This Diploma work investigates internal air ventilated crawl-space in respect to construction and damp. The Diploma work assumes from a general description of crawl-space and general dump problems in ground construction. An internal air ventilated crawl-space is a construction where you take the ventilation air from the building and bring it down to the crawl-space and lets the air circulate before it passes through a retaining aggregate on the way out from the crawl-space. In this matter you get a worm space under the building and a lot less dump problems in form of · Ground damp · Build damp The ground dump reduces through draining around the building, different layer of gravel between the ground and the building and ventilation of the crawl- space. The build dump reduces through ventilation of the crawl-space as fast as possible.