Expanding foam
Contents |
[edit] Introduction
Sealants are typically used to close openings between spaces that are too small for other materials such as concrete, timber or mortar to be used. They have a wide range of properties in terms of strength, flexibility, appearance permanence, solubility, corrosion resistance and so on.
Expanding foam filler is a common type of polyurethane filler. It can be sprayed into gaps such as those around windows and doors to stop draughts, fill gaps and dampen sound. It is designed to adhere to a variety of common building materials and can be water resistant.
[edit] Expanding foam characteristics
Foams can be divided into two different ways: type and purpose.
- Type of application: handheld dispenser or gun grade applicator.
- Purpose of application: Filling voids or securing materials through adhesion (these foams have a lower expansion rate).
Expanding foam filler is made up of materials that expand under different conditions, depending on its composition. One type of expanding polyurethane foam requires moisture in order to expand, which can make it sticky during the installation process. Another begins to expand when two different chemicals are mixed together. Dampening the surface that will be treated can help the foam set more quickly.
There are several differences between types of foam which should be clearly marked on the containers:
- Indoor or outdoor use.
- Sandable or paintable.
- Presence of HCFCs or CFCs (no longer permitted).
- Gun grade or handheld.
[edit] Possible dangers of expanding foam
It’s important to proceed with caution with the application process, since the chemicals can be toxic if they are not used properly. However, the substance should be safe once it has fully expanded and dried.
Basic foams can be flammable and may create toxic smoke if they are exposed to fire. There are some foams that can resist fire for a certain time when directly exposed to flames.
Cured foam should be protected from daylight or other light since this can degrade the effectiveness of the product over time. Dried foam can be painted, or otherwise covered, to protect it from light.
Expanding foam should be used relatively quickly once a can or gun is started, since the chemicals may not retain their effectiveness over time. It can also be difficult to remove or clean foam. There is a special type of chemical that can be used to clean wet foam, and in some instances, acetone can be used.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
The 5 elements of seiri, seiton, seiso, seiketsu and shitsuke.
Shading for housing, a design guide
A look back at embedding a new culture of shading.
The Architectural Technology Awards
The AT Awards 2025 are open for entries!
ECA Blueprint for Electrification
The 'mosaic of interconnected challenges' and how to deliver the UK’s Transition to Clean Power.
Grenfell Tower Principal Contractor Award notice
Tower repair and maintenance contractor announced as demolition contractor.
Passivhaus social homes benefit from heat pump service
Sixteen new homes designed and built to achieve Passivhaus constructed in Dumfries & Galloway.
CABE Publishes Results of 2025 Building Control Survey
Concern over lack of understanding of how roles have changed since the introduction of the BSA 2022.
British Architectural Sculpture 1851-1951
A rich heritage of decorative and figurative sculpture. Book review.
A programme to tackle the lack of diversity.
Independent Building Control review panel
Five members of the newly established, Grenfell Tower Inquiry recommended, panel appointed.
Welsh Recharging Electrical Skills Charter progresses
ECA progressing on the ‘asks’ of the Recharging Electrical Skills Charter at the Senedd in Wales.
A brief history from 1890s to 2020s.
CIOB and CORBON combine forces
To elevate professional standards in Nigeria’s construction industry.
Amendment to the GB Energy Bill welcomed by ECA
Move prevents nationally-owned energy company from investing in solar panels produced by modern slavery.
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Experimental AI housing target help for councils
Experimental AI could help councils meet housing targets by digitising records.
BSRIA Occupant Wellbeing survey BOW
Occupant satisfaction and wellbeing tool inc. physical environment, indoor facilities, functionality and accessibility.