Upgrading Existing Concrete Structures with Aestuver® Fire Protection Boards

Older concrete structures or those with minimal concrete cover may not meet necessary fire safety standards, such as those outlined in EN 1992-1-2 – Eurocode 2, often achieving only a 30-minute fire resistance rating (R30). Upgrading these structures to withstand 60, 120, or even 180 minutes of fire exposure is vital for compliance and safety. For example, in the UK, Approved Document B provides the list of building types which require fire resistance higher than R30.

Minimum Periods of Fire Resistance (Table B2)

 

1. Residential Buildings:

   • Blocks of Flats:

     • Without sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 18m), not permitted above 18m.

     • With sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 18m), 90 min (up to 30m), 120 min (above 30m).

   • Dwellinghouses: 30 min (ground/upper storey up to 11m), 60 min (up to 18m).

2. Residential (Institutional):

   • 90 min (basement), 60 min (ground/upper storey up to 18m), 90 min (up to 30m), 120 min (above 30m).

3. Residential (Other):

   • 90 min (basement), 60 min (ground/upper storey up to 18m), 90 min (up to 30m), 120 min (above 30m).

4. Office Buildings:

   • Without sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 18m), not permitted above 18m.

   • With sprinkler system: 60 min (basement), 30 min (ground/upper storey up to 30m), 120 min (above 30m).

5. Shop and Commercial Buildings:

   • Without sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 18m), not permitted above 18m.

   • With sprinkler system: 60 min (basement), 60 min (ground/upper storey up to 30m), 120 min (above 30m).

6. Assembly and Recreation Buildings:

   • Without sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 18m), not permitted above 18m.

   • With sprinkler system: 60 min (basement), 60 min (ground/upper storey up to 30m), 120 min (above 30m).

7. Industrial Buildings:

   • Without sprinkler system: 120 min (basement), 90 min (ground/upper storey up to 18m), not permitted above 18m.

   • With sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 30m), 120 min (above 30m).

8. Storage and Other Non-Residential Buildings:

   • Without sprinkler system: 120 min (basement), 90 min (ground/upper storey up to 18m), not permitted above 18m.

   • With sprinkler system: 90 min (basement), 60 min (ground/upper storey up to 30m), 120 min (above 30m).

9. Car Parks for Light Vehicles:

   • Open-sided: Not applicable.

   • Any other car park: 90 min (basement), 60 min (ground/upper storey up to 18m), 120 min (above 30m).

These fire resistance periods ensure that buildings can maintain structural integrity and limit fire spread, providing safety for occupants and firefighters. If you need more detailed information or have any other questions, contact us via the form below:
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This blog post explores how Aestuver® fire protection boards, as detailed in the European Technical Assessment (ETA-11/0458, 18 June 2021), can enhance the fire resistance of concrete slabs, walls, columns, and beams, supplemented by broader passive fire protection insights.
 

Insufficient Fire Resistance in Existing Concrete Structures

Concrete fire resistance depends on its ability to shield reinforcement steel from reaching critical temperatures (around 500°C), where it loses structural integrity. Per EN 1992-1-2, minimum concrete cover dictates fire ratings: a 10-15 mm cover typically yields an R30 rating, which is inadequate for modern requirements like R60 or R120. Retrofitting with additional concrete is often impractical due to weight, cost, methodology or space constraints. Such a repair method can also be time consuming. What is more, some areas of a building have to be completely closed off for the extended duration of refurbishment. Such approach may cause additional loss of revenue for the property owners. Aestuver® fire protection boards offer a lightweight, efficient systems, certified under ETA-11/0458 for enhancing concrete fire resistance.
 

Concrete fireproofing system with Aestuver^® Fire Protection Boards:

Aestuver^® boards are cement-bonded, glass fiber-reinforced lightweight concrete panels with no flammable components, classified as A1 per EN 13501-1 and Type-X (suitable for all exposure conditions) per EAD 350142-00-1106. It means that the Aestuver boards can be installed with full weather exposure throughout the long design life (minimum 25 years). The ETA-11/0458 specifies their use as cladding for load-bearing concrete elements (Use Type 3), replacing insufficient concrete cover to boost fire resistance. Key properties from Table 1 (ETA, p. 3) include:

Aestuver fire protection board - Thickness Options:

• From 10 mm (950 kg/m³ ± 15%) to 60 mm (640 kg/m³ ± 15%), with 15 mm and 20mm commonly used for concrete upgrades.
• Dimensions: Standard size for concrete fireproofing -  2600 x 625mm, with up to 3000 x 1250 mm possible, with tolerances of ±1 mm thickness and ±2 mm length/width.
• For concrete fire protection with R30 baseline (e.g., 10-15 mm of concrete cover), the ETA provides precise data on achieving higher ratings with 15 mm Aestuver® cladding

 
Fire-proofing of concrete slabs and walls:




Let us look at the key considerations for upgrading concrete fire rating with Aestuver fire board 15mm thick:

• Board size for this application is 2600x625mm

• Minimum edge distance of anchors is 35mm

• Recommended fixing method is a nail anchor of 6mm diameter with shallow embedment depth

• The minimum thickness of the reinforced concrete (fixing substrate) is 120mm

 
15mm fire board adds 42 mm equivalent concrete thickness (factor 2.80), per Annex D 2 (p. 41) for R60, for R90: Adds 45 mm (factor 3.00) and for R120: Adds 46 mm (factor 3.07).
Beyond 120 minutes, performance extrapolates to 180 minutes.

The table below presents a summary of different concrete cover thicknesses and which thickness of Aestuver board has to be applied to                                                                                                               achieve specific concrete fire protection for walls or ceilings:


 

Table 1. Equivalent thickness for concrete slabs/-walls cladded with 15 mm thick „AESTUVER“ fire




 

Fire proofing of concrete beams and columns:






In case of fire protection of concrete breams and columns Aestuver 15mm fire board can be used in full dimensions 2600x1250mm. For R30 to R60 fire resistance Aestuver fire protection panel adds 56 mm equivalent concrete thickness (factor 3.73), per Annex D 5 (p. 44).

For fire rating of R90 it adds 54 mm equivalent concrete thickness (factor 3.60) and for R120 it adds 50 mm equivalent concrete thickness (factor 3.33).

Table 2. Equivalent thickness for concrete beams/columns cladded with 15 mm thick „AESTUVER“ fire



These values reflect the boards’ thermal insulation performance, ensuring steel temperature within the concrete beams or columns remains below 500°C for the specified durations.
 
The table below presents a summary of different concrete cover thicknesses and which thickness of Aestuver board has to be applied to                                                                                                          achieve specific concrete fire protection for columns or beams.

 

Concrete Fireproofing with fire boards - Installation Process and Practical Considerations

The ETA outlines installation specifics for concrete elements:

1. Assessment: Review or measure existing concrete cover and fire rating per EN 1992-1-2. For an R30 baseline, select the target rating (e.g., R120).
2. Board Selection: Use 15 mm Aestuver® boards as specified in Annex D 1 and D 4 of the ETA.
3. Fixing: 
   - Slabs/Walls: - one of the potential fixings is Fischer FNA II 6 x 30 x 15 anchor, spaced ≤ 530 mm, edge distance 35-50 mm (Annex D 1, p. 40). You can also use other anchors with suitable embedment   
     depth and corrosion resistance. You should use wide washers, i.e. 28mm diameter to avoid squeezing the fire board.
   - Beams/Columns: Fischer FNA II 6 x 30 x 15 anchors, spaced ≤ 400 mm, edge distance 50 mm, plus steel wire clamps (40 x 11.25 mm, ≥ 1.53 mm) at ≤ 100 mm between boards (Annex D 4, p. 43).
   - Boards are butt-jointed, with arbitrary joint placement.
4. Finishing: Joints may remain unfilled for fire protection, though aesthetic sealing with Aestuver® mortar is an option.

Aestuver fire boards are light weight (~12 kg/m² for 15mm at 800 kg/m³) which minimizes structural load compared to concrete overlays.

Custom solutions beyond the ETA: Broader Passive Fire Protection Insights

 

The ETA’s data aligns with general fire protection principles:

- Thermal Performance: Aestuver® boards’ low thermal conductivity (e.g., ~0.125 -0.210 W/m·K, inferred from similar materials) complements concrete’s insulation, delaying heat transfer to steel.
- Durability: Type-X classification ensures resistance to water, freeze/thaw, and heat/rain cycles (ETA, p. 7), ideal for exposed or semi-exposed upgrades.
- Flexibility: While the ETA focuses on 15 mm boards for concrete, thicker options (20-60 mm) could extend performance.
If you have a custom requirement you can contact us for your specific needs.


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