The wide range of work covered by the Construction Industry Scheme (CIS) includes things like installing conservatories.

The rules say, if you pay your friends as employees, (deducting PAYE and National Insurance) you don’t need to register for the CIS scheme.

But, if you pay them as self-employed workers (not PAYE), then you must register as a contractor under the CIS rules.  You will probably need to deduct 20% tax (depending on their CIS status) from what you pay them for labour, provide them with proper statements, send monthly returns to HMRC and keep proper records.  And your friends should register as subcontractors under the CIS rules and obtain a form CIS 4(P).

The penalties for failing to comply with CIS regulations are very harsh so take advice now if you are in this position.