There is one known waterproof underlayment that has lasted this long and that is ASTM D-266 specified 30 pound or 45 pound asphalt saturated felt. Ludowici Roof Tile – The World’s Finest Clay Roof Tile, only specifies this standard. On a tile roof, this is the part of the roof that keeps the water out. The tile does shed much of the rain water but it primarily serves to protect the felt and provides appearance. It is curious that each tile is nailed onto the roof with a copper nail right through the felt! It is the ability of the asphalt saturated felt to seal around it and sometimes it becomes torn from mis-nailing and foot traffic. This is where the installation crew needs to be very vigilant or the roof will leak. We use two layers of felt off-set so that the nails that attach the felt are covered.
There are many different types, styles, profiles and color of tile roofs. These roofs are very long lasting. Interestingly there are over 250 thatched roofs in Southern England dating back to Medieval times. See: http://en.wikipedia.org/wiki/Thatching. Previously they were sign of poverty now however thatched roofs are nearly prohibitively expensive. Clay roofing tile are typically made from fired clay and can have a glaze finish of practically any color. However they are also made of glass, concrete, plastic and metal. The first clay roof tile were likely formed over a persons thigh and sun dried. Fired clay roof tile date back to 3 BC.
A favorite of mine is is a Japanese noyasu http://www.noyasu.com/catalog/de.cgi?id=48, but there are no ASTM specification of water absorption and breakage for these tile.
A clay roof tile in temperate regions deteriorates as a result of water being absorbed into the tile and repeated freeze thaw cycling. So the longevity of a roof tile here in the Midwest USA , depends on it’s resistance to absorption of water. This data is available from the manufacturer. For example Ludowici states virtually no water absorption. See: ROOF TILE SELECTION for pictures of beautiful installations and specifications from Ludowici.
Regarding the installation of tile roof, there is one known waterproof under layment that has withstood the test of time and that is ASTM D-266 specified 30 pound or 45 pound asphalt saturated felt.Ludowici Roof Tile – The World’s Finest Clay Roof Tile, until recently specified only this standard. On a tile roof, this is the part of the roof that keeps out rain driven water. The tile does shed much of the rain water but it primarily serves to protect the felt and provides appearance. Each tile is typically nailed onto the roof with a copper nail driven through the felt! It is the ability of the asphalt saturated felt to seal around it and sometimes it becomes torn from mis-nailing and foot traffic. The tile is “hung” on the roof and not pinned down to the roof deck in order for the tile to move in response to thermal expansion and occasional foot traffic. This is where the installation crew needs to be very vigilant or the roof will leak. We use two layers of felt off-set so that the nails that attach the felt are covered. At some point is is likely that we will determine that EPDM and other waterproof membranes will outlast the ASTM D 266 rated asphalt saturated felt but until then we prefer to use what has lasted 40 to 60 years and beyond.
We repair these roof using concealed copper nails and copper bibs to keep sliding snow and ice from pulling them back out. Tile leaks usually require the felt to be replaced and lapped properly with the existing felts. For over 30 years we have been stopping leaks on slate and tile roofs.
