Bird Box Glues In Fire (Q+A)
Email Correspondence with Bird Box Manufacturer
You will recall that I had a customer for our bird box, who needed a product that was “fireproof”.
Your customer needs to define performance requirements in correct fire terminology, in turn their designers need to brief the customer with requirements in correct fire terminology.
Unfortunately fire terminology is broad and complex and reading in many sources is necessary for good understanding.
‘Fire rated’ and ‘Fireproof’ and not technical terms but are often used by design professionals as a slang to mean ‘Fire Resistance’ or ‘Fire Resistant’
Fire Resistance is recognized to mean the performance of say a fire doorset (door, frame, ironmongery, glazing etc.) or a partition, wall, or floor.
- is a property of:
- an elemental assembly (E.g. floor, wall, partition)
- consisting of many components: (E.g. Partition: studwork framing, insulation, linings, fixings/fastenings and jointing materials)
- or sub-element assembly (E.g. Doorsets, glazed screens, stairs)
- consisting of many components: (E.g. Doorset: door leaf, frame, glazing, glazing beading; glues, and glazing bedding, ironmongery)
Fire Resistance is made up of 3 characteristics stability, integrity and insulation
- Stability relates to the installation of the frame and attachment to the surround, to ensure it stays in place during a fire (stability seems to have less clout and has been suppressed in terminology in recent decades)
- Integrity relates to the competency of the door leaf and frame in a fire (it must not shrink or distort, or burn away) and installation of the door leaf into the frame by ironmongery and the size and tolerance of the gaps and any fire and smoke sealing measures at those gaps. Integrity relates to fire and smoke or fire only.
- Insulation relates to radiant heat from flames of a fire and its ability to radiate heat through opaque parts, translucent and transparent glazed parts of doorsets to the other side making passage in a corridor impossible.
- Fire doors may also need to be self-closing to ensure the door leaf is closed in the frame in the event of a fire
Fire Resistance is confirmed by test carried out by an independent testing house accredited by UKAS
- Tests are carried out with some expectation of test duration
- Assessments are often carried out in advance, after years of experiencing many tests, assessors predict the time to failure of each component of any assembly.
- Test are expensive so are often stopped at point of integrity failure and timed
- The test evidence will be in the form of certificate for a specification for a duration in minutes of say 15, 30, 60 (1 hour), 90, 120 minutes (2 hour) usually.
Bird boxes will need to offer the same fire resistance to the wall they occur in, in order to maintain the integrity of the surrounding wall.
Smoke and Burning Droplets
Smoke inhalation is widely known to be the main cause of death in fires saving them from death by flames (Grenfell being an exception where many died by extensive fire penetration into flats where people were recommended to stay-put until fire fighters had intended to phased evacuate and guide them out of the building)
At the Isle of Man pleasure resort plastic transparent wall and roof glazing ignited providing smoldering and ignited droplets of molten plastics to help spread the fire and kill people by toxic smoke inhalation and by flames.
Other fire terminology
- If a flame is imposed on a material it will either: absorb the heat, conduct it away, not ignite, smolder (e.g. melting and igniting), char (i.e. burn and crate a protective layer) or ignite. When the flame is removed from the material it may: extinguish, emit smoke, continue to smolder, smoldering droplets fall or ignite other finishes, ignite itself and continue to burn. This is the materials ability to propagate (start and continue) a fire and will depend upon the materials combustibility or non-combustibility and its surface spread of flame
- Means a material is capable of burning when subjected to a source of heat or a flame along with oxygen.
- Timber is combustible
- Interestingly a 50 x 50 mm softwood batten has always been accepted as a cavity fire barrier in cladding (Post Grenfell this may have already changed)
- Timber can be made non-combustible by the addition on liquid fire treatment impregnation
- Timber panel products (e.g. chipboard) can have fire retardant salts added to the recipe
- Plastics are combustible,
- Plastics are a source of fuel if exposed to fire, but an aluminium foil facing can protect the core plastic from flames; however at corners, at butt joints or damaged surfaces the core is exposed and can join into a fire, aluminium adhesive tapes can provide back some fire protection
- When alight and combusting plastics will generally make toxic smoke emissions
- Plastics can be made non-combustible by the addition of chemistry
- These chemistry can make even more hostile smoke emissions
- Aluminium is not normally combustible
- In special circumstances aluminium can be combustible
- Steel is not combustible, 6 mm of steel can be a cavity fire barrier if secured in place
- Timber is combustible
Surface Spread of Flame:
- If a combustible material is ignited and the fire propagates, the flame can stick to the material’s surface and depending on the material’s ‘surface spread of flame’ characteristics may not get very far or even travel great distances on the materials surface.
- Corridors that are escape routes need to have low SSoF to be a safe escape route
- Corridors need also to contain no combustible material
- Gypsum is low SSoF and low combustibility
- Corridor Notice boards are covered in paper which is combustible and high SSoF
- Glass is low SSoF
- Glass windowed notice boards return the corridor to a safe route to exit in a fire
- Class 1 is best (lowest surface spread of flame)
- is a UK only Building Regulation classification combining the results of propagation and surface spread of flame class 1, when both are the best of their test results
- Class O materials will be used in an escape corridor
- Since we joined the EU and adopted CEN standards Class O still exists but is not the best classification available anymore
- Combustibility ‘A’ is best and ‘E’ is worse
- Smoke emissions ‘s’ and burning droplets ‘d’ are now the secondary characteristics that all materials must be judged by.
- As1d1 is good
- Es3d3 is bad
I went to great lengths to find materials that would not burn; including glue that, on the tube, said it was fireproof.
Unfortunately this glue was inadequate as glue.
- Burn = Combust > Combustible, See Also: Propagate (Answer A1)
- Fireproof = Slang for Fire Resistant (See Answer A1)
- Product Claims:
- Must always be backed up by certification/test evidence, etc.
- Ask for instructions methods statement or specification for a competent installation or application
- A injected foam fire protection for service penetrations through walls can give up to 4 hours fire resistance in a specific configuration but as little as 4 minutes in a different configuration.
- But injected foam has a reputation for not sticking to inaccessible surfaces, which cannot be cleaned or primed, they shrink away and fail.
- Adhesives need clean and dry surfaces and if not compatible may need surfaces to be primed.
- I recently had an enquiry from someone who wanted 10 bird boxes, but could only afford 6 bird boxes with no fireproof requirement.
- The size and type was so similar that I offered them 4 of the ‘fireproof’ bird box with no surcharge and I would disassemble them and reassemble them with a quality ‘fireproof’ glue.
- In the process I ended up with a quantity of the ‘fireproof’ glue that I scraped off the original bird box.
- I wondered to myself, what if I put a match to the glue? So I did, and it burst into flames!
- An adhesive when buried in a joint below the surface of an assembly may contribute to the fire resistance of the assembly
- but if exposed on the surface may burn due to the combustible chemistry, synthetic nature, solvents off-gassing (until set and hardened) or hydro-carbons or plastics as fuel to a fire.
- So what is the definition of fireproof we would have to satisfy?
- See Answer A1 above
- From what I can google, it is something to do with the amount of time something will survive a fire – say 60 minutes or 90 minutes.
- Apart from the glue, all of the materials in the ‘fireproof’ bird box will not burn.
- But after 60 minutes in a fire it has lost its strength (I tried it in my wood-burning stove).
- However, a bird box could not be described as a structural component, so does it matter?
- I wonder about Wooden or PVC window frames above 18 metres.
- The contribution that a few grams of glue in a bird box would make to a fire is insignificantly small.
- See Also Answer A1
- The fire resistance test will be a chamber with one wall open for the test specimen to occupy; the specimen will be a wall, door, window, screen, or a wall of known performance (previously tested) containing a test specimen.
- The chamber contains a fire and the test can be carried out from one side normally or from two sides (rebuilding the specimen in the other orientation and retesting or having two sub-specimens in the pretested partition).
- Burning the specimen in an oven is not reflective of a fire resistance test (but is more about combustibility)
- The quantity of the glue is small but its performance in the fire may be predictable by an experienced test house assessor not by the layman unfamiliar with the test method.
- The swift box becomes part of the wall, to contribute to and maintain the wall’s fire integrity and may influence i.e. improve or compromise it’s structural integrity, so it may be expected to perform in ways it may not otherwise be expected to do.
- The mistakes of Grenfell (and similar projects) are progressively being documented.
- Composite wood windows of generous section which char and provide fire resistance with a powder coated metal outer face; may be an acceptable alternative to combustible PVC-U windows, but all the infill panels around the windows were one focus for improvement, let alone the rainscreen cladding panels made of plastics (polyethylene) and aluminium sandwich panel and its plastic thermal insulation.
- Manufacturing PVC from 57% salt and 43% chemistry generates half a dozen hazardous chemical wastes
- Burning PVC makes dioxins, one of the most highly toxic hazardous to health chemistry waste products
- Small amounts of hazardous chemistry when burned can make inordinate amounts of hazardous chemistry smoke emissions in fire conditions.
Bird Box Glues In Fire (Q+A)
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