| 摘要 |
A method and apparatus is provided for preventing a composite material used in forming slabs for residential and commercial construction from entering a predefined space that is maintained open for pipes, plumbing fixtures and other conduits. The preform apparatus comprises a body, apron and cover. The apparatus is assembled by placing the preform body in position to occupy a predefined space, press fitting the apron down over and around the body and the cover on top of the body. Thereafter, the composite material is poured around the preform and allowed to cure. After curing, the preform body and the cover are removed, leaving a material free void within and below the predefined space that the preform had occupied. The preform is straightforward, inexpensive to produce, easy to use and is assembled without fasteners and without disturbing the soil below the slab or the moisture/vapor barrier.
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