Today, 80% to 90% of California's large warehouse buildings are tilt-up concrete. Though masonry isn't poised to steal the lion's share of this market, it has built its own niche and is making some in-roads in tilt-up's domain. In California, as in many other areas, masonry is almost required on building sites that are small, tight, or sloped. Usually masonry is less expensive than tilt-up concrete on buildings smaller than 20,000 square feet. California architects frequently use masonry on shopping centers and retail buildings-even large ones-for its aesthetic appeal and greater flexibility. On large buildings (100,000 square feet), some owners and developers find that masonry's faster construction and the earlier occupancy and increased income it brings more than offset its higher construction cost. And in Southern California, a construction cost estimating firm has found that masonry is less expensive than tilt-up for many buildings that must be heated or cooled. Aesthetics, flexibility, speed, and thermal properties are giving masonry definite advantages over tilt-up concrete for some building types.