Concrete condition
Identify cracks, loose material, contamination, water ingress and reinforcement defects. Necessary repairs belong ahead of insulation; foam should not conceal a structural concern.
Commercial spray foam experts · Duratite Group
Concrete Slab Underside Spray Foam Insulation
Insulation to suitable concrete slab undersides above unheated spaces, with slab edges, services and protective finishes included in the design.
Discuss your project →A specification built around your application
This service concerns the underside of an existing or proposed concrete slab. It is a different construction from insulation laid below a ground-bearing slab before concrete is poured. Define which side of the slab is accessible and what occupies the spaces above and below.
The target thermal performance needs to consider the slab, adjoining walls, supports and edges. Sprayed foam can follow a suitable prepared surface, but the design must address junctions and any required exposed-surface finish rather than treat thickness as the whole specification.
What shapes the insulation specification
Thermal continuity
Provide details of columns, downstands, perimeter walls and changes in level. The designer can then assess thermal bridges and the treatment needed at interfaces.
Use of the space below
A public car park, service undercroft and enclosed void have different exposure and access conditions. Agree protective finishes, impact risks, headroom and inspection requirements.
Relevant project experience
Duratite project library
Pondswick substation, Luton
This accessible concrete-soffit project shows how the underside of a slab was insulated and finished. Read the documented substrate, system and installation sequence; timber floors and concealed ceiling voids require a different assessment.
Read the project case study →From project brief to installation
Share the brief
Send photographs, dimensions, site location and the intended use. Include known defects and the outcome you need, such as reducing heat loss or addressing cold-surface condensation.
Assess the construction
The survey establishes the accessible substrate, preparation, moisture conditions and practical installation scope. Drawings and existing records help resolve interfaces with other parts of the building or vessel.
Agree the scope and price
Compare the complete work package: preparation, insulation, protective finish, access and reinstatement. Agree responsibilities and the programme before the work begins.
Record the completed work
Arrange inspection before the insulation is concealed. Keep the agreed specification, product details and installation records with the asset’s maintenance information.
Understand commercial spray foam costs · Compare insulation approaches
Concrete Slab Underside Insulation questions
Is this the same as insulating beneath a new concrete floor?
No. This page addresses the slab underside. A ground-bearing floor construction has its own load, moisture and installation requirements and needs a separate design.
Can insulation hide damaged or wet concrete?
The cause and condition must be assessed first. Concrete repairs, water ingress and structural issues are not resolved simply by applying insulation.
What affects the cost of concrete slab underside insulation?
The treated area, substrate condition, specified thickness, preparation, access equipment and finish all influence the price. Include the work programme and any removal or reinstatement in the enquiry so quotations cover the same scope.
What should be agreed before installation?
Confirm the product and application, prepared substrate, intended thickness, junction details, protective finish and access arrangements. Ask for the relevant product information, installation records and the specific terms of any proposed warranty.
Free survey
Get a quote for your project
Send us your building details and our technical team will specify the right system and a clear budget. No obligation.
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