Joists in home construction are usually made with 2 by 10 or 2 by 12 lumber.
Floor depth light.
Light loads for one to two light cars or trucks the concrete should be at least four inches thick.
The zone between 200 meters 656 feet and 1 000 meters 3 280 feet is usually referred to as the twilight zone but is officially the dysphotic zone.
In this zone the intensity of light rapidly dissipates as depth increases.
Light shelves also have size limits.
Deviation from due south should not exceed 15 in either direction for best solar access and ease of control.
Medium loads if the garage is used for average sized vehicles and or medium to heavy trucks the concrete needs to be six inches thick.
From south to north has been shown to be viable for daylighting.
Only a small amount of light penetrates beyond this depth.
Hardwood floors and standard carpet with pad add about 3 4 inch to the floor height.
The depth of light shelf should be equal to the clerestory or transom above it and no deeper than 30 inches.
Vinyl flooring is usually the thinnest choice for floors and 1 8 inch vinyl installed over 1 4 inch underlayment will add only 3 8 inch to the floor height.
Also light shelves should be installed high enough to be out of hanging reach and to avoid a feeling of claustrophobia.
A floor depth of no more than 60 ft 0 in.