Bonding coat
The bonding coat, bond coat or base coat in construction terms usually refers to the first coat of gypsum plaster which is laid on the existing surface such as stone, brick or existing plaster. The term base coat is usually used to mean the same but for lime based plaster products or clay based plaster products. Base or bond coat can also be used to describe the first layer of external render applied directly to the existing external structure of a building such as stone or brick, though this is most often referred to as a parge coat.
The bond or base coat is usually a coarse plaster or render which can be applied in thicknesses between 10-20mm, it has greater adherence qualities and is used to even out the existing surfaces of the wall, internally in the case of plaster and externally in the case of render. Once hardened one or two more layers can be applied, finished by the final coat, finish layer, sometimes called skim coat which is normally a thinner layer applied at 2-5mm thickness.
See also: plaster, lime plaster and clay plaster
[edit] Related articles on Designing Buildings
- Boss plaster.
- Caulk.
- Cement.
- Cement mortar.
- Clay plaster.
- Daub.
- Decorative metal ceilings.
- Dry lining.
- Drywall.
- Finishes.
- Fresco.
- Grout.
- Gypsum.
- Inspecting historic fibrous plaster ceilings.
- Lath and plaster.
- Lime plaster.
- Making Magnificence: architects, stuccatori and the eighteenth-century interior.
- Mortar.
- Parge coat.
- Plaster.
- Rendering.
- Stucco.
- Tanking.
- Tiles.
Featured articles and news
How can digital twins boost profitability within construction?
A brief description of a smart construction dashboard, collecting as-built data, as a s site changes forming an accurate digital twin.
Unlocking surplus public defence land and more to speed up the delivery of housing.
The Planning and Infrastructure bill oulined
With reactions from IHBC and others on its potential impacts.
Farnborough College Unveils its Half-house for Sustainable Construction Training.
Spring Statement 2025 with reactions from industry
Confirming previously announced funding, and welfare changes amid adjusted growth forecast.
Scottish Government responds to Grenfell report
As fund for unsafe cladding assessments is launched.
CLC and BSR process map for HRB approvals
One of the initial outputs of their weekly BSR meetings.
Architects Academy at an insulation manufacturing facility
Programme of technical engagement for aspiring designers.
Building Safety Levy technical consultation response
Details of the planned levy now due in 2026.
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.
Building Engineering Business Survey Q1 2025
Survey shows growth remains flat as skill shortages and volatile pricing persist.