Repair Systems — Upstands
Balcony & rooftop hobs and upstands
Technical product reference for the structural hobs and upstands that give the waterproofing its termination / upstand height at balcony, terrace, roof and planter thresholds and perimeters. Covers precast concrete hob frames, cast-in (lost-form) hobs, in-situ formed hobs, masonry core-filled hobs and precast lintel hobs — with size variants, forming methods, reinforcement and the governing standards.
What are hobs & upstands?
A hob (upstand) is a raised kerb at thresholds, perimeters and penetrations that provides the waterproofing termination / upstand height and contains water on balconies, terraces, roofs and planter boxes. It is a structural element built off the slab — the membrane is then dressed up and over it — so the hob sets the height the waterproofing can reach. Selection depends on the structural design, the required upstand height (NCC / AS 4654.2 and the membrane manufacturer), the substrate, and whether the hob is precast, cast-in (lost form), formed in-situ, built in masonry and core-filled, or — on some roofs — formed from a precast lintel.
Upstand height & NCC: the hob must give the required waterproofing upstand height above the finished surface (per AS 4654.2 / NCC and the membrane manufacturer). Confirm the structural design — concrete to AS 3600 (masonry to AS 3700), reinforcement and dowelling / starter bars to the slab — with the engineer. Several fields below are marked “CONFIRM” where the dimension is project- or manufacturer-specific.
Product Reference
Individual products — one card each — scroll to view all
FTI Group
FastHob™ Precast Concrete Hob Frame
Preformed precast concrete hob frame, custom-made to project measurements
FTI Group's FastHob™ is a preformed precast concrete hob frame, custom-made to project measurements to form the water barrier between living and outdoor areas on balconies. It installs without stripping and is made square and straight with no warping, reducing waste and labour. FTI publishes the product as custom-made and does not list standard dimensions online — confirm sizes, reinforcement and concrete grade against the current FTI data sheet (ph 1300 751 701).
Masterform
Cast-In Hob Formwork (Klipmaster)
Permanent (lost) galvanised-steel hob formwork, cast monolithically with the slab
Masterform's Cast-In Hob is a permanent (lost) G275 galvanised-steel formwork supported on proprietary Klipmaster legs with cast-in base plates, poured monolithically with the structural slab to form the hob in a single pour. Standard supply is 3 m long (cut to suit on site); radius / segmented hobs to a maximum 2.4 m; legs approximately 1.2–1.5 m apart with leg height customised to the slab depth (legs over ~300 mm typically need tie-wire stabilisation). Variants include Cast-In, Post-Fix, Uneven (for monolithic falls), Radius/Segmented, Removable Skin, Waterstop and Precast, with ends, corners, joiners and double rebates available. Masterform states the Waterstop Hob variant complies with AS 4654.2 — confirm against current Masterform data and the engineer.
Site-fabricated / engineer-designed
In-Situ Formed Concrete Hob
Concrete hob formed in-situ on site to the engineer's drawing
An in-situ formed concrete hob is built on site to the engineer's drawing using timber or proprietary formwork and poured in place, with reinforcement and dowels / starter bars into the slab per the structural detail. A typical minimum upstand is around 120 mm high × 150 mm wide, but all dimensions, reinforcement and substrate preparation are per the engineer's and waterproofing design.
Site-fabricated composite system
Masonry + Core-Filled Concrete Hob
Hollow concrete block laid and core-filled with concrete to form the hob
A composite masonry hob is built by laying hollow concrete blocks (e.g. 390 × 190 × 140 mm — confirm the block sizes used) off the slab and core-filling the cores with concrete that is either mixed and pumped or a bagged product, tied to the slab with vertical starter bars. Height is set by the block course. Block sizes, core-fill / grout specification and starter-bar requirements are per the engineer (masonry to AS 3700, core-fill concrete to AS 3600).
Precast concrete lintel
Precast Concrete Lintel Hob (roof)
Standard precast concrete lintel used to form a hob / upstand on some roofs
On some roofs, subject to the waterproofing and structural system, a standard precast concrete lintel can be used to form the hob / upstand. The lintel is bedded / fixed to the deck and the membrane is dressed over it. Standard lintel sections come in a range of sizes — confirm the standard sizes and sources, and that the structural / waterproofing system sanctions a lintel hob for the specific roof.
System Comparison
Hobs & upstands — confirm all selections against the current manufacturer TDS before specifying.
Scroll the table sideways to see every column →
Do not confuse structural hobs / upstands with:
- Membrane-only upstands — the waterproofing turned up a wall or face with no structural hob behind it
- Door thresholds / sill flashings — the door sub-sill and flashing, not the structural kerb
- Tiling nibs / screed kerbs — a tile or screed lip, which is not a waterproofed structural upstand
- Pre-formed metal angle upstands — folded metal trims used to terminate or trim a membrane, not a concrete hob
Disclaimer
Information is general only. Hob and upstand selection, dimensions, reinforcement and dowelling must be confirmed against the structural and waterproofing design, manufacturer technical data, NCC requirements, and Australian Standards including AS 4654.2, AS 3600 and AS 3700. Fields marked “CONFIRM” are project- or manufacturer-specific and must be verified. Do not rely on this reference as a substitute for professional engineering or waterproofing consultant advice.