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Roof Cladding Expansion Provisions

The expansion of roof cladding depends on the materials, the constraints imposed by the fixing, the heat paths in the building and the actual temperature. The following graphics are indicative of favourable and unfavourable conditions for thermal expansion and suggest what these are. They show the lengths under both sets of conditions above which special provision needs to be made to accommodate thermal expansion.
 

Favourable Circumstances for Controlling Expansion

 
 

 

Unfavourable Circumstances for Controlling Expansion

 

Notes:

  1. Roofs requiring oversized holes are solid fixed towards the ridge and provision for expansion is made towards the gutter line.
  2. These are guidelines only and special engineering of the roof, fixing or ventilation may allow greater spans to be used.
  3. These diagrams refer only to roof cladding screwed through the top. Secret or clip-fixed roofs can move more freely if installed correctly and allow for greater run lengths.
  4. The recommendations are based on preventing damage to the fasteners and are not recommendations to prevent roof noise.

 

Clause: 
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Clause Number: 
7.3.2
/cop/roofing/thermal-expansion-and-contraction#roof-cladding-expansion-provisions
Revision Category: 
3 - Substantial change to recommendation
Revision Detail: 

Revised Favourable Circumstances for Controlling Expansion to show the correct recommendations for aluminium.

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