• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
DIY Doctor
MENUMENU
  • DIY Doctor menu logo
  • Home
  • DIY Projects
    • All Projects
    • Brick, Block, Marsonary and Concrete
    • Damp, Condensation, Rot and Woodworm
    • Doors, Windows and Conservatories
    • Electrical
    • Fencing, Decking, Paving and Patios
    • Floors, Walls, Ceilings and Lofts
    • Garages, Sheds and Outbuildings
    • Gardening and Landscaping
    • General Building, Self Build and Renovation
    • General Repairs and Cleaning
    • Green Living and Eco DIY
    • Ground work, Foundations and Drainage
    • Heating, Central Heating and Boilers
    • Joinery and Carpentry
    • Materials, Fixings and Fixing
    • Painting, Decorating and Finishing
    • Planning Regs, Project Management and Safety
    • Plastering, Plasterboard and Rendering
    • Plumbing
    • Roofing and Gutters
    • Tiling and Tiles
    • Tools, Appliances and Access
    • DIY Tips
  • UK DIY Forums
  • DIY Videos
    • Bathroom DIY Videos
    • Building Foundation Videos
    • Building Videos
    • Carpentry and Woodworking Videos
    • Damp and Damproofing Videos
    • Decorating Videos
    • Electrical Videos
    • Fitting Blinds Videos
    • Flooring Videos
    • Gardening Videos
    • Green and Eco Friendly Videos
    • Hand and Power Tools Videos
    • Heating and Central Heating Videos
    • Kitchen Videos
    • Plastering and Drylining Videos
    • Plumbing Videos
    • Security Videos
  • Find Tradesmen
    • Find a Tradesman
    • Contract Download
    • Working with Tradesmen - Ultimate Guide
    • Home Improver Protection
    • Price Doctor
  • Tool Store
    • Tool Store
    • Bookstore
    • Tool Reviews and Product Reviews
  • Blog
    • Blog
    • DIY Competitions
  • About us
    • About DIY Doctor
    • What we do
    • Trade Shows and Exhibitions
    • Master Classes
    • Contact Us

Home > DIY How To Projects and Tutorial Guides > Insulating a Floor Slab – How to Lay Insulation Under a Concrete Floor Slab

Insulating a Floor Slab – How to Lay Insulation Under a Concrete Floor Slab

How to lay insulation under a concrete floor slab and advice on target U values, damp proof membranes and underfloor insulation boards. Get an understanding about the importance and what is involved in insulating a floor slab.

Don't want to do this job yourself? Let us help you find a tradesman local to you

TwitterFacebookPin ItBuffer
Project MenuProject Menu
  • How to Tutorial
  • Video
  • Find Tradesmen
  • Help

Insulation under ground floor slabs is a good way of meeting the increased requirements of parts L & F of the building regulations. These sections deal with, in one way or another, the values (called U values) which a home should be insulated to and the energy which is saved by implementing this insulation. This effectively means that if your home is insulated to a high level it has to work less hard to provide the energy to maintain the heat you need to live comfortably. Click through to our tool store for insulation.

One of the ways of saving this energy and keeping warmer is to allow less heat to be transmitted out of the floor and, at the same time, to allow less of the external cold in the ground to be transmitted into the house via a cold concrete floor slab.

The floor insulation can be placed under the slab or between the slab and the floor screed. There are arguments for, and against both, but if you are to use an underfloor heating method of some kind the insulation is often placed on top of the floor slab, under the screed. Take a look at our project on ground floor slabs to see the complete picture of ground floor slab construction and where to place the underslab insulation if the opinion of your architect, or your choice, is to place it below the concrete slab.

Slab insulation

Slab insulation

The target U value for a concrete ground floor slab is 0.22 and these days the insulation must be provided around the edge of the floor slab as well. This stops any thermal bridging across the walls leading to cold spots. A 50mm thick layer of proprietary floor slab insulation is usually enough to reach and maintain the target U value but this should be checked with an architect first. Insulation sheets should be laid tightly together with the joints staggered to avoid movement. The DPM (Damp Proof Membrane) is laid under the insulation on top of a soft blinding to ensure it is not punctured.

The underfloor insulation boards must be fully supported over their entire area with no voids and no projections. The silver foil covering acts as a vapour barrier or vapour control layer and also stops moisture from the freshly poured concrete slab penetrating the insulation.

Insulation under ground floor slab

Insulated under floor slab

All project content written and produced by Mike Edwards, founder of DIY Doctor and industry expert in building technology.

TwitterFacebookPin ItBuffer

Video

Back to the Top

Apologies, but we don't seem to have a video for this project yet, but we will do our best to get one up soon

Find a Reliable Local Tradesman

Back to the Top
Don't fancy doing this project yourself? We work with the industries best to ensure that we recommend only reliable and trustworthy tradesmen.
Let DIY Doctor help you find a tradesman

Find a tradesman now!


More Help

Back to the Top
Related Projects That May Help You:
  • Building Regulations Approved Document L – Conservation of Fuel and Power in New and Existing Properties and Dwellings
  • Building Regulations Approved Document F – Ventilation Within Buildings and Properties
  • Installing Underfloor Insulation and Water and Electric Underfloor Heating on Concrete and Timber Floors
  • Underfloor Heating – How to Fit and Install Electrical Underfloor Heating in Your Home
  • Solving problems with Concrete Floors and Replacing a Timber Floor with Concrete After Dry Rot
  • How to Lag Pipes – The Complete Guide to Insulating Outside Pipework and Water Pipes in Your Loft
Give us Some Feedback!
Was this page useful:
We read and respond to all feedback by email. To allow us to do so you will be added to our email list, however you can unsubscribe at any time using the links at the bottom of any of our emails. Find out more in our privacy policy. Any DIY questions should be posted to our Forum
Sign me up to the DIY Doctor Newsletter:

Primary Sidebar

DIY Doctor deal of the week

DIY Utility Kit:

Build your own work bench!

RRP Price: £49.99

Special Price: £39.95

Get it here now

See our other deals now!

Master Basic DIY - By DIY Doctor

Our Book - Master Basic DIY

Grab your copy now for all the DIY help you need right at your finger tips!

Buy it Here!

Signup for our Newsletter

Keep up to date with our DIY projects, tips and latest deals

Sign Me Up!

Our Sponsors

Find out about advertising on DIY Doctor

Advert

Other Similar Projects
  • Ventilation And Roof Condensation Requirements For Dwellings
  • Conservation Of Fuel And Power In Both Domestic And Commercial Buildings
  • How To Install Underfloor Insulation
  • How To Construct And Repair A Ground Floor Slab
  • How To Install Electrical Underfloor Heating To Help With Insulating Your Home

Footer

DIY Doctor

Site Menu

  • About Us
  • Contact Us
  • Blog
  • Media/Press
  • Community Work
  • DIY Projects
  • DIY Videos
  • Superstore
  • DIY Tips
  • DIY Suppliers
  • UK DIY Forum
  • DIY Webinars

Other Stuff

  • Advertise
  • Competitions
  • T and Cs
  • Privacy Policy
  • Cookies
  • NHIC
  • Sitemap

DIY Doctor Social Channels

Follow us on Facebook
Follow us on Twitter
Follow us on YouTube
Follow us on Pinterest
Follow us on Tumblr

DIY Doctor are members of:

© DIY Doctor Ltd 2021 All Rights Reserved