Pipe sleeves are casings set in the concrete before the pour so pipes can pass through them later. If they're forgotten or placed wrong, you have to drill through the concrete, which weakens it and costs you.
What does a sleeve do, and what are the common mistakes?
A sleeve is a piece (usually PVC or metal) fixed inside the concrete formwork before the pour. After the pour it leaves a ready opening for the pipe to pass through. Without it, a worker has to drill or break the concrete.
Drilling after the pour can cut the reinforcement or weaken the slab or beam, and it must not be done without the supervising engineer's approval. A sleeve in the right place does not touch the rebar, and once the pipe is fitted the gap around it can be sealed and insulated with suitable materials.
Common mistakes: placing it where the plumbing drawing does not put it, making it too narrow for the pipe plus its insulation, or not fixing it so it moves during the pour. Concrete can also get inside if both ends are not sealed.
Suppose a villa has a bathroom above the kitchen. On the plumbing drawing the plumber marks where the vertical drain pipe passes through the slab, fits a sleeve larger than the pipe, fixes it to the rebar and seals both ends before the pour. After the pour the opening is ready and the pipe passes through without any breaking.
Practical step-by-step
- Match the plumbing drawing with the structural drawing to find where pipes pass, before the rebar goes in.
- Mark the position of each sleeve on the formwork.
- Choose a size larger than the pipe so there is room for insulation.
- Fix it firmly so it does not move during the pour, and seal both ends so concrete cannot get in.
- Before the pour, confirm the number and positions with the supervising engineer.
Tick what you've done
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