The guidelines for selecting reliable tradesmen for your self build are much the same as those for choosing a house builder with personal recommendations from people you know offering the best source of information.
If you are project managing your build and appointing trades individually you need to assess each one.
The range of certification schemes and trade associations for the various trades is mind boggling and many are represented by several bodies. Be sure to check any claims of membership with the relevant body to make sure they are legitimate and current.
The Government backed TrustMark Scheme aims to pull trades together under one recognised standard making it easier for consumers to find reliable tradesmen and root out the cowboys.
Some work must have building regulation approval and/or be completed by an installer registered with one of the Government's approved "competent person schemes".
You can find more information on the Planning Portal or contact your local authority building control if you are in any doubt as to the requirements.
Find out what qualifications your prospective tradesmen have. NVQs and SVQs are now the nationally recognised qualification for many trades.
The industry now operates the Construction Skill Certification Scheme (CSCS) as a standard for occupational competence and safety awareness. CSCS cards are issued to individuals for their specific trade or profession. Not all tradesmen will have these but many of the large main contractors won't allow anyone on site without one.
Ask for references from previous customers and to see examples of work. If you can speak to some of them and ask some questions, even better!
Get online and have a look at local forums, business directories and other online resources for references and reviews about prospective firms.
There are numerous websites such as Rated People that connect customers and tradesmen. You post your job requirements and are linked with appropriate members. Ratings and reviews are posted from their previous clients.
These can be a good start point but we would still recommend that you check out references and memberships personally.
However you find them, always have a shortlist of three tradespeople to give some perspective to your choice.
To prepare a quote, tradesmen will need plans, specifications and a clear written scope of what you want them to do and when.
When you receive estimates, compare everything you have found out and decide who you think is best. It shouldn't necessarily be the one with the cheapest quote. Weigh up everything you have found out before you make a decision.