How to Build Concrete Stair Formwork (Part 1): Layout & Support System || Jobsite chronicles ||

🏗️ STAIRCASE CONSTRUCTION TECHNIQUES FROM THE GROUND UP: Concrete Staircase Formwork, Step by Step Formwork is the step that decides whether your poured staircase has even steps, the correct levels, and no sagging or cracking. In this video, I walk you through how to build formwork for a reinforced concrete staircase, from setting out levels to completing the support system, ready for rebar placement and the concrete pour. This content is suitable for homeowners supervising their own build, new tradespeople, and construction students. 📌 WHAT'S COVERED IN THIS VIDEO 1. Site preparation and setting out levels Establish the finished floor levels of the lower and upper floors, along with the positions of the stair head and stair foot. Use a laser level, spirit level, and plumb line to mark the centerline and the edges of the stair slab. Double-check all dimensions before cutting any boards, because even a small error here will throw off the entire flight. 2. Calculating the number of steps and the slope Divide the floor-to-floor height evenly into equal risers. Riser height is typically 150–180 mm and tread depth 250–300 mm. A common rule of thumb: twice the riser height plus the tread depth should fall between 600 and 640 mm. Once calculated, draw the stair profile full-size to make cutting templates for the boards. 3. Choosing formwork materials A comparison of film-faced plywood, standard plywood, timber boards, and steel modular formwork. How to choose board thickness, joists, bearers, and steel props or adjustable props suited to the load of wet concrete. 4. Erecting the scaffolding and props Space the props correctly, with horizontal and diagonal bracing so the system doesn't wobble. Props must sit on firm ground, and wedges or adjustable props are used to fine-tune the height accurately. 5. Installing the soffit (underside) formwork Lay the longitudinal and cross bearers, then place the soffit boards to the correct slope. Joints must be tight to prevent cement slurry from leaking. A slight camber at mid-span can be added to compensate for deflection during the pour. 6. Installing riser boards and side forms How to cut, position, and secure the riser boards so the steps come out uniform. Reinforce the side forms with braces and ties so they don't bulge during the pour. Chamfer the step nosing if the design calls for it. 7. Handling the landing and beam connections Connect the stair slab formwork to the landing beam and the upper floor slab, leaving openings for starter bars and construction joints. 8. Final checks before rebar placement Re-measure the slope, the level of each step, the flatness of the formwork surface, and the stability of the props. Apply form-release oil and clean the formwork surface before moving on to the next stage. ⚠️ COMMON STAIRCASE FORMWORK MISTAKES Uneven steps caused by miscalculation or incorrect level readings Too few props, or props placed on weak ground, causing the stair slab to sag Gaps at joints that let cement slurry escape, leaving honeycombed concrete Riser boards not braced firmly, shifting during the pour Forgetting the minimum headroom clearance (about 2 m) 🛠️ TOOLS YOU'LL NEED Tape measure, spirit level, laser level, plumb line, saw, drill, hammer, nails, screws, adjustable props, joists/bearers, film-faced plywood or standard plywood, and form-release oil. 📝 NOTE The figures in this video are for general reference only. Every region has its own building standards, so please check current local codes and consult a structural engineer, especially for long-span or multi-story staircases. Always follow safety practices when working at height. 💬 Which step of staircase formwork are you struggling with? Leave your question in the comments! 👍 If you found this video helpful, please Like, Subscribe, and turn on notifications for upcoming videos on rebar placement, concrete pouring, and staircase finishing. #staircaseconstruction #formworksystem #concreteformwork #stairconstruction #FormworkInstallation #concretestairs #StairBuilding #buildingtips #civilengineering #constructiontechniques #construction #homebuilding #diyconstruction #reinforcedconcrete #constructionworker #housebuilding #buildingconstruction #concretework #structuralengineering #jobsite chronicles