5 items you should never store in a shed during a heatwave, or risk damaging products and even causing a fire

Garden experts are urging gardeners to check for these 5 things in their sheds this month, as temperatures become uninhabitable for some common store items.

I know when I’m too hot, I don’t work to the best of my ability, and the same can be said for some of the items in my shed. While the best shed ideas are perfect for maximising storage space, they hardly take into consideration extreme heat.

So, when temperatures reach above 30 degrees, some items are no longer suitable to be stored in the shed and need to be moved somewhere cooler.

Latest Videos From

Watch full video here:

1. Paint

When the weather reaches temperatures over 30, you really shouldn’t be storing your paint in a shed, as the high temperatures can affect the quality of your paint.

‘Paint, varnishes and other decorating products are some of the main items that shouldn’t be left in a hot shed because high temperatures can affect the quality and consistency of paint. It will separate, thicken or become difficult to use and even if the tin looks fine from the outside, the contents may no longer perform properly when you use them,’ explains Scott Godfrey, a construction trade consultant with Black Hammer.

‘Wood treatments, stains and some adhesives can also be affected by heat, which means you may not get the finish or strength you expect from them. If you have leftover paint you want to keep, store it somewhere cool, dry and away from direct sunlight.

2. Pesticides and weedkillers

If you use pesticides or weedkillers on your garden(although there are plenty of natural methods to get rid of pests), it’s important to move these products somewhere cooler during a heatwave.

‘Many garden chemicals become unstable or degrade in high heat, which can alter their effectiveness or make them hazardous. Some products also have a lower flash point than people realise. Always check the storage guidance on the label and keep these in a cool, dark environment rather than a shed that bakes in the afternoon sun,’ says Jamie Bloomfield, co-founder and director at Eden Landscapes.

3. Aerosols

Aerosols and extreme heat do not mix, which is why many cans come with warnings to keep them out of direct sunlight. During a heatwave, sheds can become unbearably hot and stuffy, which is a less-than-ideal environment for aerosols.

‘The issue is that sheds can get incredibly hot during periods of really warm weather, which can have a big impact. For some products like paints and adhesives, this can cause thermal and polymer degradation over time, which can affect their overall quality,’ explains Sue Taylor, product expert at Complete Construction Products.

‘That can be really frustrating, and something you don't realise until it's time to use it again. But another thing to consider is safety. Most aerosols have a max tolerance of 50C, which sheds could reach in enclosed spaces, especially if cans are exposed to direct sunlight. If that happens, then internal pressure can build up so much that cans can fail. Today, many cans are designed to tear apart rather than fragment to reduce potential injury, but they can still be a serious hazard.

‘To reduce the risk, move them outside to a well-ventilated and shaded spot, like a covered porch or near a north-facing wall. Keep them out of direct heat and away from anything metal that can add to the surrounding heat.’

4. Fuel and gas canisters

If you have a gas BBQ, I can’t imagine you’ve let it go to waste during all this sunny weather, which means you might have some gas canisters to store, too. But during a heatwave, this can actually be quite dangerous.

‘Gas canisters for barbecues or camping stoves are one of the most dangerous things you can store in a hot shed. High temperatures cause the gas inside to expand and the pressure inside the canister to rise sharply. A shed in direct summer sun can reach 50 to 60 degrees on a hot day, which is well above safe storage temperatures for pressurised gas. These should always be stored upright in a well-ventilated, shaded outdoor area away from any heat source,’ says Jamie.

5. Batteries

Lastly, you should avoid storing batteries - especially lithium iron batteries - in a shed during a heatwave. They can become a fire risk when the mercury soars, making it quite simply unsafe to keep them in a shed. Plus, the heat can affect how they work, too.’

‘Rechargeable batteries and cordless garden tool batteries are another item that shouldn’t be left sitting in a hot shed. Many modern garden tools use lithium-ion batteries, which can be sensitive to high temperatures,’ says Scott.

‘Repeated exposure to heat can reduce their performance and shorten how long they last, and won't hold their charge as well. It’s better to remove batteries from cordless mowers, strimmers and hedge trimmers and store them indoors at a stable temperature. The tools themselves can usually stay in the shed, but the batteries are the part that needs extra protection.

Now, you might want to check your shed for any of these items, and move them to somewhere cooler!