- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 14 Jan 2021
A frog is an indentation in a brick that can be on one or two surfaces.
It is thought that the word frog is a translation of the Dutch word 'kikker' and refers to a kicker placed in the bottom of the wooden boxes traditionally used to make clay bricks, which forced the clay material outwards when the brick was being formed.
The frog reduces the amount of material used to form the brick, makes it easier to remove from the form, and gives the completed wall better shear resistance. It may also help heat reach the centre of clay bricks in the kiln.
The frog must be filled with mortar when bricks are laid, otherwise the structural, thermal and acoustic performance of the wall will be affected. For this reason it is best practice to lay bricks with the frog facing upwards so that it is easy to fill. Where there are two frogs, the larger frog should face upwards.
 Other 'frog' meanings
 Related articles on Designing Buildings Wiki
Featured articles and news
From biometric to electrical current, chemical and more.
Changes are due to come into force on 1st October 2022.
Heed advice and insight of this report IPA tells the government.
From the Commonwealth Association of Architects.
For the Levelling Up, Housing & Communities Committee.
BSRIA's Technical Director reflects on recent weather patterns.
A national valuation to fund old-age pensions.
The world’s largest Commonwealth memorial to the missing.
Long after the end of the defects liability period.
Occupant satisfaction and wellbeing in buildings.
From the simple to the complex.
And the UK Government guidelines.
Commitment agreed to by major built environment bodies.
Electrical skills, low carbon, high-tech and the building services revolution.
Ultra-deep drilling with millimeter-wave beam technology.
Looking at the built environment from space.
BSI standards 8671, 8672 and 8673.
Bringing life to burial grounds.
From failed modernism to twenty-minute neighbourhoods.
The gates process and change control.