Construction flaws that would facilitate an inferno in an old high-rise

Anything electrical. Old wiring is usually replaced on an ad hoc basis, and sometimes bits and pieces get overlooked. Particularly in a rundown building that isn't being actively maintained. If things are working, people are reluctant to upgrade them, but that doesn't mean they're working correctly or safely.

An old gas line that had been capped off but has deteriorated over time.

Often those old buildings had boilers in them. If it's still in operation (the one in my 1912 apartment building is) an old pipe could blow and cause some kind of reaction, maybe with that gas line.

Stupid humans are very often the cause of fires, but it seems you want this to be a little more mysterious?

There are a lot of fire hazards in old buildings. Aluminium electrical wiring. Paper mache insulation. Soot-filled chimneys. Cracked heating furnaces. Leaky propane lines. Take your pick.

But that alone is probably not enough to bring down the building. In those days, steel 'I'-beam construction was common. Most likely, the local fire dept would insist on coating the 'I' beams with some sort of retardant. It looks like a yellowish sticky plush. Old schools have plenty sticking on the ceiling of their old gymnasiums. After a few decades, flakes come off it. And a young fireman who don't know what he's hosing down might scrape it off accidentally and not think of hosing the beams to cool them off. An 'I' beam, when heated and without its protective heat coating, will start to buckle and eventually fail, taking down the building along with it.

-cb

Open communicating wall space is an old building issue, it allows the fire to spread very quickly. Also probably some layers of dry wood, paper and paste in all surfaces.

Fire doors that aren't actually made to the proper standard. Places where asbestos was taken out and not replaced.

As with most highrise buildings, it will depend on building material and if there are internal chases going from floor to floor that do not have fire stops or other forms of protection...

An elevator shaft that has been penetrated time and again over the years and never properly fire stopped is a good place for fire to spead. Same with laundry/garbage shoots, electrical and plumbing chases, etc.

NO SPRINKLER system in old buildings is a very large factor on fire spreading...

As others have said, take your pick.

Starting point is whether you're talking ignition sources or causes for fires spreading. They're entirely different problems.

If the building was upgraded to apartments, at the time that happened, it would have been brought up to code for ignition sources. Wiring would have been upgraded, sprinklers would have been installed (depending upon when this happened), and other upgrades would have been made. Further upgrades would have been made when it became public housing.

So ignition sources would have been dealt with. But ignition sources wouldn't be a big issue. Fires start all the time even in modern buildings.

Spreading, however, can remain a problem in an old building. And this goes back to the fundamental fact that heat rises. With the heat will be smoke. And in the smoke will be combustabile materials that will cause the fire to spread. Modern fire codes are designed to limit this through such things as fire doors and enclosed stair shafts.

When the building was upgraded to apartments, it probably would have had the stairwells enclosed in a fireproof barrier. Prior to this code provision, fires could spread easily up the stairwells. (Understand that with high-rise fires, the fire rarely burns down much, and its the floors above that bare the brunt of the damage.)

The most likely thing left in your building after being rebuilt would be vents that were walled off and voids. A voids is a blank spot in a building that doesn't appear to be logically there. Firefighters are trained to look at buildings and predict the logical construction. One idea is to fire out where the fire is going to travel and get there first.

A void or a vent system that extends between two floor enables a fire to travel between those floors much faster then a firefighter would expect. Voids and vents that extend between three or more floors can really screw you over.

Typical approach in fighting a multi-story building fire is to put most of your people on the fire floor(s). A small crew is put one floor below the fire, and interior command/staging will be set up three or four floors below that.

On the floor above the fire, you put a decent size crew. This crew will be dealing with ventilation, rescue, and stopping the fire from expanding vertically. But with a ventilation shaft or void that will allow the fire to leap a floor, you can be screwed.

And although these voids or ventilation systems should be dealt with in the renovations, they can be missed.

Reality is that once this building was upgraded to apartments, and then further upgraded to public housing, it would have been brought up to code and most of the reasons for fire spread in early structures would have been dealt with.

What are you trying to accomplish? I was a volunteer firefighter for many years. If I know what you want, I can probably figure out how to get from here to there.

Best of luck,

Jim Clark-Dawe

If the building is derelict, and has no residents (other then derelicts, who don't count as they aren't likely to notify the police of things), then here's how I'd go about it.

First of all, open all of the interior doors, the doors to the stairwells, and the door to the roof. Maximize the fire spread. Next determine your fire start location in the basement. Ideal location would be near the center of the building, underneath the corridor that runs down each floor (most building have each floor after the first floor set up exactly the same, so the corridor should be in the same place). Stack plenty of debris in this location, to give your fire a good start.

Now for the fun part. Head down to Lowe's or Home Depot and buy a cheap chainsaw. Cost will run you about $150. Pick up a couple of extra chains while you're down there. And some safety glasses. We won't want your protagonist to get hurt.

Taking advantage of the noise created by the construction next door, cut a hole about four feet by four feet in each floor, directly over your pile of debris in the basement. If you want to really have some fun, take plastic gas cans and place them on the side of the hole on each floor. You've now created a chimney in the building, allowing the fire to rapidly go through each floor. Light match and enjoy. The gas cans will actually tend to melt, dripping the gas onto the fire. It's unlikely you'll get an actual explosion.

And to make this better, fire departments are a lot more willing to let derelict buildings burn down. There's no sense risking firefighters for an empty building. And considering that this fire would spread throughout most of the building in about ten minutes, I'd mount an exterior attack, worry about the exposures, and get out some marshmallows to enjoy. You're not going to put this sucker out.

Best part of this is the building is going to collapse in on itself, destroying all evidence of arson. Fire department would be suspicious, mainly because of the rapid spread, but the likelihood of anything remaining is unlikely. Even if one of the floors survives with a hole in it, that's not conclusive evidence of arson. You might have a trace of petrochemicals left, but this is more likely to have been total enough to burn off the last traces of petrochemicals.

Best of luck,

Jim Clark-Dawe

Chain saw won't work on concrete flooring.

thothguard51 said:

Chain saw won't work on concrete flooring.

Click to expand...

You're right. A saws-all will work, and is available from Lowe's or Home Depot. Or for the ultimate in cool toys, the K-12 Rescue Saw. Basically a big circular saw with a gas motor. About $1500 but you can saw anything with it, depending upon blade choice.

There's a wide range of materials that were used in flooring for high rises. Floor will rest on beams of either steel or concrete and don't matter for this issue. The actual floor is not going to be too thick, as weight matters. A K-12 saw will go through anything out there for flooring material.

I've used one to go through a concrete block wall, and I've seen them used on roofs for a lot of different types of buildings.

Best of luck,

Jim Clark-Dawe

sorry, but none of those saws will work. (I'm a structural engineer). Concrete floors in any high-rise will be a minimum of four inches thick. Waffle or rib slabs may be thinner, but still at least two inches between the ribs. A diamond tipped rotary saw, which is not a portable item, woudl take a considerable time to cut through that, since it also has to cut the reinforcing bar. Usually a diamond core drill would be needed, and they are very big and very slow.

all the advice above regarding old vent shafts, cheap doors, backdrafts, no sprinklers, asbestos etc are valid, but if there has been gentrification, as you suggest, then any change of use would require that the building be brought up to date in line with contemporary fire regulations

can I suggest that you introduce a plot point where the conversion was substandard, perhaps they avoided any involvement with the planning authorities, or bribed them. Asbestos is usually a strong incentive to avoid the authorities because it can shut down a building site pretty quickly

wrote that and then remember the Kings Cross Fire in London 1987. Wikipedia has a good page on it and the chain of causes that created it. The fire started on an escalator. I recall that flammable things (cardboard garbage mostly) had been stored under the escalator and oil had dripped on it from the machinery, so when a spark ignited it it accellerated quickly

maybe your building could be derelict and inhabited by squatters. There would be doors missing, garbage, open lift shafts, old solvent-based paint

Let's go back a bit and discuss fire load. Fire load is the total of flammable material in a structure, both structural and additional material. A normal house consists of a lot of additional materials like furniture, clothing, electronics, books, et cetera. Abandoned buildings tend to not have this material, other then light trash. Anything useful is removed, either by the owners as the building is abandoned, or by scavengers. Light trash catches fire easily, but doesn't sustain a fire well.

Structural elements are the floors, ceilings, and walls. And stating the obvious, concrete doesn't burn. So the more concrete in this structure, the less material there is to burn. The interior walls would have been gutted during the upgrades and fire-resistant walls would have been added. Exterior walls would have been concrete. If you make the floors too much concrete, what do you have that will burn?

Concrete structures can have a big fire of the interior material like furniture that leaves the structure intact. This was one of the expectations of FDNY at the World Trade Centers. The paper, desks, et cetera would burn off, but the fire would not be strong enough to effect the structural aspect of the building. No one was factoring in the massive addition of jet fuel, which vastly increased both the fuel load and the temperature of the fire.

Something that would survive renovations is a wood floor on steel or concrete stringers. A floor made out of three or four inch oak would be incredibly strong, while providing you with a good fuel source for the fire. Although floors can be an important part of the supporting structure of a building, they don't have to be. And a wood floor in an old factory will have absorbed many things over the years, including oil and grease. Great for fires.

The K Saw was developed for the FDNY to deal with the many different types of roofs in NYC. Roofs in NYC include steel, concrete, tile, wood, and I don't know what else. One of the first things you do at a fire is cut a roof vent to enable the smoke and heat to leave the building. Although chain saws and axes can do a number on materials they were never designed to be used on, they have some limits. The result was the K Saw. It's not going to go through 4" of concrete quickly, but it will, including the rebar that's in the concrete. Hell, it will cut a car in half.

My guess is a K saw, in 4" concrete, would probably cut a two foot by two foot opening (eight feet of cutting) in less then an hour. Probably closer to half an hour. And once you've got most of the opening cut, a sledge hammer will take out a lot of what's left. Remember you're not looking for neat. Personally I'd try cutting three sides and then try a sledge on it. You might have some rebar left hanging, but that's not an issue.

When we cut the cinder block wall, it took less then 45 minutes to cut 2 vertical cuts about six feet long. This did not cut through the entire cinder block. However, at that point, two guys with sledge hammers took only a few minutes to knock the crap out of everything, giving us the opening we needed. Structure was a barn with a cinder block lower wall. The barn had collapsed into the wall, and we needed to get into it. But because of the design of the barn, both doors had a heavy debris load that we could only slowly remove with a bucket loader. Here's a video of a firefighter using one in training on a concrete wall: Cutting Concrete Wall with K-Saw.

However, another approach which I'd forgotten about is the elevator shaft. Although an elevator shaft uses fire resistant material to limit fire spread, elevator shafts have an opening in virtually every floor -- the door you go in and out. Closed elevator doors can be forced open through the use of a hydraulic spreader tool, such as the Jaws of Life. But you could relatively easily fabricate a tool using a hydraulic jack for force. Open the door a foot or two and you've accomplished the same thing as cutting the floor -- a vertical chimney through the building.

You might also find piercings between the floors where old ducts ran. These piercings would probably be of less structural strength then the surrounding area. All you're looking to do is open the building up vertically and horizontally for fire spread. This is why you open every door. Because even a cheap plywood door will slow the spread of a fire.

But there's got to be enough in the building to burn.

Best of luck,

Jim Clark-Dawe

I reckon it would take about 10mins for a diamond corer to go through a slab, but that's only a four inch hole - you'd need quite a few holes linked together to form a rectangular opening wide enough to get personnel access, maybe all morning cutting

I'm still dubious about that K2 floor going through a floor slab, which is higher grade concrete that wall blocks, and reinforced with steel.

he is however on the money suggesting that the lift shaft is the quickest route to spread firs, which is why they are usually heavily shielded - you'd need a few doors to be open...