Many lenders require that roofs be certified when a previously owned home is purchased. Roofing contractors usually inspect the roof, determine if any repairs need to be made, then if possible will certify the roof, usually for two years. If the roof leaks within that period, the roofing company, which certified the roof, will repair the leak free of charge. Shake roofs that are ten years or older usually need some repair work to be certified. Most roofing contractors will not certify flat roofs because they generally are difficult to repair and often must be replaced. Some roofs are beyond repair, in which case the roofing contractor will advise the home be sold as is or give the seller a bid to replace it.

If a home seller does not disclose previous leaks or damage to the roof and a problem develops, the roofing contractor may refuse to honor a certification to the new homeowner.