I Want To Renew My Roof
If the house is listed or in a conservation area you will probably need consent to alter the covering and internal structure. You may also require Building Regulation approval. You should seek advice before carrying out these changes.
Roofs have three main parts: the outer covering; the internal timber structure; and external roof features such as chimneys, finials and guttering.
The material used to cover old roofs varies widely depending on where you live and the age of your house. The main historic roof coverings in England are natural slates from Wales, Cumbria or elsewhere, various types of clay tile, and thatch. There may also be some leadwork.
Replacing an old roof covering is disruptive and expensive and can cause damage, so make sure the work is necessary and effective. Damp could be caused by defects in chimneys or lead work, or by slipped slates or tiles.
In some old houses, so-called ‘nail sickness’ can cause slates or tiles to slip. This corrosion of the nails that hold them does not mean the whole roof covering itself has to be replaced. With care, it’s often possible to re-use a high percentage of the covering, making up the difference with matching second-hand or new material. Try to keep the existing roof ridges, whether these are clay or stone.
Thatching traditions vary across the country and if your house is listed we recommend that you use the same type of thatching material or method. This will either be water reed, combed wheat reed or long straw, depending on the area.
Old thatch is an important part of your house’s archaeology, and we recommend keeping the lower layers: it’s not usually necessary to replace it all. Before re-thatching, you should seek advice from an experienced professional and talk to your conservation officer. For further advice see our guidance on Thatch and Thatching.
SPAB also provides guidance on thatched roofs and repairing timber roofs.
The roof structure is the part that supports the covering. In many old houses, this is one of the most important features, even though it’s not seen. Many historic roof structures have survived for well over 100 years, and it’s not unusual for Georgian-looking houses to still have medieval roof timbers. Old timber roofs in oak or elm often have interesting carved details and carpenters’ marks. These features, and the method of construction, tell us how old the house is, because carpentry methods changed over time.
The priority should be to keep your existing structure and avoid replacing old roof timbers. The most important are the roof trusses and the purlins (the horizontal sidebeams that support the rafters). Good joiners can repair historic timbers if they have been damaged by rot. It is usual to put in new battens (the thin horizontals the slates or tiles are fixed to) if the roof covering is being replaced, but it’s rarely necessary to replace the rafters.
The external roof features are also part of your house’s character. Keep chimneys and pots even if they are no longer used; they can still help with ventilation. Details such as original clay or stone ridges and decorative finials should be carefully taken down and refixed later.
It is wise to first seek independent professional advice from an architect or surveyor with experience of old buildings, or at least find a roofing contractor who understands the particular nature of old roofs in your area. See Finding Professional Help.
If the house is listed and you use matching materials, you do not usually need consent for roof repairs. You will probably need Listed Building Consent to alter the roof’s shape, height and pitch, internal structure or type of covering, or to add rooflights. In conservation areas this usually needs planning permission - check with your local authority.