Facade Refurbishment and Exterior Render Repair Systems
Last updated 30 September 2026
Facade refurbishment is a different problem to specifying a new wall. The substrate is already in place, the render or coating has already started to fail, and the repair has to work with whatever caused the damage. Sto Australia offers two exterior render repair systems for existing buildings: the StoArmat Remedial Render System, a reinforced render build for facades at risk of ongoing movement, and the StoColor Lastic Satin Coating System, a lighter-touch coating for facades where that risk is low. Both are installed by Sto-registered contractors and backed by a warranty and the StoService Assurance maintenance programme.
What facade refurbishment with Sto involves
Where a facade has been impaired by environmental impact or structural stress, cement-based render has its limitations. It cracks, and cracks let water into the wall. Repairing a cracked facade with another cement-based product carries those same limitations forward.
Sto's approach to render refurbishment is to change what the repair is made of. StoArmat is a cement-free, organically bound render with crack resistance six times higher than standard cement-based products, a technology Sto has developed since 1955. In a refurbishment system it is combined with elastic crack treatment, reinforcement mesh, coloured finishing renders and StoColor facade coatings, so the repaired facade is built to flex with the substrate rather than resist it.
The outcome is a weatherproof facade finished in the colour and texture the project calls for, protected by a warranty written specifically for refurbishment work.
Two exterior render repair systems, and how they differ
Sto's refurbishment range has two systems. Each answers a different question about the condition of the facade.
StoArmat Remedial Render System: for facades with movement or damage risk
The StoArmat Remedial Render System is a 4–5 mm reinforced render build applied over the existing substrate. Cracks are treated first with StoCrack Filler Fine, an elastic paste, together with StoLastic Mesh RF, an elastic reinforcement mesh with high tear resistance. Once that has dried, a full StoArmat reinforcement render is applied with Sto Glass Fibre Mesh, then finished with a Stolit finishing render and a StoColor facade coating. It is designed for fibre cement sheet, existing cracked render cladding, concrete block, brick and masonry, polystyrene insulation panels, poly block and autoclaved aerated concrete (AAC), and it carries the Sto 10 Year Refurbishment Warranty with StoService Assurance.
StoColor Lastic Satin Coating System: for facades where movement risk is low
StoColor Lastic Satin is an elastomeric coating system for refurbishing masonry and rendered facades where minor cracks need addressing and the surface needs waterproofing. The surface is cleaned and sealed, cracks are filled with StoCrack Filler Fine, window seals are checked and addressed, and two coats of StoColor Lastic Satin are applied by brush or roller. The coating can bridge hairline cracks, is highly water-repellent and remains vapour permeable, so the wall can still breathe. It suits the same range of substrates as the render system, but it is not suitable for lime substrates. It carries the Sto 7½ Year Coating Warranty with StoService Assurance.
| StoArmat Remedial Render System | StoColor Lastic Satin Coating System | |
|---|---|---|
| Best suited to | Facades where there is a risk of substrate movement or damage | Facades where the risk of substrate movement and damage is low |
| What it is | 4–5 mm reinforced render build | Elastomeric coating system, two coats |
| Crack treatment | StoCrack Filler Fine plus StoLastic Mesh RF | StoCrack Filler Fine; reinforcement mesh may be added depending on project requirements |
| Finish | Stolit finishing render plus StoColor coating | StoColor Lastic Satin, silk matt |
| Colour | StoColor System (800 shades or Spectrometer match) | StoColor System (800 shades or Spectrometer match) |
| Application | Reinforcement render with glass fibre mesh | Brush or roller |
| Where it is the lighter option | – | Lighter-touch application and a shorter installation sequence |
| Limits | Timber-framed buildings: independent assessor confirms framing is sound | Not suitable for lime substrates; not for facades with movement or damage risk |
| Warranty | Sto 10 Year Refurbishment Warranty with StoService Assurance | Sto 7½ Year Coating Warranty with StoService Assurance |
Scroll sideways to see both systems.
Which facade refurbishment system is right for your building
Sto's own selection rule is the right place to start. StoColor Lastic Satin is designed for projects where the risk of substrate movement and damage is low. If there is risk, the StoArmat system should be used.
The reason lies in what each system does. A coating can bridge hairline cracks in a stable substrate. A reinforced render build adds reinforcement, strength and durability to the facade itself, which is why it is the system Sto specifies where movement or damage is a risk. The two systems share the same list of substrates, so the deciding factor is the condition of the wall and the likelihood of further movement, not the material it is made from.
On timber-framed buildings, Sto's StoArmat Remedial specification also calls for an independent assessor to confirm the framing is sound before work starts. If you are weighing the options on a specific project, a Sto consultant can talk through the substrate, the condition of the facade and the finish you need, and recommend a system before you commit to either.
How Sto exterior render repair works
On a StoArmat Remedial installation the layers go on in a set order, and each one has a specific job.
- Confirm the substrate. The system is applied over existing fibre cement sheet, cracked render or masonry. On timber-framed buildings an independent assessor confirms the framing is sound.
- Treat the cracks. StoCrack Filler Fine fills and reinforces the cracks, and StoLastic Mesh RF adds elastic reinforcement where the system calls for it.
- Apply the reinforcement render. Once the crack treatment has dried, StoArmat render is applied with Sto Glass Fibre Mesh, which is specified for crack, stress and alkalinity resistance.
- Add the finishing render. Stolit finishing renders are organically bound, pre-coloured and impact-resistant, with textures including Stolit K, MP, MP Natural and Milano.
- Finish with StoColor. The StoColor coating range includes Lotusan for facades that stay clean for longer, X-black for strong, dark colours and Maxicryl for a natural look.
- Install through a Sto-registered contractor. The work is carried out by a Sto-registered contractor, with the Sto 10 Year Refurbishment Warranty and StoService Assurance plan in place for long-term security.
The Lastic Satin path is shorter: clean and seal the surface, fill the cracks, check the window seals, then apply two coats.
StoArmat Remedial Render System
Click on each of the layers below to view the components of the system.
01
Timber Frame
Check the timber to ensure the framing is sound (to be carried out by an independent assessor).
02
Substrate: Existing fibre cement sheet (shown)
Other options include existing cracked render cladding and masonry substrates.
03
Crack treatment:
StoCrack Filler Fine
Elastic paste to fill and reinforce cracks.
Plus: StoLastic Mesh RF
Specially engineered elastic reinforcement mesh with high tear resistance.
04
Reinforcement Render: StoArmat Render
An organic, weather-resistant, cement-free and breathable, high-impact render, with crack resistance six times higher than standard cement-based products.
05
Plus: Sto Glass Fibre Mesh 4/7mm
Easy to install, meets the highest requirements for crack, stress and alkalinity resistance.
06
Finishing Render: Stolit Renders
Organically bound, highly weather-resistant, strong, hard-wearing, impact-resistant, pre-coloured finishing renders. (No cement)
Stolit K Range
Stolit MP & MP Natural
Stolit Milano
07
Coating:
StoColor coating based on IQ Net Technology for functional facades.
StoColor Lotusan
StoColor X-black
StoColor Maxicryl
StoColor Lastic
Sto 10 Year Refurbishment Warranty with StoService Assurance
Why StoArmat suits render refurbishment
Refurbishment fails when the repair inherits the weakness of the original. StoArmat is chosen for render refurbishment because it removes that weakness, not because it covers it.
- Cement-free and organically bound. StoArmat is malleable, which is what allows it to flex with the substrate instead of cracking.
- Measured performance. Crack resistance six times higher than standard cement-based products, and impact resistance for StoArmat render of up to 50 joules, demonstrated through bend and ball-drop testing.
- One system, designed to work together. Crack treatment, mesh, reinforcement render, finishing render and coating come from a single manufacturer, made in Germany.
- Colour freedom. The StoColor System offers 800 shades, or a match to any colour using the Sto Spectrometer.
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What to expect from a Sto refurbishment project
Sto supports a refurbishment project from specification through to completion. That includes technical consultation and specification advice, on-site support, plan reviews and mock-up assistance. CAD and PDF detail sets for StoArmat Remedial are available on request, and an editable specification can be provided. Installation is carried out exclusively by Sto-registered contractors.
Warranty and long-term protection
Each refurbishment system carries its own warranty, and both sit alongside StoService Assurance, Sto's maintenance programme, which provides scheduled visits every 2.5 years for inspection, cleaning and minor repairs. The StoArmat Remedial Render System carries the Sto 10 Year Refurbishment Warranty. StoColor Lastic Satin carries the Sto 7½ Year Coating Warranty. These terms apply to refurbishment systems specifically; the StoWarranty with StoService Assurance page sets out the warranty programme in full.
Sto does not publish prices for refurbishment systems. Each project is quoted individually after a conversation with a Sto consultant. The lighter-touch coating is designed for facades at low risk of movement, and the reinforced render build for those where movement or damage is a risk, so the useful comparison is between the condition of your facade and the warranty you need, not between two prices for the same job.
Data Sheets
Download a Data Sheet:
Technical Data Sheet (TDS) / Safety Data Sheet (MSDS) / Sustainability Data Sheet (SDS)
Primers / Sealers:
Reinforcement Mesh:
Reinforcement Render / Base Render:
Finishing Renders:
Coatings:
Specifications
Request a Technical Specification
Please contact to receive an editable specification for the StoArmat Remedial Render System.
CAD or PDF Details
Frequently Asked Questions
What is the difference between StoArmat Remedial and StoColor Lastic Satin?
StoArmat Remedial is a 4–5 mm reinforced render build for facades where there is a risk of substrate movement or damage. StoColor Lastic Satin is an elastomeric coating system for facades where that risk is low, minor cracks need addressing and the surface needs waterproofing. Sto's rule is that if there is risk, the StoArmat system should be used. The remedial render carries a 10-year warranty and Lastic Satin a 7½-year warranty.
Can facade repair be carried out over existing cracked render?
Yes. Existing cracked render cladding is one of the substrates the StoArmat Remedial Render System is designed for, alongside fibre cement sheet and masonry. The cracks are treated with StoCrack Filler Fine and StoLastic Mesh RF before the StoArmat reinforcement render is applied. StoColor Lastic Satin can also be applied over existing render, although it is designed for facades with a low risk of movement.
Which substrates can Sto refurbishment systems be applied to?
Both systems list fibre cement sheet cladding, polystyrene insulation panels, concrete block, brick and masonry, poly block and autoclaved aerated concrete (AAC). StoColor Lastic Satin is not suitable for lime substrates. For any other substrate, or an unusual combination, talk to a Sto consultant before selecting a system.
How long are the warranties on Sto refurbishment systems?
The StoArmat Remedial Render System carries the Sto 10 Year Refurbishment Warranty, and StoColor Lastic Satin carries the Sto 7½ Year Coating Warranty. Both are supported by the StoService Assurance plan, with scheduled visits every 2.5 years for inspection, cleaning and minor repairs. Both systems are installed by Sto-registered contractors.
Who installs Sto refurbishment systems?
Installation is carried out exclusively by Sto-registered contractors, for both the StoArmat Remedial Render System and the StoColor Lastic Satin Coating System. Sto's consultants support the project from specification through to installation.
Can I choose the colour of a refurbished facade?
Yes. Both systems are finished with coatings from the StoColor System, which offers 800 shades and can match any colour using the Sto Spectrometer. StoArmat Remedial also allows a choice of Stolit finishing render textures before the coating is applied.
Related Sto systems
Refurbishment is one part of the Sto range. For new construction, see Sto render systems. For external wall insulation over existing timber, steel-frame or masonry buildings, see the StoTherm insulation system. For finishes, see exterior facade paints and Sto finishing renders.
Talk to a Sto consultant about your facade
Tell us about the building, the substrate and what has gone wrong with the existing facade, and a Sto consultant will recommend the right system. Request a quote, call +61 3 9768 4900 or email [email protected]. Our team is available Monday to Friday, 7:00am to 3:30pm.
Disclaimer: These drawings have been issued as a guideline. The sequence work covers various building components, each trade is responsible to ensure their elements are fully installed, including all waterproofing / sealant / flashings as is applicable.
