Tiles and fittings
Plain and interlocking clay tiles and fittings should comply with BS EN 1304.
Plain and interlocking concrete tiles and fittings should comply with BS EN 490 and BS EN 491.
Dry Fixed Hip, Ridge, and Verge Systems should comply with BS 8612. Products not covered by this standard such as ventilation tiles, proprietary soakers, outlets, proprietary flashings etc. should have UKAS accredited Third Party certification or approval for their design, installation and performance.
Where lead is used for a valley or gutter lining, flashing or saddle exposed to weathering it should be minimum Code 4 in accordance with BS EN 12588 and where it is used as a protected soaker beneath tiles it should be Code 3. Surfaces of all exposed lead should be treated with patination oil to prevent lead oxide staining of the tiles. For more detail see the Rolled Lead Sheet Manual.
Where mortar is used as a filler, a mix of 1 part Portland cement to 3 parts sand mix, with the sharp sand making up no less than one third of the sand content, with plasticizer in accordance with manufacturers instructions is recommended. Most sands conforming to BS EN 13139 are suitable. Where mortar is used to bed hip, ridge, valley or verge tiles, the tiles must also be mechanically fixed, with the exception of baby ridge and hip tiles at low level, subject to site wind uplift load requirements. Specific lime mortars may be required for historic or listed buildings. Specific guidance on roof tile mortar mixes is given in BS 5534.
Where adhesives are used the adhesive manufacturer’s recommendations should be followed to ensure that the product is suitable for securing concrete or clay tiles.
Fully supported –This includes roofing underlays laid directly onto a rigid boarding or sarking. The roofing underlay should be of adequate strength, water resistance and durability with water vapour transmission high enough to prevent the formation of condensation beneath the underlay. The method of assessment given in BS 5250 should be used to ensure that harmful condensation will not develop. If necessary, to overcome potential condensation risks, a vapour control layer should be incorporated within the structure.
Unsupported – This includes roofing underlays which are draped over the rafters or underlays laid over counterbattens on boarding or sarking. Roofing underlay should be of adequate strength, water resistance, and durability in accordance with the requirements of BS 5534 and BS EN 13859-1. Reinforced – bitumen underlays should conform to the requirements of BS 8747 for type 1F or 5U.
Flexible underlays – Reinforced bitumen underlay of type 1F or 5U that meets the requirements of BS 8747 or non-bituminous flexible underlay meeting the requirements of BS EN 13859-1 should be used. Products not meeting these standards should have a UKAS approved Third Party certificate appropriate for the conditions of use.
Rigid underlays – Rigid underlays comprising flat or profiled sheets, wood-based panels, fibre-cement sheets, corrugated bitumen sheets or sheets of other materials should conform to BS EN 14964. Products that do not meet the requirements of BS EN 14964 may be used provided there is evidence they are fit for purpose and have proven relevant experience in practice or have test method data based on UK conditions and methods of use.
Battens and counter battens
Timber species – The timber species should comply with type A or type B as specified in BS 5534 and should be preservative treated where the Building Regulations and bye-laws require protection against the House Longhorn beetle. Suitable treatments are specified in BS 5534 Annex E.
Battens should meet the requirements of BS 5534 and be graded and marked accordingly.
Note: Where there is a risk that the timber batten moisture content will be greater than 20%, treatments that react with metal fixings should be either avoided or alternative metals chosen, e.g., copper containing preservative reacts with aluminum but is benign when in contact with zinc galvanized metal or austenitic stainless steel.
Batten and counter batten sizes
Clay and Concrete Double-lap Plain tiles Up to 600mm support centres the batten size should be 38mm by 25mm minimum (width +/- 3mm, depth -0/+3mm based on 20% moisture content).
Clay and Concrete Single-lap and Interlocking tiles – Up to 450mm support centres the batten size should be 38mm x 25mm minimum; 451mm to 600mm support centres the batten size should be 50mm x 25mm minimum (width +/- 3mm, depth -0/+3mm based on 20% moisture content).
Counterbattens The dimensions of counterbattens should be sufficient to provide a ventilation gap as recommended by BS 5250 and/ or provide a drainage path beneath the battens.
Nails for tiles – Generally, clout head nails of diameter 3.35mm and 2.65mm are used for most applications (subject to withdrawal resistance determined by wind uplift calculations) and they should be a minimum of 38mm long. Clout head nails complying with BS 1202 part 2 (copper), part 3 (aluminium), BS EN 10088-3 grade 304 or 316 (stainless steel) or BS EN 10230-1 (zinc-coated steel) may be used. Nails made of other materials, including phosphor or silicon-bronze may be used for situations with aggressive environmental conditions and should satisfy the conditions of the manufacturer’s specification.
Aluminium is the most common material used for tile nails. Steel, nails should not be used for nailing tiles and where galvanized, should only be considered where there is no risk of the protective coating being damaged during installation. Stainless steel is often used where enhanced durability or strength is required. Improved nails (annular, ring shank and drive screws) to BS EN 10230-1 and BS 1202-1 or screws may be used where the wind load calculation indicates that smooth shank nails will not meet the requirement.
Tile clips – Tile clips are made from a wide variety of materials. Manufacturers supply proprietary clips to suit their tiles and it is important that they are used in conjunction with a site specific fixing specification. Use of non-tile manufacturer supplied clips may invalidate manufacturer warranties. Refer to BS 5534 for further information.
Fasteners for fittings – Hip irons are hooks that fix to the lower end of the hip rafter and provide mechanical security for the bottom hip tiles. All mortar bedded ridge, hip and verge tiles should be mechanically fixed. Manufacturers provide suitable fixings for this purpose. Alternatively, ridge, hip and verge components can be dry-fixed using proprietary products that should meet the requirements of BS 8612.
Nails and fasteners for securing battens to counter battens – Round wire nails complying with BS EN 10230-1 galvanised or BS EN 10088-3 grade 304 or 316 stainless steel should be used. The nails should generally be not less than 3.35mm in diameter and 65mm long, however, they may be longer to meet the requirements for wind loading. For exposed conditions improved nails, screws or helical fixings may be required. BS 5534 Annex H7 gives guidance on calculating the required wind load resistance for fixings used to secure battens and counterbattens.
Flashing and junctions – Where required, metal flashings and junctions should be fixed with copper or stainless steel nails. The size of the nails should be in accordance with the recommendations of the Lead Sheet Association. Aluminium nails must not be used to fix lead flashings. Flashings in exposed locations may need to be clipped and this should be in accordance with the Rolled Lead Sheet Manual recommendations.