Bath plan CAD blocks: oval, rectangular and corner shapes

The shape decision that quietly drives the whole room

Bath shape feels like a small choice when you're first blocking out a bathroom, and then you get three walls into the layout and realize the shape you picked either uses the corner efficiently or wastes a meter of floor you needed for something else. I've redone this decision late in a drawing more times than I'd like to admit, so it's worth doing the comparison up front, oval versus rectangular versus corner, against the actual room shape rather than picking whatever bath block happened to look nicest in the thumbnail. This is one of those bathroom decisions where the finished room forgives almost nothing, unlike a piece of furniture you can swap later, a bath is set in tile and plumbing, so getting the shape comparison right at the drawing stage is worth the extra half hour it takes.

Rectangular baths and why they're still the default

A rectangular bath plan block is the simplest to lay out against a straight wall, and it's the default for a reason, the footprint reads clearly, tiling around it is straightforward, and it lines up naturally with a stud wall or a tiled niche behind it. Rectangular tub footprints typically run somewhere in the range of 1500mm to 1800mm long by 700mm to 800mm wide, though shorter compact tubs down around 1200mm to 1400mm do turn up for smaller rooms.

The catch here is that a rectangular bath along one wall eats that entire wall length, so in a narrow bathroom it can end up competing directly with the vanity or the door swing for the same linear footage, which is exactly the kind of clash worth catching in plan before it becomes a site problem.

Rectangular tubs also tile the most predictably of the three shapes, since the surround is just three straight vertical planes meeting the tub deck at a right angle, which matters if your project has a tile setter working from a schedule rather than freehand, a rectangular bath plan block gives them the cleanest reference to work from.

Oval baths and where the extra floor actually goes

An oval bath plan block softens the corners of that same rectangular footprint, and functionally it can free up a bit of floor space at the ends where the curve pulls in from the straight wall line, useful when you need a sliver of extra circulation next to the tub. Oval bath blocks are typically drawn close to the same overall length as their rectangular counterparts, since the tub itself hasn't shrunk, it's just the plan outline that reads softer.

Where oval genuinely helps is in a room where the bath sits somewhat exposed rather than fully boxed in on three sides, a curved edge reads less bulky in the plan and in the finished room both, which is part of why it shows up so often in primary suite layouts rather than tight secondary bathrooms.

The tradeoff on tiling is real though, a curved tub surround needs either a curved tile detail or a bulkhead that steps down to meet the curve, both of which add cost and coordination that a straight rectangular surround simply doesn't need, so it's worth flagging that tradeoff to a client who's drawn to the oval shape purely on looks.

Corner baths and the geometry problem they actually solve

A corner bath plan block is a genuinely different shape decision, not just a stylistic one, it's built to sit diagonally or flush into a room corner, using two walls instead of one and freeing up a full wall run elsewhere for a vanity or a shower enclosure. Corner units tend to have a wider overall footprint measured across the diagonal, often somewhere in the 1400mm to 1600mm range along each wall face, so they need more total floor area than the tub itself suggests, the corner they sit in has to accommodate the full triangular or curved plan shape, not just the visible bathing area.

This is the shape I reach for specifically when a small ensuite has one awkward corner that a rectangular tub would leave half-wasted, since angling the fixture into that corner can free up the straight wall runs for fixtures that actually need them.

The catalog also carries triangular bath plan variants, drawn specifically for this diagonal corner condition, some with the faucet position shown and some without, and comparing a genuine triangular block against a standard corner unit is worth doing since the two aren't interchangeable, a triangular plan typically has a straighter outer edge than a fully curved corner unit, which changes how much usable deck space sits around the rim.

Checking the block against the room before you commit

Whichever shape you're leaning toward, bring the block in at the correct scale and actually rotate it against your real wall dimensions before locking the layout, since a corner bath in particular only works if the two adjacent walls are long enough to clear the fixture and still leave circulation space in front of it. I check this the same way every time, insert near a dimensioned wall, confirm the block's size against that reference with DIST, then walk the clearance zone around it in the plan.

Don't assume a corner bath automatically saves space just because it tucks into a corner, sometimes the diagonal footprint actually claims more usable floor area than a straight rectangular tub would along a single wall, so the comparison only makes sense once you've got both options sitting in your specific room shape, not in the abstract.

What I actually check across all three before finalizing

At the end of the day I run through the same short list on every bath decision, wall length available, whether the fixture needs to share a wall with anything else like a shower valve or a window, and how the clearance zone in front interacts with the door swing. Rectangular wins on simplicity and tiling, oval wins on softening a tight room, corner wins on genuinely awkward room geometry where a straight wall run just isn't available. None of the three is universally correct, and the floor plan itself is really the only reliable way to test which one actually fits, which is why I'd rather spend ten extra minutes comparing blocks in plan than commit early and redraw the room later.