16. Installation – prefabricated chimneys Prefabricated chimneys offer the best possible performance for woodburning & multifuel stoves and in most cases are simple to install. Because they heat up rapidly, the precipitation of moisture and tars is generally much less than in masonry chimneys. XXThe illustration at right shows a typical set-up. It is undesirable to have flames contacting the stainless sections so a short length of vitreous flue pipe (VFP) is used directly over the stove. This can be omitted for stoves with a long fluepath (typically cookers) where flame contact is infrequent and slight. XXNote three further points;- Joints must be staggered above or below the joists. These are 'hot-spots' and might otherwise represent a fire hazard if a chimney fire occurred. A 50mm gap must be maintained between the outer skin of the insulated chimney and any flammable materials. The chimney must not be supported by the stove; it must be self-supporting. A ceiling support bracket is often the neatest arrangement.