Expert: Nazim Nice - 5/12/2009

Question
My husband and I are building a small 10'x10'x6' gazebo with a metal roof but we're not sure how to make the rafters. I want it tall enough to add a ceiling fan but I can't figure out the angle of the top. Thank you.

Answer
Hi Cindy,

Well, the first thing you probably need to decide is the shape of the roof.  If it's square, then you may want a pyramid shaped roof, although this will be the most challenging to frame.  For a simpler roof, try a gabled end roof, with just one ridge along the top.  For the simplest roof design, but a more modern look, try a shed roof, with one slope in one direction.

For actually how to construct this, you might try looking for a framing construction book at the library, online, or at a book store.  You may also want to construct a structural engineer to help out.  Keep in mind that when you put a roof on a structure, it tends to push the walls or columns out, so it's often necessary to have structure that ties the walls or columns together.  The last time I designed a square room with a pyramidal shaped roof, we actually ended up having a welded steel frame fabricated  because we wanted vaulted ceilings inside.  I'm guessing you probably don't want to do this, so look for a framing example that ties the room together on the outside.

As for the actual angles to cut, that's going to be a challenge if you've never done this before, but it's just geometry.  I would suggest constructing a small mock-up first so you can establish what angles will work.  The angles will naturally depend on the slope of the roof.  With a metal roof, you're typically looking at a minimum slope of 3 inches in 12 (3:12) but you may want steeper if you want more height for the ceiling fan.    

You may want to look online too for some gazebo plans or other tools such as this one:
http://www.blocklayer.com/gazebo.aspx (it's metric but it seems to help you out with some angles).

I hope this helps and good luck on your project!

Nazim Nice
Principal / Architect
http://www.motion-space.com
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