Damp Proof Course (DPC)

What is a Damp Proof Course (DPC)?

A damp proof course (DPC) is a moisture-resistant layer set into a mortar joint in brickwork or blockwork to stop rising damp travelling up the wall. By creating a sealed break within the masonry, a DPC helps protect plaster and internal finishes from damp-related damage.

DPC Roll Sizes, Materials and Compatibility

DPC roll sizes: choosing the right width

Our DPC rolls are available in common widths from 100mm to 600mm, making it easy to match your wall and cavity requirements. As a rule of thumb, choose a damp proof course roll that fully covers the width of the masonry with a small allowance at the edges to help prevent moisture bridging.

Common size examples you’ll see on-site:

• 100mm DPC – often used for narrow masonry details and smaller sections

• 450mm DPC – suitable for wider masonry details where a broader DPC strip is specified.

• 600mm DPC – suited to the widest applications where full coverage is essential

Tip: If you’re between sizes, it’s usually safer to go slightly wider than to risk an exposed edge.

Standard and High Load DPC Materials

Our standard DPC rolls are made from polyethylene using high-quality reprocessed material. They are designed for wet-bedded horizontal and vertical applications in domestic masonry construction and feature an embossed surface to improve mortar adhesion.

The category also includes High Load polymeric DPC products designed for applications subject to greater compressive loads. Always check the individual product specification before selecting a DPC for load-critical details.

It is manufactured to the requirements of BS 6515, with the manufacturer's technical data also referencing EN 14909.

Compatibility: where DPC rolls work best

A DPC wall detail is only effective when it’s compatible with the way the wall is built. DPC rolls are commonly used with:

• Brickwork and blockwork (external and internal walls)

• Foundation-to-wall junctions, where moisture control is critical

• Cavity wall detailing, where coverage and continuity matter

For best results, pair the DPC roll width to the wall thickness and ensure the DPC forms a continuous line with adjacent waterproofing elements (for example at corners, returns, and junctions).

Choose the Right DPC Roll for Your Wall Thickness

Start with wall thickness, then match the DPC width

Pick a DPC roll that fully covers the wall thickness so the damp proof course forms a continuous barrier across the bed joint. If you’re between sizes, choosing slightly wider is usually safer than leaving an exposed edge.

Quick guide: typical wall builds and DPC widths

• Narrow sections / small details: 100mm DPC (4 inch DPC)

• Common blockwork walls: 150mm–225mm (depending on block size)

• Wider walls and some cavity detailing: 300mm–450mm

• Extra-wide applications: 600mm DPC

Consider site demands

For standard brickwork and blockwork, a regular damp proof course roll is often suitable. For heavier-duty conditions, choose a more robust option and follow the product spec.

Keep the barrier continuous

Ensure the damp proof course runs unbroken through corners, junctions, and returns, and lines up with adjacent moisture-control layers where needed.

Where to Use a Damp Proof Course (Typical Applications)

• At the base of external walls (brickwork or blockwork) to control rising damp from the ground

• Between foundation blocks and the first courses of brick/block to protect the wall build-up

• Under internal loadbearing walls and ground-floor partitions where moisture protection is required

• Around openings (doors and windows) to help prevent damp bridging at junctions

• As part of cavity wall detailing (e.g., forming a simple tray/drip path where a DPC roll is specified)

• At wall junctions and changes in level where continuity of the DPC line is critical

Damp Proof Course Costs: What Affects Price Per Roll

To judge damp proof course cost properly, compare rolls on a like-for-like spec and think in £/metre as well as £/roll. Key drivers:

• Coverage (width × length): price tracks total material. A wider DPC roll isn’t just “bigger” — it’s covering more of the wall/bed joint in one continuous strip.

• Grade/thickness (standard vs heavy-duty): higher grade rolls cost more because they’re designed to resist greater load and site handling without tearing or deforming.

• Performance spec (what the roll is rated to do): reinforced/high-load products carry a premium for strength and durability in demanding details.

• Buying the correct width first time: undersizing can force overlaps, patching, or rework at junctions — which costs more than stepping up one width where needed.

• Pack value: multiple rolls usually reduce the effective cost per metre, especially on longer runs (foundations, long external walls).

You may also be interested in:

• Damp Proof Membrane (DPM): Used under screed or concrete floors to form a continuous barrier that prevents ground moisture from rising into the floor build-up.

• Cavity Drain Membranes: Used for internal, below-ground waterproofing to manage water ingress by draining it to channels or a sump and pump, rather than relying on full tanking.