Extra traffic on a roof may require extra protection for the waterproofing layer. This usually occurs with either walkpads, walkway rolls or pavers. Many manufacturers require a walkpad outside a hatch and at the service side of a roof top unit. If the waterproofing layer is built-up roofing or modified bitumen roofing this may be all that is necessary. If the waterproofing layer is single ply membrane the extra protection becomes more important. If the roof is to be used as a deck then interlocking pavers should be installed. Concrete pavers on a single ply roof must have an underlayment pad. Carlisle, Versico and other manufacturers make interlocking rubber pavers that may be of interest. There are more paver options entering the market as roof decks become more popular.