Choosing the right radiator height from the floor may seem like a straightforward decision. But there are some smart and subtle decisions you need to make to ensure you are getting the most out of a radiator.
Placing a radiator at the incorrect height can result in a less efficient heating system with poor heat distribution. Which ultimately will lead to higher bills. So you need to get it right, whatever type of radiator you are looking to install.
Here, the experts reveal the optimal size gap required for maximum efficiency and accessibility, along with alternative options should the standard size be unrealistic.
Gordon Chalk and Alan Houghton
Working in the industry for over 15 years Gordon and Alan's mission is to help property owners get warmer and more comfortable with underfloor heating and proper floor screed.
The ideal gap between radiator and floor
The gap between the floor and the bottom of a radiator needs to be a specific height to ensure good circulation. When installing a radiator, the height can vary (more of this later), Chalk and Houghton, MDs at Next Level Underfloor Heating and Screed Solutions, point out the popular option, “The most common gap is around 150mm (six inches). This is the generally accepted 'rule of thumb'.”
The gap typically applies to all radiators, as Chalk and Houghton explain, “While the ideal height can vary slightly based on radiator size and type (e.g., convector radiators might benefit from slightly more space), 150mm is a good starting point for most standard radiators.”
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Reasons for leaving a gap
There is more than one reason that affects the decision on the size of a gap. Here, Chalk and Houghton run through the reasons with explanations.
Heat distribution The gap allows for better air circulation. Radiators heat the air around them, and this warm air rises. The gap allows cooler air to be drawn in from the floor, creating a convection current that distributes heat more evenly throughout the room. Without this gap, the heat tends to pool near the ceiling, leaving the lower part of the room cooler.
Cleaning The gap makes it easier to clean underneath the radiator.
Aesthetics A standard gap creates a more visually appealing and balanced look.
Plumbing access Provides space for pipework and valve connections.
Where to position skirting boards with radiators
Radiators are typically placed next to skirting boards, and ideally, they should be positioned above the skirting board to work efficiently. Here, Chalk and Houghton go into more detail about radiator placement: “Generally, the entire radiator needs to be above the skirting board.”
He adds, “Aim for at least 25mm (1 inch) clearance from the top of the skirting board to the lowest point of the radiator. This is important for proper air circulation.”
The same principle applies, whatever the skirting board size. Chalk and Houghton suggest, “A taller skirting board will require a higher radiator placement to maintain adequate airflow.”
However, it might not be that simple. Chalk and Houghton continue, “If you have tall skirting boards, you may need to consider a shorter radiator to avoid placing it too high on the wall.”
If placing a radiator above the skirting board is not a practical solution, it may be more feasible and cost-effective to remove the existing skirting board and replace it with new skirting boards, such as this Polymer Ogee Skirting from Toolstation. Measure the gap, take away 25 mm, and this will give you the ideal height for your new skirting board.
Minimum radiator height from floor
From a practical standpoint, a radiator needs to be above the ground to work properly. 150 mm is the common gap, but a radiator can go lower, say Chalk and Houghton, “Ideally, you don't want the gap to be less than the skirting board's height at the very minimum." They add, “A functional minimum might be around 50mm (2 inches), but anything lower than that will significantly impact heat distribution and cleaning access.”
But how low a radiator can go is dependent on a number of factors, which Chalk and Houghton list below:
Skirting board height
Radiator design (convector fins, etc.)
Room size and insulation (Poorly insulated rooms might benefit from slightly lower radiator placement to focus heat near the floor)
FAQs
Should a radiator go under a window?
The placement of a radiator isn’t just about its height from the floor; it's also about its position. A common query is whether it should be placed under a window. Here Chalk and Houghton give the reasons why it's a good choice.
Counteracts cold drafts Windows are often the coldest surfaces in a room, and placing a radiator beneath them helps to counteract cold drafts.
Air circulation The rising heat from the radiator helps to circulate warm air throughout the room.
Space saving Windows are often unused wall space, making them an ideal location for radiators.
But when placing a radiator under a window, you need to think about the gap above and below. Chalk and Houghton share the ideal gaps: “You want at least 100mm (4 inches) between the top of the radiator and a window sill to allow for adequate heat circulation.” They add, “The gap at the bottom should be the same as normal (around 150mm/6 inches).”
Do single and double radiators have the same gap from the floor?
Double-panel radiators pump out more heat than single-panel radiators, but their placement is much the same. Chalk and Houghton go into more detail, “Single and double radiators should have the same gap from the floor. The primary consideration is still proper air circulation.”
But, a double panel radiator can be placed higher, continues Chalk and Houghton, “A double radiator may benefit from being placed slightly higher (perhaps an extra 25mm/1 inch) to further enhance convection, especially in a larger room.”
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Steve Jenkins is a freelance content creator with over two decades of experience working in digital and print and was previously the DIY content editor for Homebuilding & Renovating.
He is a keen DIYer with over 20 years of experience in transforming and renovating the many homes he has lived in. He specialises in painting and decorating, but has a wide range of skills gleaned from working in the building trade for around 10 years and spending time at night school learning how to plaster and plumb.
He has fitted kitchens, tiled bathrooms and kitchens, laid many floors, built partition walls, plastered walls, plumbed in bathrooms, worked on loft conversions and much more. And when he's not sure how to tackle a DIY project he has a wide network of friends – including plumbers, gas engineers, tilers, carpenters, painters and decorators, electricians and builders – in the trade to call upon.
