A Guide to Types, Cost & How Long It Lasts
Quick answer: Damp proofing material is any substance used to create a barrier against moisture in a building. The four main types are polyethylene membranes (laid under floors), physical DPC strips (slate, PVC or bitumen built into walls), liquid-applied membranes and silicone injection creams, and cementitious tanking slurries for below-ground areas. A correctly installed membrane under a floor can last the lifetime of the building; a professionally injected chemical DPC is typically guaranteed for 20 years.
What is damp proofing material?
Damp proofing material is any product designed to stop moisture moving through a building’s floors, walls, or below-ground structures. It works by creating a physical or chemical barrier that water cannot pass through — whether that’s groundwater rising up through brickwork, rain penetrating an external wall, or water pressure pushing against a basement wall.
There’s no single “damp proofing material” because UK properties face several different moisture problems, and each one calls for a different solution. A Victorian terrace with a failed damp proof course needs a different material to a new-build floor slab, and a basement conversion needs something different again. Getting this match right — material to problem — is the single biggest factor in whether a damp proofing job lasts five years or fifty.
What can be used as a damp proofing material?
In UK construction and remedial damp treatment, four categories of material cover almost every situation a surveyor will encounter:
| Material type | Typical use | Where it’s used |
|---|---|---|
| Polythene DPM sheet | Blocks rising moisture under solid concrete floors | New floor slabs, extensions, garages |
| Physical DPC strip (slate, PVC, bituminous felt) | Stops moisture travelling up through masonry | Built into a mortar joint near ground level |
| Liquid-applied membrane / bituminous coating | Brush or roll-on waterproof barrier | Solid floors, external walls, below-ground “sandwich” tanking |
| Silicone-based injection cream | Forms a chemical DPC inside existing brickwork | Rising damp treatment in older properties with no working DPC |
| Cementitious tanking slurry | Resists inward water pressure | Cellars, basements, below-ground rooms |
In practice, most rising damp jobs we carry out across London use the silicone injection cream method, because it can be introduced into existing solid brick walls without rebuilding them — something a physical DPC strip would require. Basement and cellar conversions, by contrast, almost always need a cementitious slurry system because the wall is resisting standing water pressure rather than slow capillary rise.
The most common reason a damp proofing material “fails” isn’t a faulty product — it’s the wrong material being used for the wrong type of damp. A chemical DPC injection cream will do nothing for penetrating damp coming through a cracked render. A correct diagnosis from a qualified damp survey always comes before choosing a material.
What is damp proofing made of?
Each damp proofing material category is built from a specific base substance, chosen for how it performs under particular conditions:
Polyethylene (plastic)
Standard damp proof membranes are made from heavy-duty polyethylene — usually 1200 gauge (around 300 microns thick) for UK ground-bearing floors. It’s chosen because it’s completely impermeable to water, flexible enough to lap and seal at joints, and inert, meaning it won’t degrade chemically once it’s sealed beneath a concrete slab.
Bitumen and bituminous emulsion
Bituminous felt has been used in physical damp proof courses since the early 20th century, and rubber-enriched, solvent-free bitumen emulsions are still widely used today as liquid DPMs. Bitumen is naturally waterproof and adheres well to masonry, which is why it remains common for “sandwich” damp-proofing on solid floors and below-ground external walls.
Silicone and siloxane compounds
Modern injectable damp proofing creams are silicone-based. When injected into a mortar bed using a cartridge gun, the cream penetrates the brickwork and cures to form a water-repellent chemical barrier — effectively recreating the function of a physical DPC without disturbing the wall structure.
Cement-based polymer slurries
Cementitious tanking slurries are made from cement modified with polymer additives, which improve flexibility and adhesion compared to plain cement. They’re painted onto interior walls in high-pressure areas like cellars and basements, where they need to resist water pushing inward rather than simply sitting on top of a surface.
How long does a damp proof membrane last?
Lifespan depends heavily on the type of membrane and how it’s installed, not just the product itself:
| Material | Typical lifespan | Notes |
|---|---|---|
| Polythene DPM (under floor slab) | 50+ years / lifetime of building | Protected from UV, wear and physical damage once covered |
| Physical DPC (slate, PVC, bitumen felt) | 50+ years if undamaged | Failure is usually due to bridging or ground level rising above it, not material decay |
| Liquid-applied / bituminous membrane | 15–25 years | Can be affected by movement cracking or poor surface prep |
| Silicone injection cream (chemical DPC) | 20–30 years | Professionally installed systems typically carry a 20-year guarantee |
| Cementitious tanking slurry | 20–30 years | Performance depends on correct surface preparation and number of coats |
The figure that matters most for homeowners is the guarantee, not the theoretical material lifespan. A PCA-backed chemical DPC installation from a professional installer is typically guaranteed for 20 years and is usually transferable to a new owner if you sell — which is exactly why we issue a 20-year guarantee on our rising damp treatments. A DIY product bought off a shelf will not come with this kind of backed assurance, which matters at the point of sale.
It’s rarely the material itself breaking down. The most common causes of early failure are: a damp proof course being bridged by raised external ground levels or a patio, gaps left at membrane joints during installation, and physical damage from later building work (drilling, re-flooring) that punctures the barrier without anyone noticing.
Common DPM products in the UK — what the names actually mean
If you’ve been searching for specific products like a heavy-duty damp proof membrane, a DPM kit, or membrane rolls from a merchant such as Travis Perkins, it helps to know what you’re actually comparing. Most retail DPM products fall into the same polyethylene category described above — the differences between brands are mainly in gauge thickness, roll width, and whether the product is sold as a standalone sheet or as a kit bundled with jointing tape and primer.
For internal wall treatment specifically, retail DPM rolls and “DPM kits” are designed for surface damp-proofing before plastering or tanking a small area — they are not a substitute for diagnosing or treating rising damp at the wall’s source. A membrane applied over a wall that’s still actively drawing up groundwater will trap moisture behind it, often making the problem worse over time rather than better.
As a general buying principle: for a new floor slab or extension, any polyethylene DPM meeting the current British Standard gauge requirement will perform the same regardless of brand, provided it’s installed with properly sealed and lapped joints. For an existing wall showing signs of rising or penetrating damp, the right starting point isn’t a product at all — it’s a survey to confirm what you’re actually dealing with.
Choosing the right material for the job
- New floor slab or extension: Polyethylene DPM, lapped at least 150mm with the wall’s DPC.
- Existing wall with no working DPC (rising damp): Silicone-based chemical injection cream.
- External wall letting in rain (penetrating damp): Identify and repair the external defect first; a liquid membrane or repointing may follow.
- Cellar or basement conversion: Cementitious tanking slurry, specified to BS 8102.
- Solid floor below ground level: Bituminous “sandwich” membrane between screed layers.
DIY damp proofing material vs professional installation
DIY damp proof creams and DPM rolls are available from builders’ merchants and are genuinely suitable for low-risk jobs such as a shed base or garden room floor. For an occupied home, particularly where rising or penetrating damp is suspected, the material is rarely the limiting factor — correct diagnosis, drill spacing and depth for injection, and proper lapping for membranes are what determine whether the job lasts. DIY work also won’t carry a transferable guarantee, which most mortgage lenders and buyers expect to see if a property has any damp history.
Not sure which material your property actually needs?
A CSRT-qualified survey identifies the real cause of your damp before any material is chosen — so you only pay for the treatment that will actually work.
Frequently asked questions
What can be used as a damp proofing material?
Polyethylene damp proof membranes, physical DPC strips (slate, PVC or bituminous felt), liquid-applied bituminous or polymer membranes, silicone-based injection creams, and cementitious tanking slurries — the right one depends on whether you’re dealing with rising damp, penetrating damp, or below-ground water pressure.
How long does a damp proof membrane last?
A correctly installed polythene DPM under a floor can last the lifetime of the building, often 50+ years, since it’s protected beneath concrete. Liquid membranes and chemical DPC injections typically carry a 10–20 year guarantee, with professionally installed chemical DPCs commonly guaranteed for 20 years.
What is damp proofing made of?
Heavy-duty polyethylene plastic, bitumen or bituminous emulsion, silicone/siloxane compounds, or cement-based polymer-modified slurries — each chosen for how it resists water in a specific setting, whether under a floor, inside a wall, or below ground.
Is a thicker damp proof membrane always better?
Not necessarily. UK Building Regulations typically require a minimum 1200 gauge (300 micron) polyethylene DPM for standard floors. A heavier gauge resists puncturing during construction, but correct overlapping, sealed joints, and a proper lap with the DPC matter more for long-term performance than thickness alone.
Can I install damp proofing material myself?
DIY creams and DPM rolls are fine for small, low-risk jobs. For an occupied home — especially where rising or penetrating damp is suspected — a DIY application without a confirmed diagnosis often misses the real cause, and won’t carry a transferable guarantee that mortgage lenders and buyers typically look for.
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