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Costed: Roofing

Words:
Ruby Galloway

Ruby Galloway, associate director at Gleeds R&D, looks at cladding costs

Amendments to the Building Regulations mean the building envelope has to meet increasingly stringent performance criteria. Designers and engineers should be fully versed in all applicable safety legislation, particularly with the requirements of the Building Regulations Part B (Fire Safety), Part E (Resistance to Sound) Part K (Protection from Falling) and Part L (Conservation of Fuel and Power). 

Amendments to Part L have had major implications for cladding design, especially in respect of overheating – care must be taken when specifying insulation, and also to ensure that the air tightness of the building is sound and tested.

Many of the claddings incorporate BREAAM compliant features such as recycled polyamide for thermal bridging, reduced fossil fuels and water consumption. Some cladding types may be designed as a ventilated facade system. Electrically operated louvre-blinds have added an innovative edge to provide efficient solar and glare control to many glazing systems.

Often, the cladding sub-contractor will have design responsibility for the cladding element, but the employer and designer should ensure that the functionality of the building is communicated at the outset. Other factors to consider at an early stage of the design are buildability and access for cleaning and maintenance. 


Rates are a guide only, are Q42015 averages, excluding VAT. They do not include any contractor prelims

Flat Roof: Membrane and built-up systems    
Includes insulation (U-value = 0.25W/m2K) and vapour barriers as necessary;
excludes decking

Single layer polymer roofing membrane; insulation £75-90/m2
Bitumen three-layer polymer modified bitumen system £80-110/m2
Bitumen two-layer modified bitumen system £60-90/m2
Bitumen felt roofing system, laid flat, with solar reflective paint finish £85-140/m2
Mastic asphalt; applied flat; to concrete substrate £25-50/m2
Single layer sheet roof; composite system; warm roof covering; vapour control layer; insulation and water proof membrane £75-110/m2
Polymeric waterproof membrane; 1.2mm thick fleece backed membrane; cold roof £50-75/m2
Air cushion roof (ETFE type membrane) supported on lightweight metal structure (included) £700-950/m2
Roof walkways; 600mm x 600mm x 50mm precast concrete slabs on support system £44-55/m2

Pitched Roof: Tiles or slates
Includes reinforced underlay and battens as necessary; excludes roof structure

Natural Welsh slate tiles £110-140/m2
Natural Spanish slate tiles £70-110/m2
Synthetic slate tiles £60-80/m2
Reconstituted stone slate tiles; random slates £55-80/m2
Clay pantiles £35-45/m2
Clay tiles; handmade; sand-faced plain tiles £80-110/m2
Concrete tiles; interlocking; troughed / bold rolled £30-50/m2
Concrete tiles; plain £30-50/m2
Fibre cement slates £45-65/m2
Red Cedar sawn shingles; preservative treated; uniform length £55-85/m2

PITCHED ROOF: SHEET METAL
Includes breather membrane, underlay or vapour barrier as necessary; excludes roof structure

Copper sheet; mill finish; flat seam or wood rolled £120-170/m2
Copper standing seam roof; mill finish £140-200/m2
Extra for pre-patinated copper finish £40-70/m2
Aluminium sheet; mill finish; wood roll; insulation (U-value = 0.25W/m2K) £80-125/m2
Aluminium sheet; standing seam; mill finish; insulation (U-value = 0.25W/m2K) £70-90/m2
Extra for Pvf2 aluminium finish £10-20/m2
Stainless steel; terne coated sheet £110-140/m2
Lead roof covering; code 7; welded seam; milled lead; laid flat £120-150/m2
Lead roof covering; code 7; welded seam; milled lead, pitched roof £140-155/m2
Zinc; natural zinc sheeting; pitched £85-120/m2
Extra for pre-weathered zinc £20-30/m2

PITCHED ROOF: FIBRE CEMENT SHEET
Excludes roof structure

Profile 6 fibre cement; single skin; natural grey finish £25-40/m2
Insulated system (U-value = 0.25W/m2K); Profile 6 fibre cement external skin; metal lining panel internally £50-65/m2
Extra for coloured fibre cement £1.75-2.25/m2
Double skin GRP translucent sheeting £55-66/m2
Triple skin GRP translucent sheeting £60-75/m2

LANDSCAPED ROOF
Excludes decking

Sedum roof; 100mm growing medium; laid flat; waterproof layer; separation layer; aquafrain; low maintenance £150-225/m2


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