OZCO 51717 Ironwood 2-inch Rafter Clips, (10 per Pack), Black

Product Information

If a roof is not a simple triangle, all members should be fully supported and tied together. If necessary, temporary support to long span members should be used until the framing is complete. (c) valley and hip construction Notes for specifiers and builders. The advice provided by trussed rafters manufacturers should be carefully adhered to and bracing in non standard situations should be applied. Sin No 4 Overloading / under loading For cold roofs that incorporate a low water vapour resistance (type LR) underlay, (e.g. a vapour permeable underlay) ridge or high level ventilation equivalent to a continuous opening of 5mm should be provided in accordance with the design. (b) underlays

Where half-round tiles are used at hips, they should be supported at the base of the hip by a galvanized hip iron. (d) valleys and hidden gutters A purpose-made one-piece flashing and upstand should be used around pipes projecting through the tiling.

Advantages of Trussed Rafters

Provides support to purlins to prevent deflection and to transfer roof loads to the load-bearing structure below. Where roof coverings are of plain tiles or slates, laced and swept valleys may be used or, alternatively, a mitred valley with soakers. Celotex insulation fixings are a perfect solution when installing rigid insulation boards in between timbers.

Tiles or slates should overhang to the centre of the gutter. For slates or plain tiles, an under-eaves course should be used.

Trimming members around dormers should be large enough to take the extra load from the cut main roof members and dormer framing and cladding, as detailed in the design. When using the following materials, the detailing and workmanship should follow the design and recognised good building practice: When inspecting trussed rafter roofs, be on the look out for the removal of any internal webs or any other alteration to the trusses where bolts, nails or screws have been used to fix members. Such an addition to a roof structure would generally indicate than some other member has been removed. All abutments should be weatherproofed using non-ferrous metal flashings. Lead flashings should be at least Code 4 (colour coded blue), while soakers are normally Code 3 (colour coded green). Normally, lead flashings should not exceed 1.5m in length, with laps of not less than 100mm.

For a given span, and a set load therefore, the pitch makes a huge difference to the member forces. The diagram above shows an example of the triangle of forces that apply at a support. The vertical component is the load passed onto the support (“the reaction”), the sloping line the top chord force, and the horizontal force. As the pitch flattens the forces are greatly magnified. Battens should be set out in straight lines, parallel to the ridge and to the gauge required by the tile or slate. The lap should not be decreased because this would reduce weathertightness. The lowest batten should be fixed so that the tile projects halfway across the gutter. All verge tiles and slates should be bedded on an undercloak. Alternatively, proprietary dry verge systems should be fixed in accordance with manufacturers' recommendations. Restraint straps should be fixed to solid noggings with a minimum of four fixings of which one should be in the third rafter. The fixings should be four steel screws or four 75mm x 4mm (8 SWG) round nails. The design should specify the number of fixings for clay and concrete tiles. Tables 2 and 3 of Appendix 7.2-B contain minimum fixings for tiles. Additional nails and clips may be necessary in accordance with the design. A fixing schedule produced by the tile manufacturer, based on The Zonal Method, is acceptable.Cavity trays should be linked to the flashing to prevent water penetrating into an enclosed area where a: When the author has inspected roofs there have been some occasions when the householder has to be advised to remove or lessen the amounts of goods stored in the roof for danger of overloading it. Typically the bottom chord of a truss is designed for a superimposed load of 0.25 kN/m2 which the author often refers to as empty cardboard boxes loading. The system owner’s software is very sophisticated and not only designs the trusses, but also produces quotations, manufacturing information and production data. Advantages of Trussed Rafters CEILING JOIST or TIE: triangulates the rafters, stopping the walls and roof spreading outwards; supports the ceiling finish and any walkways, etc

Where underlay laps are not under a batten, an extra batten should be used to prevent the underlay lap opening due to wind uplift. Where the width of gable ladders exceeds that of the trussed rafter centres, noggings should be provided to reduce the span of the roofing tile battens. For any further information or prices please do call our national sales office. Buy Celotex Insulation fixings for fixing Pitched roof insulation currently unavailable PURLIN connections: support should be provided directly under joint or use a scarf joint. Any scarf joint should be made near a strut so that the joint supports the longer span.Vertical laps in the underlay should occur only over rafters and be securely fixed. Where the pitch is below 30°, the underlay should be supported at eaves level by a tilting fillet. The underlay should be dressed into the gutter and pulled tight to ensure there are no troughs to retain water. It is essential when installing celotex rigid insulation boards in cut to fit roof applications to ensure they are secured firmly. Insulation boards falling down on your head is no fun and also you really don’t want the weight of the boards resting on your plasterboard finish. Celotex insulation clips are and ideal purpose made fixing that ensures the PIR insulation boards are kept firmly in their place. The advantage of these clips is that if you have uneven timbers or if you are unable to cut the insulation to fit tightly in between the timbers. Then these fixings will work perfectly holding the insulation in position. Battens should be fixed with cut or wire nails. The nail shank can be smooth, annular ringed or helically threaded. Nails can be steel or aluminium. In coastal areas, steel nails should be hot dip galvanized. (d) slates and tiles Where straps are fixed to masonry, hardened nails 4mm in diameter x 75mm long or No 12 wood screws x 50mm long into plugs should be used.