The Collaborative International Dictionary of English v.0.48:

Roof \Roof\, v. t. [imp. & p. p. Roofed; p. pr. & vb. n.
   Roofing.]
   1. To cover with a roof.
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            I have not seen the remains of any Roman buildings
            that have not been roofed with vaults or arches.
                                                  --Addison.
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   2. To inclose in a house; figuratively, to shelter.
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            Here had we now our country's honor roofed. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Roofing \Roof"ing\, n.
   1. The act of covering with a roof.
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   2. The materials of which a roof is composed; materials for a
      roof. --Gwilt.
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   3. Hence, the roof itself; figuratively, shelter. "Fit
      roofing gave." --Southey.
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   4. (Mining) The wedging, as of a horse or car, against the
      top of an underground passage. --Raymond.
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WordNet (r) 3.0 (2006):

roofing
    n 1: material used to construct a roof
    2: the craft of a roofer

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "roofing":
   adobe, ashlar, brick, bricks and mortar, ceiling, cement, clinker,
   concrete, covering materials, eaves, ferroconcrete, firebrick,
   flag, flagstone, flooring, housetop, lantern, lath and plaster,
   masonry, mortar, overhead, pavement, paving, paving material,
   penthouse, plafond, plasters, prestressed concrete, ridgepole,
   roof, roof garden, roof-deck, roofage, roofpole, rooftop, rooftree,
   shingles, siding, skylight, slates, stone, tile, tiles, tiling,
   top, walling