The I-Joist has become a modern alternative to the traditional solid timber design. Providing a structurally advanced substitute that offers many constructional advantages. As the design is different, you now need to consider taking greater fire precautions than you would with solid timber.

When you're specifying downlights for an I-Joist ceiling installation, greater attention should be made to ensure they are certified for use with your installation. Just because a downlight is fire rated to the original fire standards of 30, 60 and 90 minutes; it doesn't necessarily mean its going to be I-Joist compliant for your specific project. This is having a game changing impact on the lighting industry, some manufacturers have performed extensive tests on their most popular downlights models.

Part B of the Building Regulations covers fire safety, and for many years; as long as you fitted a fire rated downlight in your ceiling you were fine. The building industry has evolved and the lighting industry leaders have now caught up with this revolutionary design known as the I-Joist.

We've compiled this data from the 'Big 4' downlight manufacturers who are the market leaders of fire rated downlighting technology. This includes: Ansell Lighting, Aurora Lighting, Collingwood Lighting and JCC Lighting. Each manufacturer has independently tested and gained I-Joist certification for a selection of their fire rated downlights.

The fire rating tests are performed by constructing a mock room using the exact light models of light fittings and I-Joist. The room is then set on fire under test conditions, shown in this image below:

Ceiling Inferno
Ceiling Inferno

No matter if you're preference is for GU10 or integrated LED downlights, they should be certified to the specific fire safety standards for your particular ceilings structure...The rules have changed!

1. Structurally Strong and Sturdy

I Joist Picture
I Joist Picture

I-Joists are ‘I’ shaped wooded beams designed to meet higher and more consistent performance standards.

They are light in weight but offer structural strength. The structural build consists of top and bottom flanges jointed with the web making them rigid and robust to the joist. The collars are often made of solid or laminated wood. This strong material means I-Joists typically resist bending, which reduces the risk of buckling or bowing. The web that joins the flanges is made of Oriented Strand Board (OSB) or plywood.

Solid wooden joists can have imperfections, natural flaws that can reduce their constructional strength and cause a bowing effect within the floor. An I-Joist is a specially compositely constructed alternative that is lighter but stronger.

2. Efficient Fire Blockers

Traditional fire rated downlights either come with an intumescent pad that expands at a specific temperature. In the event of a fire, this pad expands, creating a barrier that blocks off the hole that has been cut into the ceiling that allows the downlight to recess into. Or another type of fire protection comes from the black can design. Without needing to expand, the cans structure blocks flames and smoke from spreading through the hole.

Fire rated downlights help to slow down the spread of fire and are tested for 30, 60 and 90 minutes in solid joist ceilings. Without these specific downlights, your ceiling could collapse in just a few minutes after a fire breaks out. Apart from the obvious safety concerns, if you've fitted incorrectly certified equipment, your insurance company may have grounds not to pay out on your insurance claim.

These different ceiling types are explained in this helpful infographic from Aurora Lighting:

3. Fire-Rated Compliance

I-Joists fire rated downlights are tested for 30 and sometimes 60 minutes. Some conflicting information is around the 90 minute test, some manufacturers say this is not needed and some show they have tests reports available.

To become certified, each model of downlight should have been tested with either the exact brand and type of I-Joist, such as James Jones & Sons Ltd, Staircraft, Steico and Trus-Joist, or to the BS or EN standard that they're manufactured to.

This image below shows an actual fire rating test after 100 minutes of testing:

Ansell Test 100 Minutes
Ansell Test 100 Minutes

To ensure compliance, I'd recommend double checking that the exact combination of downlight and I-Joist have been tested together and obtaining the test certificates. We've obtained and listed our most popular downlights in the table at the bottom of this page. Or please contact us for further advice, as this will remain a developing area of interest.

4. Additional Versatility

The I-Joist design offers many benefits, allowing you to achieve more significant spans, as wells as reduced bounce and deflection issues. Their lightweight design allows for easier drilling to install services such as cables, ducting and pipes. I-Joists are machine made and only achieve certification after passing a battery of specific tests.

I-Joist Example

Additionally, with a high strength-to-weight ratio, they are easier to transport and install. I-Joists eliminate the need for central beams or columns by allowing for open plan applications.

Ansell and Aurora Lighting have also performed tests with metal web joists (or MWJ for short). This other form of ceiling joist contains a central metal frame that supports upper and lower wooden beams.

5. Which Downlight Models Are Certified?

The table below shows a selection of the most models of downlights that have been tested with links to each of them:

BrandModel & LinkTested ToLink to Certificates
Ansell LightingEdge30, 60 & 90 min ceilingsI-Joist 30 Minute Test Report
I-Joist 60 Minute Test Report
I-Joist 90 Minute Test Report
Ansell LightingPrism Pro30, 60 & 90 min ceilingsI-Joist 30 Minute Test Report
I-Joist 60 Minute Test Report
I-Joist 90 Minute Test Report
Aurora LightingEFD ProStaircraft, James Jones & Sons Ltd & MetsaI-Joist Test Report
Aurora LightingM-ProStaircraft, Steico, James Jones & Sons Ltd & MetsaI-Joist Test Report
Collingwood LightingH2 Lite30 min in accordance to BS 476 Part 21, BS EN 1363-1:2012 & BS EN 1365-2:201430 Minute Test Report
Collingwood LightingH2 Pro 55030 min in accordance to BS 476 Part 21, BS EN 1363-1:2012 & BS EN 1365-2:201430 Minute Test Report
Collingwood LightingH2 Pro 70030 min in accordance to BS EN 1363-1:2012 & BS EN 1365-2:201430 Minute Test Report
JCC LightingV5030 & 60 min ceilingsDownload here

I-Joist Fire Rated Downlights

Downlights Direct are experts in the downlighting industry and work closely with the UK's leading manufacturers. Feel free to get in touch with us to discuss the best lighting options for your installation, whether you're considering a renovation or a new build, we can offer solid advice and a reliable selection of products.