👉The required number of spacers (or cover blocks) for a concrete slab is generally based on guidelines to prevent the reinforcement from sagging and ensure the correct nominal cover is maintained.

💫The exact spacing isn't strictly defined as a single number per square meter in codes like IS 456:2000, but industry practice offers clear recommendations.

🏗️ Spacer Quantity Guidelines
While no specific clause in the Indian Standard (IS) or Ethiopian Building Code Standard (EBCS) dictates the exact number of spacers per square meter, the typical industry practice for slabs is:
* General Guideline: Provide 3 to 6 spacers per square meter (m^2).
* A common, practical number used on many construction sites is 4 to 5 spacers per \mathbf{m^2}.
* Alternatively, some guidelines suggest a spacing of around 1.0 meter in both directions (longitudinal and transverse) for the spacers, which approximates to one per square meter, with extra support near laps or edges.

The primary goal is to ensure the steel reinforcement remains rigidly in place during the placement and compaction of the concrete to maintain the specified clear cover.

📜 Nominal Cover Requirements (IS 456:2000)
The codes focus on specifying the minimum nominal cover, which is the clear distance between the outermost steel reinforcement (main bar or stirrup/link) and the outer surface of the concrete.

🇪🇹 EBCS (Ethiopian Building Code Standard)
The Ethiopian Building Code Standard EBCS 2: Structural Use of Concrete defines the concrete cover requirements similarly to other international codes, relating it to the exposure class and fire resistance.

@etconp