You will need to consider the siding and roofing materials you would like to use to finish this space. And you might weigh the quality of exterior materials against their visibility. Also in the cost of the addition, be careful to factor in the permits needed and the work needed to prepare the foundation.
Envelope size - 4-3/8 x 5-3/4. Card paper size - 5-1/2 x 8-1/2 (half a letter sized sheet). Finished card size - 4-1/4 x 5-1/2. A4: Envelope size - 4-3/4 x 6-1/4. Card Paper Size 8 x 12-1/4. Card finished size - 4-1/2 x 6-1/8.
In the U.S., a letter sized sheet of paper is 8.5 x 11 inches; legal size is 8.5 x 14 inches<br /><br />Much of the rest of the world, however, uses A4, which is 21 cm x 29.7 cm.