Renovating a Bathroom in a Home on Stumps

A common Gippsland situation

Drive through the older streets of Warragul, Yarragon, Trafalgar or Drouin, or along the roads into the hills, and you will see many homes raised on stumps. Weatherboard houses from the early twentieth century, postwar homes and even some later builds sit on timber, concrete or steel stumps with timber bearers and joists supporting a timber floor. These homes have character and charm, but their bathrooms need a different approach from those built on a concrete slab.

Tiles are rigid and brittle. Timber floors are flexible and move with changes in moisture, temperature and load. If a tiled bathroom is built on a floor that flexes or settles, tiles crack, grout fails and waterproofing can tear. Understanding how to prepare a timber floor properly is the key to a bathroom that lasts.

Start with the subfloor

Before any design decisions are finalised, the subfloor beneath the bathroom should be inspected. This usually involves going under the house with a torch. Things to check include:

• Stumps: are they sound, upright and bearing properly, or have some sunk, rotted or lost contact with the bearers?
• Bearers and joists: are they sized and spaced adequately for a tiled floor, and are they free from rot and termite damage?
• Moisture: are there water stains, damp soil, fungal growth or a musty smell beneath the existing bathroom?
• Ventilation: is there adequate cross-flow ventilation under the house, or are vents blocked?
• Previous repairs: have earlier renovators added packing, patched joists or made changes that affect stiffness?

Many older bathrooms on stumps have suffered years of slow water escape from failed showers. Damage is often concentrated directly below the shower and around the toilet.

Restumping and levelling

If stumps under the bathroom have settled or failed, the floor may slope or bounce. Restumping replaces failed stumps with new concrete or steel stumps and re-levels the floor. Sometimes only a few stumps under the bathroom need attention; in other cases, the whole house may need restumping. Levelling before tiling is important because a new tiled floor will reveal any slope, and doors and cabinetry need a level base.

Restumping is specialised work, and in some situations a building permit may be required. Your renovator can advise and coordinate the work.

Stiffening the floor

Even sound floors may flex more than tiles can tolerate. Floor stiffness depends on joist size, spacing and span. To stiffen a bathroom floor, options include:

• Adding joists between existing ones to reduce spacing.
• Adding a new bearer and stumps to shorten joist spans.
• Sistering new timber alongside existing joists.
• Installing blocking or bridging between joists.

The goal is a floor that does not deflect noticeably under load, particularly in the shower and where a heavy bath will sit.

Substrates for tiling

Tiles should not be laid directly onto timber floorboards or particleboard in wet areas. Instead, a wet-area substrate such as compressed fibre cement sheet is fixed to the joists or over a sound structural floor. Compressed sheet is dense and stable, providing a rigid base for waterproofing and tiles. It must be fixed according to the manufacturer’s instructions, with appropriate screw spacing and adhesive.

In showers, falls can be built into the substrate by packing or by laying a screed over the sheet. The approach depends on the shower design and the waterproofing system.

Waterproofing for movement

Waterproofing on timber floors must accommodate movement. AS 3740 requires bond breakers at wall and floor junctions so the membrane can stretch slightly rather than tear. On timber floors, many renovators choose to waterproof the entire bathroom floor rather than only the shower, adding protection if water ever escapes onto the floor. Some membrane systems are specifically suited to timber-framed buildings with greater movement. Proper curing is essential, particularly in cold Gippsland winters.

Heavy fixtures

A cast iron or stone bath filled with water and a person can weigh a great deal. On a timber floor, the structure beneath must carry that load without excessive deflection. We assess the floor framing where a heavy bath will sit and add support where needed. The same applies to stone vanity tops and large cabinetry.

Plumbing access

One advantage of homes on stumps is easier access to plumbing. Waste pipes and water supplies run beneath the floor, making it simpler to relocate fixtures or add new ones than in a slab home. However, pipes must be supported correctly, protected from frost in cold areas and laid with adequate falls. Waste pipes connecting to sewer or septic systems must meet plumbing standards, and all work must be carried out by a licensed plumber.

Insulation and cold floors

Timber floors on stumps can be cold in winter, especially in exposed hill locations. Adding underfloor insulation between joists beneath the bathroom improves comfort and helps the floor dry after showers. Underfloor heating installed beneath tiles can further improve comfort, though it must be compatible with the substrate and membrane.

Subfloor ventilation

Good ventilation under the house helps keep timbers dry and reduces the risk of rot and termites. During a renovation, check that subfloor vents are clear and adequate. Moisture from failed showers, poor drainage or blocked vents can all contribute to damp subfloors.

Termites

Termites are attracted to damp timber. Older homes in Gippsland can show signs of past or present termite activity. If damage is found during demolition, it must be assessed and treated, and damaged timbers replaced. A termite inspection before renovation can identify issues early.

Floor heights and thresholds

Building up a timber floor with a substrate, screed and tiles can raise the bathroom floor above the adjoining hallway. This creates a step or a threshold. For accessible or level-entry designs, the floor may need to be lowered between joists or the structure adjusted to achieve a flush transition. Planning floor heights early prevents trip hazards and awkward door clearances.

Types of stumps you may find

Red gum and other timber stumps

Many older Gippsland homes were built on red gum or other hardwood stumps. Red gum is durable, but after many decades in damp soil, stumps can rot at or below ground level, lose bearing or be attacked by termites. Timber stumps are often the first thing a restumping assessment checks.

Concrete stumps

Concrete stumps, often with a steel reinforcing rod and a bolt or strap connecting to the bearer, became common in later decades. They resist rot and termites but can crack or settle if footings were inadequate.

Steel stumps

Adjustable galvanised steel stumps are common in restumping and newer construction. They allow precise levelling and can be adjusted in future if the house moves.

Knowing which type supports your home helps estimate how much work the subfloor may need.

Bathrooms in rear additions and enclosed verandahs

In many older homes, the bathroom was not part of the original house. It may sit in a lean-to addition at the back, built later and sometimes to lower standards, or in an enclosed verandah with a sloping floor. These areas often have different floor heights from the main house, smaller framing and lower ceilings. Renovating them can involve rebuilding the floor structure entirely, adjusting the floor level to match the house and improving the roof and wall framing. While this adds to the scope, it also creates an opportunity to integrate the bathroom properly into the home.

Sloping blocks

Homes on sloping blocks in the hills around Warragul may have tall stumps at one end, sometimes with bracing. Tall stumps need adequate bracing to prevent movement, and access beneath may be easier on the low side. Plumbing falls on sloping sites need careful planning, especially where wastewater must travel uphill to a septic system, which may require a pump.

Working sequence

A typical sequence for a bathroom on stumps:

1. Inspect the subfloor and test any suspect materials.

2. Demolish the old bathroom back to the frame and joists.

3. Restump or level the floor where needed.

4. Repair and stiffen framing; add support for heavy fixtures.

5. Plumbing and electrical rough-in.

6. Install wet-area substrates and wall linings.

7. Form falls, install waterproofing and allow it to cure.

8. Tile, grout and seal.

9. Fit off fixtures, screens and accessories.

Common problems we find

• Rotted joists and bearers under old showers.
• Floors patched with packing or particleboard.
• Missing or inadequate subfloor ventilation.
• Plumbing supported by makeshift brackets.
• Old floorboards laid over earlier tiled floors.
• Termite damage hidden beneath linings.

Discovering these issues is common, and a good renovator will explain them clearly and confirm repairs in writing.

Choosing tiles for timber floors

Tile choice also matters on a timber floor. Very large-format tiles are less forgiving of small deflections and require exceptionally flat substrates, while medium-sized porcelain tiles are often a safer choice. Flexible, polymer-modified adhesives and grouts accommodate small movements better than rigid products. Movement joints, filled with flexible sealant at the perimeter and at intervals in larger rooms, allow the tiled surface to expand and contract without cracking. On shower floors, smaller tiles follow falls more easily and tolerate movement well.

Questions to ask your renovator

1. Will you inspect the subfloor before finalising the scope?

2. How will you stiffen the floor if needed?

3. What substrate will you use under the tiles?

4. Will you waterproof the entire floor?

5. How will the membrane accommodate movement at junctions?

6. How will heavy fixtures be supported?

7. How will you manage the floor height at the doorway?

8. What happens if rot or termite damage is discovered?

Older homes and asbestos

Homes on stumps built before 1990 may contain asbestos in wall sheets, eaves, floor coverings or the backing of linoleum. Testing suspect materials before demolition is essential. If asbestos is present, it must be removed by licensed professionals before other work proceeds.

Benefits of getting it right

When a bathroom on stumps is built on a stiff, level, well-ventilated floor with a suitable substrate and properly detailed waterproofing, it can perform as well as one on a slab. The result is a bathroom that respects the character of an older home while meeting modern standards.

Before you book the tiler

If the floor bounces when you jump lightly in the doorway, mention it at the consultation. A springy floor is a warning sign for tiles and grout, and it can usually be fixed with extra bracing, packing or stumps before the new bathroom is built. Addressing it first is far easier than repairing cracked tiles later.

Keep any reports from a restumping contractor or building inspector and share them with us before the consultation. They tell us the condition of stumps, bearers and joists, and help us decide whether extra support is needed under the wet area before any sheeting or tiling begins.

Book a design consultation

If your Warragul-area home sits on stumps and your bathroom needs renovating, book a design consultation. We will inspect the subfloor, explain what the floor needs and provide a clear written scope.

Our bathroom services

• Accessible Bathrooms
• Full Bathroom Renovations
• Bathroom Resealing and Silicone Replacement
• Bathroom Tiling
• Ensuite Renovations
• Laundry Renovations
• Bath to Shower Conversions
• Shower Screens
• Small Bathroom Renovations
• Tile and Grout Cleaning
• Vanity Replacement
• Bathroom Waterproofing