You've just fitted a brand-new insulated sectional door. It looks fantastic, everything works perfectly, and then you spot it… daylight coming through underneath.

The customer is confused. They've paid for an insulated garage door, so why is there a gap?

Well, sometimes the problem isn't the garage door. It's the concrete underneath it.

In this episode, James takes a look at one of the most common and frustrating issues facing garage door installers: uneven garage floors and the problems they can cause when fitting a new door.

It's not always obvious that there's a serious issue with the floor during the initial survey. An old door, existing bottom seal or threshold can mask variations that only become apparent once the original door has been removed and the new one is being fitted.

So what happens when the new door goes in and the floor turns out to be anything but flat?

In this episode, we cover:

• The insulated door misconception: Why an insulated garage door doesn't automatically mean an airtight or draught-free garage.
• The hidden floor problem: Why the full extent of an uneven threshold isn't always obvious until the old door comes out.
• Level versus flat: The difference between a sloping floor, an undulating surface and a genuinely unsuitable threshold.
• Bottom seals and their limitations: What they can accommodate, and why even the best rubber seal can't compensate for every uneven surface.
• Possible solutions: From additional floor seals and threshold profiles to levelling, repairs and drainage.
• The awkward customer conversation: How to explain that a new door can't correct an existing building defect without sounding like you're simply making excuses.
• Better surveying and communication: What installers can do before the job, and how to manage expectations when the problem only becomes apparent during installation.

One of the biggest lessons is that checking the floor and knowing exactly how the new door will seal against it aren't necessarily the same thing. Sometimes the problem only reveals itself once the old door is out.

That doesn't mean we should accept poor finishes or blame every problem on the building. But it does mean understanding the limitations of the product, documenting what we find and being honest with customers about what can realistically be achieved.

Because you can have the best insulated garage door in the world, but it can't magically turn an uneven concrete floor into a perfectly flat threshold.

And if anyone has invented a bottom seal that can do that, we'd quite like to buy the patent!

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