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