Thursday, April 06, 2006

Sunroom (breakfast area) added

Yesterday we added the sunroom, and this morning we pegged it together. The long wall of this room faces "solar" south, and will be 90% windows. The rafters (and roof) overhang the south wall considerably, to keep the direct sun from hitting the windows in the summer and baking us. (The summer sun is higher in the sky than the winter sun.)

Before digging our foundation, I oriented our house exactly in line with the sun at high noon. To do this, I went on to and found the sunrise and sunset for our zip code. (you can do the same with a GPS unit that gives sunrise and sunset). I then divided the difference by 2, and added that to the sunrise. That gave me the exact minute that "noon" happens at our location. I put a very long pole in the ground, careful to keep it vertical, waited for exact noon to happen at our location, and recorded the shadow line cast by the vertical pole. I then aligned everything in the foundation, according to the shadow that was cast on the ground at high noon. This was very important to us, because we plan to have solar panels on the roof of our house, and will use the windows on the south side of the house to gain some heat in the winter from "passive solar gain". (BTW, most windows nowadays are glazed so as to limit solar heat gain, so we had to order special windows for the south side of our house - but that's another article).

There are no diagonal (wind) braces in the exterior walls of this room. The main reason that I left them out is that they interfered with the windows and and french doors. My wife especially hates pictures of timberframe houses with braces in front of otherwise unobstructed windows. (I have to agree with her - seems like poor planning). But won't the room be shaky or flimsy? Well, partly I'm relying on the fact that this relatively small room is tied to a very stout structure, and partly I'm relying on the SIPs that will enclose this room to add stiffness.

In the picture, you can see that we we are flying the last rafter in to place. About 2 hours before this picture, we were scratching our heads because the rafters were not fitting at all. I had forgotten to notch the top plate to accomodate the rafters. The top plate was already in place, so we had to notch it in right there while standing on the scaffolding you see in the picture. Whoops!


Blogger oldmilwaukee said...

At least a year after writing this blog entry, I discovered that my method for finding solar south was (somewhat) flawed. As it turns out, my method will work precisely only 4 days out of the year. Fortunately, when I made my measurements, it was close to one of those 4 days. Google "analemma" and you will see why my method is not precisely right for 361 days of the year!

February 2, 2008 at 9:52 AM  

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