NBS Source
List your products

PROMATECT®-L500 is a non-combustible low density calcium silicate board, used for the construction of fire resistant ducts.

It is a Class 0 product as defined in the Building Regulations.

ROMATECT®-L500 is off-white in colour and has a smooth sanded surface on one face with a lightly honeycombed texture on the reverse face.

PROMATECT®-L500 is resistant to the effects of moisture and will not physically deteriorate when used in damp or humid conditions. Performance characteristics are not degraded by age or moisture. Untreated surfaces will absorb water which can cause some loss of strength, but full strength is regained after drying. It will not encourage mould growth and is resistant to attack by insect or vermin.

General information

As drawing ___

Uniclass 2015
Pr_25_71_52_23 Fibre-reinforced calcium silicate boardsPrimary
Specification data - Fibre-reinforced calcium silicate boards
Product Reference



As drawing ___

Accessories -
Duct stiffeners: Minimum stiffener thickness 40 mm for both methods

Method 1: Single row/ Double row of 250 mm wide vertical soldiers of PROMATECT® - L500, at maximum 600 mm centres, running down the inside of the duct, and screwed to the top and bottom boards

Method 2: Subdivide duct with a single row/ two rows of solid PROMATECT® - L500 board, with circular holes cut of a size and quantity to ensure equal crossflow of air between the two halves of the duct


50 mm x 100 kg/m³ mineral wool. For 240 minutes fire protection only

Standard product features

Maximum classification:

  • DW144: High pressure, Class C.

Product Options


  • Where boards are used for fire performance select thickness based on required duty.

Similar products from Promat UK