Finish · Charlotte NC

Decorative Overlays

A new surface bonded to a sound slab

In detail

What to know about decorative overlays

What an overlay is for

An overlay is a thin polymer-modified cementitious layer bonded onto existing concrete, from around a millimetre for a smooth microtopping up to roughly ten for a stampable overlay carrying a texture. Its legitimate purpose is cosmetic: a structurally sound slab whose surface is worn, discoloured, patched or simply dated gets a new surface without demolition, disposal or the cost of a full replacement. Used for that, on the right slab, it is excellent value and we recommend it readily.

The condition that decides everything

An overlay is only ever as good as what it is bonded to, and it adds no structural capacity whatsoever. If the slab beneath is moving, settling, or cracking because its base has failed, the overlay will crack in exactly the same places, usually within a season, and you will have paid to resurface a problem rather than fix it. The honest test is whether the slab is stable, not whether it is pretty. Sound but ugly is the ideal candidate. Cracked and moving is a replacement, and we will tell you that even though it is the more expensive answer.

Bond, and why preparation is most of the cost

Overlay failures are almost always bond failures, and bond failures are almost always preparation failures. The existing surface has to be mechanically profiled — shot blasting or diamond grinding — to give the topping something to key into, and every trace of sealer, curing compound, oil and loose material has to be removed first. Pressure washing does not achieve this, whatever the product data sheet implies. When an overlay quote is unusually cheap, the preparation is what has been left out, and it is the one part that cannot be.

Reflective cracking and joints

Every control joint and every existing crack in the slab underneath must be carried up through the overlay rather than covered over. Concrete moves at its joints, and a continuous surface across a moving joint will tear, in an ugly ragged line rather than a clean one. Any overlay we install honours the joint pattern below it, and where the existing joint layout is poor we will discuss changing it before we start rather than pretending it is not there.

Realistic expectations

A good overlay is a real improvement and can last many years. It is still a thin layer, so it is more vulnerable to impact damage, edge chipping and de-icing salts than the slab beneath, and it needs sealing and resealing on schedule. Given a sound slab and a client who understands what they are buying, it is one of the best value decisions in decorative concrete. Sold as a way to avoid replacing a failed slab, it is the worst.

Commonly used for

Patios Pool Decks Outdoor Living Areas Walkways & Entries Decorative Driveways Courtyards & Surrounds

Other finishes

Six alternatives

Stamped Concrete

Texture pressed into the slab while it is still green

Stained Concrete

Colour that reacts with the slab rather than sitting on it

Exposed Aggregate

Wash the paste back and let the stone do the work

Polished Concrete

Ground, densified and refined to a mechanical shine

Saw-Cut Designs

Lines cut into the slab as pattern, not just as joints

Colored Concrete

Pigment through the mix, or hardened into the surface