Barnet · Greater London
Roof structure repairs in Barnet
Before buying or re-roofing a house in Barnet, it is worth knowing whether the frame can carry its covering. Send photos of the loft and the ridge, and we will tell you whether the timbers look adequate or need strengthening.
Guide price from£375per rafter inc VAT

- Postcodes
- EN4, EN5, N3, N12, N20
- Population
- about 390,000
- Area
- Greater London
- Pricing region
- London
How do local ground conditions affect roof structure repairs in Barnet?
Barnet is one of the 32 London boroughs, with around 390,000 residents in districts such as EN4, EN5, N3, N12, N20. We also take enquiries from nearby Haringey (4 miles), Borehamwood (4 miles) and Potters Bar (5 miles).
Greater London is one of the parts of the UK where clay soils are most likely to move with the seasons. Ground movement here is more often linked to soils, drains and trees than to mining. Typical buildings in Greater London: Victorian and Edwardian terraces with shallow footings, inter-war semis in the outer boroughs, and converted flats and mansion blocks.
Guide prices for roof structure repairs in Barnet
The ranges below reflect typical London costs for roof structure repairs, including VAT. Scaffold, access and making good can push a job to the top of the range.
| Item | Guide price | Per |
|---|---|---|
| Repairing or doubling a rafter | £375 – £750 | per rafter |
| Purlin and strut strengthening | £1,500 – £3,750 | per roof |
| Tying in roof spread (straps and ties)est. | £1,000 – £3,100 | per roof |
Methods for roof structure repairs
Repairing or doubling rafters
Cracked, sagging or rotten rafters are strengthened by fixing a new timber alongside, often called doubling, and rotten rafter feet are cut back and spliced. The work is usually done from inside the loft with the tiles left in place, unless the covering is coming off anyway.
Best for: Individual rafters that have cracked, sagged or rotted at the feet
Purlin and strut strengthening
Undersized purlins are strengthened with extra timber or replaced, and new struts are taken down to a load-bearing wall. Where there is no suitable wall, an engineer designs the load path. Temporary props hold the roof while members are changed.
Best for: Sagging slopes, slim purlins and struts removed from the loft
From first photo to finished repair
Send photos
Photograph the roof from across the street, both slopes if you can, and the loft timbers with a torch. Include the eaves and any cracks just below them. From these we can usually tell sag from spread and whether an engineer is needed.
Loft and outside survey
On site we check rafter sizes and spacing, purlins, struts, ties and wall plates, look for rot and past alterations, and measure any lean at the wall head. The covering is noted too, because its weight affects the repair.
Engineer’s design where needed
Where purlins, struts or ties must be redesigned, or the roof carries a heavier covering, an independent chartered structural engineer is appointed to specify the work. We can arrange this, and their design sets the sizes and fixings.
Symptoms that point to roof structure repairs
- Struts, collars or ties cut out or missing in the loft
- Ridge line dipping in the middle when seen from the street
- Horizontal cracks in the wall just below the eaves or ceiling line
Rules for roof structure repairs in England
In England, underpinning and other work that alters or strengthens a wall or foundation is building work under the Building Regulations (Part A, structure), so building control approves and inspects it. Like-for-like repairs often are not, and we tell you which applies before a price is agreed. Work to a party wall, or excavation close to a neighbour’s foundations, can also need a notice under the Party Wall etc. Act 1996.
Frequently asked questions
How much should I budget for roof structure repairs in Barnet?
Guide prices for roof structure repairs in Barnet start from about £375 per rafter, including VAT, on London rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Can you survey a property in Barnet?
We do. Barnet and the surrounding area are covered, including nearby Haringey and Borehamwood. A free initial assessment from your photos is the first step.
Why do houses in Greater London crack?
Most of Greater London sits on London Clay, among the most shrinkage-prone ground in the UK, with river gravels along the Thames. Subsidence claims here are among the most frequent in the country, especially after dry summers and near street and garden trees. Only an investigation can say why a particular building has moved.
Is a sagging roof ridge dangerous?
A slight, even dip in an old roof is often historic movement that stopped long ago. A sag that is getting worse, cracking timbers, walls pushing out at the eaves or recently removed struts should be checked soon. Avoid storing heavy items in the loft until then.
Why are there cracks just below the eaves?
A horizontal crack just below the eaves, along the front or back wall, is a common sign of roof spread. The rafters push the top of the wall outward and the masonry cracks where it hinges. Corroded wall ties can cause similar cracks, so the cause needs checking.
Related work in Barnet
- Structural crack repairs
- Lintel replacement
- Structural surveys and crack monitoring
- Subsidence insurance claim repairs
- Bay window subsidence repairs
Roof structure repairs near Barnet
Seen the ridge dip at your Barnet home? Photograph it from across the road, add a few loft shots, and we will tell you what it likely needs.