Costed: Roofing Jan/Feb 2018

Words:
David Holmes

David Holmes, associate at AECOM, provides an overview of roofing costs

Choosing the right type of roof is more difficult than most people think. Roofs serve more than the practical purpose of protecting the building contents and occupiers from outside elements. They can help make it more energy efficient, bring in natural light and are important in defining the overall style of the property.

Gable roofs are some of the most popular types and are very easily recognised. They easily shed water and snow and can provide more attic space for storage or living, or be made into  vaulted ceilings. Gable roof frames need to be constructed properly with adequate supports and can be covered with a variety of materials.

Flat roofs may appear to be totally flat, but in fact they have a slight pitch to allow for water run-off and drainage. Generally  they are easier to construct than pitched roofs and require fewer materials. However, this initial low capital cost needs to be balanced with more expensive long term maintenance and repair costs.

Green roofs are aesthetically pleasing and are increasing in popularity. They are also energy efficient, thanks to all the vegetation which acts as an additional layer of insulation, and those cooling properties help combat the urban heat island effect. Layers are created using beneficial plant life, soil, drainage and waterproofing membrane. They do put a greater load on buildings than more traditional cold roofs (where the insulation is on the inside of the roof) or warm roofs (where the insulation is on top) so the designer needs to be aware of this.


The following rates are based on the UK average and represent typical prices at 2017 Q4. Please note that prices can vary significantly depending on the exact specification


Range £/m2

Flat roof: Membrane and built-up systems

Includes insulation (U-value = 0.25W K) and vapour barriers as necessary; excludes decking

Single layer polymer roofing membrane; insulation    £84-100

Single layer polymer roofing membrane; tapered insulation    £150-180

Bitumen three-layer polymer modified bitumen system    £87-120

Bitumen two-layer modified bitumen system     £65-100

Bitumen felt roofing system, laid flat, with solar reflective paint finish     £110-150

Mastic asphalt; applied flat; to concrete substrate     £30-60

Single layer sheet roof; composite system; warm roof covering; vapour control layer; insulation and water proof membrane     £85-120

Polymeric waterproof membrane; 1.2mm thick fleece backed membrane; cold roof    £50-85

Roof walkways; 600mm x 600mm x 50mm precast concrete slabs on support system    £49-65 


Pitched roof: Tiles or slates

Includes reinforced underlay and battens as necessary; excludes roof structure

Natural Welsh slate tiles    £120-160  

Natural Spanish slate tiles    £85-130  

Synthetic slate tiles    £70-90  

Reconstituted stone slate tiles; random slates    £68-90  

Clay pantiles    £42-55  

Clay tiles; handmade; sand-faced plain tiles    £85-130  

Concrete tiles; interlocking; troughed / bold rolled    £35-65  

Concrete tiles; plain    £34-53 

Fibre cement slates    £42-58  

Red Cedar sawn shingles; preservative treated; uniform length    £70-95 


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    £170-205  

Copper standing seam roof; mill finish    £175-225  

Extra for pre-patinated copper finish    £40-70  

Aluminium sheet; mill finish; wood roll; insulation (U-value = 0.25W K)    £80-135  

Aluminium sheet; standing seam; mill finish; insulation (U-value = 0.25W K)    £80-140  

Extra for Pvf2 aluminium finish    £10-20 

Stainless steel; terne coated sheet    £140-170  

Lead roof covering; code 7; welded seam; milled lead; laid flat    £150-175  

Lead roof covering; code 7; welded seam; milled lead, pitched roof    £150-195  

Zinc; Natural Bright Rheinzink; pitched    £11-150  

Extra for pre-weathered zinc    £20-30 


Pitched roof: Fibre-cement sheet

Excludes roof structure

Profile 6 fibre cement; single skin; natural grey finish    £28-40  

Insulated system (U-value = 0.25W K); Profile 6 fibre cement external skin; metal lining panel internally    £55-70 

Extra for coloured fibre cement    £1.75-2.25 

Double skin GRP translucent sheeting    £60-73  

Triple skin GRP translucent sheeting    £67-81  


Landscape roof

Excludes decking

Extensive sedum type flat roof; growing medium; waterproof layer; separation layer; low maintenance    £220-280  

Extensive rockery type green flat roof for planting with rockery type plants; growing medium;  waterproof layer; separation layer; low maintenance    £210-300 

Latest

With retail flagging how can we bring life back into towns? Architects, this is your chance to step up

With retail flagging how can we bring life back into towns?

Gundry + Ducker's innovative design for the RIBA Marketplace stand at this year's Futurebuild event is made from Rockwool insulation and Rockpanel cladding for a restful, reading room feel

RIBA hub design at Futurebuild keeps things quiet

As cuts in public services bite ever deeper it’s down to local people to save and reinvent neglected or redundant structures. Architects play a crucial role

Local activists need public-spirited architects

National Museum, Tartu, Estonia

National Museum, Tartu, Estonia

Impressive productivity gains are offset by rising payroll costs in the RIBA Business Benchmarking Survey  this year

Revenues are rising twice as fast as staff numbers