Fires are one of those things that scare some folks more than almost anything else. No doubt, once you’ve been in one and felt the magnitude of its power — or should I say heat — most people would quickly develop a healthy respect.
Depending on what your house is built out of, it could burn down in minutes or hours — the latter giving time for you and your family to safely exit the building as well as for the fire department to arrive and salvage most or at least part of the structure and what’s inside.
What Causes Fires?
Fires can be caused by many things, many of which you probably know already. There are fires caused by actual fire sources, such as gas and kerosene stoves, candles, matches, cigarettes, and bon fires, and there are those that are caused by electrical sources.
Electrical sources are a bit more tricky to deal with as they don’t have big flames practically yelling at you to be careful. Hair irons and curlers, heaters, radiators, and even just an overloaded circuit are all potential fire hazards.
Circuit breakers are vital fail-safes that shut the power off to a given circuit if loaded past its limit. However, this doesn’t protect in situations where wiring has lower power capacity than the collective load imposed on that circuit. For example, running 10 amp wiring off a 20 amp circuit breaker renders this fail-safe meaningless as the 10 amp wire can be loaded to double before being shut off.
Older homes or homes where inexperienced DIYers install their own electrical wiring are particularly susceptible to electrical fires. In many developed nations permits are required to install electrical wiring, but are rarely enforced on a non-commercial level.
Some DIYers have a fairly good working knowledge of electricity on a theoretical level but don’t have the practical know-how or up-to-date experience that is required to safely install electrical wiring. This can potentially lead to overloaded circuits, short circuits, and/or simply faulty connections — all of which can be hazardous fire sources.
Fire-Retarding Techniques and Methods — Firestops
Being that building structures only out of 100 percent fire-proof materials, or even fire-resistant materials is rather unrealistic, not to mention downright boring, there had to be another way of retarding the fire while still remaining free to use flammable materials like wood. This is where firestops come into the picture.
Firestops are simply mechanisms whereby the spread of fire is substantially retarded or delayed. As you know, fire is fueled by oxygen, and as such, spreads faster when there are large interconnected pockets of air surrounded by nice, highly flammable wood.
Obviously, using non-flammable materials is ideal, but almost any material is better than having nothing. Some housing companies use fire-resistance as a selling point for their houses, and among other things, require the installing of firestops throughout their houses.
A common firestop location is at the top and bottom of walls. Walls are typically sheetrock and/or plywood fastened to studs, and as such, have large air-pockets through which fire can quickly propagate into the ceiling and from there into the floor above. Sealing off these air-pockets greatly retards the spread of fire damage.
Technically speaking, the walls, floors, and ceilings of a house might have a particular “fire-resistance rating” indicated by a unit of time — ie, a “2 hour concrete floor slab”. This simply means that the given floor slab has been tested under specified lab conditions to be fire-resistant for up to the time indicated — 2 hours.
You should note here that firestop materials alone do not possess the fire-resistance rating, but the overall installation along with the material and arrangement of any penetrating objects determine the fire rating.
For example, plumbing, electrical wiring, and other various ducts often enter and exit through walls, floors, and ceilings. This can’t be helped. But naturally, this opening creates a weakening in the fire-resistance of the given surface which must be filled so as to ensure the original fire rating.