What Are Those Stones on My Flat Roof For, Anyway?

I get this question a lot when I’m inspecting older properties around Brighton and Hove. You look out of an upstairs window and see your flat roof is covered in a layer of gravel or small stones. It looks messy, but you assume it’s there for a reason. And it was, once upon a time.

Historically, these stones, known as ballast or chippings, had two main jobs:

  • UV Protection: Old-school felt roofs were very susceptible to sun damage. The sun’s UV rays would dry out the bitumen, making it brittle and prone to cracking. The layer of stones acted as a simple, cheap sunblock.
  • Weight: Some older roofing systems weren’t fully bonded to the deck below. The weight of the stones was literally what held the roofing material down against the wind.

Frankly, in 2024, it’s an outdated system. Modern roofing materials have advanced so much that stones are now more of a liability than a benefit.

So, Are Roof Stones a Bad Thing?

In my professional opinion, yes. They cause more problems than they solve on a modern domestic roof. I spend a lot of time dealing with the fallout from stone-covered roofs in the Worthing area, and here’s what I consistently find:

  • They hide leaks: This is the biggest issue. Water can get through a small crack, travel underneath the felt membrane, and appear as a damp patch on your ceiling metres away from the actual source. With stones covering everything, finding that original entry point is a nightmare. You can’t see the problem until it’s a big one.
  • They block gutters: Stones inevitably wash into your gutters and downpipes, especially during heavy Sussex downpours. This leads to blockages, which cause water to overflow and potentially damage your fascias, soffits, and even brickwork. If you’re constantly dealing with blockages, this could be the culprit, and it might be time to look at a full guttering and downpipe replacement.
  • They add dead weight: Your roof structure was built to support a certain load. While it was likely designed for stones, it’s still a lot of unnecessary weight sitting on your roof joists year after year.
  • They make repairs difficult and expensive: Before I can carry out a proper repair, all those stones have to be shovelled off the area and bagged up. It’s messy, time-consuming work that adds to the labour cost.

My Roof Has Stones. Should I Just Shovel Them Off?

Absolutely not. Please do not do this. The biggest risk is that the stones are the only thing protecting a very old, sun-damaged, and fragile roof membrane. By removing them, you could expose the brittle felt to the elements, causing it to crack immediately and create dozens of new leaks. You might be turning a small problem into a big, expensive one.

If you’re worried, the best first step is to get a professional opinion. I can come out and assess the condition of the membrane underneath. You can easily book a free roof inspection on my website, and I’ll give you an honest appraisal without any sales pressure.

What’s the Modern, Professional Alternative?

The solution isn’t to just remove the stones; it’s to upgrade the whole roofing system. Modern high-performance felt systems, GRP fibreglass, or EPDM rubber roofs are light-years ahead of what was used 20-30 years ago.

A modern flat roof replacement involves stripping everything back to the timber deck, ensuring the structure is sound, and then installing a new, multi-layer system. These materials have built-in UV protection and are fully bonded to the roof, so they don’t need a single stone. The finish is clean, smooth, and easy to inspect and maintain.

My Stone-Covered Roof is Leaking. How Do You Fix It?

This is where things get tricky, and why a quick DIY patch with silicone just won’t cut it. Because the stones hide the source of the leak, finding it is the first challenge. My process is methodical:

  1. I carefully remove the stones from the suspected area.
  2. I thoroughly clean the membrane to reveal any cracks, splits, or failed seams.
  3. I diagnose the problem. Often, the membrane is too old and brittle for a patch repair to be a reliable long-term solution.
  4. I’ll give you a fixed-price quote for a proper, permanent repair or, if necessary, a full replacement. For truly urgent situations, you should check my emergency roof leak repair service.

Remember, I provide a client portal with daily photo logs, so you’ll see exactly what I’ve found and what I’m doing to fix it. No guesswork, just honest work.

Can I Use My Stone-Covered Roof as a Balcony?

No, please don’t. A standard flat roof is not designed to be a balcony or terrace. It’s not built to take the foot traffic, and walking on the sharp stones will grind away at the membrane underneath, causing damage and leaks. If you want to use your outdoor space, you need a proper balcony or roof terrace waterproofing system designed specifically for that purpose. It’s a completely different job that ensures structural safety and a durable, walkable surface.