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Toilet seat types and how they fit the pan
Top-fix and bottom-fix UK toilet seats, soft-close and quick release, and how to measure a pan against the hinge spacing on the listing.
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A toilet seat is one of the few bathroom parts you can usually change without touching the water. The mistakes are about the pan. The new hinges have to reach the holes the old ones used, and you have to be able to tighten them from the side the seat is designed for. Close-coupled, low-level and back-to-wall pans are compared in close-coupled and low-level toilets. A pan on a frame is in wall-hung toilets. Some of those are sold with their own seat, and a seat that says it fits a standard pan may not match the holes.
Top-fix and bottom-fix
The hinges bolt through two holes at the back of the pan.
Bottom-fix means the nuts are under the pan. You need a hand in the gap at the back of the bowl. If the pan is close to the wall or boxed in, that gap may be too tight. Several Wickes listings use the words "Bottom Fix Fitting".
Top-fix means the work is done from above. You choose it because you can reach it, not because it is a better seat. Wickes marks those listings "Top Fix Fitting". Match those words on the seat you are buying.
One seat we opened can go either way. The Croydex listing says it can be fitted from above or below. That is that product's claim.
If the old seat is loose, the holes and the hinges have often worn together. A new seat whose spacing does not match will rock, and more force will not move the holes.
Soft-close and quick release
Soft-close hinges slow the lid so it does not slam. Wickes describes them as helping to prevent slamming. They are a damper, not a different shape of pan. Standard close is the ordinary hinge. Wickes lists a polypropylene seat both ways. The hinge ranges are not identical, so check the one you are buying.
Quick release is a button, or two buttons, so the seat lifts off for cleaning. It does not change top-fix or bottom-fix. Thermoset is sold as harder-wearing than polypropylene. That is the listing's description. We have not compared how they age.
Measure before you buy
- Shape. Round, D-shaped or square. A square seat is for a square pan.
- Holes. Measure between the centres of the two hinge holes, in millimetres, and compare that with the range on the listing. Outside the range, the hinges cannot be set to your holes.
- Reach. If you cannot get a hand under the back of the pan, a bottom-fix seat is the awkward one even when the spacing matches.
While the old seat is off, look at the china around the holes. A crack is a reason to stop. Overtightening is how a hairline gets worse. Replacing the pan, if the soil pipe is involved, is in WC pan connector. The water does not need to be off for a seat. A cistern that will not stop filling is a different job. See a running toilet.
Fit the seat as the leaflet says. In general: holes clean, hinges set to your measurement, bolts through, nuts firm enough that the seat does not slide and the china is not crushed. Stop once it is firm. If it still moves sideways, the spacing is wrong. Soft-close lids should drop on the damper. If you have to push, something is trapped or the damper has failed. Rusted bolts need patience and a release the china can tolerate, not a long bar. A snapped bolt in the hole is a miserable repair.
Seats at Wickes
Ranges below are the hinge spacing Wickes prints. Check the listing on the day.
We haven't tested this. Figures are as the maker states them (checked 13 November 2026).
Croydex Constance Flexi-Fix soft-close quick-release seat, white. Wickes says the hinges adjust to the fixing holes of any standard toilet pan, and that the seat can be fitted from above or below. It describes soft-close hinges and says the fittings are included. "Any standard" is Wickes's phrase. A wall-hung pan, or an odd hole layout, may still not suit it.
Wickes thermoset soft-close quick-release seat, white. Wickes says this is top-fix, from above the pan, with soft-close hinges and one quick-release button. It states the space between the hinges as 108 to 180 mm.
Wickes polypropylene soft-close seat, white. Wickes says this is bottom-fix, from below the pan, with soft-close hinges. It states the space between the hinges as 139 to 171 mm, a narrower span than the thermoset seat. The standard-close polypropylene seat we opened is also bottom-fix, with a stated span of 135 to 175 mm. Do not assume the two share a number.
What is the difference between top-fix and bottom-fix?
Top-fix is tightened from above the pan. Bottom-fix is tightened from underneath. If you cannot reach under the back of the bowl, bottom-fix is the awkward one. Read the words Wickes uses on the listing.
How do I measure for a replacement seat?
Measure between the centres of the two hinge holes, and note whether the pan is round or square. Compare that distance with the range on the listing, and check you can reach the side the seat is tightened from.
Will a soft-close seat fit any pan?
Soft-close is the hinge, not the shape. The holes and the pan still have to match. A square seat is for a square pan. A "standard" seat may not fit a wall-hung pan sold with its own seat.