For many years, lap splicing has been the traditional method of connecting reinforcing bars . But as many structural engineers, architects and specifiers have discovered, lap splicing has very few advantages and quite a few disadvantages when compared to mechanical couplers. More and more engineers are specifying mechanical rebar connections over lap splices because mechanical connections afford a reliability and consistency that can’t be found with lap splicing.

In this blog, we will look at some of the maybe not-so-obvious advantages of using mechanical rebar splices versus lap splicing when comparing the total installed cost for a project.

The “Hidden” Costs of Lap Splicing

In a previous post, we considered the basic design considerations of a lap splice design compared to mechanical splices, such as the grade of steel, surface condition of the bar, size of bars, grade of concrete, position of the splice with respect to concreting and design loads. With all of those considerations, each design choice has a unique tradeoff with all of the other design choices.

When comparing the cost of using mechanical couplers against lap splicing, there may be several hidden costs in lap splicing that should be considered for a true apples to apples comparison

Material waste

Mechanical couplers allow the butt splicing of rebar, without the need to overlap. This means a more material-efficient design for engineers, reducing rebar lengths while improving structural integrity and minimizing the total amount of steel needed for a project.

Rebar size

The larger the rebar size, the more cost efficient mechanical couplers become in the overall cost of a project. Working with “small” diameter reinforcing bars may require the use of larger column dimensions to accommodate a greater quantity of bars. Using mechanical splices allows the option of larger diameter rebar in a smaller column while minimizing congestion. This reduced column size results in a more efficient design and an optimum use of floor space.

Rebar and freight costs

Longer rebar length or an increased amount of rebar needed to meet code requirements increases not only the supplied material cost, but also can increase the cost of freight, fabrication and the efficiency when space is at a premium.

Congestion

Speaking of space being at a premium, rebar couplers allow for designs to be less congested. Lap splicing increases rebar congestion at the lap zone and is one of the major causes for forming rock pockets and voids in the concrete. Mechanical splices eliminate these congestion problems, leading to better concrete consolidation and will make the overall job more cost effective through minimized job site problems.