A few recent threads have raised questions about the “fire code,” and how it impacts your remodelling. I thought I’d start a thread about just what, exactly, is involved in designing for fire resistance.
Fire Code? Huh? We have a whole variety of codes … building, fire, electrical, housing, zoning, whatever. Every one has elements that address specific “fire” issues. Each also has material that is completely irrellevant. The first think you need to address is: what am I trying to protect against?
House fires, and fire protection, concern two types of fires: those outside the house, and those inside. It’s important to understand just what you are worried about.
“Outside” fires might be your house being exposed to a fire in a neighbors’ house, or a fire in the garage. Various approaches are used to prevent these “outside” fires from entering your house. These measures include setback / spacing requirements, fire-resistant facings (like brick), and fire-insulating materials (like drywall).
There are all manner of proven, detailed designs of walls that will block such a fire for whatever period of time you specify.
The biggest fire concern, however, is within the house. One could build a house comletely from asbestos, and still have a massive fire within. Why? Because it’s what’s inside the house that burns – not the house itself. The ‘contents’ includes not only your personal belongings, but your decorative parts – the carpet, the panelling, that varnished wood floor.
Let’s assume, for the moment, that a fire starts. Say, the “traditional” smouldering cigarette in the sofa cushions. Let’s look at what happens; that we can look at how we can protect against this fire,
Eventually, the sofa will burst into flame. The foam cushions are like a foamy gasoline, spewing flame and burning foam all over. The flames sear the walls, scorch the ceiling. Carpet and drapery is set on fire. All your books, your media center, the kid’s toys and the wife’s clothes add to the fire. Trim molding and the finish to the panelling ignite. As the fire progresses, it burns deeper into the wall. Flames and hot smoke are drawn into the electrical openings, and ignite any insulation found there. The stud cavity acts like a chimney, and the fire spreads to additional parts of the house. The air conditioner kicks on, and pumps fresh air to the flames… while sucking the fire into the return ductwork.
Codes require “fire blocking” between the studs. Before that blocking can perform,that fire needs to be pretty serious. How about we keep things from getting so bad? How can we do that?
Well, the first idea is to limit what can burn in the first place. Were that sofa replaced with a concrete park bench, there would be nothing for that cigarette to ignite. OK, maybe that’s a little silly, but you get my point. HOW you decorate and furnish the house makes a huge difference. With a little effort, and additional expense, you can find drapes, carpets, and furniture that don’t burn quite so enthusiastically as the “unknown content” bottom-dollar stuff you find at Discount Import World. I suspect a leather-covered sofa is harder to ignite than one covered in polyester velour.
You also limit fires by such simple things as keeping the house clean, and closing doors.
Your first line of defense is your smoke alarm. With luck, you will be there to respond before the room is filled with flames.
If you’re not there ….. how about a sprinkler to spray water, limiting the fire until someone responds? Fire sprinklers have a simply awesome record in reducing fire losses.
Panelling catching fire? Well, that drywall behind the panelling will keep the fire out of the wall itself. There’s no reason you can’t layer plywood atop the drywall. Nail the plywood to the studs, and fix the panelling to the plywood. Extensions exist for electrical boxes. Conceal the thickness with your trim molding. OR … ‘fake it’ with wood-grain wall paper behind the molding.
I simply cannot stress enough what a ‘miracle material’ we have in ordinary gypsum drywall. Nothing so easily blocks the spread of fire as a thickness of drywall. There are ‘specialty’ versions that bend easier, that are more resistant to damage, and are more water resistant. Drywall is readily available, affordable, and easily worked.
Don’t overlook your ceilings in fire protection. The ceiling is exposed to the most heat, yet often has the least protection.
Likewise, pay attention to the details. Electrical boxes need to fit tightly into their holes – and need to reach the face of the wall. A box that is “floating” somewhere in the area of a hole, and relys on that plastic cover to hide the hole, is a big opening for fire. That’s also why I don’t like the code-allowed “data rings” used for low-voltage (phone, computer, Cable TV) wiring. These are nothing but pretty hand-size holes in the wall – practically an invitation for fire and vermin to enter.
