cladding options for a low pitched roof??

ckc123

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We are renovating an old cottage, with a small, lean to extension - we cannot use the natural slate we are using for the rest of the house on this section as the pitch is too low. Our carpenters are suggesting Nordman PRofile as a solution, but I don't think it looks well in this situation. Any suggestions???
Thanks.
 
How low is the pitch? Your builder is right, you can't safely use slates below 30 degrees. However if you were to use a high performance sarking membrane (Tyvek or similar) and increase the lap you could perhaps go somewhat lower. Nordman Profile is not the way to go on an older building. You can get concrete roof tiles which resemble heavy slate in appearance, called plain flat tiles, they can be used at pitches of 25 degrees, supplier should be able to confirm suitability. They are attractive, especially the smaller format ones. If money is no object you could opt for a lead or zinc (or copper) standing seam roof, but it depends on the dwelling, could look over the top.
 
I believe the pitch is 20 degrees - would any of those options work?

Thanks, Carpenter.
 
Hi,

I have come across a product called Metrotile (www.metrotile.co.uk) which is similar to Nordman but looks slightly better (its coated and looks more like a real tile). I am planning a low pitch extension (below 15 degrees) and this is one of the few options, other than a flat roof, high cost, out of whack with the rest of the house route. My problem is that I can just imagine the builders faces when they see this on the scope of works, they'll probably have the felt torcher out....let me know how you get on,

Jack
 
I think the Metro tile is probably worth investigating, mind you sourcing a small quantity of this might prove a problem. Unfortunately any pitch below 15 degrees is considered a flat roof and roof materials which are lapped (such as tiles, slate and shingle) are not suitable for use below 30/ 25 degrees (30 for slate). There are plenty of good flat roof membranes around, you could use a modified bitumen torch on or a single ply membrane such as trocal or sarnafil,but appearance is an issue. Trocal and Sarnafil can have "standing seam" extrusions bonded onto the roof to give the appearance of a traditional seam roof. Whatever material you decide to use check it out on the Irish Agrement website to ensure it is suitable for use in this country and what limitations apply where pitch is concerned.
 
Hi ckc123. I see Jack24 who has posted above has also put queries about his low pitched roof on [broken link removed] - you might want to keep an eye out for any updates to it as well as the thread here.
 
Carpenter, excuse my ignorance but why "are roof materials which are lapped (such as tiles, slate and shingle) are not suitable for use below 30/ 25 degrees" ? Is it because the rain water will not run off fast enough or they will weigh down directly on the rood timbers ?

We have a low pitch roof (15 degrees I think) which has a felt covering. I would love to replace it with something nicer looking and with better insulation.
 
Good morning Teabag,
Re your enquiry about lap in roof tiles etc. A flat roof membrane, such as felt, butyl, rubber, pvc etc relies on keeping out water through the fact that it's composed of impermeable material, so like a drum skin it is only effective if it's free from punctures. Being continuous and impermeable it can be employed at low roof pitches 15 deg. or less. Pitched roof coverings perform in a different manner, being composed of many small rectangles/ squares which overlap to form a barrier to rain and snow. The overlap of one tile (slate or shingle) over another is referred to as lap and the amount of lap depends on the pitch of the roof, generally the higher the pitch the less lap required. This stems from the fact that overlaping tiles are subject to capillary attraction, i.e. water trapped between them will tend to migrate up hill. This effect is more pronounced at lower pitches, as gravity has less counter effect. The problems of capillary attraction are worse where standing water is concerned, such as a large thawing snow load on a roof. The lap and pitch of the covering also dictates the roofs ability to resist wind driven rain. so depending on exposure some coverings and roof pitches are more suitable than others. It is for all the reasons outlined above that tiles and slates are unsuitable for use on low pitches, as no guarantee can be given that moisture won't pentrate into the interior of the roof space. Incidentally the felt membrane (sarking) beneath tiles and slates acts as a second line of defence where any moisture does find it's way past the tiles/ slates. Hope that explains it for you.
 
Hi guys,
Does any know what is the correct method of bolting sheets of Roof Cladding (the modern version of corrugated iron) to the supporting timbers below? In the days of corrugated iron the bolt was always driven through the top of the ridge so that water could not penetrate, but the roofers who built my sheds mounted all the bolts in the troughs. Unfortunately some of the seals are not good and some of the bolts missed the wood underneath so when snow lies on the roof, water leaks through.

Thanks
 
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