A membrane tested for the job
The membrane must comply with AS 4654.1 for the way it is used. Class III stretches 300% or more. ACTFLEX 929 SL, 929 HV and 5000 are Class III.
AS 4654.2 cl 2.3 · AS 4654.1 App A● System 05 of 12 · Balconies & podiums
Balcony Waterproofing & Podiums
External balconies, podiums and decks that get tiled, screeded or paved over. Prime, detail the junctions, lay a Class III membrane, screed to falls, then the finish.
AS 4654.1 Class IIIAS 4654.2NCC Part F1
6products
1CAD details
Up to 25 yrwarranty, depending on the systemwarranty, by system
● The build-up
Seven layers, in order.
Each layer with the one figure that matters, from its data sheet. Tap a layer to see why it is there.
01
PrimerACTFLEX 700 PU4 to 6 m² per litre · one coat
Polyurethane primer under the 929 membranes, about 60 microns dry. Touch dry in 30 minutes at 20°C; put the membrane on within 24 hours. Where the slab reads over 4.5% moisture, prime with two coats of ACTFLEX EP250 instead.
02
Sealant and filletsACTFLEX 75FC15 x 15 mm fillet at every junction
Polyurethane sealant used with the 929 membranes for the fillet at each change of plane and for joints. The membrane goes over it after 1 to 2 hours. 600 mL sausage.
03
Membrane for the floorACTFLEX 929 SL1.2 mm in 2 coats · 15 L ≈ 8 to 10 m²
Self-levelling polyurethane for balconies, terraces and podiums. Class III to AS 4654.1 (Report 429-3) with 756% elongation. Two coats at 0.7 mm wet each, 24 to 48 hours apart. Full cure at 48 hours, then a 24-hour flood test.
04
Membrane, high-viscosity gradeACTFLEX 929 HV1.2 mm in 2 coats · recoat in 4 to 6 h
The thicker grade of the same polyurethane membrane, Class III to AS 4654.1. The same 1.2 mm film in two coats, about 10 m² from a 15 L pail. Recoat within 24 hours.
05
Sheet membrane optionACTFLEX 500075 mm laps, side and end
Self-adhesive sheet membrane, Class III to AS 4654.1 (NATA Report 373) with 374% elongation. Goes on concrete at least 28 days old, primed with EP250.
06
Screed to fallsSCREED X35 mm over the membrane · tile from 12 h
Rapid structural screed. Over FORSPEC membranes it goes down unbonded at 35 mm with mesh, on a double slip sheet, or bonded at 10 mm. Foot traffic in 2 to 3 hours and tiling from 12 hours.
07
Tile adhesiveACTFLEX BIOSETC2TE S1 · grout from 24 h
Full coverage and back-buttering on external work. A 20 kg bag covers about 4 to 4.5 m² with a 10 mm notch. Grout from 24 hours.
How much do I need?ACTFLEX 929 SL uses 1.4 L/m² over two coats. A 15 L pail covers 8 to 10 m² in practice.
Calculate →● The rules, in plain English
AS 4654 and the NCC, in short.
Houses follow AS 4654.1 and AS 4654.2. Concrete balconies on apartments also get the NCC's own numbers once NCC 2025 applies.
Falls go under the membrane
Water must reach the outlet with none left standing. The fall is in the slab, or in a screed under the membrane, never only in the topping above it.
AS 4654.2 cl 2.5.2Apartments under NCC 2025
On concrete balconies of Class 2 to 9 buildings: a 1:80 fall in the slab itself, a 70 mm step-down, a 70 mm hob, and the membrane directly on the slab. Not for houses.
NCC 2025 Vol One F1D4, F1D7Upturns above the finished tile
The membrane turns up high enough above the finished surface that wind-driven water cannot get over it. The standard's guide heights run from 40 to 180 mm by wind class.
AS 4654.2 cl 2.8.1.1, App ADoors, drains and joints
A sub-sill flashing at every door. The membrane turns down into each outlet and overflow. Over a structural joint it stops, or runs unbonded for 100 mm.
AS 4654.2 cl 2.8.3, 2.9, 2.10Slip sheets, then inspect
An unbonded screed sits on a double slip sheet, so it cannot rub on the membrane. On completion the membrane is inspected or tested before it is covered.
AS 4654.2 cl 2.15.2, 2.16A plain-English summary, not the standard. Ask the certifier which NCC edition your job is under, or send us the job.A summary, not the standard. Check the current documents for your job.
● Every product in this system
Balconies & podiums: 6 products.
TDS and SDS open straight from the card.
● 3D models
See every layer before site starts.
Each FORSPEC detail is modelled in 3D so the site team sees the build-up for balcony & podium waterproofing before anyone opens a pail. Send the job and we model yours.
● On site
Real jobs. Real FORSPEC.
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Send the drawings or a few photos. A FORSPEC rep comes back with the system, the CAD details and a 3D of your job.
Send us your job →● CAD library
Drawn details, ready for your set.
1 standard detail for balcony & podium waterproofing. Open one to view it and download the PDF and DXF.
● Questions we get
Straight answers, from the TDS.
How do you waterproof a balcony under tiles?
Prime the concrete with ACTFLEX 700 PU, form a 15 x 15 mm fillet at every junction, then apply two coats of ACTFLEX 929 SL to 1.2 mm dry. After 48 hours, flood test for 24 hours. Then screed to falls with SCREED X and tile with ACTFLEX BIOSET.
How much membrane do I need for a balcony?
ACTFLEX 929 SL uses 1.4 L/m² over two coats to reach 1.2 mm dry. A 15 L pail covers 8 to 10 m² in practice.
How long before I can screed or tile over the membrane?
ACTFLEX 929 SL reaches full cure 48 hours after the second coat. Flood test it for 24 hours at 50 mm, then cover it. SCREED X takes tiles from 12 hours.
What class of membrane does a balcony need?
AS 4654.1 sorts membranes by stretch: Class I under 60%, Class II from 60 to 299%, Class III 300% or more. ACTFLEX 929 SL, 929 HV and 5000 are all Class III.
How thick is the screed over the membrane?
SCREED X goes down unbonded at 35 mm over FORSPEC membranes, with mesh and a double slip sheet, or bonded at 10 mm. The 35 mm is the FORSPEC system figure from the SCREED X data sheet.
Do the NCC 2025 balcony rules apply to my job?
They apply to concrete balconies, roofs and podiums on Class 2 to 9 buildings such as apartments, not to houses. New South Wales and Queensland adopt NCC 2025 from 1 May 2027. Ask the certifier which edition your job is under.
How long after the sealant fillet can the membrane go on?
1 to 2 hours after the ACTFLEX 75FC fillet is formed.
Which primer under 929 on an external balcony?
ACTFLEX 700 PU, in one coat. Where the slab reads over 4.5% moisture, prime with two coats of ACTFLEX EP250 instead.
● Go deeper
Drawings, data sheets, jobs and news.
DrawingsCAD details for this system1 detail here, PDF and DXF to download→Data sheetsTDS, SDS and test reportsEvery document for this system→CalculatorACTFLEX 929 SL calculatorArea in, packs out→CalculatorACTFLEX 929 HV calculatorArea in, packs out→SpecifySpec clause for this systemClause, drawings, data sheets→ProjectRoof, ACTFLEX 929 SLA FORSPEC job→Projects14 buildings with these productsWhere this system has been used→NewsMoisture in concrete: how dry is dry enough?FORSPEC News→NewsScreeds on balconies: what NCC 2025 changesFORSPEC News→NewsNCC 2025: eight changes for balconies and roofsFORSPEC News→
● The other systems
Twelve systems. One warranty.
● Not sure it suits the job?
Send us the job. We spec it.
Drawings, photos or a description. A FORSPEC rep comes back with the system, the spec clause, CAD details and a 3D visual within 6 business hours.