Protecting the Foam, and What to Ask

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. insulatesThermal insulationA layer of material that lets heat through only slowly, so a home keeps its warmth in winter and stays cool in summer. and closes the way to water, but it has one weak point: the sun. What goes on top of it matters as much as the spraying itself.

Why it isn't left bare

The sun's ultraviolet light yellows the foam and slowly wears it away. Outdoors it is therefore always covered, and it's best to do this without a long delay after spraying.

The options seen in the jobs

• A white protective coating. On a bare roof and on metal roofsMetal roof sheetingMetal sheets, flat or profiled, used for roofs and sheds. Light and quick to fit, but they get very hot and rust at the screws and cut edges. it was rolled over the foam until no spot was left uncovered. The white reflects the sunCool roof coatingA white or very light top coat that reflects much of the sun's radiation, so the roof and the floor below heat up less., so the space below heats up less.
• A liquid membraneLiquid waterproofing membraneA waterproofing product applied as a liquid by roller, brush or spray. Once dry it forms one continuous, flexible membrane with no seams.. On a roof with torn membranesBitumen membraneWaterproofing that comes in rolls of reinforced bitumen. It is torched onto the roof in sheets that overlap at the seams., a white liquid polyurethane membrane went over the foam, waterproofingWaterproofingThe work and materials that stop water getting through on flat roofs, balconies, bathrooms, basements, planters and tanks. it and shielding it from the sun. It wrapped the air conditioning stands and chimneys on every side.
• TarTarA black bitumen-based material spread hot or as a liquid emulsion. It seals the pores of concrete and keeps water out. and a screedScreedA layer of sand-and-cement mix or lightweight concrete poured over the slab to create falls and a solid surface for the next material.. On a bare slab, the foam got a coat of tar and then a new screed brought up by pump, levelled with a straightedge so no hollows were left. Here the screed protects the insulation and gives a hard surface to walk on.
• Paint on an indoor ceiling. In one room the foam on the ceiling was painted white. The ceiling kept a soft, textured finish.
• RenderRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles. on walls. On the outside walls of a house under construction, render goes over the foam to protect it and give the final finish.

Which option suits depends on whether the roof will be walked on, what equipment stands on it, and how much height the thresholds 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. allow.

Maintenance

The coating over the foam wears with time, faster where it is walked on or where water pools. Take a look at the roof every so often, and certainly after a hot summer or a heavy storm. Look for spots where the foam shows through again, for crackingCrackA 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. around bases and for blocked drains. A small worn patch can be recoated locally before it grows. Don't drag heavy or sharp objects across the surface.

What to ask before the work starts

• What happens to the old materials: are they stripped or left underneath?
• Do the falls need correcting, or is a new screed needed?
• Will a primerPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly. go on, and where?
• How thick will the foam layer be, and will it go up the parapets?
• What will cover it, and when?
• How will the drainsFloor drainThe outlet in a floor where water drains away on roofs, balconies and in bathrooms, with a grate on top and usually a trap below., thresholds and equipment bases be handled?
• What needs to be covered or moved, and who in the building needs to be told?

The answers depend on your roof, so they come after someone has inspected it.