You Can Build Your Own Add-On Greenhouse

Regardless of what thickness or grade of glass you wind up using in your conservatory, each pane must be glazed properly. Fit it precisely into its opening with a little space all around and seat and seal all four edges with a firstclass glazing compound. Putty—which was "standard" for this job for years-is difficult to work with and soon becomes brittle, falls away, and must be replaced. Forget it. The new mastic-type glazing compounds are much better and the plastic glazes even better yet. Both are extremely easy to install with a glazing gun.

The solid part of your conservatory's roof and any closed portions of the building's sides, movable ventilation panels, etc., can be fabricated of new boards or plywood, recycled siding, salvaged hardwood flooring, or you name it . Once again-if you're purchasing your materials- redwood, cedar, or Douglas fir is the best way to go. Almost any good construction lumber protected by a good coat of preservative, however, will do.

Roofing? Again, that's your choice. Plain old roll roofing laid down over a base of flat boards or plywood, though, is about as inexpensive as any you'll be used to waterproof the joint where the greenhouse roof attaches to the wall of your main building. Corner guards (another kind of flashing made especially for the job) should also be used to protect the end grain of any siding applied to the walls of the conservatory.

HEATING EQUIPMENT ... AND TIPS

Whether or not you'll have to artificially heat your lean-to greenhouse depends on a great many factors: where you live, what you plan to grow in the building, the size of the structure, what kind of floor it has (a massive cement or brick floor will sop up the sun's rays during the day and then radiate the warmth back at night), what kind of wall the lean-to is built against (a masonry wall will tend to regulate the conservatory's temperature just like a massive cement floor), how much glass is in the roof and walls of the greenhouse, etc.

The article in this issue by Helen and Scott Nearing (see pages 28—30) will give you some idea of what you can accomplish with a completely passive solar-heated greenhouse in even a harsh New England climate. And there are a number of things you can do to make your conservatory stay warmer than it otherwise would on just the "free" heat from the sun.

Plant a double row of evergreens, a thick hedge, or some shrubs as a weatherbreak between the glassed room and winter's worst storms (which, in most sections of the country, strike from the north or northwest). Install wooden shutters or roll-up blinds or heavy drapes inside the glassed portions of the lean-to and deploy them at night. Weatherstrip all cracks in the greenhouse and remember that Thermopane (double glazed) windows are certainly more expensive than ordinary glazing ... but, in the long run, more than pay for themselves.