How to join fascia boards and fit corners

How do I join two fascia boards along a run?

Butt the two board ends together over a joint trim. The trim hides the gap. Fascia boards are 5m long, so any elevation longer than that needs at least one joint, and the board ends either side of it must each be fixed to timber.

Plan the joints before you cut anything. Mark where each board starts and ends along the elevation, and make sure every end lands where you can fix it, 25mm in from the end, as the guide to fitting uPVC fascia boards sets out. Leave about 5mm in each joint.

Which joint or corner trim fits which board?

The trims are chosen by board width and colour. The 300mm trims are for boards up to 300mm wide, and the 600mm double-ended trims for boards wider than 300mm. The same trims serve cover boards and replacement boards, so the choice is the same for 8mm or 16mm thickness.

Trim	Listed for	Colours
Fascia Board Joint 300mm	Boards up to 300mm wide	White, smooth black, anthracite, rosewood
Double Ended Joint 600mm	Boards over 300mm wide; cut in half for two joints on boards up to 300mm	White
External Corner 300mm	Boards up to 300mm wide	White, smooth black, anthracite, rosewood
External 135 degree Corner	Boards up to 300mm wide, for splayed corners	White
Internal Corner 300mm	Boards up to 300mm wide	White, smooth black, anthracite, rosewood
Double Ended Corner 600mm	Boards over 300mm wide; covers two board corners	White
Decorative Finial	Apex joint	White, smooth black, anthracite, rosewood

Each trim can be cut to adjust its length. The 600mm trims and the 135 degree corner come in white, so check the colour before you commit to a coloured 405mm board.

How do I fit an external corner?

An external corner is where the fascia turns round a projecting corner of the roof, such as the corner of an extension or a bay. Fit the external corner trim over the turn and run a board into each side of it.

Dry-fit the corner first, then cut the boards to it. Cut the boards to the trim, because the trim hides a clean, square end. Keep each board end back far enough to leave the 5mm gap, and fix each board 25mm in from its end.

For a splayed bay, where the roof turns through a shallower angle than a square corner, use the 135 degree external corner instead. It comes in white.

How do I fit an internal corner?

An internal corner is where two elevations meet and the roof turns inwards, as it does at the junction of an extension and the main house. Fit the internal corner trim into the angle and run a board into each side, dry-fitting before you cut, as with an external corner.

Internal corners on old houses need care, because the angle between the two walls varies. Check the angle with the old fascia still on, and measure both boards to the real corner. Where a fascia ends against brickwork, a rigid angle trim can tidy the abutment.

Where does the finial go?

The decorative finial finishes the apex joint, the point of a gable fascia where the two sloping boards meet at the top. Cut the two boards to meet at the apex, fit the finial over the joint, and fix the boards either side as normal. It comes in the same four colours as the 300mm trims.

How do I join soffit boards?

Hollow soffit has its own sections. The starting section is listed as 10mm x 5m and fixes to the wall, holding the inner edge of the board and keeping nails off its face. The joiner section, made for the 10mm board and sold in 5m lengths, takes two board ends and hides the joint. Both come in white, smooth brown, smooth black, anthracite and rosewood, so they can match the hollow soffit board.

Plan flat and vented soffit runs so every board end meets over timber you can fix to, and ring us to talk through the detail if the run is unusual. The guide to fitting soffit boards and vents covers gaps, cutting and ventilation.

What fixings hold the trims on?

Use colour-head stainless steel nails and pins, in white, black, brown or anthracite to match the board. Pins of 40mm and 30mm suit trims and soffit sections. Nails of 50mm go through a cover board into sound timber, and 65mm through a replacement board into the rafter end. Stop driving when the head touches the face. See fixings and tools.

What should I count before I order?

• The length of every elevation, so you know how many 5m boards you need.
• One joint trim for each place two boards meet. A run of 12m takes three boards and two joints.
• Every external corner, internal corner and apex, counted separately.
• The colour of each trim, remembering the 600mm trims come in white if you want colour on a 405mm board.
• Pins and nails in the right length and colour.
• Extra board, 5 to 10 per cent, for offcuts and cutting allowance.

Ring us on 0151 525 4488 with your measurements and board width, and we will check the trims with you.

How do I get the boards and trims?

Collect free from the showroom at Unit 7 The Boxworks, Heysham Road, Liverpool L30 6UR. We are open Monday to Friday 7:30am to 4:30pm and Saturday 7:30am to 1pm, to trade and public. Delivery is priced by postcode and shown on each product page and at checkout. Boards are 5m long, so check delivery to your postcode before you order.