Outdoor Fireplaces
A recent and interesting trend in house design is the inclusion of an outdoor fireplace. Sometimes this is a free-standing fireplace on a patio or terrace that might be a part of an outdoor kitchen arrangement. Or, if you live in the land of night time bugs like I do, your outdoor fireplace might be on a screened porch. The wonderful thing about outdoor fireplaces is how they extend the season of your outdoor living spaces. 
It used to be that you had to build these outdoor fireplaces the old fashioned and expensive way with bricks and concrete block. Then came the advent of pre-fab fireplace units that were built from stainless steel so they could be used outdoors without rusting. This reduced the cost, but unfortunately, these units are limited in size and it’s tough to get a roaring fire in them, the kind of fire that keeps you warm even if you’re several steps away from the firebox.
Now we have a new option. There are fireplaces you can build from prefab parts. The parts are made of lightweight concrete that is made with volcanic ash and cinders. The volcanic material gives the concrete better thermal properties, letting it reflect heat more efficiently than standard masonry. Because they are a kit of manufactured parts, the cost is less than traditional masonry. The very best part is that they are available in large sizes, even up to five feet across. That will take some big logs.
You can find out more about them at www.isokern.net and www.firerock.us.
Bill Hirsch
www.designingyourperfecthouse.com
Tags: architecture, dream house, fireplaces, homebuilding, house design, outdoor living, residential architecture, screened porch
August 19th, 2010 at 11:27 pm
Hi Bill, great tip on the masonry insert. I’m planning a wood burning fireplace on my porch. The biggest concern I have is smoke backing up out of the fire place and into the porch living area. Can you recommend a fan or blower system that will provide constant draft. The unit I saw was $1,200…..seems steep for a fan.
Thanks,
Marc
August 20th, 2010 at 11:39 am
Marc – With a properly designed fireplace and chimney, you shouldn’t need a draft-inducing fan. The chimney needs to be high enough or it won’t work properly. The way it works is the hot air from the fire rises (hot air rises and cold air falls) and it travels up the chimney. As it does this, more air is drawn into the fireplace to replace the hot air that has left. This air is then heated and it rises, thus repeating the process. This is called a convective loop. The taller the chimney, the more powerful the air flow will be and the fireplace will draw better.
Be sure that your chimney is at least three feet above the surrounding roof and at least two feet above any roof or structure within ten feet of it. If the roof shapes cause the wind to swirl and create a downdraft, make the chimney a few feet higher.
One other tip: When you start your fire, warm the air in the flue first to start the air rising. You can do this by rolling up a piece of newspaper, lighting one end like a torch, and then holding the lit end just beneath the damper. If you don’t do this, sometimes the cool air in the flue will act as a stopper, keeping the smoke from rising until it warms up. This will cause a bit of smoke to get into the room or porch and the room will smell smokey.