Part 8 - Fascia and Soffit

Fascia is a term used in architecture to describe the band under the edge of a roof that can be viewed from the outside of the property.

Usually, fascias are made from wooden boards or from a form of plastic and are used at the joint of the roof and the walls.  A horizontal fascia board is used to cap the end of rafters on the outside of a building and is often used to keep guttering in place.

The soffit is the underside of any construction element so when referring to roof construction, this can be the exposed undersurface of a section of a roof eave that overhangs on the exterior of the house.  It can also refer to the material forming a ceiling that runs from the top of the house's exterior wall to the outer edge of the roof.

Fascia and Soffit gives your eaves a professional finish and is the perfect mounting surface for a neat guttering installation.

Jobs

Fascia boards are fixed directly to the trusses of the roof and works to support the very bottom row of roofing material as well as being a place to attach the guttering.  This means they need to be strong and well fixed because they need to withstand potentially serious amounts of water in a torrential downpour in a three bed semi there could be several gallons of water pouring into the guttering every second and the fascias need to withstand this.

The bargeboard is used at the gable end of the house and can be made into an appealing feature of the property.  It is also one of the most important areas to be maintained for its visual affect after the roof has been finished.

Soffit boards are tucked under the fascia boards and are the area of the roof most commonly seen from the street.  Soffits can also be ventilated to allow airflow to the roof area, though modern techniques favour using ventilation over the top of the fascia board.  One or the other option needs to be take, however, or condensation in the roof could become a problem and lead to timber decay.

Installing Fascias

Fascias are available in a range of thicknesses and profiles to suit the style of your roof, though the recommended size is 18-25mm.  When replacing fascias, it is possible to use 10mm or less in size if there is a backing board or the fascias are being added over sound timber fascias already in place.

Soffits are available in a range of PCV-UE cellular flat boards, cellular cladding profiles or hollow boards.  Where the more robust materials are required, the first two are the prefer option of the expert.

The fixing order remains the same no matter which option you choose:

Trims soffit fascia box end bargeboard  joints and corners

Preparation

To start the preparation, remove at least one or two rows of tiles or slates at the bottom of the roof.  If you are replacing old fascias, remove the old materials or cut away any rotted or poor condition materials if you plan to leave them in place.

Next, inspect the rafter felt and make sure that it is intact and in good quality or there is sufficient present to work effectively.

The soffit

When it comes to fixing the soffit, extend a noggin from the wall or fix a batten to the wall in the spot, using the rafters as support.  Boards can be fixed directly to either the batten or the noggin and for a particularly neat finish, use a j-trim in either single or two-part form.  If you are using cladding profile or hollow soffit, it is possible to make use of short lengths from the wall of the fascia.

When it comes to the gable end there are two options; the soffit continues to the box end or it stops at an angle of 45 degrees to the corner of the wall and an H-trim is used to integrate the soffit with the box end.

Fixing fascia

The depth of the fascia will be selected so that the top edge of the fascia does not bear the weight of the tiles if 10mm or less.

1. Nail the first length of fascia into position in line with the centreline of the corner rafter, then not more than 600mm centres into the end of the rafters. When positioning, remember that when the fascia is fixed, the guttering has to follow, so ensure position of your nails is clear of where the guttering will need to be fixed.  Otherwise, screws may not go into place correctly or the brackets could move from side to side due to the projecting head of the nail.
2. Cut the fascia to length to make sure the other end coincides with the middle of the rafter, ideally just short of the rafter's centreline. Nail the fascia twice into every rafter not more than 600mm from the centre.
3. At the joins between boards, a joiner is needed. Follow the manufacturer's instructions about how to install these, though generally pre-drilling holes in the boards will be necessary.
4. If you aren't fitting bargeboards, start in the top left hand corner and fix the fascia boards along the front, joining where needed. Projecting eaves will usually have a box end on them then end caps or corner trims depending on what you have chosen will be added with nails or the recommended method.
5. If you are fitting bargeboards, box ends will need to be formed, unless you purchase ready formed ones. The cutting of the corner trim is governed by the depth of the bargeboard rather than the depth of the fascia.  For example, a 225mm deep bargeboard will need to be deeper depending on the angle being fitting to; 225mm becomes 318mm on a 45-degree angle while at 22.5 degrees 225mm becomes 242mm.

Conclusion

Remember when doing this area of roofing that you need to be safe at all times and you need a work area more than simply just a ladder.  Never go up on the roof in rain or bad weather or when you are by yourself and make sure you only go up if you know that you can manage being so far off the ground.

 

Reference URLs

http://en.wikipedia.org/wiki/Fascia_(architecture)

http://en.wikipedia.org/wiki/Soffit

http://fasciasandgutters.co.uk/ocart/Fascia_Installation_Guide