Firring
A firring is a thin strip of timber (or ‘batten’) that has been cut along its length diagonally so that it tapers, with one end deeper than the other. Firrings are used in the construction of flat roofs to create a fall, ensuring that water runs to the lower side. Typically they are designed to a fall of 1:40, which given on-site inaccuracies should result in a minimum fall of 1:80 in the finished construction.
Firrings are sometimes referred to as furring strips or furrings, when applied more generally raise building elements, such as in roof structures. In the US these might be referred to as strapping.
They are manufactured by cutting at an angle along the length of a timber batten. As this requires specialist cutting equipment, firrings are often manufactured off site. Commonly available sizes have a maximum cross section of 47mm x 50mm, 47mm x 75mm and 47 x 100mm
Firrings are cut in pairs, with the pieces on both sides of the cut line being used so as to minimise waste. They can be cut in identical pairs or folding pairs. Identical pairs are the same when cut, whereas a folding pair are cut to form a continuous fall when placed end to end.
NB: The term metal furring system or MF System refers to a technique for creating a seamless plaster internal finish with a void behind for the installation of services. Plasterboard is fixed directly to the concealed metal furrings. This can be used as an alternative to traditional timber batten construction for walls and ceilings.
For more information, see Metal furring system.
[edit] Related articles on Designing Buildings
Featured articles and news
RTPI leader to become new CIOB Chief Executive Officer
Dr Victoria Hills MRTPI, FICE to take over after Caroline Gumble’s departure.
Social and affordable housing, a long term plan for delivery
The “Delivering a Decade of Renewal for Social and Affordable Housing” strategy sets out future path.
A change to adoptive architecture
Effects of global weather warming on architectural detailing, material choice and human interaction.
The proposed publicly owned and backed subsidiary of Homes England, to facilitate new homes.
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
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).