Can firewall include perimeter columns? 4

[Pixy]

A firewall is supposed to be constructed from the ground up. But can the perimeter main columns be considered part of the firewall?

If not, then for high storey building like 10 storey. How do they make the firewall?

 

[Retrograde]

But how many minutes before it can melt? 5 minutes? 15 minutes? or you mean 0 minutes? Please give me ideas how long in minutes.

Why do you want to know this? The only way to to estimate the time is to do a full scale fire test. But that is besides the point - as far as design codes are concerned, the fire resistance of this type of roof = zero minutes.

This discussion is very similar to this thread:

https://www.eng-tips.com/viewthread.cfm?qid=479994

I assume that member stripez is also you. I also assume you are not a structural engineer as you are obviously well out of your depth.

 

[Pixy]

I'm one engineer of a waterproof subcon company and just learning basic structural engineering. Remember all structural engineers were once used to be ordinary engineer and learning from others. I review building waterproof and just study the structural members for comment to the code people.

Here is something I noticed. We don't have any provisions for fire protection from lower roof and want to learn some basic so can talk to the code committee about it for inclusion of this international provision.

Let's get to the main point. If a 0.5mm (0.02") thin metal roof has no fire rating and can melt in minutes. Then why does the US code allow for 30 inches parapet above roofline to be built when the thin metal roof can easily melt and the fire can just affect the wall above the 30 inches parapet? Here's the US code about it in the article I shared in last message. Unless you Americans allow or have provision disallowing the use of any thin metal roof adjacent to higher wall? But I can't find that provision. See image below (wait for it to load if your internet is slow).

 

[HTURKAK]

I do not look to the web everyday..

Below , my points

- Your scenario ( where one building has much lower roof than the adjacent bldg ) ; most of the city planning rules do not allow windows on exterior adjacent walls . ( assuming the area is the privacy of the lower bldg )

- Your concern regarding the columns on the higher wall , most of the codes define column fire rating equal to fire rating class of the bldg..

- making the floor below the roof unoccupied is more dangerous than occupied ..( in long term will be the storage area of broken furniture, books , used PC s....)

- the codes could not adress every scenario .. you should get opinion of the local fire department and sometimes it is necessary to get services of a fire expert..

- In your case , my approach would be ; ( both walls would be firewall , no window on the wall of high bldg, RC roof slab for the lower bldg ...)

 

[Pixy]

There are no windows in the higher wall (7 storey) or the lower 3 storey.

The higher 7 storey building has only big columns in the left and right perimeter. They don't have columns in the middle of the building. So if the column in either side got burned let's say for an hour or two. The entire building could collapse from the columns aggregates expanding and the cement/sand/grout contracting resulting in disintegration of the side of the building and collapse.

The local fire dapartment can only show the following general clauses to be followed. We don't have other fire experts good also in material science or physics.

"Provide standard fire wall with at least 100 cm (39.38 in) high parapets on all portion of the the building on the property line.". "Extend exteior masonry walls to form parapets or wings".

It is easy to put a meter (39.38 in) parapets in the roofline. No problem. But the columns and foundations can no longer support RC roof slab. Only thin metal roof.

So the major question is even if you put parapet on the edge. In the event of fire, the flames can easily breach the thin metal roof and affect the adjacent building damaging it. Right??

In the US or elsewhere. Is this really allowed where a thin metal roof is below a higher wall building?

Making the roof/floor unoccupied means removing at least 4 meters of the roofing from all the side and making it open so it won't be made storage area but maybe for aircon bay. Is this the only solution left? If the higher building collapse, they could file fire damage that could result in literally giving them the lower building making it theirs.