Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
A construction joint is a planned place where a pour stops and later resumes within the same member because the volume is too large for one pour. In slabs and beams it is usually placed in the middle third of the span where shear is lower, as the designer sets.
Why it matters on a project
A joint in the wrong place or not prepared becomes a weak point or a leak path, especially in basement walls and tanks.
Measurement and pricing
Not usually priced alone, but waterstops in tanks and basements are priced per linear metre.
Common mistake
Resuming the pour on a smooth, dirty surface without roughening and cleaning it, so new concrete does not bond to old.
Frequently asked questions
How does it differ from an expansion joint?
A construction joint is a stop and restart within one member that bonds; an expansion joint is a permanent gap that lets parts of the building move.
How is the joint surface prepared?
Roughened, weak laitance removed, cleaned and dampened before the pour, or with a bonding agent per the specification.
Related terms
- Expansion jointA joint allowing the building to expand and contract thermally without cracking.
- WaterproofingLayers preventing water ingress into structural elements or spaces, such as bituminous membranes and cementitious coatings.
- Solid slabA concrete slab of uniform thickness without voids, common for small and medium spans.
- Method statementA step-by-step description of how an activity will be carried out safely and to specification.
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