There are various greenhouse roof styles available. I always get asked what the difference is. Well, some will give you a little more headroom and some may give you a little more room to hang plants, but really the basic difference is just the looks.
Straight Eave or Gable Style – This is basically the same style of roof as a traditional or ranch style home. It is shaped like a triangle if you look at it from the end. There is a simple mathematical formula to calculate the long side of the roof, for example, if you want to buy an awning. You will need to know the width of the greenhouse and the height of the side wall and the height of the spout. You take the width of half the greenhouse in inches and square it. Take the height of the peak and subtract the height of the sidewall. Take this measurement in inches and square it and add it to the number you had before. Then take the square root of this sum and that is the length of your greenhouse roof on one side. To calculate the entire roof, simply multiply by two.
Curved eaves roof – that’s what it sounds like. You can find this in a pipe frame with polyethylene or polycarbonate film. Or, you can find it in an aluminum frame with glass or polycarbonate. You may need to size this up to replace polyfilm, polycarbonate, or a shade cloth. The easiest way to do this is to apply a tape measure to the frame and simply measure. There is no simple calculation because some of these are simply not true semicircles.
Gambrel Shaped – This is also called a barn roof. It is made up of multiple angles that form a peak. It was best to measure the size of this as well with a tape measure. These are not as common and are usually housed in a resin (or plastic) frame.
Straight eave styles are available in several different roof pitches. You will usually see a 5 in 12, 8 in 12, or 12 in 12 shades. What this tells you is the number of inches the roof drops in a distance of 12″. A roof pitch of 5 in 12 will drop 5″ for every foot the roof comes out. A field of 12 over 12 has a 45 degree angle at the top of the greenhouse.
I hope this helps you to choose which roof style you prefer for your greenhouse.
