Waterproofing

Waterproofing means making a surface impermeable to water. On a flat roofFlat roof (roof terrace)The flat concrete roof on top of a building. It is the most common kind of roof in Greece and the part that takes the most sun and rain. it keeps out the rain, in a bathroom the shower water, in basements and foundations the moisture in the ground, and in planters, tanks and pitsInspection pitA small chamber in the ground with a cover, where drain or rainwater pipes meet and can be checked and cleared. it keeps water where it belongs. In everyday Greek it is often just called "insulationThermal insulationA layer of material that lets heat through only slowly, so a home keeps its warmth in winter and stays cool in summer.", but it is a different job from thermal insulation.

There are many systems: bitumen membranesBitumen membraneWaterproofing that comes in rolls of reinforced bitumen. It is torched onto the roof in sheets that overlap at the seams. in sheets, liquid membranesLiquid waterproofing membraneA waterproofing product applied as a liquid by roller, brush or spray. Once dry it forms one continuous, flexible membrane with no seams. applied by roller, elastomeric coatingsElastomeric waterproof coatingA thick, rubbery waterproof paint for flat roofs, parapets and roofs. It stretches without cracking as the building expands and bridges hairline cracks., brush-on cement-based products for basements and bathrooms, and spray polyurethane foamSpray polyurethane foamA foam sprayed on as a liquid that expands on the spot and sets into one seamless layer. It insulates against heat and cold and closes cracks and joints.. The choice depends on whether the surface will be walked on, what is already underneath, and the details around pipes and parapetsParapetThe low wall around the edge of a flat roof or balcony. The joint between it and the floor is one of the most common places for leaks..

Waterproofing is only as good as its weakest point. Most leaks start at corners, joints, drains, railing bases and pipes that pass through the surface. That's why preparation (cleaning, removing loose material, repairing cracksCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention. and primingPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly.) matters as much as the material itself.