Underfloor Plumbing Chase Installation for Bali Renovations

1) Specific Problem/Question

In Bali renovations, owners frequently want to relocate vanities, re-plan bathrooms, or add wet-bars and laundry nooks without exposing pipes on walls or compromising the finished flooring. The central question is: how do we create a durable, quiet, and serviceable underfloor plumbing chase—within existing slabs or new topping screeds—that respects construction standards Bali requires, maintains waterproofing integrity in a tropical climate, and integrates neatly with furniture installation and interior finishing? Below we outline Teville’s technical approach to underfloor plumbing chase installation tailored to villa utilities and renovation Bali conditions.

2) Technical Deep Dive: What an Underfloor Plumbing Chase Means in Bali

An underfloor plumbing chase is a controlled, protected path beneath the finished floor (or within the plinth/back of cabinetry) purpose-built to route water supply and drain lines for fixtures such as vanities, showers, floor drains, WCs with concealed cisterns, and wet-bars. In renovation settings, the chase typically sits in a new topping screed above the existing slab, within a raised floor, or inside cabinet plinths when slab cutting is limited. The objective is to deliver code-compliant hydraulics and acoustics while preserving waterproofing, tile integrity, and future access.

Key configuration options in Bali villa construction:

• In-screed chase (preferred for renovations): Shallow channels formed in a new screed layer (40–70 mm typical). This avoids deep slab cutting, allows pre-set levels for falls, and integrates with waterproofing and tiling.
• Raised floor chase: A battened or lightweight concrete build-up creates voids for pipes. Useful where existing slabs can’t be chased or where fall to drain is limited.
• Cabinet plinth/back chase: For vanities or pantry sinks, routes within the rear cavity or plinth void. Provides high serviceability with minimal slab work. See overview of “pipe chase” principles in cabinetry contexts in this reference.

Hydraulic fundamentals for Bali renovations:

• Drain gradients: 1–2% fall is standard for horizontal runs. For short vanity drains, target 1.5% to balance scouring and noise. Where fall is impossible, consider a localized shower base recess (drop slab), a low-profile linear drain with pre-slope, or last-resort pumped solutions.
• Ventilation: Even with short runs, ensure proper venting per SNI plumbing best practice to prevent trap siphonage. Where adding new fixtures far from vents, specify an auxiliary vent or approved air admittance device (AAV) as allowed by local authority.
• Traps and cleanouts: Integrate floor traps (with anti-odor seals) and accessible cleanouts at direction changes. Maintain minimum trap seals to resist tropical evaporation.

Supply lines and thermal/acoustic control:

• Hot/cold supply: In Bali, PPR or PEX-AL-PEX are robust choices. Hot lines require closed-cell insulation to limit heat loss and avoid thermal stress in screeds. Cold lines must be insulated to prevent condensation that triggers mold and tile discoloration.
• Expansion and movement: Provide sleeves or conduits around pipes, plus expansion loops or offset fittings on long runs. Avoid hard-bonding pipes to screed; use clip spacing that controls movement but allows thermal shifts.
• Noise: Wrap uPVC waste pipes with mineral wool and mass-loaded vinyl within the chase and isolate pipe hangers with rubber grommets. Design vanity plinths with acoustic breaks to prevent drumming.

Waterproofing and finishes layering (interior finishing Bali priorities):

• Pre-slope and membrane: Build a pre-slope before applying liquid or sheet membrane; turn membrane 150–200 mm up walls and fully band all changes of plane. Fit penetrations with compatible collars and bond-breakers to accommodate movement.
• Tile assembly: Use polymer-modified thinset suited to wet areas over cured membrane, with movement joints per field size and Bali humidity cycles. Grout selection should be tropical-grade, mold-resistant, and properly sealed.
• Furniture integration: Where the chase passes beneath vanities, install removable plinth panels with discreet fasteners. Leave a service void ≥60 mm behind back-panels for easy valve and trap access.

Structural caution:

• Scanning: Before any slab chase, GPR scan to avoid rebar/post-tension. In most renovations, Teville recommends avoiding deep slab cutting; instead, use over-slab screeds or cabinet chases.
• Penetrations: Where unavoidable, core-drill with sleeves and non-shrink collars, keeping minimum cover to reinforcement and applying firestopping where required between rated compartments.

Tropical durability considerations:

• Salt air and corrosion: Within 1–2 km of the coast, prefer 316 stainless for traps/fasteners, UV-stable membrane systems, and corrosion-resistant brackets. Avoid mild steel fixings in wet zones.
• Termites and mold: Use borate-treated timber only for furniture carcasses; keep timber off slab via damp-proof shims. Ensure ventilation to plinth voids; line with moisture-resistant board if needed.
• Serviceability: Design the chase with inspection points that can be accessed without damaging the tile field—e.g., cleanout covers flush with tile or concealed behind vanity panels.

Coordination with Bali renovation specialists is critical for sequencing, especially waterproofing and tile works. For broader property maintenance insights in Bali, see Mr. Fixit Bali. For examples of Teville finishing quality, review our portfolio and villa projects.

3) Materials & Standards (Bali-Relevant)

Teville specifies materials that balance tropical resilience, service life, and maintainability:

• Pressure lines: PPR (PP-R CT) PN20 for hot/cold, or PEX-AL-PEX with brass/SS fittings. Insulate hot and cold lines with closed-cell elastomeric foam (≥9 mm thickness) to control condensation and heat loss.
• Drainage: uPVC for sanitary waste/vent with solvent-weld fittings; schedule/thickness per load and routing. Acoustic wraps for 50–110 mm lines where under living spaces or bedrooms.
• Valves and fixtures: Full-bore isolation valves on fixture branches; 316 stainless or dezincification-resistant brass in coastal zones. Use serviceable traps with cleanout feature for vanities.
• Waterproofing: Two-component cementitious or high-performance liquid membranes compatible with Bali humidity and salt air. Include pre-formed collars for penetrations and elastomeric banding on corners.
• Screed and repair materials: Polymer-modified screeds (25–40 MPa) with shrinkage control; non-shrink grout around sleeves; primer systems approved by membrane manufacturer.
• Acoustic components: Mineral wool wrap, mass-loaded vinyl, resilient mounting accessories, isolation tapes at chase edges.
• Furniture substrates: Marine plywood or moisture-resistant board for vanity bodies; sealed edges; stainless steel adjustable legs or damp-proof plinth blocks.

Applicable standards and good practice references:

• SNI 8153: Plumbing systems in buildings (design, venting, gradients, testing). Teville applies SNI-aligned practices and manufacturer literature.
• International references: ISO 15874 (PP-R), ASTM F876/F877 (PEX), and industry guidelines for acoustic drainage and membranes, adapted to Bali site conditions.
• Local authority requirements: Coordinate with banjar/pecalang guidance, local PDAM supply constraints, and any condominium/villa estate rules for wet works.

Note: On heritage or PT/post-tension slabs, underfloor chases require structural engineer clearance. Teville’s construction process embeds design checks to protect structure and finishing outcomes.

4) Step-by-Step Process (Teville Method)

1. Assessment and scanning

• Survey existing plumbing, slab thickness, and finish levels. GPR-scan slabs for reinforcement and services. Record PDAM or pump pressures and hot-water plant temperatures.

2. Layout and coordination

• Fix fixture positions, finished floor levels, door thresholds, and drain locations. Confirm vanity carcass dimensions and plinth access panels (furniture installation coordination).

3. Chase design

• Select chase type: in-screed, raised floor, or cabinet plinth. Determine drain gradients (1–2%), pipe diameters, venting strategy, and cleanout points. Model penetrations and sleeves.

4. Protection and isolation

• Isolate work zone; install dust/ moisture barriers to protect adjacent finishes. Pre-cut acoustic and thermal wraps for efficient installation.

5. Forming the chase

• For in-screed: place edge isolation strips, set screed rails to pre-slope toward floor drain/linear drain. For cabinet plinth: construct removable plinth with service void (≥60–80 mm).

6. Sleeves and penetrations

• Core-drill only where cleared by scan/engineer. Install sleeves with annular space for movement; apply firestopping if passing rated elements.

7. Pipe installation

• Lay uPVC drains first, solvent-welding per manufacturer cure times. Maintain gradient with laser checks. Add cleanouts at major direction changes. Then install PPR/PEX supplies within conduits, with isolation valves placed inside vanity/service panels.

8. Pressure and flood testing

• Pressure-test supply lines per material standard (e.g., staged testing for PPR). Flood-test wet areas 24 hours prior to tiling; check all penetrations and perimeters for leaks.

9. Acoustic and thermal wrapping

• Wrap drains with mineral wool and MLV where noise-sensitive. Insulate hot and cold supplies fully; seal insulation joints against tropical condensation.

10. Backfill and screeding

• Backfill chases with lightweight filler or protective channels; pour polymer-modified screed to required levels. Respect isolation at walls to prevent sound bridging and allow slight movement.

11. Waterproofing

• Prime substrates; apply membrane to manufacturer’s wet-film thickness; reinforce corners/penetrations with banding and collars. Maintain upturn of 150–200 mm and integrate into drain flanges.

12. Tiling and finishing

• Install tiles with tropical-grade thinset; set movement joints; grout and seal. Fit vanity/furniture, connect traps and valves, verify plinth access and ventilation.

13. Commissioning and documentation

• Open all valves; test fixtures, drains, and vents; record as-built photos of chase routes and valve locations. Provide owner with maintenance notes and warranty documentation.

5) Costs & Timeline (Indicative, Bali)

Costs vary with scope, access, finishes,