Frameless pivot shower door in a 750mm Yelahanka niche: the swing-radius calculation that architects forget, and why it traps your toilet

A 750mm-wide niche in a Yelahanka or Indiranagar apartment feels generous until you spec a frameless pivot door and realise the hinge hardware sits 40mm proud of the wall, the glass panel swings 600mm into the bathroom at full arc, and the toilet cistern now blocks the opening. The geometry is simple. The coordination is not.

This is not a design flaw. It is a specification gap — the moment when the architect's RCP shows a shower niche and a toilet, but the pivot-door swing radius lives in a different drawing layer, or no drawing at all. We have fitted hundreds of frameless pivot doors across Bangalore's post-2010 residential stock, from HSR Layout to Sarjapur Road, and the pattern is consistent: the swing-radius calculation happens too late, or not at all.

The geometry of the pivot door in a 750mm niche

Start with the niche width: 750mm clear opening, measured wall-to-wall. The frameless pivot door for this niche will be 720mm wide glass (allowing 15mm tolerance on each side for the hinge hardware). The pivot hinge assembly — top and bottom — protrudes 40mm from the wall face. This is not optional; it is the depth of the hinge barrel and the glass clamp.

Now measure the swing radius. The door swings on a vertical axis that runs through the centre of the bottom pivot hinge. When the door opens to 90 degrees (fully open, perpendicular to the wall), the outer edge of the glass panel — the far corner from the hinge — travels in an arc. That outer corner sits at 720mm from the hinge axis (the width of the glass). At 90 degrees, it projects 720mm into the bathroom.

The swing-radius formula

Swing radius = glass panel width = 720mm (at 90-degree opening). This is the distance from the hinge axis to the farthest point of the door when fully open. In a typical Bangalore bathroom, this means the door occupies a floor footprint of roughly 720mm × 720mm when open. If your toilet cistern sits within 750mm of the shower niche wall, the door will collide with it.

Why architects specify a 750mm niche and then discover the toilet problem on site

The RCP shows a niche, a toilet, and a door. The niche is 750mm wide because that is the standard reach from a 600mm-wide shower tray to the far wall, with 75mm buffer on each side. The toilet is positioned 400mm from the wall behind the niche (standard plumbing rough-in for a wall-hung pan). The architect has not drawn the door swing arc, because the door hardware spec is not yet in hand.

When the glass supplier is brought in — often at the MEP coordination stage — the pivot door is already locked into the 750mm niche. The hinge hardware is specified. The glass thickness (typically 10mm low-iron for our 10mm frameless shower panels) is locked. The swing radius is now a fixed constraint. The toilet is still there.

The coordination trap

The door does not fail to open. It opens, but it opens into the toilet cistern. The user cannot fully open the shower door without bumping the cistern, or they must step over the door frame to enter the shower. This is a site-handover failure, not a design failure — but it is preventable.

How to calculate clearance before you spec the hinge hardware

The rule: measure the distance from the shower niche wall to the nearest obstruction (toilet cistern, vanity, wall). If that distance is less than the glass panel width (typically 720mm for a 750mm niche), the door cannot swing to 90 degrees without collision.

Three options to resolve a tight niche

• Reduce the niche width to 600mm, which allows a 570mm glass panel and a swing radius of 570mm. This moves the collision point 150mm further into the bathroom. Measure your toilet position first.
• Specify a 45-degree stop on the pivot hinge, so the door opens only to 45 degrees. This reduces the swing radius to approximately 510mm (720mm × sin 45°). The user enters the shower at an angle, but the door does not hit the toilet. This is a common retrofit on Bangalore projects where the niche was already built.
• Relocate the toilet 200mm further from the wall, if the bathroom layout allows. This is the most expensive option, but it solves the problem permanently and allows a full 90-degree door swing.

We have fitted all three solutions across Bangalore bathrooms. The 45-degree stop is the most common compromise in existing Yelahanka, Indiranagar, and Koramangala apartments, where the niche was built before the door spec was finalised.

The site-dimension checklist for frameless pivot doors

Before you issue the shop drawing, verify these measurements on site. Do not rely on the architectural plan.

• Niche width: measure at three heights (top, middle, bottom). Bangalore's hard water and monsoon humidity can cause tile grout to shift; a 750mm niche may be 752mm at the base and 748mm at the top.
• Niche depth: from the wall face to the back of the tray or floor. This determines the glass thickness and hinge depth. We typically spec 10mm low-iron glass for a 200mm-plus depth; thinner glass requires bracing.
• Toilet position: measure from the niche wall to the front face of the toilet cistern. If this distance is less than 750mm, the door swing will collide. Mark this on the RCP before the hinge hardware is ordered.
• Wall plumb: measure the wall deviation over the niche height using a level. Bathroom walls in Bangalore apartments often have 5–8mm deviation over 2 metres. This affects hinge installation and joint tolerance.
• Tile profile: identify the tile edge thickness (typically 10mm for standard ceramic, 12mm for porcelain). The hinge mounting plate must clear the tile edge by 3mm minimum to avoid binding.

Hardware specification for a tight niche: pivot hinge selection matters

Not all pivot hinges have the same projection depth. Standard commercial hinges project 40–45mm from the wall. Low-profile hinges project 30–35mm, but they are rated for lighter glass loads and are not suitable for 10mm frameless panels in Bangalore's humid climate.

For a 750mm niche, specify a standard-depth pivot hinge (40mm) and accept that the usable niche width is effectively 670mm (750mm minus 40mm hinge projection and 40mm for the opposite side of the glass clamp). If this is too tight, widen the niche or reduce the door swing angle.

The hinge hardware also determines the joint tolerance at the door edge. A well-fitted pivot door will have a 3–5mm joint line between the glass and the wall at the open edge. If the niche is out of plumb by more than 8mm, the joint line will be visibly uneven, and the door may bind. This is why site dimensions matter more than the architectural plan.

Monsoon, hard water, and the long-term fit of a frameless door in a 750mm niche

Bangalore's post-monsoon humidity (June to September) can cause grout and tile to swell slightly. A niche that measures 750mm in January may measure 751–752mm in August. This is not a defect; it is the normal expansion of porous materials under 70–80% relative humidity.

When we fit a frameless pivot door, we allow for this seasonal movement by specifying a 2mm joint tolerance on the niche width. A 750mm niche is fitted with a 748mm door assembly, leaving 1mm on each side for seasonal variation and installation tolerance. If the niche swells to 751mm in the monsoon, the door still operates smoothly. If we had fitted a 750mm assembly, the door would bind.

Hard water from the Cauvery (typical TDS 200–300 ppm in Bangalore) deposits mineral scale on the glass and hinge hardware. This does not affect the swing radius, but it does affect the visual appearance of low-iron clear glass with brass hardware. Scale builds up visibly on the hinge barrel and the glass edge. We recommend a water-softening system for any frameless shower in Bangalore, or weekly vinegar rinses to prevent mineral buildup.

The as-built drawing and the toilet coordination

When the shower is fitted, the hinge hardware is mounted to the wall and the glass panel is hung. At this point, the swing radius is fixed. If the toilet was not accounted for in the specification, it is too late to move it. The as-built drawing should include a note on the swing radius and the clearance to the nearest obstruction. This becomes part of the handover documentation and protects both the architect and the builder if the door operation is questioned later.

We provide a swing-radius diagram with every frameless door we fit. It shows the 90-degree arc, the collision points, and the final joint tolerance. This diagram is filed with the as-built drawings and serves as a record of what was specified and what was built.

Questions we get asked

Can we reduce the swing radius by moving the hinge axis away from the wall?

No. The hinge axis must sit at the wall face to support the glass panel. Moving the hinge away from the wall would require a cantilever support, which is not suitable for a frameless door. The swing radius is determined by the glass width, not the hinge position.

What happens if we spec a 700mm door in a 750mm niche to get more clearance?

A 700mm door leaves 50mm of clear niche on one side and 0mm on the other (because the hinge hardware occupies 40mm). This creates an uneven joint line and looks unfinished. It also reduces the usable shower width. Better to specify the full 720mm door and solve the toilet collision by relocating the toilet, reducing the swing angle, or widening the niche.

Does the door swing radius change if we use a different glass thickness?

No. A 10mm panel and an 8mm panel have the same swing radius if they are the same width. The glass thickness affects the hinge load rating and the visual weight of the door, but not the arc it travels.

Can we install a frameless pivot door in a 750mm niche with the toilet directly behind it?

Yes, if you specify a 45-degree stop on the hinge. The door will open only to 45 degrees, reducing the swing radius to approximately 510mm. The user enters the shower at an angle. This is a common retrofit and works well if the toilet cannot be moved.

How do we account for the swing radius on the RCP before the glass supplier is involved?

Draw a 90-degree arc from the niche wall with a radius equal to the planned door width (typically 720mm for a 750mm niche). This arc shows the footprint the door will occupy when fully open. If this arc intersects the toilet, the toilet must be moved or the door swing must be restricted. Do this at the coordination stage, not at handover.

Commissioning your frameless pivot door: the next step

If you are specifying a frameless pivot door for a Bangalore project, bring the site dimensions and the toilet position to the atelier before you finalise the niche width or the hinge hardware. We will calculate the swing radius, verify the clearance, and flag any collisions. This takes one conversation and prevents a site-handover failure. Talk to the atelier to commission your fitting.