The best paint for cinder block depends on which side of the wall the water is on. For an interior basement wall that gets damp, use a masonry waterproofer such as DRYLOK Extreme — a thick, cement-modified latex designed to fill the block's pores and resist water pushing through. For a dry, above-grade wall in a garage, workshop or house exterior, an acrylic masonry paint or an elastomeric coating gives a better-looking, more breathable finish. Ordinary exterior house paint is the weakest choice on raw block: it soaks in, leaves pinholes, and does nothing for moisture.
Two things matter more than the product. Paint will not stop an active leak — if water is running through a crack or seeping in after every storm, the fix is outside the wall, and any coating applied first will blister and peel. And porous block drinks paint: expect roughly 75–100 square feet per gallon for a waterproofer, which is a third or less of what a can of wall paint promises on drywall.
Our Top Picks
- BEST OVERALL: DRYLOK Extreme Masonry Waterproofer
↓ Jump to Review - BEST VALUE: DRYLOK Original Masonry Waterproofer
↓ Jump to Review - HIGHEST PRESSURE RATING: Zinsser WaterTite-LX Waterproofing Paint
↓ Jump to Review - BEST PAINT-STORE OPTION: INSL-X WaterBlock Acrylic Masonry Waterproofer
↓ Jump to Review - BEST FOR DRY ABOVE-GRADE WALLS: KILZ Masonry, Stucco & Brick Flat Paint
↓ Jump to Review
The Four Kinds of Block Paint
Most "which paint" confusion comes from treating these as interchangeable. They are not: each does one job well and at least one job badly.
| Type | What it does | Best on | Breathability | Typical coverage on block |
|---|---|---|---|---|
| Masonry waterproofer | Fills pores, resists water pressure from the far side | Interior basement walls, damp block | Low | 75–100 sq ft/gal per coat |
| Elastomeric masonry coating | Thick, flexible film that bridges hairline cracks and sheds rain | Exterior above-grade walls | Low to moderate | 75–125 sq ft/gal per coat |
| Acrylic masonry paint | Decorative finish, alkali-resistant, sheds rain | Dry walls inside or out | Moderate to high | 150–250 sq ft/gal on raw block (label figures are higher) |
| Block filler primer | Fills pores and pinholes so a topcoat looks smooth | Under acrylic or elastomeric on raw block | Moderate | 75–100 sq ft/gal |
| Standard exterior house paint | Decorative only | Previously painted, smooth block | Moderate | Unpredictable — soaks in |
Masonry waterproofers are heavily filled latex or cement-modified coatings designed to go on bare masonry and pack its pores. They are rated by the hydrostatic pressure they resist in a standard lab test — 10 to 20 psi on the products below — which is what lets them hold back moisture wicking through a below-grade wall. They are low-permeance by design, and they generally must go on bare block or over the same product, not over existing paint.
Elastomeric coatings are very high-build acrylics that stay flexible, stretching over hairline cracks as the wall moves with temperature. On an exterior above-grade wall they are the most weatherproof decorative finish available. They are not rated for water pushing from behind, and on raw block they look and perform best over a block filler.
Acrylic masonry paint is a decorative paint formulated to cope with the alkalinity of fresh masonry and to bond to rough texture. It breathes more than a waterproofer, which makes it the safer finish on any wall where moisture needs a way out.
Block filler primer is a thick, sand-filled latex primer whose only job is to fill the open texture of concrete block so the topcoat goes on smooth and continuous. It is the step most DIY jobs skip and the reason many painted block walls still look pitted.
If what you want is invisible protection rather than a coloured finish, that is a different product category altogether — see our guide to cinder block sealers, which covers penetrating silane/siloxane and silicate sealers that soak into the block and leave its appearance unchanged.
The Best Paints for Cinder Block
The first four are masonry waterproofers for basement and damp walls; the fifth is a decorative masonry paint for dry walls. Pressure ratings and coverage come from the manufacturers' published data sheets.
What We Like
- 15 psi hydrostatic rating, higher than DRYLOK Original
- Interior and exterior, above and below grade
- Two coats in one day
- Widely stocked, easy to match for touch-ups
What We Don’t Like
- Must go on bare or previously DRYLOK-coated masonry
- Heavy, slow to apply on rough block
- Limited colour choice
Product Specs
- Type: Masonry Waterproofer / Latex
- Rank in this guide: #1
DRYLOK Extreme is the upgraded version of the best-known basement wall waterproofer, and it is the one to buy if your block gets genuinely damp rather than just looking dusty. The manufacturer rates it to resist 15 psi of hydrostatic pressure — equivalent, by its own reckoning, to a column of water about 33 feet high — tested to ASTM D7088. It is rated for interior and exterior use, above and below grade.
The data sheet lists coverage of about 75 square feet per gallon for the first coat and 75–100 for the second, with two coats required for the warranty. Those figures are realistic for block because they assume a thick film packed into open texture, which is exactly what the product is designed to do. It dries to the touch in under an hour and can be recoated in about two, so both coats fit comfortably in one day.
The trade-offs are the usual ones for this category. It needs bare masonry, it is thick and tiring to roll, and it is not a decorative paint — the colour range is limited and the finish is flat and slightly textured.
What We Like
- Proven, widely available formula
- 10 psi rating is ample for most damp-but-not-wet walls
- Water cleanup, low odour
- Accepts a latex topcoat after 24 hours
What We Don’t Like
- Lowest pressure rating of the waterproofers here
- Same bare-masonry requirement as Extreme
- Thick; first coat is slow going
Product Specs
- Type: Masonry Waterproofer / Latex
- Rank in this guide: #2
DRYLOK Original is the long-standing latex version and the sensible buy for a basement that is damp in wet seasons but never wet. The manufacturer rates it to 10 psi, equivalent to about 22 feet of water, which is lower than Extreme but more than a dry-to-occasionally-damp wall will ever ask of it. It typically costs less per gallon than Extreme and comes in white, grey and a few other ready-mixed shades.
Its instructions are a good template for the whole category: minimum two coats, 75 square feet per gallon for the first, a 3/4-inch nap roller or a stiff masonry brush, and back-brushing the first coat to drive it into pinholes. Air and surface temperature must be at least 50°F. A decorative latex topcoat can go over it after 24 hours if you want a colour the range does not offer.
Where it falls short is on walls with real seepage. If the wall weeps visibly after rain, spend the extra on Extreme or WaterTite-LX — or, better, on the drainage that is causing it.
What We Like
- 20 psi rating with two coats
- Mildew-resistant film for humid basements
- Water-based, low odour
What We Don’t Like
- Label coverage optimistic on very porous block
- Limited colours
- Harder to find in some stores than DRYLOK
Product Specs
- Type: Masonry Waterproofer / Acrylic
- Rank in this guide: #3
Zinsser's water-based WaterTite-LX carries the highest hydrostatic rating among the water-cleanup products here: Rust-Oleum states it resists up to 20 psi with two coats, tested to ASTM D7088, on concrete and masonry indoors or out, above or below grade. It is sold as mold- and mildew-proof, meaning the dried film itself resists growth — useful in a basement where humidity stays high through summer.
The data sheet puts coverage at roughly 100–125 square feet per gallon on masonry, which on rough split-face or open-textured block will come in at the low end or below. Zinsser also makes an oil-based WaterTite with a higher rating, but the strong solvent odour makes it a poor fit for an enclosed basement unless ventilation is excellent.
Treat the higher psi figure for what it is: a lab result on a properly prepared, fully cured surface. On a real wall, the weak points are mortar joints, cracks and pinholes, and preparation decides how well any of these products performs far more than a few psi on the label.
INSL-X WaterBlock Acrylic Masonry Waterproofer
See It on AmazonWhat We Like
- 12 psi rating
- Clear, specific application guidance
- Sold where you can get knowledgeable advice
What We Don’t Like
- Less widely stocked than DRYLOK
- Walls only, not floors
- Narrow application temperature window
Product Specs
- Type: Masonry Waterproofer / Acrylic
- Rank in this guide: #4
INSL-X is Benjamin Moore's specialty-coatings line, and WaterBlock is its acrylic masonry waterproofer, sold through paint stores and independent hardware retailers rather than every big-box shelf. Benjamin Moore rates it to resist 12 psi of hydrostatic pressure when applied properly, which sits between the two DRYLOK products.
The technical data sheet is unusually candid about how to use it: 75–100 square feet per gallon at a recommended wet film of 16–21 mils, two unthinned coats, all holes and voids filled first, and an extra coat if seepage persists after two — because that means pinholes remain open. It is intended for vertical walls, not floors, and should be applied between 50°F and 90°F.
It earns its place mainly on availability and support. If your nearest source of decent advice is an independent paint store, this is likely what they stock, and they can tell you exactly how to use it on your wall.
KILZ Masonry, Stucco & Brick Flat Paint
See It on AmazonWhat We Like
- Self-priming on bare masonry
- Alkali-resistant to pH 12
- More breathable than a waterproofer
- Interior and exterior
What We Don’t Like
- No hydrostatic rating — not for damp walls
- Small ready-mixed colour range
- Open-textured block still benefits from a filler
Product Specs
- Type: Acrylic Masonry Paint / Interior-Exterior
- Rank in this guide: #5
This is a decorative masonry paint, not a waterproofer, and that is the point of including it. For a garage wall, a block workshop, a party wall or the exterior of a block house — anywhere that is above grade and dry — a waterproofer is overkill and its heavy, low-permeance film is the wrong tool. KILZ's acrylic latex is self-priming on properly prepared masonry, mildew-resistant, rated alkali-resistant up to pH 12, and formulated to bond to rough and textured surfaces.
Ready-mixed colours are limited to white, grey and tan in the standard range, which suits most utilitarian block. New block or mortar should cure 30 days first, and loose or peeling paint has to come off. For the smoothest result on raw split or open-textured block, roll a block filler primer first; on smoother block, two coats of this alone are usually enough.
Its limitation is the flip side of its strength: because it breathes rather than seals, it will not hold back water pushing through a below-grade wall. Do not use it as a basement waterproofer.
Also worth knowing about: for exterior above-grade block where you want the toughest decorative finish and a wide colour choice, Behr Premium Elastomeric Masonry, Stucco & Brick Paint is the obvious big-box elastomeric. Behr describes it as a flexible, high-build coating that bridges hairline cracks, with coverage of 75–125 square feet per gallon over two coats, and it can be tinted to a far wider range than any waterproofer. It is sold through Home Depot rather than widely online, and like all elastomerics it works best over a block filler on raw block. Behr's contractor-line Behr Pro Block Filler Primer is one such filler, rated for interior and exterior above-grade block at about 75–100 square feet per gallon.
Which Paint for Which Wall
| Wall | Use | Avoid | Why |
|---|---|---|---|
| Interior basement, seasonally damp | Masonry waterproofer, 2 coats | Standard wall paint | Moisture wicking through block lifts ordinary paint |
| Interior basement, dry | Waterproofer or acrylic masonry paint | Oil-based products in a closed space | Dry walls do not need the pressure rating; odour matters |
| Interior basement, actively leaking | Nothing yet — fix drainage first | Any coating | Water under pressure blisters every product |
| Garage or workshop, above grade | Block filler + acrylic masonry paint | Waterproofer (unnecessary) | Appearance and washability matter most |
| House exterior, above grade | Block filler + elastomeric, or acrylic masonry paint | Interior-only products | Rain from outside, vapour from inside — needs to shed and flex |
| Retaining wall | Breathable masonry paint or stain, or leave bare | Waterproofers and elastomerics on the exposed face | Wet soil behind pushes moisture out through the face |
Interior Basement Walls
Below-grade block is surrounded by soil that is damp for much of the year. Moisture wicks through the block toward the drier, warmer basement air, carrying dissolved salts that it leaves behind as white crust — efflorescence. A masonry waterproofer is designed for exactly this direction of travel: applied on the inside face, it fills the pores so that moisture cannot easily reach the room. It is the one situation where painting the "wrong" side of the wall makes sense, simply because the outside is buried.
It works within limits. A waterproofer copes with vapour and capillary moisture and with modest pressure. It does not cope with a wall that has water standing against it because the gutters dump at the foundation or the ground slopes toward the house. Our guide to waterproofing basement walls walks through diagnosing which situation you have and the order of fixes.
Exterior Above-Grade Walls
Here the water arrives as rain from the outside, while vapour from the house travels outward in winter. The coating needs to shed rain and tolerate movement. Elastomeric is the most protective choice; acrylic masonry paint is the more breathable one. On a heated block building in a cold climate, a breathable paint is the safer default; elastomeric makes most sense where wind-driven rain is the main problem and the wall has hairline cracks to bridge.
Retaining Walls
Retaining walls trip people up. The back face is permanently against wet soil; the front face is the only place that moisture can escape. Coat that face with a sealed film and moisture accumulates behind it, efflorescence builds underneath, and the paint peels in sheets — often within a season or two. If you want colour on a retaining wall, use a breathable masonry paint or a penetrating masonry stain, make sure the weep holes are clear, and accept that it will need redoing more often than a house wall. Waterproofing a retaining wall properly is done on the soil side, during construction.
What Paint Cannot Do: Leaks and Pressure
Hydrostatic pressure is the force of water in saturated soil pressing against a wall. Every foot of water depth adds about 0.43 psi, which is how a 10 psi rating translates to roughly 22 feet of water. Those ratings come from a lab test on a coated specimen, and they sound like more protection than any house will ever need.
The reason paint still fails on wet walls is that the weak points are not the coating itself. Mortar joints, hairline cracks, the junction between wall and floor, and the pinholes you missed all let water past. Once water gets behind the film it collects there, and the coating that was keeping water out is now holding it in. The result is blistering, peeling and, very often, more efflorescence than before.
Check what you are dealing with before buying anything:
- Tape a square of plastic or foil to the wall for 48 hours. Moisture on the room side means condensation — a humidity problem better solved by a basement dehumidifier than by paint. Moisture on the wall side means water coming through the block, which a waterproofer can address if it is modest.
- Look for running water or puddles after rain. That is a leak, and it needs drainage work outside or a crack repair, not a coating.
- Look at the efflorescence. A light dusting is normal on old block. Heavy, fluffy crust that comes back within weeks means a lot of water is moving through, and a coating will be fighting it.
- Walk the outside. Downspouts that discharge at the foundation and soil that slopes toward the house cause most damp basements. Extending the downspouts and regrading is cheap and does more than any paint.
Active leaks at a crack can be plugged first with a hydraulic cement, which sets in minutes even against running water, before the waterproofer goes over the whole wall. For a full rundown of the coatings and sealers that go on basement walls, see our best basement wall sealer guide.
Coverage: Why You Will Need More Than You Think
Paint labels quote coverage on smooth, sealed surfaces. Concrete block is neither. Its open texture has far more actual surface area than its nominal square footage, and the porous body absorbs the first coat. That is why masonry waterproofers quote 75–100 square feet per gallon rather than the 350–400 a can of wall paint claims — the waterproofer figure already assumes rough block, and the wall-paint figure does not.
For ordinary acrylic paint on raw block, plan on roughly half the label figure for the first coat, and expect the second to go further once the pores are partly filled. Split-face and open-textured lightweight block are at the thirsty end; smooth, dense block and previously painted walls at the generous end.
A Worked Example
A 30 × 40 foot basement with 7.5-foot walls has 140 linear feet of wall and 1,050 square feet of surface. Subtract a door, a couple of windows and the area behind the furnace and call it 1,000 square feet.
- First coat at 75 sq ft/gal: about 13 gallons.
- Second coat at 90 sq ft/gal: about 11 gallons.
- Total: roughly 24 gallons — five 5-gallon pails, with a little left for touch-ups.
Someone working from a wall-paint figure of 350 square feet per gallon would buy six gallons and run out a quarter of the way round. Buying in 5-gallon pails rather than single gallons usually lowers the per-gallon cost noticeably, and in this category it is the realistic quantity for any full basement.
| Wall area (2 coats) | Waterproofer needed | Acrylic over block filler |
|---|---|---|
| 250 sq ft (one wall) | 6–7 gallons | 3 gal filler + 3 gal paint |
| 500 sq ft | 11–13 gallons | 5–7 gal filler + 5 gal paint |
| 1,000 sq ft (typical basement) | 22–27 gallons | 10–13 gal filler + 8–10 gal paint |
The filler-plus-paint column assumes one coat of block filler and two coats of acrylic at about 200–250 square feet per gallon once the surface is filled. As a rough category guide, masonry waterproofers and elastomerics generally run $35–$75 a gallon and block fillers somewhat less, so a full basement typically costs several hundred dollars in material alone.
Preparation, Step by Step
Every manufacturer in this category says the same thing in different words: the coating bonds to clean, sound, bare masonry, and nothing else. Most failures trace back to one of these steps being skipped.
- Remove existing paint. Waterproofers generally need bare block or a previous coat of the same product. Wire-brush, scrape or grind off old paint. If it will not come off and you cannot tell what it is, a waterproofer is not the right product for that wall.
- Wire-brush the whole wall. A stiff wire brush, or a wire wheel on a drill for large areas, removes loose mortar, dust, efflorescence and the weak surface skin. Vacuum or brush down afterwards.
- Treat efflorescence. Brush off the white salt dry first. What remains comes off with a masonry efflorescence remover or a dilute acid wash, followed by thorough rinsing so no residue is left. Coating over efflorescence is coating over a layer of salt — the bond fails where the salt is.
- Deal with mildew. Wash any mould or mildew with a suitable cleaner and let the wall dry fully. Mildew-resistant coatings stop growth on the film; they do not kill what is underneath.
- Repair cracks and holes. Hydraulic cement for active leaks and larger voids; masonry patch or mortar for chipped block and failed joints. Fill every hole you can find — the coating will not bridge them.
- Let it dry, and check the temperature. Most products need air and surface temperatures of at least 50°F, and new block or mortar should cure around 30 days. Avoid coating during a humid spell when the wall is sweating.
Filling the Pores: Application Technique
Block has thousands of pinholes, and each one left open is a path for water and a visible pit in the finish. The whole technique is about getting product into them.
Use a heavy-nap roller. A 3/4-inch nap is the minimum on block; a 1-inch nap is better on split-face or very open texture. A thin nap glides over the surface and bridges the pores without filling them.
Brush or back-brush the first coat. DRYLOK's instructions say that if you roll, you should back-brush the first coat to fill pinholes. Rolling a section and then working it in with a stiff masonry brush, using a scrubbing motion, is slow but is what makes the first coat effective. Many people brush the first coat entirely and roll the second.
Back-roll when spraying. If you spray a block filler or masonry paint, roll over it immediately while it is wet to push material into the texture. Sprayed coatings on their own tend to sit on the surface.
Apply thick, not thin. Waterproofers are meant to go on heavy — the INSL-X data sheet specifies 16–21 mils wet, several times a normal paint film. Thinning defeats the purpose.
Inspect and recoat. After the second coat dries, look closely for pinholes, especially at mortar joints. Any you find should be dabbed with a brush, and if a wall still shows seepage after two coats, an additional coat over that area is the standard fix.
Do not forget the joints and corners. Mortar joints, the bottom course and the wall-floor junction are where water most often gets through. Brush them generously. If you are painting the floor too, finish the walls first, and see our guide to basement floor paint for the floor side — it has its own moisture test and its own product category.
Colour and Topcoats
Waterproofers come in a narrow palette — white, grey, beige and a handful of other ready-mixed shades — and the heavily filled formulas generally tint only to lighter colours. White is the most popular choice in basements for good reason: it makes a dim space noticeably brighter and shows any new damp patch or efflorescence immediately, which is useful early warning.
If you want a different colour on a waterproofed wall, the usual approach is a latex topcoat once the waterproofer has dried — DRYLOK's own instructions allow a decorative latex topcoat after 24 hours. Use a quality interior acrylic, and accept that the topcoat is decorative only; the waterproofer underneath is doing the work.
For above-grade walls, colour choice is wide open. Elastomerics and acrylic masonry paints tint to most colours. Lighter colours on a south- or west-facing exterior wall run cooler and show less fading. Flat or low-sheen finishes hide the texture and minor imperfections of block better than gloss, which tends to highlight every pit.
The Short Version
For a damp basement block wall, use DRYLOK Extreme or Zinsser WaterTite-LX, two coats, first one brushed into the pores — but only after gutters, grading and cracks are sorted. DRYLOK Original is enough for walls that are only seasonally damp.
For dry above-grade block, use a block filler primer and an acrylic masonry paint such as KILZ Masonry, Stucco & Brick, or an elastomeric if the wall faces heavy weather.
For retaining walls, use something breathable or nothing at all.
And buy for real coverage: 75–100 square feet per gallon per coat for a waterproofer on block. Most people who run out mid-wall bought by the wall-paint number.
Frequently Asked Questions
It depends on the wall. For interior basement block that gets damp, a masonry waterproofer is best — DRYLOK Extreme (rated 15 psi), Zinsser WaterTite-LX (20 psi) or DRYLOK Original (10 psi) for walls that are only seasonally damp. For dry walls above ground, such as a garage or the outside of a block building, use a block filler primer followed by an acrylic masonry paint or an elastomeric coating. Ordinary house paint on raw block is the weakest option: it soaks in unevenly, leaves pinholes and offers no moisture resistance.
On dry, above-grade block, yes, but it works far better over a block filler primer. Raw block is very porous and alkaline; regular paint soaks in, leaves a pitted finish and can be degraded by the alkalinity of new masonry. A block filler fills the texture and gives the topcoat a uniform surface. On basement walls or anywhere moisture comes through the block, regular paint will blister and peel, and a masonry waterproofer is the right product.
No. Masonry waterproofers handle moisture wicking through block and modest dampness, but not water running through cracks or seeping in after every storm. The weak points — mortar joints, cracks, the wall-floor junction — let water behind the film, where it collects and pushes the coating off. Fix gutters, downspouts and grading first, plug active leaks with hydraulic cement, and only then coat the wall. Applied in that order, a waterproofer is effective; applied first, it usually fails within a couple of years.
Far more than a wall-paint label suggests. Masonry waterproofers cover about 75–100 square feet per gallon per coat on block, and you need two coats — roughly 2–2.7 gallons per 100 square feet of wall in total. A typical 1,000-square-foot basement takes around 22–27 gallons, or about five 5-gallon pails. For acrylic paint over a block filler, budget about one gallon of filler per 75–100 square feet plus two coats of paint at around 200–250 square feet per gallon.
Not under a masonry waterproofer — those go directly onto bare masonry, and the first coat effectively acts as the primer. Under acrylic masonry paint or elastomeric, a block filler primer is strongly recommended on raw block: it fills pinholes and texture so the topcoat goes on smooth and continuous, and it usually saves topcoat. Some masonry paints, including KILZ Masonry, Stucco & Brick, are self-priming on properly prepared surfaces, but open-textured block still benefits from a filler.
Brush off as much of the white salt as possible with a stiff dry wire brush first — wetting it just redissolves the salt into the block. Then clean the remainder with a masonry efflorescence remover or a dilute acid wash, following the product directions, and rinse thoroughly so no residue remains. Let the wall dry fully before coating. If the efflorescence comes back heavily within weeks, a lot of water is moving through the wall and the source should be fixed before any coating goes on.
Only with something breathable. A retaining wall has wet soil against its back face, so moisture constantly moves out through the exposed front. A waterproofer or elastomeric on that face traps the moisture behind the film, and the result is peeling, blistering and efflorescence underneath, often within a season or two. A breathable masonry paint or a penetrating masonry stain lets the moisture out. Keep the weep holes clear, and expect to recoat more often than a house wall.
A paint or waterproofer forms a coloured film on the surface. A penetrating sealer — silane, siloxane or silicate — soaks into the block and leaves its appearance largely unchanged, reducing water absorption without a visible coating. Sealers are the better choice when you want the block to look like block, or on walls where moisture needs to escape; waterproofing paints are better when you want a bright, uniform finish on an interior basement wall. Some masonry waterproofers are marketed under both names, so check whether a product forms a film or penetrates.