Riser shafts are so prominent in high-rise buildings, but there are some misunderstandings when understanding what they are and why they are needed from a fire protection perspective. For example, there are problematic misunderstandings regarding the fire protection rules during and after construction and the difference between intumescent coatings and fireproof packaging. 

Riser is an essential infrastructure for building operations. However, in terms of its design and construction, there are two major misunderstandings that need to be resolved.

The first involves the difference between fire protection rules and codes of practice during construction (ie HSG 168 and the Joint Code of Practice) and post-construction codes. The approval document B of the building code covers fire safety matters in and around the building. Both need to be observed, but the former is rarely understood and usually ignored.

To ensure safety, the design of the riser well must be carefully designed in accordance with the requirements of the approval document B. The riser well is usually enclosed in a firewall around it for two hours. The door to the shaft needs to be protected for one hour. The shaft itself can be any number of floors from 2 to 50 vertically; the design standard does not specify any details about the temporary protection required during construction. It requires horizontal fire protection where it enters different fire compartments. These compartments may enter the machine room on the 1st or 50th floor of the basement. The horizontal fire protection layer must be supported by A2 or better material.

No matter where the fire compartment is located, it requires two hours of horizontal fire protection, that is, a two-hour fire-resistant floor. At this stage, the architect is responsible for designing in accordance with these standards so that fire safety will not be compromised when the building is handed over.

However, during construction, there is a completely different set of rules. Since designers and general contractors must design details to prevent smoke and flames from passing from one floor to another, temporary fire doors should be installed on each floor, and every 10 floors require half an hour to fire.

For example, here is the RiserSafe® system, which forms and seals the riser shaft in one action, prevents smoke and flames from passing through each floor, and provides 90 minutes of fire integrity on each floor.

But there is a contradiction. In the first case, you might have a 50-story open-air shaft with two-hour fire compartments at the top and bottom of the structure. However, during the construction process, every ten floors must be fireproofed for half an hour.

The two do not add up, resulting in a lot of confusion. Both are necessary, but neither complement each other. 

The next problem is the failure to understand the difference between the intumescent coating on the steel and the wrapping of the steel beam. Steel structures are usually designated as having a two-hour fire resistance. This is achieved by applying intumescent paint to the steel that expands in the event of a fire. When this happens, it forms a form of insulation on the steel to prevent it from reaching over 550 degrees within two hours and softening causing structural failure.

Now, it is important to remember that the two-hour fire compartment is different. A wall or two-hour floor must be tested in two ways: integrity and insulation. In terms of completeness, if it is placed in a 1,000-degree furnace for more than two hours, will it withstand it? Or is it compromised? Speaking of heat preservation, the heat transfer of 1000 degrees to the other side of the compartment cannot exceed 140 degrees. The problem is that 140 degrees is not 550 degrees. The two are quite different.

What happened was that in the riser of a steel frame building, each floor had steel beams, and the walls were under the steel structure. Therefore, the intumescent coated steel is sandwiched between the two compartments (usually the riser and the office compartment). There is a misunderstanding here, thinking that the two-hour protection on steel is the same as the two-hour protection required on the wall. But this is not the case, because when only 140 degrees is allowed, 550 degrees are entering the compartment.

To solve this problem, the steel must be wrapped. However, the problem here is that there has not been enough attention to the size of the fireproof enclosure. This will have a knock-on effect on the available space for risers and M&E services. What is really worrying is that it produces extremely difficult details that must be remedied on site at a huge cost, the M&E model must be redesigned, and the fire-resistant packaging details must be added to the dry liner package.

Therefore, more attention needs to be paid to including it in drawings and models so that the packaging can enter the electromechanical modeling. In extreme cases, regardless of the size of the shell, the size of the riser can be reduced by 30%.

Each question raised can lead to a large number of problems in the field, and the best way to overcome these problems is through better education. Main contractors—increasingly becoming key stakeholders—need to understand the different fire compartments. On the other hand, designers need to understand the temporary site rules, because currently their designs are not translated as effectively as they should be.

Finally, there must be better education to understand the difference between intumescent coatings and fireproof enclosures. Many construction professionals mistakenly believe that the two are interchangeable, but in fact they are completely different.

Education must be top-down to filter everyone. With the addition of building safety regulators, things must get better, especially when it comes to fire safety. While things like technology can certainly play a role in visualizing what is right to highlight errors, education is something that comes earlier in the process, which means it is more likely to have an impact. We cannot continue to move in the current direction-we must change direction and use education to eliminate misunderstandings related to legislative affairs. After all, it does have an impact on everyone engaged in construction projects.

Alex Bardett is the MD of Ambar Kelly

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