A Green Building Project - Window Awnings

Jim wanted to design a better support system for the awnings on the house we are building. The system must be strong, weatherproof, attractive, and easy to fabricate and install. Although the awnings themselves are very lightweight, they will have to resist strong wind loads and the weight of workers who might happen to stand on them.

Chain link fence parts.
Using standard chain link fence parts seemed like a good possibility. The relevant pieces were the round fence pipes, plus a standard part called a “loop cap.” In the photo, the loop cap is the little piece that secures the angled vertical pipe to the horizontal pipe.

Selecting a pipe size.
Fence pipe is sized by its outside diameter. The smallest 1 3/8 inch fence pipe was too small and too weak. In conversations with local suppliers Jim learned that fence pipe comes in a standard grade, or you can get the heavier Schedule 40 grade, which is also known as "rigid" pipe. The 1 5/8 inch pipe had a nice size to it and appeared to be strong enough in the Schedule 40 grade.

Is the pipe strong enough?
Jim called Metalink fence supply in south Austin and asked if two heavy men were to do chin-ups in the middle of a 7 foot length of 1 5/8" Schedule 40 pipe, would the pipe sag? They assured him it would not. Then they mentioned a new product - SS 30 High Strength Pipe, from Allied Tube. It is stronger, lighter and cheaper. So he selected the SS 30 - 1 5/8" pipe for both the horizontal (header) pipes and the angled vertical struts that would support the headers.

Attaching struts to headers.
To put the support system together, the first requirement is to attach the struts to the headers. This was done with the standard fence part called the "loop cap."

Jim intended to attach the loop cap to the top of the struts with ¼” bolts. However, he realized that this would require drilling the pipe with exactly perpendicular holes through both sides of the pipes. Another problem was that the loop on the loop cap was bigger than the size of the pipe. This would allow the header pipe to move around inside the loop. When he bought the parts, he planned to install a bolt across the loop to create a space just big enough to snugly receive the 1 5/8" pipe. But, due to the irregular shape of the loops this began to seem impractical, if not impossible.

As an alternative to bolts, a thick self drilling screw could be used. However, Jim was not sure that the shear strength of the screw was adequate. So he and Tom, the lead carpenter, made a test sample using the self drilling screws. Before putting in the screws, they drilled two holes on opposite sides of the loop. These holes would steady the screws in position as they penetrated the pipe. It was surprisingly easy to penetrate the thick pipe with the screws and secure the loop cap around the pipe.

Testing the screws.
Tom took the test sample and placed the loop cap down on the floor. He then beat on the pipe with his large framing hammer. When the high strength pipe began to deform without the screws giving way or the loop cap collapsing, it was clear that their system was more than adequate in strength.

Attaching struts to house.
Jim could not find a fence component that would hold the struts and attach them to the house wall. While visiting a friend's construction project, Jim noticed some 2" x 2" x 1/8" galvanized angle iron was being used. He bought two 10 foot pieces of the angle iron and had it cut into 5 1/2" pieces for under $88 at Westbrook Metals in north Austin.

Attaching the struts to the wall with the 2" x 2" angles was very simple. They drilled each angle with holes for two 1/2" x 3" lag screws to go into the structure. They also drilled a 3/8" hole through the bottoms of the strut pipes to receive a galvanized hex head bolt. In the photo you can see how the strut is attached to the house, using the angle iron.

Attaching the header pipe to the awing.
The last step was to find a part to secure the header pipes to the underside of the awning rafters. At the suggestion of our good friend, Bill Moore, Jim bought some straps at Lowe’s that are used for securing electrical conduits. In the photo, these are the metal straps that hold the pipe and attach it to the underside of the awning rafter.

Once figured out, this system is not expensive or hard to do. And, for someone like Jim, figuring it out is the fun part. View our blog for this project at: www.weloveaustin.com