St Austell · Cornwall
Roof structure repairs in St Austell
Many older roofs, in St Austell and across Cornwall alike, were built with slim purlins and few ties. A little historic movement is normal, so we check whether the roof is still moving before recommending how far the strengthening needs to go.
Guide price from£310per rafter inc VAT

- Postcodes
- PL25
- Population
- about 24,000
- Area
- Cornwall
- Pricing region
- South West
What should you know about the ground under St Austell?
Postcode districts PL25 cover St Austell, a Cornwall town of about 24,000 people. If you are just outside St Austell, we also cover Bodmin (9 miles), Truro (13 miles) and Newquay (14 miles).
Most of Cornwall is on firmer ground than the clay belts of the south-east. Old metal-mine shafts and workings are recorded in places, so mining searches are routine for some properties. Across Cornwall, most homes are granite and slate-stone cottages, cob buildings, Victorian terraces and post-war estates.
Roof structure repairs prices in St Austell
Prices in St Austell are worked out on South West rates. They include VAT and are a starting point: access, the extent of the damage and whether an engineer or building control is involved all move the figure.
| Item | Guide price | Per |
|---|---|---|
| Repairing or doubling a rafter | £310 – £620 | per rafter |
| Purlin and strut strengthening | £1,250 – £3,100 | per roof |
| Tying in roof spread (straps and ties)est. | £825 – £2,600 | per roof |
How we usually approach 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
What happens during roof structure repairs, step by step?
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.
Prop, strengthen and tie
The roof is propped where members are being changed, then rafters, purlins, struts and ties are repaired or added as specified. Coverings disturbed by the work are relaid, and building control inspects where the work needs it.
What to look for before calling about roof structure repairs
- Top of an outside wall leaning out at eaves level
- Horizontal cracks in the wall just below the eaves or ceiling line
- Roof slope looking hollow or wavy between the ridge and the gutter
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.
Questions about roof structure repairs in St Austell
How much will roof structure repairs cost in St Austell?
Guide prices for roof structure repairs in St Austell start from about £310 per rafter, including VAT, on South West rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Do you cover St Austell?
Yes, St Austell is covered, along with postcode districts PL25. We also cover nearby Bodmin and Truro.
Is the ground in Cornwall prone to subsidence?
Cornwall is mostly granite and slate with little shrinkable clay, so clay subsidence is less common than in the south-east. Historic tin and copper mining has left shafts and workings in places such as Camborne and Redruth, and mining searches are routine there. Only an investigation can say why a particular building has moved.
Can the roof be strengthened without removing the tiles?
In most cases, yes. Doubling rafters, adding struts and fitting ties can all be done from inside the loft with the coverings in place. Tiles usually only come off where timber near the eaves is badly decayed, or the roof is being re-covered anyway.
Do I need a structural engineer for roof repairs?
For like-for-like repairs to a few rafters, often not. Where purlins, struts or ties are being redesigned, the covering is getting heavier or the walls are being pushed out, you usually do. Where the repair needs an engineer’s design or sign-off, an independent chartered structural engineer is appointed, and we can arrange this.
Other structural repairs in St Austell
- Resin injection ground stabilisation
- Structural crack repairs
- Lintel replacement
- Underpinning
- Chimney stack repairs
Roof structure repairs near St Austell
Get a free initial assessment of a sagging or spreading roof in St Austell from your photos or a call, and find out whether an engineer is needed.