window geometry

Nov 16, 2004 5 Replies

I am building a chalet style house with a 14/12 pitch roof. There will be triangle shaped windows near the peak and I want them to follow the roof pitch. The face or prow of the house with be angled back 15 degrees on each side so my question it will the windows look right if they are 14/12 or does the angled back face of the house cause a geometric problem. I similar house can be seen here.



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The geometry will cause a problem. To convince yourself, imagine to rotate out the walls with the triangular window, as you do this, the height of the triangle gets smaller and smaller until it vanishes when the walls are rotated a full 90 degree.

The slanted side of the triangle would match the roof pitch if the wall was simply straight, the slant disappers if the wall is at 90 degree because now it meets the roof eve jutting out straight. At intermediate angles, the triangle is intermediate from 14/12 to 0/12.

Hope this is clear.

MG

So how could I calculate what pitch window will follow the roof pitch when the each side of the face is set back 15 degrees. Or actually what roof pitch will match my 14/12 windows which I now have because the brilliant draftsman didn't foresee this problem. Thanks for you help.

The windows rise 14" for every 12" sideways they run. Since they're 15 degrees out of plane, then the horizontal component will cos(15) * run of the window, or .9659.

So the matching roofline would be very close to 29/24

--Goedjn

If we chose a 12/12 pitch roof what would the proper window pitch be?

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