I've been moulding for a little while making smallish parts.  Fortunately I can get all these moulds up in the loft.  Recently I've been making some fairly large bodywork moulds.  This has given me a storage issue!  Does anyone store moulds outside?  Do they suffer from osmosis?  My other option is to rent a storage unit.

Never leave out side weather will destroy,best off making space I store in shed and cover up with plastic sheets and dust sheets.