Question 1

What is the difference between P2 and P5 chipboard?

Accepted Answer

P2 chipboard is general-purpose for dry conditions only (kitchens and bathrooms excluded). P5 chipboard is moisture-resistant, with a green-dyed core to identify it. P5 is required for floor decking in domestic construction per BS EN 312 and is the standard for all structural flooring applications. P5 can withstand intermittent wetting during construction.

Question 2

What thickness MDF do I need?

Accepted Answer

Common MDF thicknesses: 3 mm for backing panels and templates, 6 mm for panel inserts, 9 mm for wall panelling, 12 mm for shelving and light doors, 15 mm for cabinet doors and panels, 18 mm for worktops, cabinets and heavy shelving, 25 mm for acoustic panels and heavy-duty surfaces. MDF is available up to 30 mm for specialist applications.

Question 3

Is moisture-resistant MDF waterproof?

Accepted Answer

No. Moisture-resistant (MR) MDF has added wax and resin to resist swelling from humidity, but it is not waterproof. It is suitable for kitchens and bathrooms where it may be exposed to occasional moisture but must be painted or sealed. For wet areas, use marine plywood or cement board instead. MR MDF is typically identified by its green-dyed core.

Question 4

What are standard sheet sizes in the UK?

Accepted Answer

The most common UK sheet size is 2440 x 1220 mm (8 x 4 ft). Larger sheets are available at 3050 x 1220 mm (10 x 4 ft) and 3050 x 1525 mm (10 x 5 ft). Chipboard flooring panels are typically 2400 x 600 mm with tongue-and-groove edges for easy installation at 400 mm or 600 mm joist centres.

Sheet Size (mm)	Imperial	Thicknesses Available (mm)
2440 x 1220	8' x 4'	3, 6, 9, 12, 15, 18, 22, 25
3050 x 1220	10' x 4'	6, 9, 12, 15, 18, 25
3050 x 1525	10' x 5'	12, 15, 18, 25

Type	Density (kg/m³)	Identifier	Typical Use
Standard MDF	680–750	Natural brown core	Furniture, shelving, mouldings
Moisture Resistant (MR)	680–750	Green core	Kitchen units, bathroom cabinets
Fire Retardant (FR)	680–800	Red/pink core	Commercial interiors, escape routes
Ultralight MDF	500–600	Lighter weight, pale core	Mouldings, decorative panels
HDF (High Density)	800–1000	Very dense, dark core	Laminate flooring substrate

Grade	Type	Conditions	Typical Use
P1	General purpose	Dry	Packaging, temporary
P2	Interior fitments	Dry	Furniture, shelving, partitions
P3	Non-structural	Humid	Kitchen/bathroom furniture
P4	Structural	Dry	Structural flooring (dry only)
P5	Structural, moisture resistant	Humid	Floor decking (standard domestic)
P7	Heavy-duty structural	Humid	Heavy-load flooring

UK MDF & Chipboard Sizes & Grades

Standard MDF Sheet Sizes

MDF Types

Chipboard Grades (BS EN 312)

Chipboard Flooring Panels

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