Last updated: 15 September 2026
A magnetic shower door that will not close does not always mean the magnets have failed.
Sometimes the two strips push away from each other. Sometimes the door shuts but the strips still do not meet. In other cases, the top catches while the bottom stays open, or the door seems to close properly but slowly opens again when you let go.
They can all look like the same fault, but the cause may be quite different.
Before replacing anything, close the door slowly and watch what the two magnetic strips actually do.
Do the Two Magnetic Strips Push Apart?
If the strips clearly push away from each other as the door closes, weak magnets are probably not the problem.
The two sides are more likely to have the wrong magnetic poles facing each other.
Magnets have sides that attract and sides that repel. If the same poles are facing one another, the strips will push apart instead of pulling together.
This is especially common when only one strip has been replaced.
On some framed shower doors, the original magnetic strip sits inside the door frame or track. You usually cannot tell which magnetic pole is facing out just by looking at it, and different manufacturers do not always use the same magnetic arrangement.
So a new strip can be the right size and still have plenty of pull, yet fail to work with the strip already fitted to the door.
If the two sides repel each other, do not start by looking for a stronger magnet.
First check whether the new and old strips are actually able to attract each other.
If the original brand, model or magnetic direction is no longer known, replacing just one strip makes this problem more likely.
What If the Two Magnetic Strips Never Meet?
This is a different problem.
Both strips may still be magnetic, but when the door is fully closed there is a visible gap between them.
If they cannot physically meet, stronger magnets are unlikely to help.
Look at how much space is left when the door is closed.
The gap may simply be wider than the seal is designed to cover. A seal may also fit the glass correctly but hold the magnet too far back, so the two sides still cannot reach each other.
The seal may not be pushed fully onto the glass either, or the door may have moved slightly and made the original gap wider.
One common mistake is assuming:
If the seal fits my glass, it must be the right one.
Not necessarily.
It may fit the glass thickness, but the magnetic strips still need to meet when the door closes. The glass thickness, gap and door arrangement all matter when choosing the right magnetic seal.
If there are still several millimetres between them, check the gap and the shape of the seal before looking for a stronger magnet.
Does the Top Close but the Bottom Still Have a Gap?
If the magnetic strips meet at the top but move further apart towards the bottom, look at the door position first.
The fact that the top still catches tells you the magnets are still doing something.
What matters more is whether the gap stays even from top to bottom.
If it is small at the top but clearly wider at the bottom, the door may have dropped slightly or moved out of line.
We see this quite often in fitting photos sent to SIMBA. The strips meet normally near the top, while a clear gap remains lower down.
In that situation, we usually compare the top and bottom gaps before blaming the magnetic strip.
A magnetic seal can only bridge so much distance.
If the top closes but the bottom cannot reach, check whether the glass edges are slightly out of line.
If the difference between the top and bottom gap is obvious, it is better to check the door alignment rather than keep changing the magnetic seal.
Does the Door Stick, Then Open Again When You Let Go?
This can feel like weak magnetic strength.
Before deciding the magnets have worn out, close the door slowly and check whether the strips are actually touching all the way down.
Sometimes only a short section near the top or middle makes contact.
While you are pushing the door closed, that small area can hold for a moment and make the door look properly shut. Once you let go, the hinge or the natural return of the door can pull the strips apart again.
A large closing gap can cause the same thing. The strips may only just touch at the edge instead of meeting properly along their full length.
The important thing is how much of the two strips is actually touching.
If only a small section meets, the door can easily open again.
If the strips make good contact from top to bottom and the door still will not stay closed, then worn magnets, weaker magnetic pull or the return force of the door become more likely.
Replaced Only One Side? Why Don’t the Old and New Strips Line Up?
Even if the new and old strips attract each other, that does not mean they will work properly once fitted.
At this point, the issue is whether the two strips sit in the right place.
Start by checking whether the new seal fits the door in the same way as the old one.
Once fitted, the magnetic parts should line up reasonably well. One should not sit noticeably further in or further out than the other.
A replacement seal can still have good magnetic pull but place the magnet in a different part of the profile. When the door closes, only a small section may meet.
The door position matters as well.
If the strips line up at the top but move further apart lower down, the problem is no longer just the old and new seals.
So after replacing only one side, check whether the new seal fits the door correctly, whether the magnetic parts line up, and whether the closing edge stays even from top to bottom.
Two strips can attract each other and still fail to work properly once fitted.
If the original seal type is no longer known, replacing both sides can sometimes make it easier to rule out a mismatch between old and new parts.
That does not mean every magnetic shower seal must always be replaced as a pair.
Why Does the Magnetic Strip Keep Sliding Out of the Track?
This is more common on framed shower doors.
Some framed doors use a magnetic strip that fits into a track in the frame rather than a seal that clips directly onto the glass.
These strips often have a T-shaped section that locks into the track.
If the strip keeps moving up or down, or falls out after the door has been opened a few times, the problem is usually not the magnet.
More often, the strip is simply not being held properly by the track.
For example, the original track may need a fairly wide T-shaped fitting, while the replacement strip has a much smaller one.
It may slide into the track easily and look as though it fits, but it is not actually locked in place.
As the door opens and closes, the strip gradually works its way out.
Older frames can have another problem.
The track itself may be worn, distorted or cracked. The part that originally held the T-shaped strip in place may also have broken.
In that case, even a replacement strip that is close to the original size may still refuse to stay in place.
If a magnetic strip keeps falling out of a framed door, check whether the T-shaped fitting really matches the track and whether the track can still hold it securely.
That is a fitting issue, not a question of how strong the magnet is.
The Magnet Still Works, So Why Is the Door Still Not Closing Properly?
If the two strips still pull towards each other when tested, but do not work properly once fitted to the door, look at the fitting and the door position next.
Is the seal pushed fully into place?
Are the magnetic parts facing each other?
Has the gap become wider than it used to be?
Has the door dropped slightly?
If the strip has just been replaced, check whether its shape and fitting style suit the original door.
Heavy soap residue, limescale or dirt can also be cleaned away, as a thick build-up can stop the two sides sitting flat against each other.
But this is only a basic check.
If the strips are not lined up, or there is a clear gap between them, cleaning alone will not solve it.
When Is the Magnetic Strip Not the Real Problem?
If the top closes but the gap becomes wider towards the bottom, look at the door position.
If a new magnetic seal cannot reach the other side at all, look at the gap and the shape of the seal.
If the two strips push apart as soon as they get close, check whether the magnetic poles of the old and new strips work together.
If they attract but only a small section meets once fitted, look again at the seal position and whether the door is still aligned.
All of these can look like a failed magnetic shower door seal.
Sometimes the magnet is fine. The problem is the magnetic pairing, the door position, the track, the gap or a replacement seal that does not suit the original setup.
If you are still unsure, there is no need to keep buying different strips and hoping one works.
Send SIMBA Seals UK a photo of the whole shower door, the two magnetic strips with the door closed, the gap at the top and bottom, and the end profile of the old seal.
For a framed door, include a clear photo of the track as well.
From those photos, we can usually narrow the problem down to the magnetic pairing, poor alignment, a mismatch between the old and new strips, the wrong track size, or a magnetic strip that genuinely needs replacing.
Once the door position and gap have been ruled out, and the existing seal is distorted, no longer matches properly or genuinely needs replacing, it makes more sense to compare magnetic shower door seals that suit the actual glass thickness and closing gap.