Cost a roof install.

Whether you are replacing an ageing slate roof or installing modern concrete tiles, understanding the process and costs helps you avoid "cowboy" builders and ensures your home remains watertight for decades to come.

What Does the Work Involve?

• Scaffolding and Access: Erecting safe working platforms around the perimeter of the property to comply with Health and Safety executive (HSE) guidelines.
• Stripping the Old Roof: Removing existing tiles, slates, or felt, and disposing of the waste in a skip.
• Timber Inspection: Checking the rafters and roof joists for signs of rot, woodworm, or structural sagging, replacing timber where necessary.
• Membrane and Battens: Installing a breathable waterproof underlay (membrane) followed by treated timber battens spaced to suit your chosen tiles.
• Tiling or Slating: Laying the new roof covering from the eaves up to the ridge, ensuring correct overlap for wind and rain resistance.
• Leadwork and Flashing: Installing lead around chimneys, valleys, and dormers to prevent water ingress at the joints.
• Ridge and Hip Tiles: Securing the top-most tiles using modern "dry-fix" systems or traditional mortar bedding.

Typical Costs

Prices are influenced heavily by your location (London and the SE are typically 20% higher) and the complexity of the roof's pitch and valleys. If your existing rafters need structural reinforcement, expect the total cost to increase by 15-20%.

Replacing more than 25% of your roof usually requires an upgrade to your loft insulation to meet current UK Building Regulations, which may add to the initial quote.

How Long Does It Take?

• Small Flat Roof: 1–2 days.
• Standard Terraced House: 3–5 days.
• Large Detached Home: 7–10 days.
• Complex Roofs (Valleys/Dormers): 10+ days.

DIY or Professional?

Roofing is not a DIY job. Beyond the extreme risks of working at height, an incorrectly installed roof can lead to catastrophic water damage and void your home insurance.

Professional roofers provide "workmanship guarantees" and are familiar with Part L of the Building Regulations regarding thermal insulation. Furthermore, a professional installation is often required to obtain the necessary completion certificates for future house sales.

Choosing the Right Tradesperson

• Check Accreditations: Look for membership in the National Federation of Roofing Contractors (NFRC) or the "CompetentRoofer" scheme.
• Insurance: Ensure they have specific Public Liability Insurance that covers "working with heat" if they are doing flat roofing.
• Local Reputation: Ask for addresses of local projects they have completed in the last 12 months to see their work in person.

• Are you a member of a Competent Person Scheme (allowing you to self-certify Building Regs)?
• Does the quote include scaffolding and the removal of all old materials?
• What happens if the weather turns bad mid-project?
• What is the duration of your workmanship guarantee?

UK Regulations

• Building Regulations: You must notify Building Control if you are replacing more than 25% of the roof area. A "CompetentRoofer" member can do this for you.
• Part L: Requires you to improve the thermal insulation of the roof space when performing a significant reroof.
• BS 5534: The British Standard for slating and tiling which dictates how tiles must be fixed (e.g., mechanical fixing rather than just mortar).
• Planning Permission: Usually not required for "like-for-like" replacements unless you live in a Listed Building or Conservation Area.

Common Problems

• Unexpected Rot: Once the tiles are off, "hidden" rot in the rafters may be discovered, leading to extra costs.
• Poor Flashing: Reusing old lead flashing is a common shortcut that leads to leaks around chimneys within a few years.
• Inadequate Ventilation: Modern breathable membranes still require proper eaves ventilation to prevent condensation and "loft damp."
• Weather Delays: UK rain can stop work instantly; ensure your roofer has high-quality tarpaulins to "dry-in" the house overnight.

Frequently Asked Questions