How Canvas Keeps Your Gear Protected Without the Mould.

Winter has a way of doing quiet, invisible damage to the things you leave outside. You cover everything up in April with the best of intentions, come back in September, and find that what should have been safely stored has instead spent six months sitting in its own trapped moisture — mould on the furniture cushions, rust creeping across the tool surfaces, timber that’s swelled and cracked, and that general musty smell that tells you something went wrong under the cover while you weren’t looking.

The frustrating thing is that covering your gear is exactly the right instinct. Leaving things exposed to direct rain and frost through a southern Australian winter is genuinely damaging. The problem isn’t the decision to cover things — it’s the way the covering traps moisture rather than allowing it to escape.

Canvas changes that equation. As a naturally breathable woven fabric, canvas lets moisture vapour pass through the weave rather than sealing it in, which means the things stored underneath can stay dry and protected without the humid, stagnant conditions that cause mould and mildew to take hold. Understanding why this matters — and how to apply it practically across the things you’re storing — is the difference between winter storage that actually works and winter storage that creates as many problems as it solves.

Why Moisture Is the Real Enemy of Winter Storage

Before getting into specific applications, it’s worth understanding what’s actually happening when stored items develop mould or moisture damage under a cover, because it isn’t always obvious.

Everything stored outdoors — timber, fabric, metal, leather, rubber — contains some moisture. The items themselves aren’t dry in the way a piece of paper in a drawer is dry. They exist in equilibrium with the humidity of the air around them, absorbing and releasing small amounts of moisture as conditions change. When you cover these items with a fully sealed cover and trap that equilibrium, a few things happen.

As temperatures drop overnight, the air inside the covered space cools and its capacity to hold moisture reduces — causing condensation to form on the surfaces of whatever is inside. During warmer parts of the day the temperature rises, the condensation evaporates, and the humidity inside the covered space increases. This daily cycle of condensation and evaporation, repeated across hundreds of days of winter storage, creates persistently damp conditions that are ideal for mould and mildew growth and steadily damaging to almost everything they’re applied to.

Breathable canvas interrupts this cycle by allowing moisture vapour to escape rather than cycling endlessly inside the covered space. When condensation forms and evaporates, the vapour can pass through the canvas weave rather than being trapped. The result is a covered environment that stays genuinely drier over time rather than becoming progressively more humid.

Outdoor Furniture: The Storage Challenge Most People Get Wrong

Outdoor furniture is probably the most common winter storage application for canvas tarps, and it’s also where the breathability advantage is most immediately obvious — because outdoor furniture, particularly anything with cushions, fabric elements, or timber components, is extremely susceptible to mould damage under sealed covers.

Timber furniture is particularly vulnerable. Timber that’s been rained on, dried, rained on again and dried throughout summer has a higher moisture content than kiln-dried indoor timber, and covering it under a sealed surface for winter traps that moisture in. Over the course of a winter, trapped moisture in outdoor timber can cause swelling, cracking, paint and varnish lifting, and the growth of surface mould that stains and degrades the finish. Canvas allows the timber to continue breathing through winter — releasing moisture slowly into the air rather than holding it trapped against the surface.

Fabric elements — cushions, woven chairs, upholstered outdoor sofas — are even more sensitive. These materials are essentially sponges for moisture and provide the organic material that mould needs to establish and spread. A set of outdoor cushions stored under a sealed cover through winter in a humid climate can develop significant mould growth that renders them unusable and impossible to fully clean. Under a breathable canvas cover, the same cushions stay dry enough that mould never gets the foothold it needs.

For covering outdoor furniture with canvas, size your tarp to cover all items with a comfortable overhang to the ground on the sides, but avoid sealing the base of the cover to the ground or deck surface. A small gap at the bottom allows fresh air to enter and replace humid air that passes out through the canvas — maintaining the airflow that makes the breathable cover work. Weighting or loosely securing the sides is enough to keep the cover in place through wind without sealing the base.

Our CrocSkin Canvas Tarpaulins in 380gsm are well suited to furniture cover use — heavy enough to drape well over irregular shapes and stay in place in moderate wind, while remaining light enough to handle easily for seasonal deployment and removal.

Timber and Firewood: Keeping It Dry Without Locking In Moisture

Stored timber and firewood present a slightly different version of the moisture management challenge. With firewood in particular, the goal isn’t just to keep moisture out — it’s to allow the timber to continue drying and seasoning while protecting it from direct rain. These two requirements are in direct tension if you use a fully sealed cover, but canvas handles both simultaneously.

Seasoning firewood needs airflow to continue releasing moisture from the wood fibres over time. This is a slow process that happens across months and requires moving air around and through the stack. A fully sealed cover stops that process entirely — the humidity inside a sealed firewood cover rises as the wood releases moisture, and that moisture eventually cycles back into the wood rather than escaping. Canvas allows the moisture being released by the drying timber to pass through the cover and disperse, while still shedding rain from above.

The correct approach for covering firewood with canvas is to cover the top and allow the sides to remain open or minimally covered — a technique that protects the top of the stack from direct rain while allowing maximum airflow around the sides. This is the configuration where canvas performs best, because the breathability of the fabric means the top cover isn’t creating a sealed humid zone above the stack even when the sides are open.

For stored building timber — hardwood boards, structural timber, treated pine — canvas offers similar advantages. Timber stored under a breathable cover maintains more stable moisture content through winter than timber sealed under non-breathable alternatives, which means less movement, less warping, and less cracking when it’s eventually brought inside or used.

Tools and Equipment: Rust Prevention Through Breathability

Tools and metal equipment stored outside through winter face a specific threat that’s distinct from the mould challenges facing fabric and timber — rust. And rust, like mould, is fundamentally a moisture problem. Steel and iron corrode in the presence of moisture and oxygen, and the condensation cycle described earlier is a highly effective rust accelerator when it happens repeatedly inside a sealed cover over months of winter storage.

The counterintuitive truth about metal storage is that a breathable cover often does a better job of rust prevention than a sealed one, because it prevents the condensation cycle from concentrating moisture against the metal surfaces. When moisture vapour can pass through the canvas rather than condensing on the metal, the surfaces stay drier over time — and drier surfaces don’t rust as readily.

For garden tools — spades, forks, rakes, hoes — a canvas tarp draped over a tool rack or storage area provides effective protection from direct rain while allowing enough airflow to prevent the persistent dampness that causes handle rot and blade rust simultaneously. The same approach works well for larger equipment like wheelbarrows, garden carts and fertiliser spreaders that can’t easily be brought inside for winter.

For powered garden equipment — lawn mowers, leaf blowers, chainsaws, hedge trimmers — canvas covers protect the external surfaces effectively while allowing internal moisture from fuel systems and engines to dissipate rather than condensing inside a sealed cover. This matters particularly for equipment that’s been used in wet conditions and then stored — sealing damp power equipment under a non-breathable cover for winter is a reliable way to find rust and corrosion issues in spring.

Outdoor Machinery: Protecting What You’ve Invested In

For larger outdoor machinery — ride-on mowers, tractors, wood splitters, generators and similar equipment — a canvas tarp is one of the most cost-effective winter protection measures available. These are significant investments that deteriorate quickly when left unprotected, and canvas covers provide meaningful protection without the condensation and moisture problems that undermine sealed alternatives.

The breathability advantage is particularly significant for machinery with upholstered seating, rubber components, and complex metal surfaces with multiple nooks and cavities. Sealed covers create a microclimate inside that promotes condensation in exactly the areas that are hardest to inspect and treat — inside engine bays, behind panels, under seat cushions. Canvas allows these areas to breathe, dramatically reducing the moisture accumulation that causes hidden corrosion and deterioration.

Sizing is important for machinery covers. A canvas tarp sized to provide good coverage of all components — including wheels, attachments and protruding elements — with enough side overhang to keep direct rain off the base of the machine will serve well. For machinery with non-standard dimensions, our Made to Order Canvas Tarp service allows you to specify exact dimensions and eyelet placement — a worthwhile investment for equipment that needs to be covered and uncovered regularly through a long storage season.

Bicycles, Motorcycles and Recreational Equipment

Bikes — both pedal and motor — are an interesting winter storage case because they combine metal frames and components that rust with rubber that perishes, electrical components that corrode, and upholstered elements that mould. This range of materials and failure modes makes breathable canvas particularly appropriate, because it addresses moisture management across all of these material types simultaneously.

Motorcycles stored under breathable canvas through winter maintain better condition across all components than those stored under sealed covers. Chrome and polished metal surfaces stay cleaner and develop less oxidation. Rubber seals and tyres are less likely to perish from the ozone-like effect of trapped stagnant air. Electrical connections remain drier. Upholstered seats don’t develop the mould growth that characterises winter storage under sealed covers in humid environments.

For bicycles, particularly higher-end bikes with carbon fibre or aluminium frames, canvas provides effective protection without any risk of the cover material itself causing problems — some sealed covers can trap abrasive grit against frame surfaces and cause paint and finish damage over a long storage period. Canvas drapes softly and doesn’t create the mechanical abrasion risk that stiffer materials can.

Recreational equipment — kayaks, surfboards, camping gear in storage mode, outdoor sports equipment — benefits similarly from breathable storage covers that protect from rain and UV while allowing the materials underneath to stay dry and properly ventilated.

Getting Canvas Winter Storage Right: The Practical Details

Using canvas effectively for winter storage comes down to a few consistent principles that apply across all of the applications described above.

Sizing generously is always the right call for winter storage. A canvas tarp that reaches comfortably down the sides of what it’s covering sheds rain away from the base of the covered item rather than directing it straight down the sides. Aim for at least 30 to 40 centimetres of overhang on each side as a minimum, and more for taller items or those in exposed positions.

Secure covers against wind without sealing them at the base. The goal is a cover that stays in place and doesn’t flap or lift in winter wind, but that allows some airflow at the base. Rope through the eyelets and tied under or around the item being covered, or weighted at the base with timber or bricks, achieves this without creating the sealed environment that causes moisture problems.

Store canvas clean and dry at the end of winter before putting it away for the warmer months. A canvas tarp that’s put away damp or dirty after the storage season will develop mould in storage, which affects both the tarp and anything it’s then used to cover. Clean, dry and store properly — the tarp will be in excellent condition when winter comes around again.

For items with particularly complex shapes or dimensions that make standard tarp sizes awkward, the Made to Order Canvas option allows you to get a cover that fits properly rather than working around the limitations of standard sizing.

The Investment That Pays for Itself Every Winter

The cost of a quality canvas tarp is modest relative to the value of what it’s protecting. A set of outdoor furniture that lasts an extra five years because it’s been properly covered every winter. Tools that don’t rust out and need replacing. Timber that arrives at spring projects in usable condition. Machinery that starts first time in September rather than requiring expensive repairs.

Canvas winter storage covers are one of those purchases where the return on investment is quietly enormous — paid back not in a single dramatic moment but in the accumulated absence of the problems that poor storage causes. Get the cover right and you simply stop having those problems.

Browse our full range of CrocSkin Canvas Tarpaulins and Made to Order Canvas options and find the right cover for everything you need to protect this winter.