resin laid on ply), and the tiles are really just a decorative layer on top. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
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What's the shallowest allowable slope for a slate roof?
On 26/07/2017 10:45, Martin Brown wrote:
On 26/07/2017 09:51, Capitol wrote: Phil L wrote: wrote: Hey boys dont even bother laying slates any lower than 30degrees Forget that underlay etc keeping it watertight Wider slates can go slightly lower Dont try and change whats been tried and tested our years Architects Dont try and reinvent the wheel ?? Cheers for the ancient info. Roof tiles can go as low as 22 degrees Some of mine are 17.5. If clay pantiles are too shallow they stay damp for too long in winter and freeze thaw will shorten their life. This typically only shows up as a problem after many decades and on paths that have also been weakened by walking on - notably the path up to the TV aerial on a chimney. There are special tiles for low slope roofs with a second underside ripple on them to make them more weather proof against bad weather. Marley Modern can go down to 20 degrees (AFAIK) but the shallower the angle the greater the overlap needed, and *most* importantly with wide tiles, they absolutely must be laid flat. Never 'curved up' at the eaves. As a consequence the undercloak (?correct term) must tilt down by about 3 degrees to stop water running back under and down the top of the barge board at the gable end. However, just try telling that 19 out of 20 'professional roofers' who haven't a clue. |
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What's the shallowest allowable slope for a slate roof?
On 27/07/2017 17:27, Andrew wrote:
Marley Modern can go down to 20 degrees (AFAIK) "Mendip" and "Wessex" go down to 15 degrees. -- Reentrant |
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What's the shallowest allowable slope for a slate roof?
On Tuesday, 17 March 2009 10:57:50 UTC, hulk hogan wrote:
My architect has specified slate on a roof with a slope of 16.8 degrees. Is that too shallow? Googling implies that 4:12 is the shallowest you can go with slate. That's 20 degrees. PS: does anyone have a digital copy of BS 5534 they could... 'make available for download'? Thanks. I would never specify a slate roof at that pitch...Normally a min'm is 30 degrees. At that shallow angle, you would need a waterproof sub layer and the slates would have to be twice nailed at the head and at mid point otherwise they'll lift if a strong gust of wind gets underneath. Marley Eternit do a slate appearance tile with a thin Edge called the Edgemere Duo which looks like slate. That has a guarantee of going as low at 17.5 degrees. |
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