Neoprene, rubber, or etc. type gaskets have been used with vinyl gutters wherever leaky joints can be tolerated, but glued joints are always used where leakage cannot be tolerated; as with hidden gutters or over flowerbeds, entryways and walkways. Gasket type seals can breakdown due to chemical action, but usually fail due to mechanical action ( abrasion from grit as expansion / contraction occurs or ice pops the joint open ). In addition gasket sealed systems will not seal if the fittings are not in careful alignment. A rounded glued gutter does not require such careful alignment. Creepage of vinyl gutter while contracting can also pull the gutter out of gasket seals. As with water supply systems the only leak proof joint is a glued or solvent weld bond. Caulking do not work without rivets because of PVC's high coefficient of expansion. In addition to leaking, gasket systems usually allow debris accumulation at the joints which causes flow reduction and clogging. To avoid leaks and promote self cleaning choose a solvent welded joint system.