Studio Matrx Monthly · Volume 1 · Issue 2 · July 2026
Amogh N P
✦ In loving memory of Amogh N P — Architect · Designer · Visionary ✦
A bathroom under construction — a sunk slab with a black waterproofing membrane coated over the floor and turned up the walls, a floor drain set in the falls, exposed concealed pipes, and a stack of wall tiles, warm site light, no people, no legible text.
Unit VInterior Materials & Construction II

Doors, Wet Areas & Services

Openings, waterproofing, the trade sequence, and green detailing.

≈ 55 min + a wet-area sectionByAmogh N P· Architect & interior designer

The detailing that makes or breaks an interior. Learn door and window systems and the door schedule; wet areas in detail — the sunk slab and the waterproofing SYSTEM (a membrane turned up the walls, with falls to the drain, flood-tested before tiling); interior services and the sequence of trades whose order must not be broken; and sustainability in detailing — low-VOC finishes, certified boards, durability, and GRIHA/IGBC awareness.

Learning objectives

By the end of this lesson, you will be able to — mapped to the course outcomes for Interior Materials & Construction II:

1
CO5 · Apply

Detail door and window systems and compile a door schedule.

2
CO5 · Apply

Detail wet-area waterproofing as a system, with falls and a flood test.

3
CO5 · Analyse

Explain concealed services and the sequence of trades that finishes depend on.

4
CO6 · Evaluate

Apply sustainability in materials and detailing, and green-rating awareness.

Openings and wet areas

Doors, windows & waterproofing

Door and window systems and the door schedule, and wet-area waterproofing as a system on a sunk slab.[1, 2, 3]

Doors & windows: the detail Door frame (chowkat) plan holdfast into masonry rebate flush shutter (IS 2202); the door schedule lists every door Window (glazing on beads) insulated / safety glazing on gaskets aluminium (IS 1948) / uPVC / timber Toughened glass is SAFETY glass (blunt granules), not unbreakable; laminated holds together.
DiagramA door frame chowkat with holdfasts into masonry and a rebate, and a window section with insulated glazing on beads
Bathroom waterproofing = a SYSTEM sunk slab membrane turned UP the walls ~150–300 protective screed + falls (~1:80–1:100) floor drain FLOOD-test (pond 24–72 h) BEFORE tiling Skipping the wall turn-up or the flood test is why bathrooms leak at the skirting. (IS 3067)
DiagramBathroom waterproofing section — a sunk slab, membrane turned up the walls, protective screed, falls to the drain, and a flood test

Systems, frame, and the schedule

DOOR types: flush (solid/hollow core, ply/MDF faced — the Indian internal default), panelled, glazed, sliding (surface or pocket, top-hung), folding, and fire-rated. The FRAME (chowkat) is the structural surround — seasoned hardwood, pressed steel (IS 4351), WPC or aluminium — detailed for rebate depth, holdfasts into masonry and the hinge/lock jamb. IRONMONGERY: hinges, mortise lock and handles, tower bolts, closers and stoppers. And the DOOR SCHEDULE — the coordination document listing every door by number with size, type, material, frame, finish, fire rating, handing and the full ironmongery set (the equivalent of the RCP for openings). Flush doors are specified to IS 2202 and tested to IS 4020.[1, 2]

Coordination and green detailing

Services, sequence & sustainability

Concealed services and the sequence of trades that must not be broken, and sustainability in detailing with green-rating awareness.[1, 4]

The sequence of trades (do not break it) 1 · structure 2 · plumbing & electrical rough-in 3 · waterproofing (wet areas) 4 · plaster 5 · ceiling framing + MEP first-fix 6 · screed / flooring 7 · wall finishes / tiling 8 · joinery install 9 · paint 10 · second-fix & handover Rough-in & waterproofing come BEFORE plaster & tiling. Break the order — chase a wall after tiling — and you cut open finished work. The finish plane is set out around switch plates, taps and grilles.
DiagramThe sequence of trades — structure, rough-in, waterproofing, plaster, ceiling, flooring, wall finishes, joinery, paint, second-fix, handover
Sustainability is mostly detailing discipline Low-VOC finishes water-based paint, adhesive, sealant → indoor air Certified / low-emission boards FSC, no-added-formaldehyde E0–E1, recycled, bamboo Durability & low embodied energy durable, repairable, local → fewer replacements Less waste demountable KD joinery, dry construction, segregation Often COST-NEUTRAL — and always better indoor air. India rates it: GRIHA (national), IGBC, and the ECBC energy code. Sustainability is NOT an expensive add-on — it is disciplined material & detail choices.
DiagramSustainability in detailing — low-VOC finishes, certified low-emission boards, durability, demountable joinery, and GRIHA/IGBC awareness

A system, not one coat

The make-or-break of interior construction. Bathrooms sit on a SUNK SLAB (~200–300 mm below the surrounding level) so plumbing and fall-fill sit below the finished level. Waterproofing is a SYSTEM: surface prep → a cementitious/crystalline/acrylic/PU membrane carried UP THE WALLS ~150–300 mm (full height in showers) → a protective screed → FALLS (~1:80–1:100 to the drain, steeper at the shower) → tile bed → tiles with EPOXY grout in the wet zone. FLOOD-test (24–72 h pond) BEFORE tiling. Skipping the wall turn-up or the test is why bathrooms leak at the skirting.[3, 4]

Myth vs reality

At a glance

AspectOne sideThe other
WaterproofingMyth: one coat of chemical on the floorReality: a system turned up the walls, with falls, flood-tested
Epoxy grout in showersMyth: a luxuryReality: a functional waterproof, stain-proof joint
Trade sequenceMyth: tile first, run services laterReality: rough-in & waterproofing BEFORE plaster/tiling
Toughened glassMyth: unbreakableReality: safety glass — stronger, breaks into blunt granules
SustainabilityMyth: an expensive add-onReality: detailing discipline — often cost-neutral
Vocabulary

Key terms

Chowkat

The door's structural frame/surround — hardwood, pressed steel, WPC or aluminium.

Door schedule

The document listing every door with size, type, finish, rating, handing and full ironmongery.

Sunk slab

A bathroom slab dropped ~200–300 mm so plumbing and fall-fill sit below the finished level.

Waterproofing system

A membrane turned up the walls, protected, with falls to the drain and flood-tested before tiling.

Sequence of trades

Rough-in and waterproofing before plaster/tiling; break the order and you cut open finished work.

Low-VOC / certified boards

Low-emission finishes and FSC / E0–E1 boards for indoor air quality — GRIHA/IGBC-rewarded.

Apply it

Detailing task

Draw a sectional detail of a bathroom floor and wall — showing the sunk slab, the waterproofing membrane turned up the walls, the protective screed, the falls to the floor drain, and the tiles with epoxy grout — and mark where the flood test is done. Then compile a short door schedule (three doors) listing size, type, material, finish, handing and the ironmongery set for each. Finally, list five sustainability moves you would specify for the same bathroom, and which are cost-neutral.

Check your understanding

Self-assessment

1. Bathroom waterproofing is done correctly by —

2. In the sequence of trades, concealed plumbing and electrical are done —

3. Sustainability in interior detailing is best described as —

In a nutshell

Recap

Door systems (flush, panelled, glazed, sliding), the chowkat frame and ironmongery are pulled together in the door schedule; flush doors follow IS 2202/IS 4020.
Windows (casement, sliding; aluminium, uPVC, timber) use insulated and safety glazing — toughened and laminated glass in low, door and wet zones.
Wet-area waterproofing is a system on a sunk slab — a membrane up the walls, protected, with falls to the drain, epoxy grout, and a flood test before tiling.
Concealed services drive the finishes, and the sequence of trades (rough-in and waterproofing before plaster/tiling) must not be broken.
Sustainability in detailing is largely discipline — low-VOC finishes, certified low-emission boards, durability, demountable joinery and less waste — and India rates it via GRIHA and IGBC.
The evidence

References & further reading

  1. [1]David Kent Ballast, Interior Detailing: Concept to Construction, Wiley (door/window details, wet-area sections, schedules).
  2. [2]Francis D.K. Ching, Building Construction Illustrated (doors, windows, glazing, moisture control); BIS IS 2202, IS 4020, IS 4351, IS 1948.
  3. [3]Dr. Fixit (Pidilite) Waterproofing Handbook, and Fosroc / Sika / MYK Laticrete technical guides (bathroom waterproofing systems, falls, coving, testing); BIS IS 3067.
  4. [4]GRIHA and IGBC reference manuals; NBC 2016 (Part 9 Plumbing, Part 11 Sustainability); CPWD Specifications.

Further reading

  • David Kent Ballast — Interior Detailing: Concept to Construction.
  • Francis D.K. Ching — Building Construction Illustrated.
  • Dr. Fixit — Waterproofing Handbook.

Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.

A

The author

Amogh N P

Architect, interior designer, and creative polymath. Studio Matrx began in his notebooks — his vision of design made honest, useful, and open to everyone. Its Academy is written and taught in his memory, and free, forever.

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