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Easy Roof System
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Following years of development it is now possible to extend the boundaries of slate roofing whilst still maintaining the traditional appearance and installation methods that remain such an important part of the roofing trade.

The unique and patented Easy Roof Slating System offers:

- Compatibility with any slate and any system

- Low pitch slating

- Improved roof ventilation

- Elimination of wind slate rattle

- Prevention of broken and slipped slates

- A low impact that is the ideal solution for listed and conservation buildings

- High level of versatility

- A dramatic improvement in the performance of any slate roof by between 200 and 500%

- 40 year guarantee*

The Easy Roof System is designed not only for use on problem roofs, but it can be used to improve the performance of any slate roof, and is therefore ideally suited to public and socially responsible roofs.

*Easy Roof System is a Permavent product and its performance can only be guaranteed when used as a complete system using Permavent DRYROOF breather membrane in conjunction with Easy Verge/Easy Vergetrim, Easy Soaker, Easy Valley, Easy Tray and Plain Easy.

How Slates Work

Layout & description of a conventional slate roof


‘P’ is Permavent Max, high performance breather membrane. ‘B’ is the roofing batten minimum 25mm thick by 50mm wide. Line ‘L’ is the length of the slate. Line ‘W’ is the width of the slate. Point ‘N’ is the nail hole of the slate. Line ‘H’ is the holing Gauge. Line ‘K’ is the Bond or side lap of the slate. Line ‘M’ indicates the margin of slate on the finished roof. Line ‘A’ indicates the abutment of each slate or ‘perp’ meaning ‘perpendicular join’. Line ‘G’ shows the gauge of the slates and works in relation to the battens. Point ‘C’ is the critical junction or weakest point of the roof. Roofing products that do not have a weatherproof perp joint need to be ‘double lapped’. Line ‘D’ is the amount that 3 slates lap on top of each other and is the Head Lap, This is often simply referred to as ‘the lap’. Point ‘I’ is the primary leak point or ingress where water will first overcome the weatherproofing of the slates. The arrows ‘S’ indicate the typical spread of water that travels from point ‘C’ and down through the perp join and spreads between the slates.

Slates are laid in double lap format (D) using slates of many differing sizes and gauges. The width (W) of the slate will decide the bond (K) of the slates. When this bond is used in conjunction with an appropriate lap (given that the slates are or are not holed), then this will decide the weather resistance of a roof at a given roof pitch (angle). All four things are an important factor in how the water would ingress the roof. The water first starts to penetrate the slates when it leaves the slate above and enters the abutment (A) at the critical junction (C). The water flows through the perp join, landing on the holing margin of the slate below (even without the influence of wind or pressure). This water will then ‘creep’ sideways from this perp join, underneath the margin section (M) of the slates on either side, but still on top of the holing gauge (H) section of lower slate. This water will eventually exit at the tail of the slate, back onto the surface of the roof. If the pitch of the roof is too low then gravity will be weaker and will allow this water to traverse across the slate until it reaches either the nail holes (N) or the point of ingress (I). With the addition of a little air pressure, and if the gap between the upper and lower slate is consistently below 0.5mm, then ‘capillary action’ will draw the water even further across the slates. This action can also draw water vertically between the lap (D) of the slates. The risk of a leak is reduced if the bond (K) is wider because the water has further to travel and will pass below the critical junction and will not ingress the roof. If the slates are pre-holed for nails then these holes are closer than the critical junction and will pose a further risk.In higher wind conditions the water can be held onto the roof or even driven up the roof. This creates greater pressures and will increase the capillary action as well as force the water up the roof and between the laps of the slates. This is where the shorter length of the lap can be considered to be a weak point and it is important that the length of this lap is increased. Because extreme weather conditions are rare then it is normal practice to allow a slight ingress of water through the slates in such conditions. When water ingresses the roof it will be either through the nail holes, or at point (I). Water that enters through the nail hole will affect the life span of the nail with nail rot being a major cause of roof failures in the past, especially when ferous nails are used. The use of roofing battens is preferred in the southern areas of the UK but they cannot be allowed to be continually saturated by leaking slates. This water will fall onto the underlay and must run under the battens to ultimately exit the roof. The use of sarking boards to fully cover the roof before slating will reduce the pressure on a roof and is therefore more weatherproof. This is preferred in places of extreme weather such as Scotland and is commonly reffered to as ‘Scottish practice’. It is therefore important that a good quality underlay such as Permavent MAX breather membrane is used to keep the building watertight.

How Easy Slates Work

Roof with Easy SlateIt has always been recognized that the perp join is the place where rainwater first enters the roofing layers. Many years ago manufacturers of roof tiles introduced a side check to their tiles and this allowed the tiles to be laid in single lap format thus improving tile performance and this in turn reduced the amount of tiles used as well as the weight burden on the roof.

The Easy Slate is a ‘side check strip’ that works by sealing the perp join on the slate. When the perp joint is sealed then the water cannot enter through the critical junction, nail holes or the point of ingress. Easy Slate has the effect of removing these points and extending the lap from the tail of the upper slate to the head of the slate below. For example, a roof using 500x250mm slates with a 100mm lap and a sealed perp join will now have an effective head lap of 300mm.

On a normal slate roof there is often less than 0.5mm gap between the layers of the slates, little or no gap between the slates means that air pressure will draw the rain water between the slates, this is called capillary action and this is the main reason for slates leaking. When Easy Slate is installed the slates are raised by 1mm, this increased gap allows the free movement of air below the slates and releases the pressure thus eliminating the capillary action.

With a 300mm lap and no capillary action the slates can now be installed on many roofs where it was not previously possible to use them.

Extending the Boundaries of Slating

With the Easy Slate it is now possible to use any type of slate on many different styles of building where it was not previously possible. For example, the pitch of a ‘lean-too’ extension can be restricted by the window of the upper floor, the further out the extension then the lower pitched angle of the roof must be. With much of Britain designated as ‘severe exposure’ standard slates are restricted under BS 5534 to a minimum pitch of 30 degrees and this would restrict the average extension to just over 2 metres long. The height of many new buildings are controlled and the reduction of the pitch can now be offered as a solution to this problem with the added bonus that the roof will have less slates and that means less weight as well as offering a cost saving. A slate roof of 35 degrees will need approx. 16% more slates, batten and fixings than a roof of 20 degrees. The average weight of slates is approx. 40kg per m2. Future tests will establish the suitability of the Easy Slate to perform at much lower head laps and on a wide variation of slates and on different roofing styles. These tests will offer further improvement in the performance of a slate roof as well as considerable weight and cost savings.

Increase Roof Life

broken_roofSome methods of installing slates at a low pitch involve installing a waterproofing system below the slates and allowing the slates to leak. These systems will keep the water out of the home but the slates will always leak onto the fixing batten. This constant saturation will prematurely age the batten, loosen the fixings and considerably reduce the life of the roof. The Easy Slate System ensures that the slates remain completely waterproof and well ventilated and thus by contrast offers a considerable increase in the life of the slate roof.

Slates do not absorb water and therefore cement will never properly adhere to slates with the result that cement pointed verges are the main cause of failure or maintenance on the slate roof. Initially the cement will loose its colour and because the cement pointing is absorbent then the rain can penetrate the pointed verge, and in time this will rot the ends of the roofing battens. When the batten rots then the nails are released and the slates can fall off the roof.

Increase Airflow

easy slateThe Easy Slate System not only offers a low pitch solution but it also provides a considerable increase in the airflow through the slates, thus reducing any condensation problems in the roof space. Slates that fit together tightly on top of each other (such as manmade) do not allow air to pass freeley between them and cannot be considered to be ‘air open’. The circulation of air is needed in order to clear the condensation that can be trapped ‘interstitially’ in the void between the breather membrane and the slates. Because Easy Slate raises the slate by approximately 1mm, it allows air to circulate beneath the slates and this will clear the condensation that is passing through the Breather Membrane. There is now no need to use a counter batten when you use the Easy Slate.

Extensive Testing

bre_test

Easy Slate has undergone extensive testing by the Building Research Establishment (BRE). These tests first required the slates to be fully tested without the Easy Slate and the data was recorded. The slates were then removed and reinstalled, this time using Easy Slate, in the same place, on the same rig, so as to give an accurate comparison of performance of Easy Slate. Easy Slate was subjected to the severest weather test whereby the rain was driven up and over the roof. The back of the test rig was sealed in order to monitor the conditions and results. There is a large fan attached to the back and up to 200 Pascal’s of suction is applied in order to induce the capillary action. The Easy Slate was tested at a pitch as low as 12.5 degrees and is the only roofing product to pass this test with no leaks at all.

Wind Slate Rattle

During the test on the normal slate roof that did not use the Easy Slate system it was noted that in these conditions the slates were buffeted and ‘rattled’ with the severe wind and air pressure that was created. Wind slate rattle can cause the slates to fracture and break. This should be considered as the major cause of broken slates and damaged roofs. The installation of the Easy Slate eliminates the air pressures that can lift the slates. The rubber sealing strips cushion the slates and stop them from rattling and this will considerably increase the life of the roof.

Testimonial

barrett homesThe Mansard style roof has a 20-degree low pitch slate roof that follows the elegant curve of this crescent development. The tradesmen from V Turney Roofing had to use their full range of skills and experience to overcome the problems of laying this very complicated roof. The strength, durability and high performance of Permavent MAX was installed as a breather membrane with John Brash Red (high spec roofing batten) being bent into position. The Easy Roof System allows this type of roof to be installed in the same manner that many conventional roofs are installed. The unique Easy Slate 600 sealing strips were installed under the vertical ‘perp’ joints of the Marley Eternit Thrutone slates. The slates were laid in the traditional manner following the line of the curve with the gap between each slate slightly triangulated but because there is no angle of creep with the Easy Slate system then the weather proofing of the roof was not compromised. As the vertical courses of the slates began to run out of line, they were corrected by stitching in hand cut ‘double’ slate that realigned the Perp’ joints and the roof was continued across. The roof was finished with a butyl sealed dry hip and ridge system to provide the perfect solution for this complex project.

On the finished roof you can see it is virtually impossible to even notice that the Easy Slate 600 has been used to provide a permanently weatherproof roof covering on this complex project. The high levels of workmanship and the shine of the Thrutone slates provide a smooth flow that compliments this prestigious Barrett Homes development.

  Download our new brochure which will give you all information about our new low pitch solution.

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Newsflash

Following the success of the Queen’s award winning Easy Verge, here at Permavent we are proud to announce the launch of the recently developed Easy VergeTrim. This latest addition to the Easy Roof System has been specially designed to meet the requirements of the Scottish and refurbishment markets.