At some stage in a pitched roof’s life it is going to need more than just minor roof repairs. (See Pitched Roof Problems And Roof Repairs for details on individual repairs). A well constructed pitched roof can last 50 years and longer but if a couple of lead valleys have gone, a few ridge tiles have cracked, some individual tiles or slates have slipped and there are leaks or condensation appearing in the loft then it may be time for a full refurbishment of your roof.
What does renewing a roof involve?
Creating a new roof on an existing house involves:
- Putting up scaffolding to eaves level
- Removing old tiles including ridge tiles and hip tiles along with mortar from ridges / verges. Dispose of or sell any tiles that can be reclaimed (unless you intend to reuse on new roof)
- Removing old wooden battens and disposing of in skip (if untreated timber then it can also be used as kindling wood for a wood burning stove)
- Remove any lead from valleys (there is scrap value in old lead)
- Removing old roof felt or torching and dispose of in skip
- Checking wooden rafters and joists are sound. Replace any that are rotten. Remove /hammer down all protruding nails
- Add new breathable membrane
- Add new pressure treated wooden battens at correct spacing
- Put on new tiles or slates or re-use old ones. Clay tiles will be hung on nibs. Slates will be nailed to battens
- Add roof ventilators if required for bathroom extractor fan
- Create new valleys (joins between roofs) with new code 4 lead or GRP
- Bed down any ridge tiles with mortar and bed down tiles on verges
- Add thermal insulation between rafters if cold roof (or lay insulation on floor of loft if cold roof)
- Remove scaffolding and leave site in tidy condition
- Remove skip
It is assumed here that the rafters and joists are reasonably sound. Where these all need to be replaced then there will be an additional cost for new roof trusses.
Additional repairs that can be done at the same time include:
- Replacing rotten fascias, soffits and bargeboards
- Painting fascias, soffits and bargeboards (using the scaffolding for access)
- Replacing guttering
A new roof can mean all new roof tiles or slates or it may involve replacing those tiles which are damaged or have little life left in them. Clay tiles and slates can last for 100 years or more and concrete tiles 50 years plus. If the majority of the tiles are still usable then the ones that are damaged can be replaced with reclaimed tiles. Alternatively the older usable tiles / slates can be sold and an all new tile roof can be constructed.
Major factors which contribute to the cost of a new roof are:
- The area of the roof in square meters
- The material used for the roof covering
- Ease of access to the roof – bungalows will cost less as the scaffolding costs will be much lower
- The complexity of the roof – how many valleys, hips and chimneys are there
- The amount of roof tiles that are to be reused – depending on the state of the tiles often 60-80% of the clay tiles on a roof can be reused. A roof with 100% new tiles will cost more.
Let’s look at a few typical examples.
New Concrete Tile Roof
|Small Terrace||55 sq m||£800||£670||£700||£1,300||£3,470|
|Semi-detached||70 sq m||£1,600||£860||£840||£2,080||£5,370|
|Detached||100 sq m||£2,000||£1,220||£990||£3,120||£7,340|
Assuming use of a Redland 49 concrete tile (382mm x 226mm) with coverage of 16.3 tiles per sq metre.
New Plain Clay Tile Roof
|Small Terrace||55 sq m||£800||£1,420||£820||£1,300||£4,340|
|Semi-detached||70 sq m||£1,600||£1,810||£980||£2,080||£6,470|
|Detached||100 sq m||£2,000||£2,580||£1,200||£3,120||£8,900|
Assuming use of a Marley Clay Plain Acme Single Camber Roof Tile (265mm x 165mm) Red Sandfaced with coverage of 60 tiles per sq metre.
This cost does not make any allowance for sale of old clay tiles. Depending on condition then these could be worth 50% or more of value of new tiles.
These prices are a general guide. Where specific materials are used then the cost may vary. The clay tile quoted here is a mid range tile which is widely available. Specialist alternative clay tiles can double or even treble the roof covering cost.
Plain Clay Tile Re-Roof with 20% reclaimed tiles
|Small Terrace||55 sq m||£800||£280||£820||£1,300||£3,200|
|Semi-detached||70 sq m||£1,600||£360||£980||£2,080||£5,020|
|Detached||100 sq m||£2,000||£520||£1,200||£3,120||£6,840|
Assuming 80% of tiles can be re-used and 20% will be reclaimed to match existing.
New Natural Slate Roof – Using Spanish Slate
|Small Terrace||55 sq m||£800||£1,350||£840||£1,300||£4,290|
|Semi-detached||70 sq m||£1,600||£1,720||£1,010||£2,080||£6,410|
|Detached||100 sq m||£2,000||£2,460||£1,240||£3,120||£8,820|
Assumes 500mm x 250mm Spanish slate with 50mm x 25mm battens. For welsh slate, for many the best slate you can buy, you can double or more the roof covering cost.
Natural Slate Re-Roof with 20% Reclaimed Slate
|Small Terrace||55 sq m||£800||£540||£840||£1,300||£3,480|
|Semi-detached||70 sq m||£1,600||£690||£1,010||£2,080||£5,380|
|Detached||100 sq m||£2,000||£980||£1,240||£3,120||£7,340|
Assuming 80% of slates can be re-used and 20% will be reclaimed to match existing.
New Fibre Cement Slate Roof
|Small Terrace||55 sq m||£800||£770||£840||£1,300||£3,710|
|Semi-detached||70 sq m||£1,600||£980||£1,010||£2,080||£5,670|
|Detached||100 sq m||£2,000||£1,400||£1,240||£3,120||£7,760|
Assumes 500mm x 250mm fibre cement slate.
How long does a new roof take to build?
Assuming an existing roof has to be removed and two people are working full time on the roof then typical timescales are:
- Small terraced house: 1 week
- Semi-detached house: 2 weeks
- Detached house: 3 weeks
Detached houses tend to have more complex roof designs with gables, hips and more valleys. That’s why it costs more per square metre than a terraced house which tends to have a very simple roof design. Scaffolding for detached houses tends to be more complex as well.