How do you waterproof a wall from the inside?

Author: scraper  |  Last update: Monday, September 14, 2026

Waterproofing a wall from the inside involves a straightforward, 4-step process: prepare the surface, patch cracks, apply waterproofing paint or membrane, and install a drainage system if hydrostatic pressure is an issue.

Can you waterproof walls from the inside?

You can waterproof your clients' basements from the inside or the outside, but the most thorough jobs will use a combination of both. Always apply sealants on both sides of a basement and foundation to prevent water from getting trapped in the concrete and damaging it over time.

How to waterproof an internal wall?

How do I install a Damp Proof Membrane?

  1. Cut the damp proofing membrane to size.
  2. Place the damp proofing membrane on the wall.
  3. Neatly fold the damp proofing membrane around the corners.
  4. Drill then fix the damp proofing membrane to the walls ensuring a tight fit.
  5. Apply wall finish to the damp proofing membrane.

Can you waterproof regular sheetrock?

Yes, you can waterproof drywall, but standard drywall is highly porous and will degrade in wet environments without proper preparation. For high-moisture areas like shower surrounds, bathrooms, and basements, use specific waterproofing methods depending on your application:

What is the best waterproofing for interior walls?

Sealants: Use sealants to fill gaps and cracks around windows, doors, and plumbing fixtures. Silicone sealants are ideal for such areas owing to their flexibility and durability. Waterproof Membranes: For moisture-prone areas such as basements, apply waterproof membranes.

How to Waterproof a Basement | This Old House

Do interior walls need waterproofing?

Waterproofing can be applied to both exterior and interior walls, and it serves as an effective safeguard against water-related problems such as seepage, dampness, mildew growth, and structural damage.

What is the cheapest way to waterproof a room?

Waterproof Paint & Sealants

If your wall is flat, mold-free, and in reasonably good condition, a waterproof paint or sealant can make a huge difference. This solution forms a barrier against water infiltration - and it's much cheaper than adding tile or a separate membrane.

What can I put on drywall to make it waterproof?

To make drywall waterproof, apply a liquid waterproofing membrane (like RedGard or AquaDefense), or install waterproofing fabric membranes embedded in thin-set mortar. For areas being tiled, use a paint-on liquid membrane. For non-tiled areas, use a waterproofing primer and specialized paint.

Can I use Kilz to seal drywall?

KILZ® Drywall Primer & Sealer seals new uncoated drywall which helps achieve a uniform professional quality finish in less coats. It dries fast (ready to paint over in 1 hour), easy to clean-up and ready to apply with standard applicators. KILZ Drywall Primer prevents new drywall surface from absorbing too much paint.

What is the cheapest way of waterproofing?

The most affordable waterproofing method is the use of basic acrylic waterproof coatings. However, these coatings may not last as long as premium waterproofing solutions.

How to stop inside walls from getting wet?

The best way to do this is by installing damp proofing which can come in the form of a cream and rods that are inserted into your masonry, or paint and a fabric membrane that can be installed onto your wall. These form a barrier to stop rising damp and condensation from soaking your walls and causing further issues.

What are common waterproofing mistakes?

Avoiding common basement waterproofing mistakes can save you time, money, and frustration down the road.

  • Mistake 1: Ignoring the Source of the Water.
  • Mistake 2: Using Interior Sealants Alone.
  • Mistake 3: Poor Gutter and Downspout Maintenance.
  • Mistake 4: Ignoring Foundation Cracks.
  • Mistake 5: Poorly Installed Drainage Systems.

How to waterproof an existing wall?

The best way to waterproof exterior wall panels is by plastering them. Plastering not only enhances the cosmetic appearance of the walls, but also makes them solid, and protects them against water seepage.

How to do waterproofing from inside a house?

1) Interior Sealants

Interior sealants are a type of basement waterproofing method that involves applying a sealant to the inside of the basement walls and floors. Water can seep into a basement through cracks, gaps, or porous concrete, particularly in areas where there is high groundwater or poor drainage.

Does drylock really work?

Drylok works well for stopping minor moisture seepage and dampness, but it is not a fix for active leaks or severe drainage issues. It is designed as a vapor barrier and masonry waterproofer, not a structural repair.

Is it better to waterproof from inside or outside?

Exterior waterproofing stops water at its source outside your foundation, while interior systems manage water after it enters. Exterior methods provide superior structural protection but are highly invasive and expensive. Interior methods are more affordable and easier to service, making them the standard choice for existing homes.

Which kilz is waterproof?

KILZ® Basement & Masonry Waterproofer. KILZ® Basement & Masonry Waterproofing Paint is a premium, interior/exterior waterproofing paint designed for porous concrete and masonry surfaces.

Can I put primer directly on drywall?

Yes, using a paint primer on drywall is highly recommended—and often essential—for a professional-looking, long-lasting finish. Primer seals the porous paper and joint compound, creates an even surface for paint, and ensures proper adhesion so the paint doesn't peel or flake.

Can mold grow through kilz paint?

Though the name itself is misleading, KILZ paint and primers do not actually 'kill' mold. But it will prevent mold. The brand does well to kill a stain's ability to show through the final coat of paint by sealing over the stained surface with an impermeable interior barrier.

Is there a such thing as waterproof sheetrock?

Is there such a thing as truly waterproof drywall? No traditional gypsum drywall product is truly waterproof. Standard drywall and moisture-resistant drywall will absorb water and deteriorate when exposed to flooding. Cement board does not dissolve in water, but it is not designed as a flood-resistant wall system.

Why do you put Dawn dish soap in drywall mud?

Some people add a small amount of dish soap to drywall mud to reduce surface tension, which helps release air bubbles and create a smoother, more even finish, especially when applying the final "skim coat"; however, this practice is not recommended by professionals as it can potentially weaken the adhesion of the mud ...

Do gold bond products resist mold?

Offers the same advantages as a traditional moisture-resistant board with added mold resistance in the core and paper.

How to make DIY waterproof?

For DIY waterproofing on a budget, mix 100% clear silicone caulking with odorless mineral spirits in a 1∶5 ratio. Shake until dissolved and brush this liquid onto tents, packs, or boots. For wood and masonry, apply commercial penetrating siloxane sealers directly to clean, dry surfaces.

How to make interior walls waterproof?

Waterproofing a wall from the inside involves a straightforward, 4-step process: prepare the surface, patch cracks, apply waterproofing paint or membrane, and install a drainage system if hydrostatic pressure is an issue.

How long does a tanking kit last?

When installed properly using high-quality products like the AquaTank Waterproofing Kit, tanking can last many years — often the life of the bathroom or wet room. Maintenance and correct application are key.

Previous article
How do I stop my air conditioner from leaking water?
Next article
What happened to colored Kleenex?