Fireshield is a vapour permeable walling underlay with an intumescent coated surface. Fireshield is suitable for all walling applications including those in multiple storey buildings. The intumescent coating helps protect the substrate by reducing the risk of fire taking hold and reduces the formation of droplets and smoke. It is installed and f ixed to the substrate in the same manner as standard breather membranes using mechanical fixings.
Fireshield (right) and a competing fire retardant membrane (left) are fixed to a 10mm OSB panel with staples. A butane torch is positioned approx. 10cm from the face of the membranes at a 45 degree angle. Two cameras capture the view from front and back.
Immediately after the butane torch fires, the competing membrane begins to melt and shrink away from the heat source, exposing the OSB. There is no physical change to Fireshield.
On the left side, the competing membrane retreats further from the flame and the OSB begins to burn. On the right side, the flame has caused Fireshield’s intumescent surface to react and ‘puff up’ which
The reverse-side of the OSB on the left begins to discolour and smoke as the flame penetrates the OSB under the competing membrane. Fireshield’s fire-proof surface continues to intumesce in response to the fire. No discolouration or smoke on the reverse-side of the OSB on the right is observed.
The OSB panel under the competing membrane on the left is breached by fire, and flames appear on the reverseside. Fireshield continues to puff-up. No discolouration or smoke on the reverse-side of the OSB on the right is observed.
The competing membrane exposed the OSB directly to fire from the outset and, as a result, the OSB burned completely through before the test was over. The torch over Fireshield was left on for a full 20 minutes. Even though the membrane itself did not catch fire during that time, the front-side of the OSB panel only received minor scorch marks and did not ignite.
In the design process of any building, project professionals will consult Building.
Regulations, Standards and Codes for information on fire safety and compliance. This process usually focuses on the level of life safety related to fire of occupants in and around a completed building only.
This is due to an absence of technical guidance in Building Regulations and Standards for fire safety during construction, specifically the determination of the safe fire space separation between buildings under construction and existing buildings outside the site boundary.
To address fire prevention while construction is happening, designers can consult the Construction(Design and Management) Regulations (2015) and, if it is a timber frame structure being built, extensive guidance published by the Structural Timber Association (STA). We will look at the STA’s guidance in greater detail in this document.
