Although there are a variety of measuring units, firewood is normally sold by the cord, or a fraction of a cord. The dimensions of a "standard cord" is a stack of wood piled 8 feet long, 4 feet wide and 4 feet high. You won't get a full 128 cubic feet of firewood with a standard cord because of the airspace between the pieces of the wood; the amount of wood in such a stack will depend upon the size and straightness of the pieces, how they are split and how the wood is stacked. Because of this, the total cubic feet in a cord can vary from 70 to 90 or more cubic feet.
When hiring a roofing contractor, the lowest-bidder is not always the best for the job. Roofers with good insurance, good safety equipment, and well-trained, skilled employees charge more than fly-by-night outfits, and rightly so. Quite often, that roofer will have a standing relationship with a reliable manufacturer who puts out a good product and backs it up. Check the insurance, license, professional certifications, and references of any roofer you interview. The right shingle and the right roofer will make for a lasting job.