New Roofs in Cambourne - Repair or Replace: Making the Right Call

Expert New Roofs
in Cambourne

The Central Question: Repair or Replace?

When something goes wrong with your roof, the first question most homeowners ask is whether it can be patched. The honest answer is: sometimes yes, sometimes no, and knowing which situation you are in before spending any money is the most important thing. A repair that buys another year when the roof needed replacing is not a saving - it is a delay that costs you more in the end.

This page sets out how to think through the repair-or-replace decision, what signals point in each direction, and what a new roof in Cambourne actually involves when replacement is the right answer.

When a Repair Makes Sense

Roofs do not wear out uniformly. A covering that is broadly sound can develop isolated faults - a slipped tile after wind, a cracked slate, a failed flashing at a chimney - that are entirely worth repairing. The repair cost is low, the rest of the roof has years of life left, and replacing it would be wasteful.

A repair is the right call when:

• The fault is isolated and clearly defined - a small number of slipped or broken tiles, a cracked ridge piece, a lead flashing that has lifted.
• The surrounding tiles or slates are in sound condition, mechanically fixed, and not approaching the end of their expected lifespan.
• The underlay beneath the covering is still intact and doing its job - you can often tell this by whether the loft stays dry after rain even before the repair is done.
• The roof timbers are dry and structurally sound.
• The roof has been in place for under 20 to 25 years and the materials used were of reasonable quality at installation.

In this situation, a targeted repair extends the life of a sound roof without unnecessary cost. It is straightforward work and should be priced as a fixed job, not an open-ended day rate.

When a Repair Is Not Enough

The harder conversation is when a repair will not fix the underlying problem. A common pattern is a roof that has been patched multiple times over several years - each patch holding for a season or two before a new leak appears somewhere else. The individual faults look random, but they are not. The covering is at or past the end of its useful life and failing progressively.

Replacement is the right call when:

• The tiles or slates are brittle, porous or de-laminating across most of the roof, not just in one area. Concrete tiles from the 1970s and 1980s are particularly prone to this.
• The nail holes in slates have rusted and widened to the point where slates are sliding out regularly across the whole slope. This is called nail sickness and it cannot be fixed by re-nailing individual slates.
• The underlay is original felt from the 1960s, 1970s or earlier and has become brittle and holed. Once underlay fails, the roof lets in wind-driven rain regardless of the condition of the tiles above.
• The ridge mortar has failed extensively, not just at one or two points, and the ridge tiles themselves are loose or cracked.
• The roof timbers have areas of rot or significant deflection that need structural work in any case.
• The cost of repairing the most urgent faults is more than 40 to 50 per cent of the estimated replacement cost. At that point, you are spending heavily to extend a roof that will need replacing within a few years regardless.

Getting an Honest Assessment

The difficulty is that most homeowners are not in a position to make this judgement themselves, and it requires a contractor who will tell you the truth rather than the answer that generates more work. When you have a roofer out to look at a problem, ask directly: is this a repair or a replacement situation? Ask them to show you or describe what they are seeing on the roof that leads to that conclusion.

A roofer who recommends a full replacement without being able to point to specific evidence - failing tiles across the slope, failed underlay, nail sickness - is worth questioning. Equally, a roofer who patches the same roof three times in three years without raising the question of replacement is not giving you the full picture.

What a New Roof in Cambourne Involves

When replacement is confirmed as the right answer, the process is methodical. The old covering is stripped completely, back to the bare timber structure. Every rafter, purlin and ridge board is inspected. Any timber that has softened, split or shows signs of insect damage is replaced at this stage, before anything goes back on. It is far simpler and cheaper to do timber repairs during a strip than after new tiles are on.

New breathable underlay is laid over the rafters, lapped correctly at the horizontal joints and taken down into the guttering to direct any water that gets past the tiles safely away. Treated softwood battens are then fixed through the underlay into the rafters at the correct gauge for the tile or slate chosen.

Flashings at chimneys, abutments, valleys and soil pipes are cut and dressed in lead before the covering goes on around them. Getting this sequence right matters: flashing dressed over tiles rather than under them is a common source of future leaks and something to check when assessing any completed roofing job.

The tiles or slates are fixed mechanically - nailed and, where the pitch or exposure requires it, clipped as well. The building regulations specify minimum fixing requirements and a competent roofer will meet or exceed them. The ridge is finished with a dry-ridge system or bedded and pointed in mortar, depending on the material and the property.

Material Choices for a New Roof

The right covering depends on the roof's pitch, the property's character and any planning conditions:

• Concrete interlocking tiles - practical and cost-effective for most post-war housing. Currently the most widely specified product for replacement roofs.
• Clay plain tiles - the traditional material for older properties. More expensive than concrete but with a longer expected lifespan and a colour that does not fade in the same way.
• Natural slate - Welsh or Spanish slate is used where the roof pitch suits it and where a premium finish is wanted. Properly fixed natural slate outlasts almost any other roofing material.
• EPDM rubber membrane - for flat or very low-pitch sections. A fully bonded EPDM system is the standard modern approach for flat roofs, replacing multi-layer felt systems that have a significantly shorter lifespan.

Typical costs for a pitched roof re-covering currently range from around £70 to £110 per square metre in concrete tiles, and £90 to £150 per square metre in natural slate. These figures are market-rate indicators; the price for your specific roof depends on its area, pitch, complexity and the condition of the structure underneath.

Flat Roof Sections: Repair or Replace?

Flat roof sections - common on kitchen extensions, bay windows and garage roofs - follow a similar logic. A localised blister or small split in a felt roof can be repaired if the rest of the membrane is sound and the deck below is dry. But felt flat roofs that are pond-ing water, showing widespread cracking or have softened decking beneath them are beyond repair. In those cases, stripping to the deck, checking and replacing any wet plywood or boarding, and laying a new EPDM system is the correct approach.

An EPDM flat roof, properly installed with a fully bonded membrane and correctly dressed edge detail, is a long-lasting solution that does not have the same vulnerability to UV degradation that aged felt does.

Covering Cambourne and Nearby Areas

Cambridge Roofers works across Cambourne and the wider area, including Cambridge, Royston and St Ives. If you are unsure whether your roof needs a repair or a full replacement, call us to arrange a roof survey. We will tell you what we find and give you an honest, itemised quote for whichever option is the right one for your roof.