You Can Build Your Own Add-On Greenhouse

Generally, then, a conservatory measuring 10 X 12 or 10 X 16 is all you'll need to add a real touch of elegance to your house. And do consider the height of your glassed-in addition. In the first place, there's nothing like a tall ceiling to give your personal plant palace that old-fashioned conservatory look we all love. And, in the second, you'll find a high roof line essential if you ever decide to mix a few big and gorgeous tropical beauties in with your smaller potted plants.

TOP LIGHT

When you're planning your structure's top light, do not—I implore you!—do not make the greenhouse's roof all transparent glass or plastic. If you do, the conservatory will be far too hot in the summer and too cold during the winter. There's no need to admit that much sunlight anyway. Almost any plant you'll ever want to raise will do fine with 30% top light ... even if the illumination is admitted through skylights or plastic bubbles.

MATERIALS

For a handsome, durable plant room floor that resists both stains and water, use concrete. For what it does, it's very inexpensive ... and you can pour it yourself.

Bricks—when laid on a level base of sand—also make a good greenhouse floor. And, while they may cost you more than concrete (unless you salvage the bricks from a demolished building), there's no question that most homeowners find it easier to set bricks in sand than to pour and trowel concrete.

In a pinch, cinders or gravel can be spread several inches deep directly on the ground as temporary greenhouse flooring. Neither is nearly as satisfying over the long haul as concrete—or bricks embedded in either sand or mortar—however. If used at all, neither cinders nor gravel should be thought of as anything more than stopgaps that will eventually be replaced by something more durable.

You can buy new lumber and sashes for your conservatory's walls and roof if you like ... but recycled doors, windows, boards, and beams can be just as satisfactory, can look just as good, and most certainly can cost a great deal less. If you can't scrounge up such used materials yourself, try finding what you need at salvage yards and bargain centers. And pick up your recycled lumber, doors, and windows first. It's much easier and far less expensive to construct as much of the greenhouse as possible from recycled materials and then fill in around them with new ... than to try to work the other way around.

CONSTRUCTION: FOOTINGS AND FOUNDATION

It will probably take more time and muscle—but not necessarily more money—to put in the base for your conservatory than it'll take to construct all the rest of the add-on room. For this reason and because of the foundation's importance (after all, the footings do have to hold up everything else in the building), you may prefer to have this part of the greenhouse done by professionals.