Lots of people request documents on this site, some are given, and some are not.
Contracts have to be legally enforceable, contracts can be written, or in the case of small or infrequent contracts can be verbal.
When dealing with contract cleaning, nearly all contracts are written, contracts deal with such items as payment terms, scope of services etc.etc. A solid, legal written contract, that can be enforced, through the courts if required, actually costs a lot of money.
I have submitted an old copy of our terms and conditions to the site, this could form the basis of a contract, to which you would need to add, scope of service etc.etc.
Our present commercial cleaning contract cost us nearly £3,000 to have written, it gets updated yearly, usually costs about £100, so the likelihood of anyone posting a decent contract is very small.
If you are a small firm, a one page contract from a solicitor will perhaps cost between £200 to £400, let a professional do it, at least that way it will be enforceable and legal.
