Water ingress is one of the most destructive forces affecting heritage buildings. Moisture accelerates decay in masonry, corrodes embedded metal, and destroys decorative finishes. Unlike modern structures, heritage buildings cannot be treated with standard waterproofing methods — doing so risks trapping moisture, damaging original materials, or altering the building's historic appearance.
Our heritage waterproofing service provides targeted, reversible, and breathable solutions that respect the building's original materials and construction techniques. We combine the science of modern waterproofing technology with heritage conservation expertise to create protection systems that stop water but still allow the structure to breathe.
Initial Investigation & Diagnosis
- Moisture Mapping & Tracing – Identifying exact water ingress pathways using thermal imaging, moisture meters, and salt testing.
- Material Analysis – Determining the porosity, strength, and condition of masonry, render, or timber to select compatible waterproofing systems.
- Condition Assessment Reports – Providing photographic and written documentation for heritage authorities, owners, and engineers.
Waterproofing Solutions for Heritage Applications
- Breathable Surface Treatments
- Silane/siloxane-based impregnations that penetrate masonry to repel water while allowing vapour escape.
- Ideal for sandstone, brick, and lime-rendered façades.
- Discreet Membrane Systems
- Thin, concealed sheet or liquid-applied membranes beneath new roof sheeting, terrace surfaces, or planter boxes.
- Fully reversible without damage to original fabric.
- Specialist Lead & Copper Flashings
- Traditional materials used to replace or upgrade roof junctions, parapets, and cornice interfaces.
- Parapet & Cornice Waterproofing
- Low-visibility cappings and hidden drainage channels to prevent saturation of decorative features.
- Basement & Subfloor Protection
- Negative-side waterproofing with mineral-based slurry systems designed for masonry substrates.
Execution Process
- Surface Preparation – Gentle cleaning and removal of debris or vegetation without abrasive damage.
- Repair of Defects – Repointing, crack stitching, or render patching to create a sound substrate.
- Application of Heritage-Safe Products – Selected from a tested range proven to perform without harming heritage materials.
- Integration with Existing Elements – Ensuring new waterproofing works in harmony with existing drainage, flashing, and ventilation.
- Final Inspection & Testing – Flood testing, moisture readings, and photographic records for compliance.
Heritage Compliance
- All methods comply with Burra Charter principles and local heritage council guidelines.
- Approvals and method statements prepared for regulatory submission.
- Full traceability of materials and techniques for future conservation work.
Benefits of Specialist Heritage Waterproofing
- Stops Water Ingress without altering the building's character.
- Extends Lifespan of Materials by preventing moisture-related decay.
- Preserves Decorative Features by protecting vulnerable parapets, mouldings, and cornices.
- Reduces Maintenance Costs through long-term preventative protection.
Why Choose Atomic Projects
- Heritage Expertise – Our trades and project managers are trained in conservation practices.
- Proven Track Record – Delivery of waterproofing works on heritage-listed and state-significant buildings.
- Custom-Tailored Systems – No "off the shelf" approach — every project receives a bespoke solution.
- Integration with Broader Works – Can be delivered alongside façade, roofing, or structural restoration for a complete preservation package.
Frequently Asked Questions
Why can't standard modern waterproofing products be used on a heritage building?
Standard modern waterproofing — particularly acrylic or bitumen-based film-forming products — creates a barrier that blocks both liquid water and water vapour. In modern constructions with controlled vapour barriers, this is acceptable. In heritage buildings with masonry walls, moisture is always present within the fabric and needs to escape. Sealing the surface traps this moisture, causing spalling, salt crystallisation, and accelerated decay of the original material. Heritage waterproofing systems are specifically formulated to repel liquid water while remaining vapour-permeable.
What is silane/siloxane waterproofing and is it suitable for sandstone?
Silane and siloxane are penetrating water repellents that enter the pores of masonry and chemically bond with the substrate, creating hydrophobic surfaces at a molecular level without blocking pores. This allows water vapour to escape while preventing liquid water from entering. They are well-suited to porous masonry including Sydney sandstone, brick, and lime-rendered surfaces. Crucially, they are largely invisible and do not alter the surface appearance — an important consideration for heritage facades. Treatment typically lasts 10 to 20 years before reapplication is needed.
My heritage building has a leaking parapet. What does waterproofing this involve?
Parapet waterproofing on heritage buildings typically involves removing the existing capping, inspecting and repointing the parapet masonry, then installing a new cap with concealed flashings and hidden drainage slots to shed water away from the face. Traditional materials such as cast lead, pressed zinc, or copper are used where heritage appearance requires authentic detailing. On heritage-listed parapets with decorative copings, we design the waterproofing to integrate behind or beneath the existing decorative elements rather than covering them.
Can heritage basement walls be waterproofed from the inside?
Yes — negative-side (internal) waterproofing is often the only viable option for heritage basements where excavating around the external face would damage original foundations or streetscape. We use mineral-based crystalline or cementitious slurry systems that are compatible with masonry substrates. These penetrate the pores and crystallise when activated by moisture, blocking water pathways while allowing vapour movement. While not as effective as external positive-side waterproofing, internal systems provide substantial protection and are the heritage-appropriate solution in many cases.
How do you waterproof around heritage roof flashings and lead details?
Heritage roof junctions — particularly at chimneys, parapets, and dormer windows — traditionally use lead flashings. We inspect existing lead for fatigue cracking, lifting, and failed overlaps, and either repair or replace with matching lead or copper. New flashings are custom-fabricated to replicate the original profile and dressed to maintain the visual character of the roofline. Sealants used at transitions are specified for compatibility with lead and copper to avoid galvanic or chemical reactions that could accelerate failure.
Related Services
A heritage building's greatest threat is water — and our specialist waterproofing ensures it remains protected without compromising its identity.
