How do I know when a job needs a professional?

Most home repairs are within reach of a careful amateur. A small number are not, either because the law says so or because the cost of getting it wrong is disproportionate. Recognising the difference is the most useful DIY skill there is.

What you'll need

• An honest assessment of your own experience (optional)

Step by step

1. Rule out anything legally restricted.Gas work requires a registered engineer almost everywhere. Much fixed electrical work is notifiable and restricted. These are not judgement calls.
2. Ask whether a mistake would be dangerous.Gas, mains electricity, structural work, roofs, asbestos, working at height. The consequence of an error, not its likelihood, is what matters.
3. Ask whether it is structural.Removing walls, altering joists, anything load-bearing. This needs both professional work and, usually, formal approval.
4. Ask whether the mistake would be hidden.Anything buried in a wall, under a floor, or behind tiling. Hidden failures cause damage for months before they show.
5. Compare the cost of failure with the cost of the job.A £200 job that risks £5,000 of water damage is a poor gamble. A £200 job that risks £200 is fine.
6. Consider certification and insurance.Some work needs a certificate for insurance or for selling the property. Unrecorded work can complicate both, sometimes expensively.
7. Be realistic about tools and access.A job needing scaffolding, specialist tools or two competent people is often not economic to do yourself once you have hired everything.
8. Do the preparation yourself and pay for the skilled part.Clearing, stripping, making good and decorating are often the bulk of the hours. Splitting the job this way saves real money legitimately.

Tips

• Get three quotes and ask each what they would do and why. The explanations tell you more about the job than the prices do.
• Check registration numbers directly with the relevant scheme rather than trusting a logo on a van or website.
• Never pay a large sum up front. A deposit for materials is normal; the balance on satisfactory completion is standard.

Common mistakes

• Doing gas or fixed electrical work yourself — It is legally restricted in most places, dangerous, and can invalidate insurance and complicate a future sale.
• Judging by whether the job looks easy — Many restricted jobs are physically simple. The restriction exists because of the consequences of error, not the difficulty.
• Not keeping certificates and paperwork — Insurers and buyers ask for them, and undocumented work on regulated systems causes problems years later.

Questions people ask