Discover the correct way to install intumescent strips and perimeter smoke seals. Find out more in our step‑by‑step guide.
Written by Esme
5th May 2024
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When Does a Door Need an Intumescent Strip?
The Building Regulations indicate where you have fire doors, these require intumescent strips. Without them, fire and smoke can quickly spread through the small gaps around the door and frame, putting building occupants at far greater risk.
A fire door needs a small gap around its perimeter to operate properly and move freely within the frame. If the gap is too wide, it can compromise the door’s ability to contain fire and smoke. That’s where intumescent materials come in. When exposed to high heat, they expand to seal the gap, slowing the spread of fire and smoke. This protects property, but most importantly, saves lives.
How Do Intumescent Strips Work?
Intumescent strips are either fitted around the fire door or the frame. When exposed to high temperatures, they swell to fill the gap between the door and the frame, creating a protective barrier. This helps contain the fire to a single room or compartment.
For more information on intumescent strips, visit our blog that answers all of your frequently asked questions.
Lorient | The Power of Intumescent Strips
Tools Required
Depending on whether you choose rebated or surface-mounted strips, you may need:
Cutting knife or hacksaw
Router and router bit for the groove (only if using option 1 below)
Clean, damp cloth
How to fit Intumescent Strips
Intumescent strips can be placed in one of two places; centrally around the door frame or the door itself. Many fire doors are supplied with pre-cut grooves for ease of installation, and most strips come with a self-adhesive backing.
Check that the gap between door and frame is 3–3.5mm at the closing stile and across the head, and 1mm down the back edge as the standard strip is only 1mm.
Clean painted or varnished frames with white spirit/detergent water and allow to dry. For new woodwork, ensure surfaces are sealed before application.
Measure and cut the strips to fit, noting lock positions.
Remove adhesive backing and press into place around the frame.
Fit strips over hinges if required (this helps to cool hinges and screws during a fire).
Test the door assembly to ensure smooth operation.
Note: Panel pins are supplied to secure through the brush smoke seal at each end and every 300mm apart along its length. These panel pins must be fitted as requested by building control officers and fire officers.
Smoke seals are fitted around the fire door frame, and often line the corners at an angle. They provide both acoustic and cold smoke protection, and come with a self-adhesive backing for simple installation.
Measure the frame at the top and both sides.
Cut the product to size using a cutting knife or scissors, mitring the top corners.
Remove both pieces of protective backing one foot at a time.
Adhere seal to the exact location of the frame where section is to be installed. Do not remove and relocate.
Inspect the seal to assure proper location.
Ensure this product does not impede the opening or closing of the door. The door assembly must operate effectively.
How we can help
With 50 years of industry experience, we supply an extensive range of passive fire protection products, including intumescent strips from leading manufacturers such as Lorient and Pyroplex.
Our knowledgeable team are here to support you with product selection, compliance advice and installation best practices.
📞 Call us on 02920 857 959 💬 Use our Live Chat feature 📧 Email us at [email protected]
For more expert insights, visit our Advice Centre for guidance on fire safety legislation and product installation.
