Soffit
In its broadest sense, the term ‘soffit’ can be used to refer to the underside of any construction element, such as an arch, architrave, or projecting cornice. However, most commonly it refers to the underside of the eaves, that is, the underside of the part of the roof that projects beyond the external wall of a building.
Typically soffit boards will be fixed to the underside of projecting rafters to form the soffit, whilst fascia boards are fixed along the vertical faces of the rafters forming a fascia. In combination, these elements help to ‘seal’ the roof at its edges. However, they may include small openings to allow ventilation of the roof void, helping prevent the accumulation of moisture which could result in condensation and cause the roof to decay.
Soffits are traditionally constructed from timber, however, a wide range of other materials may also be used, including metal cladding, UPVC, vinyl and composite materials.
Inside buildings, the term soffit may refer to any portion of a ceiling that is lower than the rest of the ceiling. This can be used as an accent in rooms for decorative reasons, or in rooms with high ceilings to make the room feel smaller. They can also be required to conceal structural beams, plumbing elements, heating/cooling ducts or light fixtures.
In classical architecture, the soffit can be decorated with ‘tooth-like’ blocks used in a close repeating pattern, known as ‘dentils’. In the Doric order, rectangular blocks were commonly hung from the soffit of the cornice over the triglyphs, known as ‘mutules’.
[edit] Related articles on Designing Buildings Wiki
- Arches.
- Architrave.
- Barrel vault.
- Bas-relief.
- Classical orders in architecture.
- Corbel.
- Cornice.
- Cornice coving and architrave definitions.
- Definition of ceiling.
- Elements of classical columns.
- Entablature.
- Fascia.
- Fillet.
- Frieze.
- Integrated service module.
- Moulding.
- Pedestal.
- Pediment.
- Pilaster.
- Types of ceiling.
Featured articles and news
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.
UK Infrastructure: A 10 Year Strategy. In brief with reactions
With the National Infrastructure and Service Transformation Authority (NISTA).
Ebenezer Howard: inventor of the garden city. Book review.
The Grenfell Tower fire, eight years on
A time to pause and reflect as Dubai tower block fire reported just before anniversary.
Airtightness Topic Guide BSRIA TG 27/2025
Explaining the basics of airtightness, what it is, why it's important, when it's required and how it's carried out.
Construction contract awards hit lowest point of 2025
Plummeting for second consecutive month, intensifying concerns for housing and infrastructure goals.
Understanding Mental Health in the Built Environment 2025
Examining the state of mental health in construction, shedding light on levels of stress, anxiety and depression.
The benefits of engaging with insulation manufacturers
When considering ground floor constructions.
Lighting Industry endorses Blueprint for Electrification
The Lighting Industry Association fully supports the ECA Blueprint as a timely, urgent call to action.