Handbook›Splice & Lap Length Tables

Splice & Lap Length Tables

IS 456:2000 · Clause 26.2.5 — Lap Splices

Lap length is the overlap required between two reinforcing bars to transfer stress from one bar to another. In tension, lap length = 1.5 × Ld (for bars in the same layer). In compression, lap length = Ld. Development length Ld = (ϕ × 0.87 × fy) / (4 × τbd). Design bond stress τbd values are per Table 26 of IS 456.

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Tension Lap Lengths (Fe415)

Lap length in tension = 1.5 × Ld. σs = 0.87 × 415 = 361 MPa. τbd for deformed bars = 1.6 × τbd(plain).

Bar Dia	Grade	Lap Length	Ld	Multiplier
8 mm	M20	903 mm	602 mm	1.5 Ld
10 mm	M20	1128 mm	752 mm	1.5 Ld
12 mm	M20	1355 mm	903 mm	1.5 Ld
16 mm	M20	1806 mm	1204 mm	1.5 Ld
20 mm	M20	2258 mm	1505 mm	1.5 Ld
25 mm	M20	2822 mm	1881 mm	1.5 Ld
32 mm	M20	3612 mm	2408 mm	1.5 Ld
8 mm	M25	774 mm	516 mm	1.5 Ld
10 mm	M25	968 mm	645 mm	1.5 Ld
12 mm	M25	1161 mm	774 mm	1.5 Ld
16 mm	M25	1548 mm	1032 mm	1.5 Ld
20 mm	M25	1935 mm	1290 mm	1.5 Ld
25 mm	M25	2420 mm	1613 mm	1.5 Ld
32 mm	M25	3096 mm	2064 mm	1.5 Ld
8 mm	M30	722 mm	481 mm	1.5 Ld
10 mm	M30	903 mm	602 mm	1.5 Ld
12 mm	M30	1083 mm	722 mm	1.5 Ld
16 mm	M30	1445 mm	963 mm	1.5 Ld
20 mm	M30	1806 mm	1204 mm	1.5 Ld
25 mm	M30	2256 mm	1504 mm	1.5 Ld
32 mm	M30	2889 mm	1926 mm	1.5 Ld

Tension Lap Lengths (Fe500)

Lap length in tension = 1.5 × Ld. σs = 0.87 × 500 = 435 MPa. τbd for deformed bars = 1.6 × τbd(plain).

Bar Dia	Grade	Lap Length	Ld	Multiplier
8 mm	M20	1088 mm	725 mm	1.5 Ld
10 mm	M20	1359 mm	906 mm	1.5 Ld
12 mm	M20	1632 mm	1088 mm	1.5 Ld
16 mm	M20	2175 mm	1450 mm	1.5 Ld
20 mm	M20	2720 mm	1813 mm	1.5 Ld
25 mm	M20	3399 mm	2266 mm	1.5 Ld
32 mm	M20	4350 mm	2900 mm	1.5 Ld
8 mm	M25	932 mm	621 mm	1.5 Ld
10 mm	M25	1166 mm	777 mm	1.5 Ld
12 mm	M25	1398 mm	932 mm	1.5 Ld
16 mm	M25	1865 mm	1243 mm	1.5 Ld
20 mm	M25	2331 mm	1554 mm	1.5 Ld
25 mm	M25	2913 mm	1942 mm	1.5 Ld
32 mm	M25	3729 mm	2486 mm	1.5 Ld
8 mm	M30	870 mm	580 mm	1.5 Ld
10 mm	M30	1088 mm	725 mm	1.5 Ld
12 mm	M30	1305 mm	870 mm	1.5 Ld
16 mm	M30	1740 mm	1160 mm	1.5 Ld
20 mm	M30	2175 mm	1450 mm	1.5 Ld
25 mm	M30	2720 mm	1813 mm	1.5 Ld
32 mm	M30	3480 mm	2320 mm	1.5 Ld

Compression Lap Lengths

Lap length in compression = Ld (no multiplier needed). Compression bond stress is 25% higher than tension per IS 456 Cl. 26.2.1.1.

Bar Dia	Grade	Lap Length	Ld	Multiplier
8 mm	M20	482 mm	482 mm	1.0 Ld
10 mm	M20	602 mm	602 mm	1.0 Ld
12 mm	M20	722 mm	722 mm	1.0 Ld
16 mm	M20	963 mm	963 mm	1.0 Ld
20 mm	M20	1204 mm	1204 mm	1.0 Ld
25 mm	M20	1505 mm	1505 mm	1.0 Ld
32 mm	M20	1926 mm	1926 mm	1.0 Ld
8 mm	M20	580 mm	580 mm	1.0 Ld
10 mm	M20	725 mm	725 mm	1.0 Ld
12 mm	M20	870 mm	870 mm	1.0 Ld
16 mm	M20	1160 mm	1160 mm	1.0 Ld
20 mm	M20	1450 mm	1450 mm	1.0 Ld
25 mm	M20	1813 mm	1813 mm	1.0 Ld
32 mm	M20	2320 mm	2320 mm	1.0 Ld

Mechanical Splices

Mechanical splices per IS 456 Cl. 26.2.5.2 — permitted as alternative to lap splices, especially for larger diameter bars.

Bar Dia	Grade	Lap Length	Ld	Multiplier
16 mm	All	N/A	N/A	N/A
20 mm	All	N/A	N/A	N/A
25 mm	All	N/A	N/A	N/A
32 mm	All	N/A	N/A	N/A

Notes

• Lap splices shall be staggered — not more than 50% of bars shall be lapped at any one section (IS 456 Cl. 26.2.5.1).

• Lap splices should not be used in zones of maximum stress (e.g., at mid-span of beams in tension zone or at column faces).

• For bundled bars, lap length shall be increased by 10% for 2-bar bundles and 20% for 3-bar bundles.

• Where lapping is done in flexural tension zone with more than 50% bars lapped, use 2.0 × Ld instead of 1.5 × Ld.

• IS 13920 requires lap splices in columns to be in the central half of the member and special confining reinforcement over the full lap length.

• All Ld values computed using formula: Ld = (ϕ × 0.87 × fy) / (4 × τbd × 1.6), where 1.6 factor is for deformed bars.

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