Kitchen and laundry room waterproofing: a practical guide to prevent leaks

Kitchen and laundry room waterproofing is one of the most effective ways to prevent leaks to downstairs neighbors, damp patches on walls, and damaged floors—especially where you have a washing machine, dishwasher, sink, and multiple water connections. While kitchens are not always treated like bathrooms, in real life they concentrate many small leaks and high-risk details.

When is it worth waterproofing a kitchen or laundry area?

• During a full renovation or when replacing the floor.
• If you’ve had repeated leaks into the apartment below.
• Swollen skirting boards, open joints, or staining on nearby walls.
• Laundry areas in enclosed terraces/utility galleries with old drains.
• Commercial kitchens (higher risk due to intensive use).

If there is an active leak (hose, trap, appliance), fix it first. Waterproofing reduces damage from spills and micro-leaks, but it won’t compensate for faulty plumbing.

Critical points (where most kitchens fail)

Floor-to-wall junction (sanitary upstand)

Water often gets in at the perimeter: joints, skirting, and poorly sealed transitions. A reliable solution requires turning the waterproofing up the wall (commonly 10–15 cm, more if risk is higher).

Pipe penetrations

• Water supplies and shut-off valves
• Sink and washing machine drains
• Pipes crossing walls or slabs

These penetrations should be treated with collars/sleeves, elastic bands, or compatible reinforcement pieces.

Under cabinets and appliances

Small leaks are detected late because they stay hidden. That’s why you want a continuous membrane with properly detailed edges.

Common systems for kitchens and laundry rooms

Liquid-applied membrane (polyurethane / flexible cementitious)

Widely used in renovations thanks to seamless application.

• Pros: adapts to corners, easy to reinforce transitions.
• Key points: correct primer, specified thickness, proper curing time.

Bonded sheet membrane (under-tile waterproofing sheet)

A robust solution when you’re tiling.

• Pros: controlled thickness, high reliability.
• Key points: overlaps, sealed joints, corner pieces.

Local sealing only (not recommended as the only measure)

Silicone and isolated sealant repairs can help, but they rarely solve the issue if there’s movement, open joints, or water traveling under the floor.

Recommended build-up (step-by-step)

1. Substrate prep: clean, sound, free of dust and loose coatings.
2. Crack repair and slope correction if there’s a wash zone.
3. Primer as required by the system.
4. Reinforce details:
   • Perimeter floor-to-wall band
   • Corner reinforcement
   • Pipe collars/sleeves
5. Apply waterproofing (two cross coats for liquid membranes, or install sheet with overlaps).
6. Water test when feasible (especially in laundry areas with drains and frequent water exposure).
7. Protection and finish: compatible adhesive, tile/floor installation, and elastic sealing at perimeter joints.

Common mistakes that lead to leaks

• Not turning the system up the wall (only coating the floor).
• Ignoring pipe penetrations and corners.
• Tiling before full cure.
• Using incompatible adhesives or sealants.
• Treating grout as “waterproofing.”

Homeowner communities in Madrid: who should act?

In Madrid, many incidents are first noticed as stains on the downstairs ceiling or in service shafts. If the leak originates in a private kitchen, it’s usually the owner’s responsibility, but it’s important to confirm the source (plumbing vs. waterproofing vs. a shared downpipe). In apartment buildings, a technical inspection helps avoid repeated works and disputes.

How long does it last and what maintenance is needed?

A properly installed system protected under a floor can last for many years. Still:

• Check hoses and shut-off valves periodically.
• Keep an eye on perimeter joints and sealants.
• Act fast at the first sign of staining to prevent structural and wall damage.

Need help with your kitchen or laundry area?

If you’re renovating or you’ve had leaks, Impermyna can assess your case and propose a waterproofing system that matches your floor finish and usage (home, community building, or commercial space) in Madrid and Toledo. Get in touch and we’ll guide you through the best option.