Roof replacement and new roofs in Farnborough

Stripping a roof back to its rafters opens up the layers that keep heat in the house, and the Building Regulations treat that as a chance to improve them. The panel gives the Approved Document L figures for a roof that is renovated rather than built new.

When a re-roof counts as renovation

The Building Regulations 2010 define renovation of a thermal element (a wall, floor or roof) as providing a new layer in it or replacing an existing layer. A re-roof replaces layers of the roof, which is why building control looks at insulation as part of the job and not only at the covering. Roof windows and rooflights sit outside that definition: the regulations exclude them from thermal elements, and they have their own figures.

Where the existing roof's U-value (the rate at which heat passes through it, in W/m²K) is worse than 0.35, Table 4.3 asks for it to be brought to 0.16. That is a demanding target on a roof with shallow rafters, and paragraph 4.13 allows for it. If reaching 0.16 cannot be done in practice, or the saving would take more than 15 years to repay the cost, the roof is improved as far as a 15-year payback allows. Generally, an upgraded element should not be left worse than 0.7.

A re-roof follows the same order on almost every house, and knowing it makes the time on site easier to follow. The figures in the panel are the standards the new layers are built to.

From scaffold to ridge

1. Scaffold goes up with a working platform at the eaves and edge protection around the roof.
2. The old covering, battens and underlay come off one section at a time, and the open area is sheeted against the weather at the end of each day.
3. The rafters are checked. Soft or split timbers and rotten wall plates are repaired or replaced, and you see the photos before anything extra is agreed.
4. New underlay is laid and lapped, then new battens are fixed at the spacing the chosen tile or slate needs.
5. The covering goes on, with lead flashings, soakers and valleys renewed where the old ones are tired.
6. Ridges, hips and verges are fixed, the fascias, soffits and gutters are finished, and the scaffold comes down after a final check.

Each slate, and every tile at the eaves, verges and ridge, is fixed rather than left to hang on its nibs. Since the 2014 revision of BS 5534, mortar on its own is no longer treated as enough to hold a ridge or hip tile, so each one is also screwed, clipped or wired. A dry-fix system is the alternative to a mortar bed, and BS 8612:2018 is the specification such systems are tested to. Marley points out that installing to BS 5534 isn't required by law. What the law asks, through Approved Document C, is for each tile to be fixed in an appropriate manner, and working to the code is the usual way of showing that.

A new roof is a large contract, so the paperwork around it deserves the same care as the battens. The panel gathers the figures that apply to it.

Your rights when you sign at home

When the contract is agreed in your home after a survey, rather than at the trader's premises, it is an off-premises contract under the Consumer Contracts Regulations 2013. You can cancel it within 14 days of the day it is made, without giving a reason, and if you were not told about that right the period can stretch by up to 12 months. If you want work to begin inside the 14 days, ask for that on a durable medium, which in practice means in writing you can keep. The right falls away when you called the trader out yourself for urgent repairs, so a storm make-safe is handled differently from a planned re-roof.

Under the Consumer Rights Act 2015 the work must show reasonable care and skill. Citizens Advice recommends at least 3 written quotes before you choose, and its consumer helpline is 0808 223 1133. When you set quotes side by side, make sure each one states whether VAT and the scaffold are in the total, and that each names the same covering, underlay and ridge system, so the totals describe the same roof.