How to Install Soffit and Fascia — Step-by-Step UK Guide

What You'll Need

Before You Start

• Remove the guttering first — you cannot replace fascia with gutters in place. Label brackets and components if you plan to refit existing guttering.
• Inspect rafter feet for rot from ground level. Budget for timber repairs — rotten rafter ends are common on older properties.
• Measure the total lengths of fascia and soffit needed, noting widths and any angles. Use our Soffit and Fascia Calculator to estimate quantities.
• Choose a UPVC colour and profile — white is standard but black, grey, golden oak and rosewood are popular alternatives.
• Check the weather forecast — you need dry conditions, especially if the roof will be exposed during the work.

Step-by-Step Instructions

Step 1: Remove Guttering

Remove gutter lengths, brackets and downpipes. Store them safely if you plan to refit. If replacing guttering at the same time, simply remove and discard.

Step 2: Remove Old Fascia and Soffit

Pry off old soffit boards first using a pry bar. Then remove old fascia boards — they are usually nailed to the rafter ends. Remove all old nails and fixings. Inspect the rafter feet and any backing timbers for rot.

Step 3: Repair Rafter Ends

Cut out any rotten timber and splice in new treated timber, bolted or screwed alongside the existing rafter. Ensure all rafter ends are straight and level — the new fascia will follow the rafter line. Pack out any low spots with plywood shims.

Step 4: Fix Soffit Bearer Battens

Fix a 25×50mm treated timber batten to the wall at soffit height, level with the underside of the rafter feet. Use wall plugs and screws into the masonry at 400mm centres. This batten supports the inner edge of the soffit board.

Step 5: Fit the New Fascia Board

Cut UPVC fascia boards to length. Fix to rafter ends using stainless steel screws or poly-headed nails (colour-matched). Start at one end and work along, ensuring each board is level. Join boards using a fascia joint cover piece — leave a 5mm expansion gap at each joint in warm weather, 8mm in cold.

Step 6: Fit the Soffit Board

Slide the soffit board into the groove on the back of the fascia board (most UPVC fascia boards have an integral soffit groove). Fix the inner edge to the wall batten with screws or pins. If using vented soffit, ensure the ventilation openings face downwards and are not blocked.

Step 7: Fit Ventilation

If using flat (non-vented) soffit boards, install continuous soffit strip vents or individual circular vents to provide the required roof ventilation. Building regulations require a continuous 10mm equivalent gap at both eaves for a cold roof. Position vents evenly along the run.

Step 8: Fit Corner Trims and Joint Covers

Fit external corner trims at hip and verge junctions. Apply joint cover strips over all board joins. Use colour-matched exterior silicone to seal any gaps at corners, joints and where soffit meets the wall.

Step 9: Refit Guttering

Once fascia and soffit are complete, refit the guttering. Fix brackets through the fascia into the rafter ends behind (not just into the UPVC). Set the correct fall towards the outlets and test with water.

Step 10: Final Inspection

Check all joints, corners and fixings from ground level. Ensure the line is straight and consistent. Verify that ventilation is unobstructed. Clean off any marks or fingerprints from the UPVC boards.

Common Mistakes to Avoid

• Over-cladding rotten timber: Covering rotten rafter ends and backing boards hides ongoing decay. Always strip back, inspect and repair before fitting new boards.
• Forgetting ventilation: Blocking eaves ventilation causes condensation in the roof space, leading to rot and mould. Always ensure adequate ventilation.
• No expansion gaps: UPVC expands significantly in heat. Without gaps at joints, boards buckle and bow. Leave 5-8mm at each joint.
• Fixing gutters to UPVC only: Gutter brackets must screw through the fascia into the timber rafter ends behind. UPVC alone will not hold the weight of full gutters.
• Poor joint alignment: Misaligned joints look unsightly and can allow water ingress. Use joint cover pieces and keep boards level.

Cost Estimate (2026 UK Prices)

Use our Soffit and Fascia Calculator for exact quantities for your project.