Your choice of structure will have a huge effect on what your new roof costs — in fact it will have just as much of an impact as the type of roof covering you end up opting for.
While it is types of roof that commonly seem to dictate the structural choices made by homeowners, when it comes to roof trusses, it is important to understand what's what so that you can make an informed decision on the right option for your home.
Here we explain the costs behind some of the more traditional structural choices and the costs outlined below apply to a 10x8m rectangular roof.
"The cost of both roofing materials and labour spiked between 2020 - 2022 due to a shortage of materials, delivery drivers and skilled roofers," says Gian-Carlo Grossi, MD of Roofing Megastore. "For materials such as steel roof sheets, PVC roof sheets and others, the cost of materials increased by as much as 40%.
"Thankfully, the cost of these materials has begun to drop again as demand levels and material availability improves. As a result, undertaking a roofing project is now much easier and cheaper."
Do types of trusses affect new roof costs?
There are many different ways roof structures can be built — some simpler to construct and cheaper to build than others.
"Roofs are one area of housebuilding which is changing fast," says Mark Brinkley, author of the Housebuilder’s Bible and an experienced builder. "In Victorian and Edwardian times, there was really just one way to build a roof and its still widely used. But since then we have seen the introduction of many other options."
So, just what are the most common?
- 1. Fink roof truss: The cheapest option. It’s lightweight, uses relatively small timber sections, and can be erected on most roofs in a day. However, it’s no good if you want to use the roof space for more than light storage or on more complex roof shapes.
- 2. Traditional cut roof: In cost terms, there is not much to choose between an attic truss and a traditional cut roof. In fact, it can often be hard to tell how an open-attic roof has been built, but it tends to come into its own when the roof shapes are complex.
- 3. Attic truss: As its name suggests, the attic truss gives you an empty attic space within the simplicity of a trussed roof design. However, attic trusses are made from much heavier timbers than fink trusses, and therefore cost considerably more to buy.
- 4. Panelised roofing: Panelised roofing uses large pre-insulated sheets, laid across roof beams, so works best on simple-shaped roofs. It is more expensive to buy a roof this way, but fitting costs are reduced because the panels are pre-insulated.
Which factors most affect new roof costs?
One of the main factors that affects the price of the roof structure is the same factor that impacts on the price in so many other elements of the building: complexity. Consequently, the simpler the shape of roofs, the cheaper their price.
Undoubtedly, moving away from a fink trussed roof to either an attic truss or a purlin and spar roof will add to the costs. But, even so, it provides the opportunity for ‘cheap’ space either immediately or at a later date and is therefore cost-effective in real terms. Thought does, however, have to be given as to how one is to gain access to this additional storey and the knock-on effects, such as the need for fire doors if a third storey is provided.
How much do different types of roof cost?
On to the nitty gritty — just how much do all these different types of roof structure cost these days. We asked the experts at Roofing Megastore for their advice.
Fink trussed roof
Undoubtedly the cheapest form of roofing for most situations, a ‘fink’ truss is identified by having a ‘W’-shaped formation of cross beams and supports within the basic triangle formed by the rafters and the ceiling joists. There are other slightly different forms but they employ the same principles.
The trusses are light and often seem quite flimsy when taken or handled individually. But by being very light allows them to be lifted on to the scaffolding and the roof plate by one man and an assistant, and then stood up and held into place with a temporary batten, nailed across each truss, while the binders and bracings are fixed, locking all of them into a homogenous structure.
An average cost for each truss, assuming a span of around 8m with a 30° pitch, including supply of the necessary binding, bracing and truss clips, would be £56.
|17 trusses with bracings, bindings and truss clips
|£1,128 - £1,347
|Labour (carpenter plus mate) for one and half days
|£548 - £750
|£1,676 - £2,097
Attic trussed roof
The huge advantage of the traditional purlin and spar roof was the fact that it provided clear space within the attic that could easily be converted for use as living space.
The attic truss, however, provides that option by doing away with the ‘W’-shaped supports within the main triangle and replacing them with upright supports close to the eaves, together with a cross tie support at what would be ceiling level. Effectively this creates an open space along the length of the roof with sloping ceilings to the occupation section, together with eaves storage.
Not unnaturally, the timbers have to be bigger. And the result is a much heavier truss, which can’t easily be manhandled on to the roof and may need a crane or some other form of lifting assistance. Once they are up on the wall plate their erection proceeds in much the same format as for the fink trussed roof.
An average cost for each attic truss, assuming a span of around 8m, with a 45° pitch (necessary to provide sufficient headroom in the proposed attic), including supply of the necessary binding, bracing and truss clips, would be £163.
|17 trusses with bracings, bindings and truss clips
|£3,284 - £4,918
|Labour (carpenter plus mate) for two days
|£548 - £750
|£385 - £500 per day
|£4,217 - £6,168
Purlin and spar roof (or cut and pitch)
A traditional cut roof is constructed on site using loose sawn lumber with the timber sizes determined by a set of tables or by the recommendation of a structural engineer. Because the rafters do not have support struts within the triangle formed by them and the ceiling/floor joists, they require some form of support at their mid span between the eaves and the ridge. This is provided by heavy timbers, on each side of the roof, running counter to the rafters and built in, and supported by the end and cross walls of the house.
The pile of lumber that arrives on site can be quite daunting and the labour involved will be counted in weeks rather than days, which tends to put the cost up.
|Labour (carpenter plus mate) for seven days
|£2,555 - £3,000
|£5,458 - £5,903
How can I save on my new roof costs?
You can’t skimp on the materials. The roof trusses have to be what the manufacturers say they must be and the timber sizes have to be what the architect or engineer specifies.
What you can do is shorten the time that labour will be on site. With light trusses, getting them up on to the wall plate yourself can save at least half a day’s labour. Sorting out the piles of lumber into sizes and, if possible, uses such as rafters, joists, purlins, hips etc., will save at least a day and possibly more of an expensive carpenter’s time.
You can then make savings on the roof covering, and insulation:
- Getting the slates onto the roof is a long job and one that the self builder could do. But it’s not easy, although one could save around five days of labour
- Plain clay tiles would cost roughly the same as slate but if you swapped to concrete interlocking, the tiling costs would almost half
"Whilst not always an avenue you can take, if you’re replacing your roof because it is damaged, we would always suggest checking in with your insurance provider to see if replacement is covered in your policy," advises Gian-Carlo Grossi. "In the majority of cases, full coverage will only apply if your roof was already in good condition and the cause of the damage was an act of nature (such as a falling tree). However, most will still cover at least a portion of your costs as long as the damage was not a result of a long-standing and unresolved issue.
"There are also several additional costs involved in replacing a roof that you may not consider when budgeting. These can include equipment hire, material disposal and issues with access, to name just a few. You may well be able to knock the price of the job down by resolving some of these yourself, such as offering to dispose of any waste."
Gian-Carlo is founder and managing director of Roofing Megastore.
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David is one of the UK's leading self build and plotfinding experts, and a serial self builder who has been building homes for 50 years. The author of Building Your Own Home, David spent decades as a speaker and expert at self build exhibitions such as the Homebuilding & Renovating Show. He has recently finished his fourteenth self build project.