|Project by Thepps||posted 06-11-2013 01:17 PM||11403 views||35 times favorited||17 comments|
This is an attached pergola built mostly out of western red cedar. The main front support 4×12 beam is Douglas Fir. I chose this for strength since it spans almost 18 feet. Everything else is cedar. No visible screws or nails. Lag screws were countersunk, then pegged. Rafters were toe-screwed from above. Shade planks were also screwed from above. Every board’s edges were rounded over with a router.
First off, this is not your usual looking pergola. I built it this way so it would fit our specific needs and to look unique. It is not a square design. The left post sits about 3 feet out of square. If I had built it square, the post would end up very close to the pool steps and would be quite obtrusive. 16’ overall length at the house, 21’6” overall length by the pool and extends 16’ from the house. About 10’6” tall.
There are exposed rafter tails on three sides and the rafters extend past the front support beam about 3’, which is longer than usual. We wanted to keep a comfortable distance from the pool to the posts, but also provide plenty of shade.
All of the 4×12 timber beams connect to the posts by a sliding tapered dovetail joint. A 10” powerlag screw went through each joint. The side 2×10 rafters also connect to the main rafters with this same joint.
All wood is rough
Posts – 8×8”
Support beams – 4×12”
Knee braces – 4×10”
Rafters – 2×10”
Shade planks – 2×6”
Now, to the timber framing:
I built jigs to enable me to cut these joints with a router. I bought the biggest dovetail bit I could find – Amana 45814 – http://www.amazon.com/Amana-45814-DOVETAIL-DIA-SHANK/dp/B000P4LTZ6
After some trial and error, I had a pretty accurate jig – similar to this : http://www.timberwolftools.com/tools/arunda/arunda.html but with a much smaller price tag.
This is a sliding, tapered dovetail. It creates a very strong joint.
4×12 mortise jig
2×10 tenon jig
Built the entire pergola in shop. Stained in shop, also. Then moved it to the house and assembled permanently.
All of the beams are notched for the rafters.
After seeing the pergola installed, I did not like the short timber tails on the front. I made new, longer 4×12 timber tails to extend equally past the posts the same as the rafter tails. This also added some support to the some of the small rafters.
Attached to the bottom of the posts is a 1” polymer standoff, so the post does not sit in water when the concrete is wet. 1/2” rebar connects the post to the concrete
-- Thepps - Freeburg, IL