Field & trade terms
Concrete cover
Also called: rebar cover, cover, clear cover
Concrete cover is the distance from the face of a concrete member to the nearest reinforcing bar. That layer of concrete is what protects the steel: it keeps moisture and chlorides from reaching the rebar and starting corrosion, and it gives the reinforcement its fire protection. Cover is set by the design and the exposure — more where the concrete faces weather or soil, less indoors — and it is held in the field with chairs, spacers and bar supports before the pour.
Why it matters
Too little cover is one of the most common causes of premature concrete failure. When the steel sits too close to the surface, moisture reaches it, the bar rusts, the rust expands, and it drives the concrete off in sheets — the spalling seen on aging structures. Getting cover right at the pour is far cheaper than the repair.
Cover is also fire protection. The specified thickness is part of how the member achieves its fire rating, so a bar left short of cover is not just a durability problem — it can compromise the assembly's rated performance.
How it shows up on site
Bar supports and spacers set to the specified cover, checked at the pre-pour inspection before concrete is placed, and the reinforcement photographed in position so the record shows the steel was held off the forms and the surface.
Standards it's verified against
Checklists that put concrete cover to work
Free, field-ready checklists, each with the photo every item needs before it can be submitted.
Related terms
- SlumpA measure of fresh concrete's consistency — how far a molded cone of concrete sags when the cone is lifted — used to check the mix at delivery.
- SpallingConcrete or masonry breaking, flaking or chipping off the surface — often driven by corroding reinforcement, freeze-thaw or poor placement.
- HoneycombVoids in hardened concrete where the mortar did not fill around the coarse aggregate, leaving a rough, porous surface with stones showing.
- ToleranceThe allowable amount a dimension or condition can vary from the target and still be acceptable — the plus-or-minus on a spec.
- MEP (mechanical, electrical, plumbing)The mechanical, electrical and plumbing trades — the systems run through a building's structure that get inspected at rough-in and again at final.
- FirestoppingSealing openings where pipe, conduit or cable pass through a fire-rated wall or floor so the assembly's rating is restored.
Knowing the term is step one. Proving it is the job.
RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.