Turnout Rug Waterproofing and Breathability

Turnout rug performance is often reduced to two words: waterproof and breathable. In technical terms, however, these describe different behaviours. Waterproofing is resistance to liquid water entering from outside. Breathability is the ability of moisture vapour and, in some constructions, air to move from the horse-side of the textile towards the external environment. A rug can perform well in one area and poorly in the other.

For horse owners, the distinction matters because a rug may keep out rain yet become wet internally through sweat, condensation or trapped humid air. Conversely, a highly breathable textile may be comfortable in light rain but insufficiently resistant to prolonged driving rain, pressure from lying down or water entering through seams and openings.

When comparing rug construction, fit and seasonal use, it can be useful to look at current retail examples alongside technical guidance. JSM Equestrian Supplies’ horse rug collection includes turnout, stable and lighter seasonal options for comparison across different management needs.

This article considers turnout rugs principally as textile systems rather than as isolated pieces of fabric. The outer cloth, finish, membrane or coating, lining, insulation, seam construction, pattern, closures, fit, condition and care regime all influence real-world performance.

What waterproofing actually means

A waterproof turnout rug is intended to prevent rain from reaching the horse through the main body of the outer fabric. In practice, no rug is a completely sealed envelope: neck openings, leg arches, tail openings, fastenings, stitching and areas of movement create potential routes for water entry. WeatherBeeta therefore distinguishes between a waterproof outer fabric and the complete rug, which necessarily contains constructional openings and stitched components.

Water resistance is not the same as waterproofness. A water-resistant textile may shed showers for a period but eventually allow penetration under sustained rainfall or pressure. A waterproof laminate or coated fabric should resist penetration for longer, subject to its specification, condition and construction.

Hydrostatic pressure and hydrostatic head

The principal laboratory concept used to assess resistance to liquid-water penetration is hydrostatic pressure. ISO 811:2018 specifies a hydrostatic-pressure method for determining the resistance of textile fabrics to water penetration. In simplified form, water pressure is progressively applied to one side of a test specimen until penetration is detected.

Results are commonly expressed as a pressure value or as the height of a water column, often described in millimetres. A higher figure indicates that the tested material resisted greater pressure under that particular test method. It does not mean that the finished rug will withstand an equivalent amount of rain in every situation.

Hydrostatic-head figures are influenced by the test protocol, specimen preparation, conditioning, pressure rate, fabric support and whether the tested item is a flat fabric sample or a finished product. A fabric-only result cannot, by itself, account for needle holes, seam leakage, worn areas, compression, flexing, contaminated surfaces or water entering around the neck and closures.

Pressure in use is also not limited to rainfall. A horse lying on wet ground, rubbing against a hedge, rolling, or carrying mud against the rug can expose parts of the textile to localised pressure and abrasion. A rug intended for continuous field use therefore needs more than a high laboratory water-column figure: it needs adequate construction and durability.

Durable water repellency is not the waterproof barrier

Many turnout fabrics have a water-repellent finish on the outer face. This finish encourages droplets to bead and run off rather than spread across the cloth. It can improve comfort, reduce the amount of water held by the face fabric and help the textile dry more quickly.

However, the outer water-repellent finish is not necessarily the component that provides the main waterproof barrier. In a coated or membrane fabric, the coating or membrane normally provides the principal resistance to liquid-water penetration, while the face finish helps manage surface wetting.

When the face fabric becomes saturated, often called wetting out, it may feel cold and heavy and can reduce the efficiency of moisture transfer. The underlying waterproof layer may still be intact, but the rug can feel less breathable and may dry slowly. Beading is therefore a useful practical indicator of surface condition, but lack of beading does not prove that the waterproof barrier has failed. Equally, strong beading does not prove that seams, aged coating or damaged areas remain waterproof.

Reproofing products can restore or improve surface water repellency. They cannot reliably recreate a degraded membrane, repair punctures, close failed seam tape or reverse extensive hydrolysis of a polyurethane coating. Reproofing should therefore be regarded as maintenance, not as a permanent replacement for the original waterproof construction.

How breathable turnout fabrics work

Breathability generally refers to the movement of water vapour from the warmer, more humid horse-side of a textile towards the cooler, drier outside. The driving force is a difference in vapour pressure. If the external air is already very humid, or if the rug is covered in liquid water, the gradient may be weak and vapour transfer will slow.

Breathability is not the same as ventilation. A microporous membrane may permit water vapour to pass while blocking liquid droplets, but it does not necessarily allow significant air movement. A non-coated fabric may permit air exchange and dry quickly but provide less resistance to prolonged rain. Some rugs combine a waterproof outer textile with design features that assist ventilation, such as generous cut, breathable linings or openings positioned away from direct rainfall.

MVTR and RET

Two terms appear frequently in technical clothing and outdoor-textile literature:

• MVTR or WVTR: moisture or water-vapour transmission rate, usually expressed as the mass of water vapour passing through a square metre over 24 hours.
• RET: resistance to evaporative transfer. A lower RET value indicates lower resistance to vapour movement and therefore greater breathability under that test method.

These figures should not be compared casually. Different laboratories and manufacturers may use different test methods, temperatures, humidity gradients, air movement and sample preparation. MVTR and RET are not interchangeable units, and a high MVTR from one protocol is not automatically equivalent to a high MVTR from another.

Most importantly, a flat textile result is not a complete prediction of the horse’s experience. Breathability depends on the complete system: the outer surface, membrane, lining, fill, contact with the coat, fit, movement, temperature, humidity, wind and the amount of moisture generated by the horse. A rug may have a technically breathable fabric but perform poorly if it is saturated, heavily soiled, pressed tightly against the coat, or used in warm, still and humid weather.

Construction types used in turnout rugs

Coated fabrics

A coating is applied to the back or face of a woven or knitted textile. Polyurethane coatings are common in waterproof outdoor products. Coated fabrics can provide a good balance of flexibility, cost and waterproofing, but performance depends on coating thickness, adhesion, formulation and resistance to flexing, abrasion, detergents and ageing.

Some coatings become brittle, crack or peel after prolonged use. Others may suffer hydrolysis, in which moisture and heat contribute to chemical breakdown. These failures can appear as sticky, flaky or delaminating areas and cannot normally be corrected by adding a surface proofer.

Membrane laminates

A membrane is bonded to one or more textile layers. Microporous membranes contain pores intended to be small enough to resist liquid droplets while allowing water vapour to pass. Hydrophilic, or non-porous, membranes use a polymer structure through which water vapour moves by molecular transport rather than through visible pores.

Membrane systems can offer high waterproofness and useful vapour transfer, but they are not invulnerable. Contamination, oils, residues, abrasion, flexing and inappropriate cleaning can affect performance. The laminate also relies on a sound bond between layers.

Woven and tightly constructed fabrics

A dense weave can provide useful water resistance without a separate membrane. Such fabrics may be quiet, flexible and durable, but the balance between density, weight, flexibility and breathability is difficult. A tightly woven cloth may resist rain well while offering less vapour transfer than a specialist membrane system.

Ripstop and reinforcement

Ripstop construction uses heavier reinforcement yarns arranged within a woven structure to limit the spread of tears. It improves tear resistance but does not automatically make a textile waterproof. Waterproofness still depends on the yarns, coating or membrane, seams and condition of the fabric.

Seams, stitching and design details

A rug can fail at the seams before the main fabric fails. Every needle hole is a potential water path, particularly along exposed back seams, gussets, surcingles, tail flaps and areas subject to repeated flexing. Waterproof products may use seam tape, sealed seams, specialised construction or protective seam placement, but manufacturers do not always publish the extent of seam sealing.

Closures also require careful assessment. Chest fastenings, hook-and-loop panels, zips and surcingles create interruptions in the waterproof layer. A design may be highly resistant across the back while allowing water to enter at the front during driving rain. Neck shape, wither coverage, tail flap overlap and the position of the hindquarter seams all influence exposure.

Fit is a waterproofing issue as well as a welfare issue. A rug that shifts can expose the withers, shoulder or hindquarters. Excessive tension can stress stitching and cause rubbing; excessive looseness can allow gaps, drag through mud or create opportunities for straps to catch. The rug should remain correctly positioned during grazing, walking, rolling and lying down.

Insulation, moisture and the horse’s microclimate

Waterproofing and breathability do not determine warmth on their own. A turnout rug’s thermal performance depends on fill weight, fibre type, loft, lining, compression and the horse’s coat and condition. A wet outer layer may feel colder even when the inner side remains dry. A damp lining can increase conductive and evaporative heat loss and create discomfort.

Insulation can also reduce apparent breathability because moisture must pass through more layers. A heavyweight rug has a more complex moisture pathway than an unlined rain sheet. In cold weather this may be acceptable or desirable; in mild, damp conditions it can increase the risk of condensation and overheating if the horse does not need the additional insulation.

Over-rugging is not solved simply by choosing a more breathable fabric. A horse can become too warm under a technically breathable rug if the insulation and environmental conditions are unsuitable. UK welfare guidance emphasises that rug weight and construction should be appropriate to the weather and the individual horse, and that rugs should be removed regularly so the horse and rug can be checked.

Common causes of apparent waterproof failure

• Surface wetting: the outer fabric no longer beads water and becomes saturated, reducing drying and vapour-transfer performance.
• Dirty fabric: mud, grease, sweat, stable residues and grooming products can contaminate the surface and affect finishes.
• Incorrect washing: biological detergents, fabric conditioner, high temperatures, harsh agitation and dry cleaning may damage finishes or coatings.
• Mechanical damage: tears, punctures, pulled stitching and abrasion can create direct water paths.
• Ageing: repeated flexing, ultraviolet exposure, heat, storage while damp and chemical degradation can weaken coatings and laminates.
• Failed seam tape: tape may lift, crack or peel, particularly in high-flex areas.
• Water entry at openings: chest, neck, tail and leg areas may admit rain even when the main panel remains sound.
• Internal condensation: the rug may be externally waterproof but wet inside because vapour production exceeds the rate at which the system can release it.
• Horse-side wetness: sweat, rain entering at the neck, or a wet horse being rugged can make the rug appear to have leaked.

Care, washing and reproofing

Care instructions supplied with the individual rug take priority. BETA’s outdoor-rug guidance recommends removing excess dirt, following the manufacturer’s instructions, using cool washing temperatures and a mild non-biological soap, then drip- or line-drying. It advises against dry cleaning and recommends keeping rugs dry and well ventilated in storage.

In practical terms, brush or hose off loose mud once dry, close fastenings before washing if the manufacturer permits, avoid ordinary biological laundry products and do not assume that a household waterproofing product is suitable for a breathable equestrian laminate. Some products are designed specifically for breathable waterproof equipment, but compatibility should still be checked.

Do not store a turnout rug damp. Dry it fully before folding, and inspect the lining, binding, straps, buckles, elastic, stitching and waterproof panels. Small tears should be repaired promptly because continued movement can enlarge them and damage adjacent coating or membrane.

Reproof when the surface finish has deteriorated and the fabric no longer sheds water effectively, rather than applying product automatically at fixed intervals. The treatment should match the textile system and be applied according to its instructions. Reproofing cannot be used to conceal a structural fault, and it is not a substitute for professional cleaning or repair where seam tape, coating or laminate has failed.

How to assess a rug before purchase

1. Define the use: consider exposed hill grazing, sheltered paddocks, daily turnout, occasional rain protection, heavy mud, group turnout and likely abrasion.
2. Check what is actually specified: distinguish fabric waterproofness from a claim about the complete finished rug. Look for test methods where numerical claims are made.
3. Ask about construction: find out whether the rug is coated, laminated or densely woven, and whether important seams are sealed or protected.
4. Consider breathability in context: a useful technical claim should identify the metric and, ideally, the test method. Treat an unexplained “highly breathable” statement as a marketing description rather than a comparable specification.
5. Assess durability: outer denier, ripstop construction, reinforcement and repairability may matter more than a very high headline waterproof figure for rough turnout.
6. Inspect fit: the rug must remain stable without restricting the shoulder, rubbing the withers or creating excess gaps.
7. Match fill to conditions: waterproofness does not determine whether the horse needs a sheet, light fill or heavier insulation.
8. Plan maintenance: buy from a source that provides clear washing, repair and warranty information, and keep a spare suitable rug available.

Quality indicators and useful questions for manufacturers

For businesses and trade professionals, credible technical documentation should separate material properties from finished-product performance. Useful information includes the fibre and coating or membrane type, test method, reported units, seam treatment, care limitations, repair policy and conditions under which claims apply.

Related industry reference: For businesses moving from technical research into trade sourcing, explore horse-rug and textile suppliers on EquiGuild.

A responsible specification avoids implying that “breathable” means ventilated or that “waterproof” means every opening is sealed. It also explains that performance changes with wear, contamination, washing and mechanical damage. Where comparative figures are published, the test method should be named so that buyers can judge whether products are genuinely comparable.

Manufacturers should also consider the whole-life performance of the rug. A repairable, washable rug that retains its coating and has replaceable hardware may deliver better practical value than a technically impressive but fragile product. For equestrian businesses, clear care instructions and inspection procedures are part of product performance, not merely after-sales material.

Key conclusions

• Waterproofness is resistance to liquid water; breathability concerns moisture-vapour transfer. They are different properties.
• Hydrostatic-head testing describes resistance of a tested textile specimen to water pressure. It does not guarantee performance of the complete rug.
• Water-repellent beading is useful but does not prove that the underlying waterproof barrier is intact.
• Seams, openings, fit, abrasion and damage are often as important as the fabric specification.
• MVTR and RET figures are only meaningful when the test method and conditions are understood.
• Breathability is affected by humidity, temperature, wetting, dirt, insulation, fit and the horse’s moisture production.
• Reproofing can restore surface repellency but cannot repair failed membranes, coatings or seam tape.
• Correct weight, fit, inspection and access to shelter remain essential; no turnout rug replaces sound welfare management.

Sources and further reading

• ISO 811:2018 — Textiles: Determination of resistance to water penetration — Hydrostatic pressure test
• British Equestrian Trade Association — Guide to Purchasing Your Outdoor Rug
• WeatherBeeta UK — Waterproof and Fault Guide
• Nikwax — Rug Proof technical and care information
• WeatherBeeta — Turnout rug technology information
• Horseware Ireland — Product technology and innovation
• GOV.UK — Keeping farm animals and horses in extreme weather
• GOV.UK — Advisory standards concerning equine environmental conditions and rug use

Related research

How Horse Rug Liners WorkContinue research →Horse Rug Sizing and FitContinue research →Detachable Neck vs Combo Turnout RugsContinue research →Horse Rug Fill Weights ExplainedContinue research →Horse Rug Denier ExplainedContinue research →