Types of Rebar Spacers — Complete Guide

Rebar spacers are small components with outsized importance. They maintain the designed distance between reinforcement and formwork (concrete cover), which directly determines the structure's durability and fire resistance. Eurocode 2 (EN 1992-1-1) specifies minimum cover requirements based on the environmental exposure class, and spacers are the means of achieving them.

This guide covers all four main spacer types, their strengths and weaknesses, and helps you choose the right one for each application. As a PVC spacer manufacturer, Plast Commerce specialises in linear and point spacers that offer the best combination of performance, consistency and value.

The Four Main Spacer Types

Linear Spacers (Strip Type)

Continuous support along entire strip length

Heights:15–50 mm

Material:PVC

Consumption:2–4 pcs/m²

Best for:Slabs, foundation mats, walls

Advantages: Even load distribution, consistent cover, economical, fast installation

Point Spacers (Omega/Chair)

Point support at discrete locations

Heights:20–50 mm

Material:PVC

Consumption:4–6 pcs/m²

Best for:Beams, columns, heavy reinforcement

Advantages: Strong point support, suitable for heavy bars, versatile positioning

Concrete Spacers (Blocks)

Rigid block support

Heights:20–75 mm

Material:Concrete/morite

Consumption:4–8 pcs/m²

Best for:Large covers, aggressive environments

Advantages: High compressive strength, fire resistant, no thermal bridging

Metal Wire Chairs

Wire frame support

Heights:25–100+ mm

Material:Steel wire

Consumption:3–5 pcs/m²

Best for:Top reinforcement, deep beams

Advantages: Very strong, large height range, good for top bars

Comparison: PVC vs Concrete vs Metal

Criterion	PVC	Concrete	Metal
Corrosion risk	None	None	High — creates rust stains
Thermal bridging	None	Minimal	Significant — cold spots
Installation speed	Fastest — snap fit	Slow — requires tying	Moderate
Cover accuracy	Excellent — factory-made	Good — if well made	Good
Cost	Low	Very low (if site-made)	Moderate
Surface quality	No marks	May leave marks	Rust stains possible

Why Concrete Cover Matters

The cost of getting it wrong is enormous. Insufficient concrete cover is the single most common cause of premature reinforcement corrosion. Corroding steel expands up to 6 times its original volume, causing cracking, spalling and ultimately structural failure.

5–10 mm

cover deficiency can halve the structure's service life

€50–200/m²

typical repair cost for corroded reinforcement

€0.10–0.50/m²

cost of proper spacers — prevention

Frequently Asked Questions

Which spacer type should I use for a residential slab?

For a standard residential slab (exposure class XC1), use PVC linear spacers at 20–25 mm height, spaced at 500–600 mm centres. This provides consistent cover with minimal material cost and fast installation.

Can I mix different spacer types on the same project?

Yes, it's common and often recommended. For example, use linear spacers for the bottom reinforcement of slabs (economical, consistent) and point/chair spacers for top reinforcement or beam cages (strong point support). The key is maintaining the correct cover everywhere.

What happens if concrete cover is insufficient?

Insufficient cover exposes reinforcement to moisture and chlorides, leading to corrosion. Corroding rebar expands (up to 6× its volume), cracking and spalling the concrete. This is the most common cause of premature concrete structure failure and is extremely expensive to repair.

How do I verify concrete cover after pouring?

Use an electromagnetic cover meter (also called a rebar locator or covermeter). These non-destructive devices can measure cover depth and locate reinforcement through up to 100 mm of concrete. Cover verification is increasingly required by quality control plans.