This is great information! So many homes have a fireplace, even here in Florida and I would bet that MOST of us don't have this information!
Perhaps one of the single most “expendable” components of a home today is the solid masonry chimney. In new construction they are almost entirely absent----even on very high-end homes. They have given way, to any number of cheaper versions of chimneys----often without any masonry at all.
When inspecting older homes, that do have brick chimneys, they are often in need of repairs----like the one pictured at the left in one of the old Seattle neighborhoods near Volunteer Park. The costs of these repairs often run into the many thousands of dollars.
Because bricks are heavy, these chimneys can be a serious safety hazard as well. No one wants to have a brick bounce off their head when they visit you.
Sometimes converting these old brick chimneys to direct-vent gas burning fireplaces can be an economical thing to do, instead of taking on these costly repairs. While gas fireplaces are not cheap-----if you have to rebuild the top six feet of your chimney----that is not cheap either. It is not possible to construct a wood burning fireplace that will be as efficient as an air-tight, direct-vent, gas fireplace. These gas fireplaces will provide heat and romance. When you are lying on your bear skin rug (a sleeping bag will do) in front of the fireplace with your sweetie, neither one of your back-sides will be cold like they used to get with that old fashioned wood burning fireplace. Old fireplace chimneys sucked tremendous amounts of heat out of the home. You felt warm as long as you faced the fire----but surfaces away from the fire(like your naked butt), or other rooms, became colder----even drafty.
Wood burning chimneys required that the top of the chimney be specific distances away from roof surfaces to protect the roof from fire, therefore, these chimneys could end up being VERY tall. Typically, inspectors will look for the top of the chimney to be 24” higher than any part of the roof 10’ away---horizontally.
Gas burning appliances do not have to follow the same rules. Therefore the top part of the brick chimney----which is usually in the worst condition and the most poorly maintained----can be removed down to the roof line----or even below the roof line if the chimney runs up through the center of the house. The old chimney flue is lined with a metal vent pipe and a metal cap is then installed to cover the top. The new metal vent for the gas fireplace (or other gas appliance) then runs through this cap.
Many newer homes avoid the entire masonry structure and vent directly out though the side wall of the house----saving way more money than what it would have cost to build a masonry chimney. Sometimes it is cheaper to take down the whole chimney than it is to rebuild one that is in poor condition (and doesn't everyone need patio bricks?).
As I stated already, gas vents do not have to stick though the roof very far. Most roofs (6/12 pitch and lower) only require that the vent stick through the roof 12”----barely enough to become “unsightly.” This is true whether the vent is for a gas water heater, or a gas furnace or a gas fireplace.
So go ahead and roll out that bear skin rug----or sleeping bag!
Charles Buell, Seattle Home Inspector
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