The vacuum tube in a CRT can implode if it is broken or punctured. The surrounding air will rush violently into the unsealed vacuum in the CRT, spraying broken glass in every direction. Color CRTs may contain mercury or other potentially toxic materials.
Instructions. Build a hearth for a fireplace that is 16 inches deep, according to This Old House writer Harry Sawyers. This is the standard requirement for municipalities and homeowner associations. The hearth should also extend a minimum of eight inches on either side of the fireplace.
Hearth. â The area on the floor in front of a fireplace. It will normally be some type of masonry material: stone, brick, slate or marble. Most building and fire codes around Philadelphia and Montgomery County, PA, call for it to extend at least 18â³ away from the front of the fireplace.earth. â The area on the floor in front of a fireplace. It will normally be some type of masonry material: stone, brick, slate or marble. Most building and fire codes around Philadelphia and Montgomery County, PA, call for it to extend at least 18â³ away from the front of the fireplace.