BBA Approved clear polythene damp proof membrane, 1000 gauge / 250 micron. A reliable groundwork staple for moisture exclusion under concrete floors and as temporary site protection sheeting. 4m wide x 25m roll.
This clear polythene DPM 1000 gauge is exactly what it says on the tin, or rather on the roll. A 250 micron, BBA Approved damp proof membrane supplied in a 4m x 25m sheet, giving you 100 square metres of moisture protection per roll. Whether you are laying a new concrete slab, preparing a sub-floor for screed, or wrapping materials on site, this is the product most groundworkers reach for without a second thought.
The BBA Approval matters here. The British Board of Agrément tests polythene membranes against real-world conditions, so when a building inspector or warranty assessor asks what DPM you used, you have a straight answer. Not every polythene sheet on the market carries that certification, and it can make a difference at sign-off.
Where Clear Polythene DPM 1000 Gauge Earns Its Keep
At 1000 gauge, this membrane sits in the sweet spot for most standard floor applications. It is thick enough to resist puncture from aggregate or rough blinding concrete underneath, but manageable enough to fold and position without a fight. The clear finish makes it easy to see where it has been laid, spot any tears before you pour, and check laps are correctly overlapped without lifting the sheet.
In practice, this membrane gets used under ground-bearing concrete slabs in new builds, beneath floor screeds in extensions and conversions, and as a vapour check layer in suspended timber floor situations. It is also widely pressed into service as temporary protection sheeting during groundworks, covering stored materials, protecting freshly laid concrete from rain, or sheeting over openings on site during bad weather.
A Note on Coverage and Laps
The 4m width is particularly useful. Many domestic floor plans can be covered in one or two sheets without a central join, which is always preferable. Where laps are unavoidable, Building Regulations guidance recommends a minimum 150mm overlap, taped for integrity. Factor that into your coverage calculations before you start cutting.
A clean, dependable product that does what groundwork demands of it. Available at trade pricing with next day delivery on stocked rolls.
Pro Tip: Always unroll the DPM before you pour and walk the sheet to check for small tears or punctures caused by rough blinding material underneath, a missed hole under 100 tonnes of concrete is a problem nobody wants to find five years later.
Used primarily under ground-bearing concrete floor slabs and sand-cement screeds to prevent ground moisture rising into the structure. Common on new builds, house extensions, garage conversions, and basement floor preparations. Also used as a vapour check layer beneath suspended timber floors and floating floor systems where moisture from below is a concern.
On site it doubles as a general-purpose protection sheet for covering stored materials, protecting fresh pours from rain, and sheeting over openings. The clear polythene lets you see through it, which is genuinely useful when you need to check the work below without pulling the sheet back.
Best For
Ground-bearing concrete slab installations
Under floor screed moisture exclusion
Suspended timber floor vapour checks
Temporary site protection sheeting
Garage and extension floor construction
Key Properties
BBA Approved for damp proofing applications
1000 gauge / 250 micron thickness
Clear polythene for easy inspection
4m x 25m per roll (100m² coverage)
Resistant to ground moisture and vapour
Compatible With
Sand-cement screed systems
Ground-bearing concrete slabs
Insulated floor build-ups
Floating floor installations
Underfloor heating substrate layers
Not suitable for: Not suitable as a replacement for tanking or structural waterproofing in basements or areas subject to hydrostatic water pressure. For those situations a specialist tanking membrane or cavity drain system is required.
Prepare the sub-base first. Any sharp projections, large aggregate, or rough concrete blinding should be levelled off before laying the membrane. A sharp stone that would not bother a boot will go straight through polythene under the weight of wet concrete.
Roll the membrane out across the floor area, lapping up the walls by at least 150mm on all sides and taping joints with a compatible polythene tape where sheets meet. Overlaps between sheets should be a minimum of 150mm and taped for a continuous moisture barrier. Take care when walking on the laid sheet before pouring, particularly on rough surfaces.
Prepare and level the sub-base, removing any sharp stones or projections that could puncture the membrane
Roll out the clear polythene DPM across the floor area, starting from one end and working to the other
Lap the membrane up all surrounding walls by a minimum of 150mm
Where two sheets meet, overlap by at least 150mm and seal the join with a compatible polythene jointing tape
Walk the sheet carefully before pouring to check for tears, particularly over rough blinding
Pour concrete or screed directly over the membrane once you are satisfied it is undamaged and correctly lapped
Is this DPM suitable for use under underfloor heating systems?
Yes, in most cases. The membrane is laid as part of the floor build-up beneath the screed or concrete layer, which is where underfloor heating pipes or cables typically sit. Check your UFH system manufacturer's guidance on the full floor construction, but a BBA Approved 1000 gauge DPM is a standard part of most insulated floor systems.
What is the difference between 1000 gauge and 1200 gauge DPM?
Gauge refers to thickness. 1000 gauge is 250 micron, which meets the requirements for most standard ground-bearing floor applications under Building Regulations. 1200 gauge (300 micron) is a heavier option sometimes specified where the sub-base is particularly rough or where additional puncture resistance is needed. For typical domestic and light commercial floors, 1000 gauge is the standard choice.
Manufactured from low-density polyethylene (LDPE), this membrane provides a continuous physical barrier against ground moisture and water vapour. At 250 micron (1000 gauge) it meets the minimum thickness requirement for damp proof membranes under BS 8102 and complies with relevant sections of Approved Document C. BBA Certification confirms independent testing for vapour resistance and durability in below-slab conditions.
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