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Exchange of Information

Please refer also to BS.5268-3 Section 1

Information to be provided to the Trussed Rafter Designer by the Building Designer

1. The position of roof hatches, chimneys, walkways and other openings.
2. The service use of the building in respect of any unusual environmental conditions and type of preservative treatment if required.
3. The spacing of the trussed rafter and any special timber sizes in particular if matching with an existing construction.
4. The site snow load or basic snow load and site altitude, or OS grid reference for the site.
5. The position, dimensions and shape of any adjacent structures higher than the new roof and closer than 1.5m.
6. Any special requirement for minimum member thickness (eg. For the purposes of fixing ceiling boards or sarking).
7. The height and location of the building with reference to any unusual wind conditions.
8. The profile of the trussed rafter (including any required camber).
9. The span of the trussed rafter (overall wall plates or overall length of ceiling tie or both as appropriate).
10. The pitch or pitches of the roof.
11. The method and position of all supports.
12. The type and weight of roof tiles or covering, including sarking, insulation and ceiling finishes.
13. The size and position of water tanks, or other equipment and plant to be supported by the trussed rafters.
14. The overhangs of the rafters at the eaves or apex if appropriate and details of any special eaves details.
Information to be provided by the Trussed Rafter Designer to the
Building Designer

The Trussed Rafter Designer should provide the Building Designer with the following information, on suitably detailed drawings, to enable a check to be made that trussed rafters supplied are suitable for their intended use:-
1.The methods of support for tanks and other equipment, together with the capacity or magnitude of the additional load assumed.
2. The range of reactions to be accommodated at the support positions including those required to resist wind uplift forces.
3. The basis of the design.
4. Details of changes in spacing required to accommodate any opening eg. At a chimney.
5. Any special precautions for handling, storage and erection of the roof trusses, in addition to those covered by BS.5268-3.
6. Finished sizes, species, strength classes of members.
7. The type, sizes and positions of all jointing devices with tolerances or the number of effective teeth or nails (or plate areas) required in each member at each joint.
8. The position and size of all bearings.
9. Loadings and other conditions for which the trusses are designed.
10. The spacing of the trussed rafters.
11. The position, fixings and sizes of any lateral supports necessary to prevent buckling of compression members.