Waterproofing, plumbing and ventilation: the invisible work of a sustainable renovation

When imagining a new bathroom, we first think of the visible elements: the shower, the tiles, the vanity unit, the faucets, or the lighting. However, the room's longevity depends primarily on work that will be concealed behind the walls, under the floor, and above the ceiling.

Waterproofing, plumbing, ventilation, electrical work, and surface preparation form the technical foundation of a successful bathroom renovation. When properly designed and executed, they protect the building against water infiltration, mold, leaks, and premature material deterioration.

These works represent a significant portion of the project and budget. Understanding their role helps to compare bids and recognize a truly sustainable renovation.

Why are invisible tasks so important?

A bathroom is exposed daily to water, steam, condensation, and temperature variations. Therefore, the quality of decorative materials alone is not enough to guarantee its longevity.

High-end tiles laid on an unstable surface can crack. An elegant shower without proper waterproofing can cause leaks. An undersized or improperly connected fan will fail to remove moisture.

The technical work allows, in particular:

• to properly direct the water towards the drains;

• to protect the walls and the floor;

• to ensure the proper functioning of sanitary equipment;

• to remove moisture;

• to secure electrical installations;

• to create stable surfaces for coatings;

• to limit the risks of subsequent repairs.

The quality of a renovation should therefore not be assessed solely from photographs of the final result. It also depends on what was done before the installation of the ceramic tiles and fixtures.

Mineral Oasis Bathroom

1. Post-demolition inspection

The demolition provides access to parts of the building that were previously hidden.

After the removal of the equipment and old coatings, the contractor can examine:

• the supply lines;

• evacuations;

• the subfloor;

• the structure of the walls;

• insulation;

• electrical installations;

• ventilation ducts;

• traces of moisture;

• damage caused by previous leaks.

A bathroom can appear to be in good condition while concealing a slow leak or a deteriorated substrate. It is important to correct these problems before closing up the walls.

This inspection may sometimes lead to a change in the bid or schedule. The contractor must then present the necessary additional work and obtain the owner's agreement before carrying it out.

2. Preparing the floor and walls

Bathroom wall coverings need a solid, stable and sufficiently flat base.

The preparation may include:

• the replacement of damaged parts of the subfloor;

• the strengthening of the structure;

• leveling the ground;

• wall correction;

• the installation of suitable panels;

• the closing of openings created for plumbing;

• the preparation of angles and joints;

• creating a stable base for the shower.

A floor that flexes slightly can cause cracks in the tiles or grout. Uneven walls complicate the installation of a glass partition and make alignment less precise.

This step directly influences the quality of the finishes. It should not be shortened to speed up the installation of visible elements.

3. Waterproofing of the shower and wet areas

Ceramic tiles and grout alone do not constitute a waterproofing system. Appropriate protection must be installed behind or beneath the coverings in areas directly exposed to water.

Depending on the system chosen, the work may include:

• preparing the support;

• the installation of a waterproofing membrane;

• the treatment of angles;

• the protection of plumbing fittings;

• the seal around the drain;

• the creation of the drainage slope;

• respecting drying times;

• checking the connections.

Particular attention must be paid to niches, benches, thresholds, and changes in plan. These areas have several angles and junctions that could allow water to enter if they are not properly prepared.

The products used must form a compatible system and be installed in accordance with their manufacturer's recommendations.

What problems can poor sealing cause?

A leak is not always immediately visible. It can develop slowly behind the tiles or under the floor.

Possible consequences include:

• joints that are deteriorating;

• tiles that are coming loose;

• a persistent musty smell;

• stains on the ceiling of the room below;

• the swelling of materials;

• the appearance of mold;

• the deterioration of the structure;

• a repair requiring the demolition of the shower.

Investing in rigorous waterproofing is generally much less expensive than having to redo a shower a few years after its renovation.

4. Slope and water drainage

In a shower, water should flow naturally towards the drain without forming stagnant areas.

The quality of the drainage depends in particular on:

• the position of the drain;

• the slope of the ground;

• of the shower base type;

• of driving ability;

• the quality of the connections;

• the precision of the tile laying.

An insufficient slope can leave water on the floor. Too steep a slope can be uncomfortable and complicate the installation of ceramic tiles.

The choice between a central drain and a linear drain also influences floor preparation and tile layout. This decision must be made at the project design stage.

Discover the solutions offered by BonBain for the installation of a walk-in shower and the integration of its drainage system.

5. Bathroom plumbing

The plumbing supplies and removes the water used by the shower, bathtub, toilet and sink.

As part of a renovation, the work may include:

• the replacement of old pipes;

• the relocation of water inlets;

• the modification of evacuations;

• the installation of the taps;

• the connection of the devices;

• preparing a custom-made shower;

• checking the ventilation of the drains;

• flow and sealing tests.

Keeping the existing fixtures in place can sometimes limit the scope of the work. However, a new layout can significantly improve the flow and functionality of the bathroom.

Relocating a toilet or shower should be considered from the design stage, as drainage pipes require sufficient space and a proper slope.

BonBain coordinates the bathroom plumbing work required for the modification or modernization of installations.

Signs of plumbing problems to check

Certain clues can reveal an existing problem:

• irregular water pressure;

• a slow flow;

• noises in the pipes;

• an odor coming from the drain;

• traces of moisture;

• a leaking tap;

• a toilet that moves;

• old or corroded connections.

A complete renovation provides an opportunity to inspect accessible parts of the installation and replace deteriorated components before they are concealed again.

6. Bathroom ventilation

Ventilation plays a vital role in protecting a bathroom. Every shower or hot bath releases a significant amount of steam. Without adequate ventilation, this moisture condenses on the walls, ceiling, mirrors, and furniture.

In the long term, poor ventilation can cause:

• persistent condensation;

• mold stains;

• the peeling of the paint;

• the swelling of the furniture;

• the deterioration of the joints;

• unpleasant odors;

• a decrease in air quality.

Replacing the fan is not always enough. The duct's path, condition, and outlet must also be checked.

The page dedicated to bathroom ventilation presents more precisely the role of this installation.

How to improve ventilation efficiency?

The system must be adapted to the characteristics of the room and correctly installed.

The entrepreneur is examining, in particular:

• the surface area of the bathroom;

• the length of the conduit;

• the number of elbows;

• the position of the fan;

• the exit to the outside;

• the noise level of the device;

• the available commands;

• air circulation under the door.

A fan that's too noisy is unlikely to be used much. A quiet model equipped with a timer or humidity sensor can make it easier to use for a sufficient amount of time after a shower.

The presence of a window is useful, but it does not necessarily replace adequate mechanical ventilation.

7. Electrical installations

Humidity and proximity to water require rigorous electrical design.

The work may involve:

• the sockets;

• the switches;

• general lighting;

• the lighting around the mirror;

• the fan;

• underfloor heating;

• the towel dryer;

• illuminated mirrors or cabinets.

The locations must be planned according to the layout of the room and the equipment used on a daily basis.

Lighting deserves special attention. A single light source placed on the ceiling can create shadows in front of the mirror. A combination of general, task, and ambient lighting offers greater comfort.

Electrical work must be entrusted to qualified professionals. BonBain organizes bathroom electrical work as part of its complete renovations.

8. Underfloor heating and insulation

Underfloor heating improves comfort, particularly during the colder months. However, its installation must be integrated into the floor preparation and coordinated with the laying of the floor covering.

In particular, the following must be taken into account:

• compatibility with the support;

• the final thickness of the floor;

• the location of the fixed elements;

• the electrical connection;

• the position of the thermostat;

• the products used to coat the system.

Poor planning can create a difference in level with neighboring rooms or complicate the installation of equipment.

The insulation of exterior walls can also be checked when they are open. A cold wall promotes condensation if the insulation or airtightness is insufficient.

9. Coordination of the various professionals

The technical work must be carried out in a specific order.

For example :

1. The plumbing and electrical wiring are prepared when the walls are opened.

2. The supports are then repaired or installed.

3. Waterproofing has been completed.

4. The floor coverings are installed.

5. The devices and equipment are connected.

6. The finishing touches and checks have been completed.

A coordination error may require reopening a completed surface or modifying an element that has already been ordered.

BonBain's turnkey bathroom renovation service centralizes this organization and ensures continuity between design and construction.

How can we verify that invisible work is included in the submission?

Before signing, look for the following items in the submission:

• demolition and removal of materials;

• inspection and repair of supports;

• plumbing work;

• electrical work;

• ventilation;

• shower waterproofing;

• floor preparation;

• connecting the devices;

• tests and verifications;

• managing unexpected discoveries.

Important products or methods should be described sufficiently to understand the scope of the work.

If a quote only mentions ceramic tile installation, ask what is included for the substrate and waterproofing. If it mentions the installation of a fan, check whether the duct and its outlet will also be inspected.

Consult our guide to learn how to compare bathroom renovation quotes.

Should less budget be allocated to visible elements?

It's not necessarily about sacrificing design or quality materials. A bathroom should also be pleasant to use and reflect the owners' tastes.

However, when the budget is limited, it is better to simplify some decorative choices rather than reduce the quality:

• of the waterproofing;

• plumbing;

• ventilation;

• electrical installations;

• of the preparation of the supports.

It is always possible to replace a mirror or accessories later.

Repairing a leak behind a finished shower is much more complex.

A well-thought-out design allows the budget to be allocated between technical work, equipment, and finishes.

The main warning signs

Certain situations should prompt the owner to ask more questions:

• a submission that does not mention waterproofing;

• the lack of information on ventilation;

• technical work described in a very vague manner;

• a complete renovation promised in a few days;

• the use of incompatible products;

• laying ceramic tiles on an unstable surface;

• plumbing modifications without explanation;

• the lack of qualified professionals;

• the refusal to show the work before the walls were closed;

• a strong demand for payment before their completion.

A contractor specializing in bathroom renovations should be able to explain the technical steps and clearly answer the homeowner's questions.

Sustainable renovation begins behind the walls

The finishes give a bathroom its character, but the invisible work ensures its solidity.

Rigorous sealing protects against leaks. Well-designed plumbing ensures the proper functioning of equipment. Effective ventilation limits condensation. Appropriate electrical installations improve safety and comfort. Finally, properly prepared surfaces allow finishes to maintain their appearance over the years.

BonBain Construction takes care of these different stages in its bathroom renovation projects in Montreal , Lachine, Laval, Longueuil, Brossard and on the South Shore.

View our completed projects , then contact BonBain Construction to request an estimate for your project.