Over the years, I’ve received countless calls from homeowners across London who found themselves in serious trouble halfway through a building project. In many cases, the story was similar: the builder had stopped answering calls, work had been left unfinished, costs had spiralled out of control, or the quality of workmanship was far below what had been promised.
As a builder myself, I’ve visited properties where the situation was genuinely shocking. I’ve seen extensions built incorrectly, structural work completed without proper approvals, projects abandoned halfway through, and homeowners forced to spend thousands of pounds fixing mistakes that should never have happened in the first place. In some cases, entire sections of work had to be demolished and rebuilt, resulting in major delays and budgets being stretched far beyond what was originally planned.
The reality is that choosing a builder is much harder than it looks. Most people only undertake a major renovation, extension, or loft conversion once or twice in their lifetime. Without experience in the construction industry, it can be difficult to spot warning signs before it’s too late.
We’ve all heard stories about rogue builders, unfinished projects, and renovation nightmares. Unfortunately, these situations are more common than many homeowners realise. A poor choice can affect not only your finances but also your daily life, leaving you living in a building site for months longer than expected while trying to resolve disputes and find someone capable of putting things right.
In fact, these problems continue to make national headlines.
In 2026, the BBC reported on a family who paid their builder £44,000 for extension works, only to be left dealing with serious building defects, Building Control failures and a lengthy legal battle. The case ultimately resulted in criminal convictions under the Building Act, compensation awards and a suspended prison sentence for the contractor involved. Stories like this are an extreme example, but they highlight just how serious the consequences can be when the wrong builder is chosen.
One of the most common problems I encounter is hidden costs. A quote may look attractive at first glance because it appears significantly cheaper than others. However, many homeowners later discover that important items were never included, specifications were left vague, or additional charges appear throughout the project. What initially looked like the cheapest option often becomes the most expensive.
Another issue is what I call the “low-price builder trap”. Some builders secure projects with an attractive quote, only to charge extra for every variation, unexpected issue, or item that wasn’t clearly detailed from the start. In many cases, potential risks were never discussed during the quotation stage, leaving homeowners with unexpected bills later.
I’ve also seen homeowners face serious problems when work was completed without the correct Building Control inspections and sign-offs. These issues may not become apparent until years later when the property is being sold, refinanced, or surveyed, creating unnecessary complications and expenses.
Perhaps the most stressful situation of all is when a builder walks away from a project before completion. Finding a new contractor willing to take over someone else’s unfinished work is rarely easy. Many builders are understandably cautious about inheriting existing problems, which can leave homeowners stuck with an incomplete project for months.
The good news is that most of these problems can be avoided. Before hiring a builder in London, there are several simple but essential checks that can help protect your budget, your property, and your peace of mind.
In this guide, I’ll walk you through the 12 checks every homeowner should make before signing a contract.
