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Plumbing and waterproofing held on one licence

Bathroom Remodeling

Full gut and rebuild, including the rough plumbing and the waterproofing. Both classifications are on our own licence, which means the drain detail and the membrane detail are not being coordinated between two subcontractors.

What does a bathroom remodel involve?

A full bathroom remodel runs demolition, framing and blocking, rough and finish plumbing, waterproofing, ventilation and then finishes. The waterproofing layer under the tile is what decides whether the room is still sound in ten years, and it is also the part of a remodel where a saving is hardest to see. Ecostep holds both the plumbing and the waterproofing classifications in house.

This page covers what a full bathroom remodel contains trade by trade, why waterproofing matters more than any finish choice and exactly which details leak, how ventilation fits in, and what moves the cost. It does not price your bathroom or give a schedule, since both come out of a site visit.

Bathroom remodel by Ecostep

What is in a bathroom remodel

A small room with the highest consequence of getting it wrong.

A bathroom is the only room in a house where you deliberately throw water at the walls every day. Everything in the build sequence below exists to keep that water where it belongs.

Line items a full bathroom remodel carries, grouped by trade.
TradeLine itemsWhy it is in this order
Demolition and protectionHazardous material assessment, demolition, temporary protection, progress cleaning, final cleaningAssessment before demolition. Older tile beds and mastics are a common place to find asbestos.
Framing and carpentryRough carpentry, blocking for fixtures and grab bars, interior trim, base and shoeBlocking has to go in before the walls close. Adding a grab bar later means opening the wall again.
PlumbingRough and finish plumbing, bathtubs, showers, lavatories, faucets, supplies and trim, water heaters, plumbing equipmentRough plumbing is inspected before anything is covered. Moving a drain is a rough-in decision.
WaterproofingDampproofing and waterproofing, waterproofing of shower and bath, weather barriersThis is the single most important line on the sheet and the one most often skimped. It happens after rough-in and before tile.
VentilationDucting, vents, ventilationAn extract fan that terminates in a roof space rather than outside is a mould problem waiting to happen.
FinishesDrywall, flooring, painting, bath cabinets, cabinet hardware and installation, countertops, tile installation with wall, trim, base and floor materials, niches and ledges, grout, sealer, tub and shower doors, mirrors, toilet and bath accessories, shelvingTile goes on a waterproofed substrate, not the other way round. Glass is templated after tile.

The part you will never see

Waterproofing is what decides whether the bathroom lasts.

Two bathrooms can look identical on the day they are finished and be completely different buildings five years later. The difference is behind the tile, and it is also the part of a remodel where a saving is hardest to see.

A construction budget carries waterproofing as its own line, separate from tile, and a separate line again for waterproofing of the shower and bath specifically. That separation matters. Tile and grout are not waterproof. Grout is porous and cementitious backer board is not a membrane. What keeps water out of the framing is the waterproofing layer underneath, the detailing at the corners and the change of plane, and the way the membrane is lapped at the curb and the drain.

Ecostep holds the C-2 insulation and acoustical classification, which covers dampproofing and waterproofing, and the C-36 plumbing classification. Both of those live in a bathroom. The rough plumbing, the waterproofing and the prime contract are held by the same company, which means the drain detail and the membrane detail are not being coordinated between two subcontractors who each assume the other handled it.

The details that leak

  • The change of plane where the wall meets the floor, and the inside corners
  • The shower curb, particularly the top and the outside face
  • The connection between the membrane and the drain flange
  • Niches and ledges for shampoo and soap, which are deliberate holes in the wall and need the membrane returned into them properly
  • Penetrations for mixer valves, shower arms and body sprays
  • The threshold, where the bathroom floor meets the rest of the house

Niches are on the budget sheet as their own line for exactly this reason. They are the thing homeowners most want and the thing most likely to be detailed badly.

Moisture and air

The second half of the problem is vapour, not water.

Liquid water is handled by the membrane. Vapour is handled by ventilation, and it is where a surprising number of otherwise well-built bathrooms fail. An extract fan has to actually move air to the outside of the building, through a duct that is the right diameter and short enough to work, terminating outdoors rather than in a roof space or a soffit.

Ducting, vents and ventilation are separate lines in a construction budget. On a remodel in an older house the awkward question is usually where the duct can physically run, and that is a design question rather than a site question.

What else changes the number

  • Moving a drainRelocating a shower or toilet drain means opening the floor. On a slab that is a different job from on a raised floor, and it is the largest single variable in a bathroom layout change.
  • Going from tub to walk-in showerDrain position, curb or kerbless threshold, floor build-up and the waterproofing detail all change. A kerbless shower is the more demanding detail by a distance.
  • Tile choiceFormat and material drive labour more than price per square foot suggests. Large-format tile needs a flatter substrate, mosaic needs far more grout line, and natural stone needs sealing.
  • GlassTub and shower doors are templated after the tile is finished, so it is a fixed lead time at the end of the job that cannot be compressed.
  • Water heaterA new high-demand shower can expose an undersized or ageing heater. Worth checking at the start rather than discovering at first use.
Completed bathroom remodel with tiled shower by Ecostep

The public record

Where our permitted bathroom work is.

Residential building permits are public record, each carrying a licence number, a scope and a valuation. Ecostep's permitted kitchen and bathroom work appears in San Francisco, Belmont and San Leandro, with whole-house remodels in Berkeley and Fremont and accessory dwelling units in Alameda, Berkeley and Concord. Recorded values across our residential permits run from $25,000 to $210,000.

CSLB #1006147 carries B general building, C-2 insulation and acoustical, C-6 cabinet and millwork, and C-36 plumbing, and is active through 31 August 2027. Amer Abusafieh has held a California general contractor licence since 2003 and has worked in the trades since January 1986, including a career in mechanical insulation that is where the waterproofing and moisture control classification comes from.

Before the tile goes on

The membrane, the curb and the drain decide how long the room lasts.

Tile and grout are not a waterproofing layer. What keeps water out of the framing is the membrane beneath it, the way it is detailed at the inside corners and the change of plane, and how it connects to the drain flange and returns into the curb.

Questions

What homeowners ask.

What does a full bathroom remodel include?

Demolition with a hazardous material assessment first, framing and blocking for fixtures, rough and finish plumbing, waterproofing, ventilation, then finishes: drywall, flooring, painting, bath cabinets and hardware, countertops, tile with its trim, base, niches, grout and sealer, tub and shower doors, mirrors, accessories and shelving. The waterproofing sits between the rough-in and the tile and is the line that decides whether the room lasts.

Do I need a permit for a bathroom remodel?

If you move plumbing, alter electrical, or change the ventilation, yes. A like-for-like replacement of fixtures in the same positions sometimes does not, but a full gut and rebuild normally does. We prepare and submit the drawings and carry the application through to an issued permit with our licence number on it. Unpermitted bathroom work has a habit of surfacing during a sale.

How much does a bathroom remodel cost?

Recorded values across our residential building permits run from $25,000 to $210,000, which is public record rather than a quote. Within a bathroom the biggest variables are whether you move a drain, whether you go from a tub to a walk-in shower, and the tile format and material. A written scope and price comes out of a site visit.

Why is waterproofing so important, and how do I know it was done properly?

Because tile and grout are not waterproof. Grout is porous and backer board is not a membrane. What keeps water out of the framing is the waterproofing layer underneath and the detailing at the inside corners, the change of plane, the curb and the drain flange. The curb detail and the membrane connection at the drain flange are the two things worth asking about on any bathroom quote.

Can you convert my tub into a walk-in shower?

Yes, and it is one of the most common requests. It changes the drain position, the threshold, the floor build-up and the waterproofing detail. A kerbless or level-access shower is the more demanding version because the whole floor has to fall correctly to the drain and the membrane has to be continuous across the threshold. It is very achievable, and it costs more than a standard curbed shower.

What is a shower niche, and is it a risk?

A recess in the wall for shampoo and soap. It is a deliberate hole in a waterproofed surface, so the membrane has to be returned into it and detailed at every internal corner. Detailed properly it is completely reliable. Detailed poorly it is one of the first places a shower leaks. Niches and ledges appear as their own line in a construction budget for precisely that reason.

Do you do the plumbing yourselves?

Yes. C-36 plumbing is on our licence, so the rough and finish plumbing is done by the company holding the contract rather than by a subcontractor whose schedule you are waiting on. In a bathroom that matters because the rough plumbing has to pass inspection before anything is covered, and the plumbing detail and the waterproofing detail have to agree with each other at the drain.

What about ventilation?

An extract fan has to move air to the outside of the building through a duct of the right diameter and a run short enough to work, terminating outdoors rather than in a roof space or soffit. Ducting, vents and ventilation are separate budget lines. In an older house the hard question is where the duct can physically run, and that is answered on the drawings rather than on site.

How long does a bathroom remodel take?

It depends on the scope and we will not invent a figure for a project we have not seen. What is worth planning around is that some lead times cannot be compressed: waterproofing has to cure and be tested before tile, and tub and shower doors are templated only after the tile is finished. Those two sit at either end of the finishing sequence.

Will a new shower overwhelm my water heater?

It can, particularly with a high-flow or multi-outlet shower on an older or undersized heater. Water heaters are a line in the plumbing division for that reason. It is worth checking capacity at the start rather than finding out on the first morning after handover.

What happens if you find asbestos or lead?

The budget carries a hazardous material assessment line before demolition and a remediation line after it. Older tile beds, mastics and paint layers are common places to find both in Bay Area housing stock. Finding it is routine. Finding it with no line in the budget for it is the problem.

Do you make bathroom cabinets and vanities?

Yes. We hold the C-6 cabinet and millwork classification and run our own wood shop with a five by twelve foot CNC router, so a vanity is made to the room rather than ordered to the nearest stock width. In a small bathroom where every inch is contested, that is usually the difference between a vanity that fits and one that nearly fits.

Which areas do you work in?

Contra Costa, Alameda, San Francisco, San Mateo, Santa Clara and Marin counties. Our permitted kitchen and bathroom work on public record sits in San Francisco, Belmont and San Leandro.

1006147CSLB licence

Reviewed by Amer Abusafieh

President and responsible managing officer of Ecostep, Inc. Amer has worked in the trades since January 1986, completed a union apprenticeship and earned his Journeyman Heat and Frost Insulator card in 1995, and has been a licensed California general contractor since 2003. Before founding Ecostep in 2015 he worked refineries, power plants, pharmaceutical plants, offshore platforms and ships, and opened a cabinet shop in Pittsburg.

Licence
CSLB #1006147, active, expires 31 August 2027
Classifications
B general building, C-2 insulation and acoustical, C-6 cabinet, millwork and finish carpentry, C-36 plumbing
Entity
Ecostep, Inc., a California corporation
Counties
Contra Costa, Alameda, San Francisco, San Mateo, Santa Clara, Marin

Page last reviewed September 2026. California ADU statute is amended most years, so figures on this page carry the date they were checked. Verify anything decision critical against your local planning department before you rely on it.

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