Roofing

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Roofing is another critical element of the project and there are many different options for style of roof:

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  •     Tiled roofs can be concrete, steel or clay (terracotta)
  •     Long-run steel or other metal such as copper
  •     Wooden shingles
  •     Membrane (for flat roofs), and more. 

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The important thing to think of here is the look of the roof and how it fits in with your overall design: 

 

  • Choose roofing in keeping with the style of your house and its projected performance.
  • Roofing products are defined as lightweight or heavyweight depending upon their classification within the New Zealand standard (NZS) 3604.  A lightweight material is one that weighs under 20Kg per square metre when fixed and finished on the roof.  Heavyweight materials exceed this limit but do not exceed 60Kg per square metre.
  • Make sure the roof you’ve chosen will perform at the pitch of your roof (some tiles won’t perform at less than 12 degrees, for instance)
  • Concrete and Terracotta tile roofing requires less maintenance than most other roofing materials.
  • Select the right grade of metal for the location of your house – for instance, if you’re at a coastal location
  • Non standard colours on colour coated metal roofing may have longer delivery times and cost more
  • Concrete and Terracotta roofing perform well in high wind zones.
  • Concrete roofs reduce airborne sound and help provide effective thermal insulation.
  • Water runoff from Concrete and Terracotta roof tiles does not contain zinc or aluminium ions.
  • Concrete and Terracotta tile roofs allow moisture vapour to escape.
  • There are two widely used products within the light roofing classification. Both use steel as the core and generally weigh much less than the upper limit for this category (around 8Kg per square metre). Different coatings and processes are carried out with these products.
  • Longrun steel:  is made from coils of steel, usually but not always painted, that are formed into a variety of longrun profiles.  They extend as one sheet with laps along edges and ridges. There are many more options for profiles than just standard corrugated iron.
  • Metal tiles are individually pressed out from blanks of primed or painted steel. They are available in a range of profiles designed to achieve different appearances once on the roof. There are advantages in the level of protection achieved where the coatings are applied after pressing the blank, as there is a reduced tendency for microcracking, where the paint cracks micro-scopically at bent edges and exposes the base metal to immediate contact with the elements.
  • Other products that can fit under the lightweight code include bituminous shingles, fibre cement tiles, wooden shingles and some slate products.
  • Heavyweight products include concrete tiles and most slate products.  Because of their greater weight, concrete tiles generally weigh around 45Kg per square metre.
  • The house structure must be engineered to ensure all weight can be withstood by the house structure. This means that where necessary, frames, lintels and trusses are increased in size or placed closer together to ensure sufficient structural strength.
  • For all types of roofing NZS3604 ensures there are standards defined for structural performance, fixing standards etc. thus there are no concerns regarding safety of different roofing systems.
    However achieving these standards may only be accomplished through additional expense in timber and framing, hence it is necessary to talk with your designer, builder or architect to clearly understand the differences in design requirements for the various roofing options available. 
  • They can show you the specific cost savings or penalties involved in the different roofing products.