Fascia and Soffit - Keeping everything neat and tidy

Often referred to as the ‘roofline’, the fascia is the point where the roof meets the outer walls of the house. In the past the roofline has typically been made up of wooden board or sheet metal, but in recent years there has been an increase in the use of plastic fascias as they require much less maintenance.

The fascia provides a good aesthetic finish to the roofline; it acts as an extra barrier against weather conditions, and is used to support guttering. Although many people refer to the roofline as the ‘fascia’, it is actually made up of a number of different components:

fascia and soffit parts labeled diagram


The fascia board is the long, straight board that runs along the lower edge of the roof. It is fixed directly to the roof trusses and usually supports the bottom row of tiles and carries the guttering.


The bargeboard is the board that is fitted to the gable end of the house. The bargeboard makes a big contribution to the aesthetics of a property, and a variety of different shapes and styles can be used to create a striking finish.


The soffit board is the length of board that is tucked away underneath the fascia. This is the piece of board that is most visible from street level, looking up. The soffit can be ventilated to allow air flow into the roof area, although it is becoming more common to add ventilation to the top of the fascia board. Either way, ventilation is essential to prevent condensation in the roof which could lead to timber decay.

Box end

The box end is the piece which connects the fascia, soffit, and bargeboard at the gable end of a house. It must take into account the various angles from each of the connecting boards to create a clean finish to each corner.



  • If you are replacing the fascia boards on an existing property you should start by removing the bottom two rows of tiles.
  • Then remove old fascias, soffits and bargeboards to prevent any moisture that remains from rotting the supporting timber. If any parts of the original boards are left in place, ensure that any rotten timber is cut out and replaced with treated timber.
  • Inspect the felt or underlay between the rafters and replace as necessary with felt or eaves protector.
  • Provide adequate support at the wall for the soffit by extending a noggin from the wall, fixing a batten to the wall, or using the rafters as support.
  • The soffit board can be fixed directly to the noggin or batten with plaspins. For a neat finish J-Trim can be used in single or two-part form to hold and give a clean finish to the inside edge of the soffit at the wall.
  • If you are using cladding profile or hollow soffit, they can be used in short lengths from the wall to the fascia.
  • The gable end can be finished with the soffit running all the way down to the box end, or terminated at an angle of 45 degrees to the corner of the wall, and a H-Trim used to integrate with the soffit forming the base of the gable box.
  • Ventilation is provided by purpose-made slotted soffit boards or by means of over fascia ventilation.

Fixing the Fascia

  • The depth of the fascia should be chosen so that the top edge of the fascia does not bear the weight of the tiles if 10mm or less in thickness.
  • Nail the first length of fascia into position, starting exactly in line with the centreline of the corner rafter, then at no more than 600mm centres into the ends of the rafters.
  • Bear in mind that once the fascia is fitted the guttering will follow, so it is important to position the nails so that they will be clear of the subsequent screw fixings. This will ensure that the screws go in without any problem, and that the brackets won’t suffer movement because of a protruding nail head behind them.
  • At the gable end, cut back the fascia leg at a 45 degree angle.
  • Cut the fascia to length to ensure that the other end meets with the centre line of a rafter.
  • Nail the fascia twice into the tail of each rafter, at no more than 600mm centres.
  • A joiner will be required at the joint between each length of fascia board. Pre-drill and twice pin it to either one of the left or right hand fascia board, ensuring that a minimum of 5mm space is left between the board ends to allow for expansion.
  • If bargeboards are not going to be used, the fascia boards can be fixed along the front of the house with joints at rafter tails as necessary. The projecting eaves usually have a small box end which is cut from a single piece of fascia board. If a separate fillet to cover the tilting fillet is required, the additional triangle can easily be integrated into the new box end. When fascia and box ends are in place, fix end caps or corner trims to both ends.
  • If bargeboards are to be used on the project, the procedure is slightly different as the box ends have to be formed as part of the process. Before cutting the corner trim, bear in mind that the height is not governed by the depth of the eaves fascia, but it is the depth of the bargeboard which is critical. A 225mm deep bargeboard, when cut vertically at the end, must be deeper as it is not being cut at right angles. If the pitch of the roof is 45 degrees, 225mm becomes 315mm, and 22.5 degrees the depth required is 242mm. A tilting fillet can add approximately 50mm extra. Remember that the leg of the fascia will support the outside edge of the soffit.

uPVC and plastic fascias, soffits, and bargeboards have become much more common over recent years as they are virtually maintenance-free. Traditional wooden fascia boards require periodic painting to retain their good look, and to protect against rot and decay.

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