The short answer
A soffit is the panel that shuts off the underside of the roof overhang, between the wall and the fascia. It keeps weather, birds and insects out of the eaves, and it often carries a vent so air can flow into the roof space. Soffits are made of timber, uPVC and other boards, and older external ones can contain asbestos insulating board.
Where soffits sit and what they do
The eaves are the lower edge of a pitched roof, where it overhangs the wall. Looking up from the garden, you see the soffit, the panel that spans the underside of the overhang. It spans from the wall to the fascia, the front-edge board that carries the gutter.
Its first job is protection. Without a soffit, the space between the wall and the rafter ends would be open, and birds, wasps, squirrels and rain could enter the roof void. The board shuts that gap and keeps the rafter ends and the wall top dry.
Its second job is appearance. A soffit gives the eaves a finished, tidy line, and with a matching fascia it forms the roofline that frames the house.
Its third job, in many roofs, is ventilation. A vent built into the soffit lets outside air flow into the roof space, where it carries away moisture. BS 5250:2021 is the current code of practice on managing moisture in buildings.
Soffits are part of a set. The fascia fixes to the rafter ends and carries the gutter, the soffit closes the underside, and on gable ends the bargeboard finishes the sloping edge. Our page on rotten fascia boards covers the neighbouring board, and the two are often replaced together.
Ventilation at the eaves
Roof spaces need airflow. Household steam rises into the loft, and if it cannot escape it condenses on cold surfaces, wetting timber and insulation. Air drawn in at the eaves and let out elsewhere carries that moisture off.
The soffit is the usual entry point. Marley's advice, drawing on BS 5250, is a 25 mm ventilation gap at the eaves for pitches up to 15 degrees for a cold roof laid with HR underlay, and 10 mm on steeper pitches. Where breathable LR underlay and a tightly sealed ceiling are used, normal eaves construction may do, if the product's certificate allows.
The vent can be a continuous strip, a row of round or rectangular grilles set in the board, or a gap left behind the fascia, and it should carry a mesh that stops birds and insects. It has to stay open: quilting jammed into the eaves chokes the airflow, and a ventilation tray keeps a channel clear above it.
A soffit with no vent on a roof that needs one, or a vent that has been blocked by paint, debris or insulation, is a common cause of damp and condensation in the loft.
Not every roof wants eaves vents, because a warm roof with a sealed, insulated build-up is designed differently. The construction decides, and a roofer checks before fitting or removing vents.
Materials and an asbestos check
Soffits have been made from several materials. Timber boards, usually softwood, are traditional and are painted. Plywood and other sheet materials have been used. uPVC is the common modern choice, in flat boards or as hollow sections with vents, needing no paint. Aluminium and fibre-cement boards also appear.
Age and material matter, because some older soffits contain asbestos. HSE guidance names external soffits as a location for asbestos insulating board, and concedes that it cannot be told apart from lookalikes by eye. For any building dating from before 2000, the HSE's advice is to presume asbestos is there.
The rule that follows is simple: do not drill, cut, break or scrub an old soffit until it has been checked. Longer-duration work on this board is licensable, which means a specialist contractor, and any waste travels double-wrapped and labelled as hazardous waste.
Older boards get no risks from us. Where a house of that age has soffits of unknown type, we advise testing a sample before any work that would disturb them, and the plan follows the result.
New uPVC soffits fitted over old boards can hide what lies beneath, which makes the age of the house a useful guide even when the visible boards look modern.
Problems, repair and what we do
Common faults are rot in timber, sagging or split boards, peeling paint, gaps at joints that let birds and wasps in, blocked vents and staining from a leaking gutter above. Sagging often means a fixing has failed or the board behind is wet.
Repairs range from re-fixing a loose board or replacing a short section to renewing the whole run. Where a gap has let birds in, closing it needs care if a nest is active, and our page on birds nesting in soffits explains the rules.
Our survey checks the boards from the ground and from access, check the vents, probe timber for softness and photograph faults. We ask the age of the house, note any signs of asbestos boards and advise accordingly.
Soffits are usually renewed with the fascias and gutters, since they share access and age at the same rate. Doing them together saves on scaffold, and gives a uniform roofline, with proper vents fitted where the roof needs them.
For capping fascias and soffits, MyJobQuote's figure is around £800 on a three-bedroom semi (MyJobQuote, Sep 2026). Our price follows a survey, as one written total.
The gutters, soffits and fascias hub covers the whole roofline.
