For further information please contact SLE Cladding Ltd. Tel. 01948 666 321. Fax.  01948 66 55 32
 

To visit Onduline Roofing Sheets main page
 

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To Visit the Onduline Oversheeting main page
 
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Guarantee. The Ondutile system is guaranteed to remain weatherproof for 30 years, when fixed in strict accordance with the manufacturer's fixing instructions. See bottom of page.
 
Ondutile is a unique roof underlay system utilising Onduline PP corrugated roofing sheets below tile, slate, or shingle roof coverings to create an independent secondary weatherproof roof. this enables the primary roof to be used safely below the manufacturers minimum recommended pitch.

 

Onduline gives these construction benefits
  • Reduced roof pitch. Allows tiles to be fixed below manufacturer's minimum pitch by providing assured secondary weathering below the primary roof.
  • Immediate weather protection. Onduline is quick to install, requires no specialist equipment or trade skills, and provides immediate weather protection to the building prior to fixing tiles.
  • Ventilation. The sheet corrugations supply 17,000mm2 per linear metre ventilation above the sheet into the tile batten cavity and below into the roof space. This significantly enhances the roof ventilation.
  • Moisture protection. With tile battens and fixings positioned above the moisture flow line in the base of the corrugations, excellent moisture control is achieved in the tile batten cavity.
  • Thermal Insulation. The provision of an Onduline deck in practice significantly improves the thermal performance of the roof structure.
  • Sound Insulation (27%) The Onduline tile system provides a 27% reduction in sound penetration through the roof covering, a considerable benefit for buildings on airport flight paths.
  • Safety. Onduline forms a tough, non-reflective and safe working environment for roofing operations.
  • Versatility. The onduline underlay is flexible enough to be used on existing uneven roof structures, but with intrinsic stiffness to eliminate the noise generated by lightweight membranes under fluctuations in wind pressure.
  • Protection.  Onduline significantly reduces the risk of expensive consequential damage to the building and contents as a result of damage to the roof through storms or vandalism.
  
The complete manufacturers information sheets are reproduced below.   CLICK HERE for the manufacturer's detailed Fixing Guide.
 

System specification. Deciding on the right specification for Ondutile is very easy. First note the tile slate type to be used and match it to the appropriate system specification detailed below, either Type A or Type B. Check the minimum recommended roof pitch it can be laid to (see Low pitch applications) and finally note the mechanical fixing specification details

Type A. Developed to suit concrete interlocking tiles, Pantiles, Fibre-cement and Natural Slates. The system forms a composite structure created by fixing support battens to the rafters set at the same gauge. centres as required for the tile battens
 
Type B. developed for a small double lap plain tile and small slate type which, due to the closeness of the tile battens, make the alignment of support battens and tile battens impracticable. Therefore the cross batten supports are replaced with 20mm exterior quality plywood deck fixed to the rafters. Ventilation into the roof space is provided by means of a slot in the decking above the eaves tray line.
   
         

Insulated Pitched Roof Construction

    
         
The trend of maximising available living space has promoted the growth in insulated pitched roof construction which can easily be achieved using the Onduline system.

Fixing specification.

To minimise the increased risk of roof void condensation and additional wind loading, it is essential that these rigid board insulation systems are laid and fixed strictly in accordance with the manufacturers instructions and any independent third party assessment. This will include fitting an effective water vapour barrier beneath the insulation with all joints sealed at all roof details, i.e. hips, valleys, ridge, abutments and around any penetrations through the vapour barrier.

This will minimise the risk of harmful interstitial condensation occurring within the insulation and the system.

The 50mm x 25mm counterbattens laid over the rigid insulation boards must be securely fixed through the insulation into the rafters. Special fixings such as helical fasteners supported by independent approval (WIM LAS/BBA) are normally recommended.

A suitable water vapour permeable underlay should be laid over the counterbattens draining into the eaves gutter

The Ondutile system is fixed to the  counterbattens which now replace the rafters as the primary fixing point to the roof structure.

  

In the interests of clarity only, this illustration above shows the vapour permeable membrane laid under the counter battens. The correct procedure is shown in the white insert.

The Onduline fixings into these counterbattens must be either ring shank nails or screws of adequate strength, durability and pull our resistance to satisfy the roof dead and imposed loads and comply with relevant European and British Standards and Codes of Practice.

NOTE: Comprehensive information relating to insulated pitched roofing is included in NFRC Report: Technical Bulletin 21 and BRE Report no. GBG37.

 

Low pitch roof applications
The minimum pitches/laps for tiles are normally specified by the manufacturer with reference to BS5534, Part 1 Design 1990. These are design situations, however when these specifications cannot be attained as shown opposite. Here the window line of the main building restricts the roof pitch of the extension. The use of Onduline allows the same tile as used on the main roof to be used on the extension at a pitch below the manufacturers recommended minimum.

Suggested minimum recommended roof pitch.

Interlocking concrete tiles:                                12.5 deg.

Pantiles, natural and fibre-cement slates:           17.5 deg.

Plain double lap tiles:                                       22.5 deg.

Onduline will provide a weather tight roof below these suggested pitches but three significant areas of risk are introduced that will affect the durability and longevity of the roof covering

  

1/.   Increased moisture content in the tile batten cavity can promote deterioration to the tile battens and fixings

2/.   The higher moisture content of the tile can result in frost damage, this is a particular risk to porous tile coverings such as clay, as it causes spalling and tile delaminating.

3/.   Increased wind uplift loadings.

NOTE Check with the tile or slate manufacturer to ensure the material is suitable and will not suffer spalling/frost damage due to the high moisture retention. Ask also for guidance on the need for enhanced fixings to combat the increased wind uplift loading.
     

Roof Ventilation
The increased use of labour saving machines, tumble dryers and dishwashers etc, have significantly increased the amount of water vapour in dwellings. When this effect is combined with improvements to insulation, double glazing and draught proofing, a roof void condensation risk may be produced unless adequate ventilation is provided. Condensation results in metal corrosion, timber rot and mould growths, with serious costly structural consequences. Ondutile due to its corrugations provides ventilation channels of 17,000mm2 per linear metre into both the roof space and the tile batten cavity. Ondutile ventilator strip provides a 4mm gap to prevent access by birds or large insects. In areas badly affected by bird infestation, additional screening may be required. Ventilation requirements to B.S. 5250: 1989.  
Roof pitches less than 15 deg. Low level ventilation at eaves should not be less than 25,000mm2 per linear metre. Onduline requires additional ventilation at soffit.

Roof pitches of 15 deg. or more. Low level ventilation at eaves should not be less than 10,000mm2 per linear metre. High level ventilation in each case should not be less tan 5,000mm2 per linear metre.
 

Mechanical fixings specification
In determining the mechanical fixing specification for Ondutile as with any roofing system, the wind uplift loadings need to be calculated taking in to consideration such factors as the height of the building, the buildings shape and roof pitch, as well as the altitude and topography of the site.

The specifications set out below are divided into three geographic areas reflecting the predicted wind loadings acting on the roof in different areas of the UK and Ireland as follows.

     Area 1. Equal or less than 46 m/s (metres per second).
     Area 2. Greater than 46 m/s and equal or less than 52 m/s.
     Area 3. Greater than 52 m/s and equal or less than 54 m/s

The specification also cover the two versions of Ondutile system - Ondutile Type A for interlocking tiles, pantiles and fibre-cement and most natural slates. Ondutile Type B for double lap plain tiles and small tiles.

  

Ondutile Nailing Specification. Nail Types to B,S. 1202 Part 1 1974, hot dipped galvanised (smooth shank) and sheradised (ring shank) . Care should be taken to ensure that the fixing nail penetrates the support batten centrally.
 

 The table below indicates the minimum nail specification required for the Ondutile system as used on standard building types in typical urban environments. These are based on wind loadings described above. For non standard buildings in exposed locations more specific detailed calculations are necessary. (Full details are set out in in B.S. 6399 Part 2 1997 and B.S. 5534 Part 1 1997)
AREA PRODUCT RAFTER CENTRE 450mm RAFTER CENTRE 600mm AREA
TYPE  A Cross Batten Support 50 x 25mm 75mm x 3.35mm (Smooth) 75mm x 3.35mm (Ring) A
1 Tiling Batten Size 50mm x 25mm 85mm x 3.75mm (Smooth) 85mm x 3.75mm (Ring) 1
TYPE B Decking Support 20mm thickness 75mm x 3.35mm (Smooth). Nail to each rafter at 250mm centres B
  Tiling Batten Size 38mm x 25mm 75mm x 3.35mm (Smooth) Nail to each batten at 300mm centres  
TYPE A Cross Batten Support 50 x 25mm 75mm x 3.35mm (Ring) 75mm x 3.35mm (Ring) A
2 Tiling Batten Size 50mm x 25mm 85mm x 3.75mm (Smooth) Special Enhanced Fixing 2
TYPE B Decking Support 20mm thickness 75mm x 3.35mm (Smooth). Nail to each rafter at 250mm centres B
  Tiling Batten Size 38mm x 25mm 75mm x 3.35mm (Smooth) Nail to each batten at 300mm centres  
TYPE A Cross Batten Support 50 x 25mm 75mm x 3.35mm (Ring) 75mm x 3.35mm (Ring) A
3 Tiling Batten Size 50mm x 25mm 85mm x 3.75mm (Ring) Special Enhanced Fixing 3
TYPE B Decking Support 20mm thickness 75mm x 3.35mm (Smooth). Nail to each rafter at 250mm centres   B
  Tiling Batten Size 38mm x 25mm
75mm x 3.35mm (Smooth) Nail to each batten at 300mm centres
  

Product Specification
Ondutile is a patented system (UK Patent Number 2233683) designed for use with Onduline PP professional sheet, an extremely durable roofing material which is maintenance free, resistant to rot, rust, fungal decay and insect attack.

Onduline PP is manufactured from a 3mm mono layer cellulose fibre based sheet impregnated with bitumen asphalt under intense pressure and heat. The sheet is sealed with an impregnated colour resin finish.

Only the quality standard of Onduline PP is able to cope with the service requirements of under tile applications in accordance with BBA certification.

  
 

To facilitate the installation of the system a comprehensive range of components and accessories is available as per below. Full detail of these accessories can be found on the Onduline accessories page.   CLICK HERE

ONDULINE PP SHEET DATA
Batten
   Sheet Size Cloaking
   Length (Overall)                                                           2000mm Piece
   Width (Overall)                                                              960mm
   Thickness (nominal)                                                          3mm
Ventilator
   End Lap                                                200mm (cover 1800mm)  Strip
   Side Lap                                     one corrugation (cover 855mm)
   Average Coverage                                                           1.5m2
   Colour                                                                            Black
Eaves
   Corrugation Pitch                                                            95mm Tray
   Corrugation Depth                                                           38mm
   Material Weight (nominal)                                          3.3 kg m2
   Sheet Weight (nominal)                                                  6.4 kg
Onduline
   Thermal Resistance                                   R value 0.04m2K/W Apron
   Thermal Conductivity                                              0.066W/mk Flashing

Guarantee. The Ondutile system is guaranteed to remain weatherproof for 30 years, when fixed in strict accordance with the manufacturer's fixing instructions. The guarantee is limited to the cost of Onduline materials only, and does not extend to the cost of labour or to primary tile/slate roof covering.

 
For further information please contact SLE Cladding Ltd. Tel. 01948 666 321. Fax.  01948 66 55 32

Copyright (c)1999 SLE Cladding Limited.