A person or company that specializes in applying dampproofing treatments to buildings, or the material used to make something dampproof.
From 'dampproof' plus the agent suffix '-er,' meaning someone who performs dampproofing, or a substance that does it. This trade became formalized in the 20th century.
Calling someone a 'dampproofer' sounds almost comical, but it's a real specialized trade—these experts can tell if your house is about to get destroyed by moisture creeping up from the ground!
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