Backyard #4 - Patio Cover

Now that the fire pit is done, and the patio has had a chance to cure, I have moved on to the patio cover. I was able to get the main structure in place this weekend - here is a rendered image of what I plan to build...


It's a pretty simple design:

Ledger attached to the house

Main beam to support the rafters

Four posts (two on each end) with stone bases

Large 4x6 rafters, on a 4/12 pitch (same as the rest of the house)

Solid wood roof deck, stained on the under side for the vaulted ceiling

Total area is about 160 square feet

Here is the progress so far...


The main beam is built up of three 2x8's glued and nailed together. Here is how I calculated the needed beam size:

The span between the two inner posts is just under 12 feet, and the rafter span from the beam to the house is 6.5 feet.

The general load requirements for Portland, Oregon are 10lb dead load / 25 lb live load (for snow). Even though there are no formal requirements for patio covers under 200 sf in my area, I of course want my project and my house to last (not sag).

I looked at various span tables for patio covers (I will link to these below) and determined that I needed either a 4x10 or a 6x8 beam. I wanted a thicker looking beam anyway, so I chose the 6x8. I built it from 2x8's since I am going to wrap it in hardiplank later on. Doing 3 pieces also allowed me to easily leave mortice holes for the posts.

The rafter requirements are very light - 2x4's on 24" centers. I think going that route would save a few dollars, but the cover would look light-weight and cheap. After looking at 2x6 and 4x4 rafters on other houses, I decided to go with 4x6's. They are substantial enough to give the cover a "craftsman" feel, and not really much more expensive. These are painted the brown color that we are going to paint the house trim. They should contrast nicely with the stained roof deck. I put these on 32" centers - the spec sheets say I can go up to 48", but I like the look of them closer together. At $11 a peice for 10' long ones, it only cost me $22 extra.


The ledger on the house took longer to get in place than I thought it would. I took my time to make sure it was square, level and centered with the beam I put up. I attached it with 1/2" lag bolts on 32" centers. If this isn't installed very level and even, then getting everything else lined up later on will be painful.

I decided to go with a 2x8 ledger, so I could attach a 1x2 lip at the bottom for the rafters to sit on. I did this for two reasons: It makes holding the rafters much easier when you are attaching them, and it covers the bottom gap where the rafters meet the ledger. I noticed this on a number of patio covers I looked at.




The rafters are attached to the beam with L-brackets and then lag bolted through the tops in to the beam.

Helpful documentation that I used to design the patio cover:

This patio cover building permit form gives a lot of design information. Note that is for a 10lb live / 10lb dead load (no snow)

This document is for patio covers in Fort Collins, CO - 30lb live / 10lb dead loads (lots of snow).

Finally, here is a good middle of the road one at 20lb live / 10lb dead load.

From these three sources, you should be able to spec an appropriate cover for your area and design choices.