Before going to any extra expense, consider a few points. Attics get hot in the summer, so make sure the items that you plan to store can handle the heat. You can dramatically cut the heat with attic foil and good ventilation, but it still gets pretty toasty up there.
Also, consider the access opening to the attic and its convenience. Are the items big and heavy? Will you take them down often? Will they stack nicely in the attic? Do you have an obscure location for a large attic access opening? You may determine that your attic is not an ideal location.
Now, let’s assume that you reviewed it, and attic storage will work. I store a lot of small ceramic items in my attic. The heat does not affect them. The fall to the bedroom floor when I nearly pass out from the attic heat is hardest on them.
If you want a highly pitched roof, it may provide enough headroom to build a large attic room with an 8-foot ceiling. Obviously, the steeper the roof is, the more headroom inside. With your needs, you’re probably better off just building a lower-cost attic storage space.
Roof trusses are computer-designed for your house plans, size, roof pitch, etc. The most efficient use of lumber for a strong truss is a design made of many triangular sections. As your (hopefully former) builder indicated, the lumber will get in the way.
Truss designers and builders can create light storage trusses. The lumber support members in these trusses are designed to leave a large open square area in the center instead of all triangles. To attain the necessary strength with this less optimum design, more lumber is used and each one costs about 30 percent more.
If you decide to go all-out and build an 8-foot-high room in the attic, you will need full-room attic trusses. These trusses typically cost slightly more than double the price of a standard truss.
Roof pitch is measured in rise over run. For example, a 6/12 roof rises 6 inches for each horizontal foot. This may sound steep, but it is less than 30 degrees and easy to walk on. I consider any roof over about 10/12 (40 degrees) to be steep and difficult to walk on.
If you remember your high school geometry, you can determine the maximum width of a full-height room for various spans (house depth) and roof pitches. For example, a house with a 38-foot span and an 8/12 pitch could accommodate a 12-foot-wide room. With a 10/12 roof, the room width could be 16 feet. Your truss builder can help you with the numbers.
Another factor to consider with your plan for a steep roof is the cost of the roofing material and the labor to install it. A steeper roof has more surface area than a flatter roof, so the roofing costs will be higher. A large, steep roof like this is a good candidate for an attractive residential-type metal roof.
By this time, you probably realize that you need to go back to the drawing board and thoroughly think through your storage area needs and your construction budget. This should not delay your beginning date because there is much work to do before you get to the roof.
