Tips on Choosing Your Basement Contractor

A basement conversion is one of the most exciting ways to add space and value to your home, in cities like London, where space is limited, they are especially popular. But it’s also one of the trickiest building projects to get right. Pick the wrong contractor, and you could be dealing with leaks, cracks, or worse. 

The good news? Choosing the right basement contractor doesn’t have to be complicated. Even if you know nothing about basements, these 10 simple checks will help you protect your home, your budget, and your peace of mind. 

The first question to ask any basement contractor is simple: are you fully insured? 

Insurance is paramount. Before you start looking at skills or experience, make sure there’s a safety net in place. The right policies mean that if something goes wrong whether it’s a minor issue or a major structural problem you’re protected. 

It’s important to check that the cover isn’t just a general builder’s policy. Basement construction carries unique risks, so your contractor should have insurance specifically tailored for this type of work. That typically includes protection for employees, the public, the works on site, and any professional advice given. 

The key point: don’t proceed until you’ve seen evidence of valid insurance in place. 

Experience is key in basement construction. The contractor you choose should be able to demonstrate a strong track record of building basements similar to your expectations. Don’t just rely on polished photos of the finished job. Ask to see how they managed the entire process, from excavation to completion, so you know the work was carried out safely and professionally. 

When reviewing their experience, make sure to ask for: 

1. Case studies of basements similar to your project 

2. Photos or videos showing each stage of construction 

3. Client references you can speak to directly 

4. The opportunity to visit both a live project and a completed basement 

Share this information with your architect and engineer for approval, as they’ll know what to look out for. Always request references and contact details from previous clients any contractor unwilling to provide these may have dissatisfied customers. If possible, take the time to see both a live project and a finished one as part of your vetting process. 

When a basement is being built, the ground and surrounding structure need to be held in place while excavation is carried out. This is known as temporary works, and it’s one of the most critical parts of the project. Temporary works must follow strict British Standards and Health & Safety Law, so it’s vital your contractor can demonstrate the right systems and people are in place. 

Every professional basement contractor should have: 

1. A Designated Individual, responsible for overseeing and maintaining the company’s temporary works standards. 

2. A qualified Temporary Works Coordinator, who manages the process day to day.

3. A trained and competent Temporary Works Supervisor, who signs off all on-site work.

 These roles require specific training and certification, and you should always ask to see evidence. If a contractor cannot clearly show how they manage temporary works, consider it a major red flag