The direct answer: 30- or 60-minute timber protection requires a complete system selected for the actual timber, construction and required period of fire resistance. It is not achieved simply by applying a generic “fireproof paint”.
Confirm the building element, timber, exposed faces, required fire-resistance period and evidence expected by the approving body. The product manufacturer or technical department can then specify the preparation, primer, intumescent build-up, protective finish and application rates.
01 · Start with the requirement
What does 30- or 60-minute protection mean?
Fire resistance describes the ability of a component or construction to satisfy defined criteria for a stated period. A requirement for 30 or 60 minutes should identify the building element, construction, exposure and evidence expected—not simply ask for “fireproof wood”.
The existing timber, thickness, density, joints, fixings, exposed faces and complete construction can all affect whether a coating system and its supporting evidence are relevant. The product manufacturer or technical department should prepare or confirm the project specification before materials are purchased or work begins.
A 30- or 60-minute fire-resistance requirement is not the same as a reaction-to-fire classification such as B-s2,d0 under BS EN 13501-1. The correct route must be confirmed by the project designer, fire consultant, building-control professional or other approving body.
The UK Government describes fire resistance as a component or construction satisfying relevant criteria for a stated period, commonly expressed as 30 or 60 minutes. See Fire safety risk assessment guidance.
02 · A complete specified system
Why the work involves much more than one coat
A clear timber system can require an adhesion primer, two or three intumescent coats and one or two protective top coats. The precise number, spreading rate and finish depend on the timber, existing surface, required rating and manufacturer’s application schedule.
- Clean, dry and sound timber
- Abrasion or removal of contamination
- Adhesion primer where specified
- Masking and protection of adjacent finishes
- Two or three intumescent coats
- Drying after every individual coat
- One or two protective top coats
- Recorded coverage and application rates
Each coat must be sufficiently dry before the next is applied. Some clear systems require the sequence to be completed within a specified application window and cannot simply be left part-finished overnight before the protective top coat.
Manufacturer instructions vary by product and project. Envirograf’s timber coating guidance describes primer, multiple intumescent coats, protective top coats and temperature-dependent drying. Thermoguard states that its 30/60-minute Timbercoat system requires a technical application schedule. See Envirograf timber coatings and Thermoguard Timbercoat Intumescent.
03 · Drying and site conditions
Why location, season and project size matter
Drying is part of the specification—not dead time that can safely be ignored. Temperature, humidity, ventilation, timber moisture, film thickness and external weather can all change the time available for the next stage.
A cold room or winter site can slow drying and prevent the planned coating sequence from being completed.
The job must be divided into sections small enough for every required coat and drying stage to be completed correctly.
The programme must allow for preparation, coating, drying checks and any return visits required by site conditions.
On large projects, plan workable sections around the manufacturer’s drying and overcoating windows. Allow for ventilation, safe access, protection of adjacent finishes and changes in temperature or humidity throughout the day.
04 · Commissioning the work
Use a suitably experienced local contractor
We advise customers to approach a local contractor experienced with specified timber intumescent systems. Envirograf and Thermoguard both manufacture relevant products, but the brand name alone is not a specification or a guarantee that a system is suitable for the proposed timber and construction.
We no longer undertake 30- or 60-minute intumescent timber coating projects. These multi-stage jobs are better managed by a suitably experienced local contractor who can work around drying conditions, follow the manufacturer’s specification and provide the required records.
Questions to ask before appointing a contractor
- Who has confirmed the required fire rating?
- Which tested system and project specification will be followed?
- Does the evidence cover this timber and construction?
- What preparation or adhesion primer is required?
- How many intumescent and protective coats are specified?
- What coverage or wet-film rates must be recorded?
- How will temperature, moisture and drying be monitored?
- What supply certificate and application report will be provided?
Keeping the contractor local makes it easier to schedule around drying conditions, split larger areas into sensible sections and return if site conditions interrupt the coating programme.
05 · Project evidence
What paperwork should be retained?
The responsible person or project team should agree the required evidence before work begins. A certificate of supply and a detailed report of application serve different purposes and should be retained with the manufacturer’s specification and supporting test or assessment information.
The timber, construction, required rating, preparation, products, coat sequence and application rates.
Evidence of the specified product system supplied for the declared area, where available from the manufacturer.
The contractor’s record of preparation, products, batches, areas, coverage, coats, conditions and completed work.
Thermoguard states that certification is reviewed against the product quantity, declared area and project details. Customers should not assume that purchasing a tin or receiving a generic certificate proves that the specified system was correctly applied to the actual construction.
See Thermoguard’s fire-certificate application guidance for the information it requests when reviewing a certificate application.
06 · A different classification
When the requirement is Class B timber treatment
Fire Proofing Ltd continues to assess suitable raw, untreated and absorbent timber for its separate impregnation treatment supported by BS EN 13501-1 B-s2,d0 evidence. This is principally a reaction-to-fire service for suitable timber cladding; it does not create a 30- or 60-minute fire-resisting construction.
Ask for the exact wording before choosing a route
If the requirement says B-s2,d0 or refers to reaction to fire, review our timber-cladding treatment service. If it requires 30 or 60 minutes, appoint a local passive-fire contractor and obtain the full project specification before coating begins.
See the Class B timber treatment service →07 · Common questions
30- and 60-minute timber questions
What should be confirmed before choosing a system?+
Confirm the required fire-resistance period, the building element and construction, the timber species and dimensions, the exposed faces and the evidence expected by the approving body.
How many coats might be needed?+
A clear system may require an adhesion primer, two or three intumescent coats and one or two protective top coats. The manufacturer’s project specification must determine the actual sequence.
Why must every coat dry first?+
The specified application rate and complete coating build-up depend on each layer being sufficiently dry before the next is applied. Cold, damp or poorly ventilated conditions can extend drying and disrupt the planned sequence.
Who should carry out the work?+
Use a suitably experienced local contractor who can obtain and follow the coating manufacturer’s specification, manage the site conditions and provide the required supply and application records.
Is your Class B treatment an alternative?+
Only when the actual requirement is reaction to fire and the raw timber is suitable for the supported impregnation system. Class B treatment is not an alternative to a specified 30- or 60-minute fire-resistance requirement.