Fire protection

All Thermalite® products provide excellent fire protection. They are classified as A1, non-combustible in accordance with BS EN 771-4.

Compliance with Building Regulations
The following requirements of the Building Regulations can therefore be easily satisfied: 

1. Means of escape 
2. Internal fire spread (surfaces): surfaces within the building should be such as to inhibit the spread of flame 
3. Internal fire spread (structure): the structure shall be designed so as to inhibit the spread of fire and retain its stability for a reasonable period 
4. External fire spread: the external surfaces of the building shall offer equate resistance to the spread of fire from one building to another

Combustibility
Thermalite® blocks are classified as non-combustible in accordance with the Building Regulations, and Class A1, non-combustible, in accordance with BS EN 771-4.

Fire resistance
Information contained in the Building Regulations and in BS 5628–3 confirms that Thermalite® may be used to achieve fire resistance grades as given in the following table. It is consistent with the information contained in BS EN 1996-1-2. All data has been adjusted to suit available block sizes.

Wall type	Fire resistance grade w (hr) for for block thickness (mm)
	1 hr	2 hr	3 hr	4 hr	6 hr
Non-loadbearing single leaf unplastered	75	75	75	100	150
Loadbearing single leaf unplastered	90	100	140	190	215
Non-load bearing cavity wall (per leaf) unplastered	75	75	75	75	90
Loadbearing cavity wall (per leaf) unplastered	90	100	140	150	150

Surface spread of flame
It is often sufficient that materials should not be readily ignitable and that their tendency to spread flame be limited.
 
The surface spread of flame tests in BS 476: Part 7 define spread of flame as ‘propagation of a flame front over the surface of a product under the influence of proposed irradiance’.

Thermalite® blocks have a Class 0 resistance to surface spread of flame as described in the Building Regulations.