I answered a question recently about a someone’s possible attic space, this is what they wanted to know -> “How much space will I have in my garage attic if it is 25′x25′ and the roof pitch is 6?” I believe this person was trying to put a room in the attic of the garage (not sure if it was for a frog or storage)… Here is how you work out this problem. First when someone says they want a roof pitch of 6 they are saying that the roof rises at 6 inches per foot of travel (approx 27 degrees). We will assume that the garage will have a Gable roof, not a Hip roof (a gable roof is like putting two rectangles at an angle at either side of the building with gables on the other sides, a hip roof would have 4 triangles with the points of the four triangles meeting at the apex of the roof like a 4 sided pyramid – for a square roof).
Split the width of the building in half for easy measurement – 25/2 = 12.5ft. If we want to find the approximate area that will be 8 ft in height we will need to take 12.5 ft run x 6 in (.5ft) rise = 6.25ft. – This means that with this current set-up the garage roof will never reach 8ft. We will have to change the pitch if we want to use this space for a frog (or add a 3-4 foot wall before adding the roof, which would raise the roof). If we change the roof to a 12 pitch (45 degrees), we will reach 8 feet rise in 8 feet of run – this means that we will have 4.5 feet of floor space in 12.5 feet of run (12.5 – 8 = 4.5) and 9 feet in a 25 feet of width. If we take the total length of the gabled roof 25 feet x 9 feet for the width = 425sq ft. This is approximate square feet, it could be more or less depending on framing, usage of areas under 8ft., etc. Remember when you change the pitch to 12, there will be more shingles and more rafter material. Also the roofer will charge you more because 12 pitch is too steep to walk on without some sort of mechanical assistance (usually 2×4 toe boards). Compare price and design with adding 4 feet of wall after the floor level and determine which one fits your budget and house best.

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