Waterproofing also helps prevent moisture absorption. Without protection, a tarpaulin can wick water into its fibers over time from continuous exposure to damp conditions. This leads to mildew, mold growth, and degradation of the protective material.
Why Waterproof a Tarpaulin?
There are several key reasons why waterproofing your tarpaulin is important:
Protect Contents from Rain
One of the main purposes of a tarpaulin is to shield items from precipitation. By waterproofing your tarp, you can better ensure anything stored under it stays completely dry.
Extend Durability
Most Heavy Duty Tarpaulins UK are constructed from heavy-duty fabrics like polyethylene or vinyl. However, even tough materials will break down faster when subjected to constant wetness without waterproofing. The UV radiation in sunlight also damages fabrics more rapidly in the presence of water.
Allow Wider Range
By making your Tarpaulin fully impervious to water, you open up new potential applications. For example, a waterproof tarp could be used as a groundsheet, adding an extra layer of protection for items on bare soil or sand during rains. It may also be suitable as a short-term roof or tent material where otherwise a non-waterproof tarp would soak through.
Choosing the Right Waterproofing Materials
The type of waterproofing product you select will depend on factors like the tarpaulin material and how extensively you need it to be sealed. Here are some common options:
Self-adhesive Waterproof Tapes
Seam sealing with tape provides a reliable patch for leaks along with stitching or repairs. Tuck Tape self-fuses itself while Gruenberg Waterproof Seam Tape uses adhesive.
Rubberized Undercoatings
Products like POR-15 and Hycote form a rubber-like membrane underneath. They’re suited for waterproofing porous substrates or reinforcing seams.
Outdoor Waterproof Sprays
These are affordable and easy to apply as they come in spray bottles. Look for flexible sealants labeled for use on tarps, canvas, or other fabrics. Some effective spray brands include Krylon, Rust-Oleum, and Thompson’s.
Marine Grade Sealants
For maximum protection, especially if using the tarpaulin in harsh marine environments, choose sealants designed for boats. They withstand immersion and come in roll-on or brush-on consistencies. Examples are Flex Seal and Boeshield T-9.
PVC Coatings
Heavier-duty coatings based on polyvinyl chloride form a resilient barrier. They’re best for industrial tarps but require time-consuming application with rollers or brushes. Tappy Coat and PlastiKote make good PVC coating options.
Repairing an Existing Waterproofed Tarpaulin
Even with proper care, waterproofed tarps can develop issues over time. Here are steps to repair one:
Inspect for Damage
Check for punctures, tears, cracking sealant, deteriorating seams, or other problems letting water penetrate.
Dry Problem Area
Thoroughly scrub any dirty spots then allow to fully dry as previously described. This prepares the area for a new waterproofer.
Reapply Waterproofing
For small issues, apply a matching sealant by brushing or rolling over the defect and 4-6 inches surrounding it in multiple thin coats.
Reinforce Repairs
Consider adding extra protection over repairs by patching larger holes with fabric or using tape on seam fixes.
Recheck Frequently
Monitor repaired areas, especially when first used, to catch any new leaks early on. Reapply sealant if water gets through.
Applying Waterproof Sealant or Coating
Once your tarpaulin is thoroughly cleaned and dry, it’s time to apply the waterproofing product. Follow these guidelines:
Spraying
For spray sealants and lightweight coats, apply in a smooth, even coat using long sweeping motions. Overlap 30-50%.
Rolling
Roll on thicker sealants and coatings using a synthetic roller cover in an even V or horizontal pattern.
Brushing
When rolling isn’t practical, use a high-quality synthetic brush meant for waterproofing work. Apply with downward, even strokes.
Preparing the Tarpaulin for Waterproofing
Proper preparation is essential for waterproofing products to properly seal and adhere to the tarpaulin surface. Follow these steps:
Inspect for Damage
Examine the tarpaulin carefully before waterproofing. Make note of any punctures, tears, or other defects so you can repair them.
Clean Thoroughly
Dust, dirt, and other debris will prevent the waterproofer from forming an effective bond. Wash with a pH-neutral soap (something mild like Dawn) and rinse fully with a garden hose or pressure washer.
Allow to Fully Dry
The surface must be completely dry before applying any waterproofing. Hang the tarpaulin in the sun if possible until pliant with no moisture remnants. This could take 24 hours or more depending on material thickness and weather.
Alternatives to Sealants and Coatings
While sealants and coatings provide robust protection, they aren’t the only options. Consider these suitable alternatives:
Seam Sealing
Welding or taping seams prevent pinhole leaks. Hot-air weld seam-sealed tarps or use polyurethane or waterproof tape along vinyl or canvas stitching.
Reinforcing Potential
Apply a dab of sealant or a small piece of tape over grommets, fabric punctures, or other vulnerable areas prone to stress and flexing.
Simple Rain Cover
For occasional light precipitation, a simple tighter-weave fabric like vinyl, Sunbrella or polyester strapped over the top may suffice instead of a full waterproofing treatment.
DIY Waterproofing
Make a reversible barrier by dipping or brushing on melted wax or mixing rubberized sealant with paint for a DIY undercoating and topcoat.
Protective Undercoating
Layer a non-permeable fabric or soft plastic under the tarpaulin to block moisture passage without fully coating the tarp. Options include poly sheeting, Ground Cloth, or pond liner material.