Non-Toxic Waterproof Sealants & Stains for Exterior Wood

This article covers non-toxic and natural waterproofing sealants and stains that are specially formulated for exterior applications like wooden decks, fences, furniture, windows, doors, play gyms, and planters.

This post covers both water-based sealants and natural oil-based options that are either zero or very low VOC. They are safe for sensitive individuals, as well as children and pets.

• Natural oil sealants can be remarkedly durable at providing protection from water and the elements, and work perfectly over oily dense woods like Ipe, Teak and Mahogany.
• Synthetic penetrating sealers can provide water resistance while leaving a natural look to raw wood.
• Film-forming sealants provide a durable topcoat, that can go over lightly sanded wood.

If you are working with pressure-treated wood, all stains require that the wood has time to dry out first which can take anywhere from 3 months to a year.

Technically wood sealers are not water-proof but water-resistant, certainly enough to weather the storms outside.

Top picks:

• Top water-based option: Vermont Natural Coatings PolyWhey Exterior Wood Stain
• Top invisible look option: Vermont Natural Coatings Penetrating Water Proofer with Juniper
• Top oil-based natural options: Outdoor Defense Oil or Rubio Monocoat Hybrid Exterior

This post contains affiliate links. Upon purchase, I earn a small commission at no extra cost to you.

1. Vermont Natural Coatings & Böhme – Terra Plus Exterior Deck Stain

What is it: This is an oil / waterborne hybrid penetrating stain and sealer.

• Water resistance.
• UV protection. It has better UV protection than the other options by this company.
• Abrasion resistance.
• Semi-transparent stain in 16 colors including grey and whitewash.

Where to use it: On exterior wood like decks and stairs.

Types of wood: Use on new or properly prepared exterior wood. You can use it on oily woods like Ipe, Mahogany, and Teak as well as non-tropical exterior woods.

Specs: Low VOC. One person who was super sensitive thought this was better than PolyWhey. The company describes the smell as a sunflower or pumpkin odor, not a linseed odor, though it’s not clear what the full ingredients are.

Where to buy: Through the Vermont Natural Coatings website; sometimes on Amazon.

2. Penetrating Water Proofer Infused With Juniper

What is it: This is a water-based penetrating sealer. It does not form a film – it leaves the wood looking totally bare and raw.

• Water-resistance (only) for a natural look.
• It does not provide any UV resistance, the wood will gray out naturally.
• It does not provide abrasion resistance.
• No stain or change in color or sheen.

Where to use it: Despite being only a waterproofer this can be used on decks, railings, shake roofs, siding, fencing, indoor/outdoor play gyms, the exterior of planters/raised garden beds, outdoor furniture, and animal hutches/pens. Like the other synthetic sealers on the list, is not suitable for subterranean or submerged wood. It can be used on interior and exterior applications.

Types of wood: It can be used on new, or weathered wood as well as pressure-treated wood. For pressure-treated wood allow 6-12 months before application. It can work on Teak and other oily woods and it is a good choice for cedar, pine, spruce, and fir. It cannot go over or under another product.

Specs: It is zero-VOC and contains no solvents, dyes, biocides, or fungicides.

Where to buy: From Walmart and you can sometimes find it via Amazon.

3. PolyWhey Exterior Penetrating Wood Stain

What is it: This is one of the most durable water-based non-toxic deck stain/sealers that I know of.

• Water resistance.
• Some UV resistance, you get more UV resistance the darker the stain color.
• Comes in 14 semi-transparent stain colors, including greys.
• Abrasion resistance.

Where to use it: Wood siding, decks, fences, outdoor furniture, log cabins, exterior wood doors, play gyms, swing sets, beehives (it’s well-known for this application), pet hutches, barns, chicken coops, and other outdoor wood surfaces.

This coating is great for the exterior of raised garden beds with AFM Dynoseal as the synthetic waterproofer for the interior. More in the post on raised garden beds.

Types of wood: It can be used on new, pressure-treated, and weathered wood. Like with all wood stains and sealers, pressure-treated wood needs to dry out for 6 months to a year before application. This one is not for use on exotic super dense oily woods such as Teak, Ipe, or Garapa/Brazilian Ash.

It can be applied over older oil-based stains or finish, as well as other water-based finishes if it’s been fully sanded first so that it can penetrate into the wood. No product can go over top of this in exterior applications.

Specs: It is non-toxic, low odor, low-VOC, and contains no biocides, fungicides, or anti-microbial agents. The pigments act as natural UV inhibitors.

The folks at Green Building Supply have tested the non-toxic options on fences and found this to be as durable as oil-based stains and more conventional toxic stains/sealers.

Where to buy: You can buy it online at Walmart and sometimes via Amazon.

4. AFM Safecoat EXT Exterior Polyureseal

What is it: A clear acrylic-urethane coating for exterior use on wood (and concrete too).

• Water-resistant topical coating .
• Good abrasion resistance.
• UV resistance.
• Clear coating, but can be paired with their stains.

Where to use it: On walkways, decks, fences, floors, patios, doors, and pet cages. It can be applied to raw wood or wood stained with AFM Safecoat wood stains, as well as concrete or previously painted (with water-based paint) surfaces.

For abrasion resistance on outdoor furniture, tables, or decks, a paint and sealer combo would work well: AFM Safecoat All Purpose Exterior Satin and then AFM Safecoat EXT Exterior Polyureseal.

Types of wood: Use on dry and absorbent wood. It can be applied to raw wood or wood stained with Safecoat DuroTone, concrete, and previously painted surfaces that are properly prepared. This product can not be used over oil-based coatings.

Specs: It’s a low-VOC formula. It also can function to seal in offgassing of chemicals and odorants.

Where to buy: Through Green Design Center/Building for Health.

5. Milk Paint Outdoor Defense Oil

What is it: The is the only totally natural waterproofer on this list, this still functions really well. This is a natural oil sealer made from pure tung oil, pine oil, and zinc. Out of the natural penetrating oils, tung oil is the most durable.

• Water resistant penetrating sealer, not a topcoat.
• Durable, abrasion resistance.
• UV resistance.
• Naturally darkens the wood but does not come in different stain colors.
• Food contact safe

Where to use it: On outdoor wood like picnic tables, wooden Adirondack chairs, wood furniture, decks, siding, wood fencing, front porches, concrete patios, park benches, wooden storage sheds, wood doors, and windows. You can use it on beehives with a full 30-day cure. This is the all-natural option for sealing raised garden beds (both inside and out), more info here.

You can also use this over Milk Paint to protect it from the elements or you can mix (some) pigments into the tung oil.

Types of wood: You can use this on all wood types. Extremely dense woods such as Teak, Ipe, etc may require thinning with more (natural) solvent. Not for use over new oil-based sealers/stains or other finishes like film-forming topcoats. You can use it over aged penetrating oil finishes (like aged linseed oil).

Specs: No metallic driers. Full ingredient disclosure: pure tung oil, pine oil (which acts as a solvent), and zinc. Some highly chemically sensitive folks have preferred these natural oil coatings to synthetic coatings like PolyWhey (others would find the opposite preferable). Always test for your own tolerance and I would recommend not using or being exposed to these natural solvents when they are wet if you are sensitive.

Where to buy: Through the Real Milk Company’s website. You can use code mychemicalfreehouse for 10% off.

PS to clean your tung oiled wood, you can use gentle soaps, but some non-toxic cleaners can damage it – this post goes over the best options.

6. Monocoat Hybrid Exterior Wood Protector

What is it: A modified linseed oil and wax penetrating oil finish that is applied with just one coat.

• Water-resistant, penetrating sealer (not a topcoat).
• Natural and modified ingredients.
• UV protection except for the color “Pure” which has no UV protection.
• Comes in 22 different stain colors, including bright colors.

Where to use it: Wooden decks, façades, patios, shutters, portals, garden furniture, pontoons, windows, doors, etc.

Types of wood: Works well over almost all wood types including oily exotic woods (Ipe, Teak, Mahogany etc).

Specs: Solvent-free, technically it’s no-VOC because it’s a natural product. Though see my in-depth review of Rubio Monocoat and other linseed oils for information on naturally occurring VOCs. Rubio Monocoat is preferred to plain linseed oil in many ways because it’s lower in odor. You need a part B accelerator, be sure to test that out as well.

Where to buy: Directly through their website.

PS To clean your linseed oiled wood, make sure to use specialty products that won’t damage the surface.

Top Picks for Exterior Wood Stains:

Most Durable Water-Based Option: Vermont Natural Coatings PolyWhey Exterior Penetrating Wood Stain

Best Bare Wood Look Water Proofer: Vermont Natural Coatings Penetrating Waterproofer with Juniper

Best Clear Topcoat for Over Paint: AFM EXT

Only All-Natural Option (+ Most Durable Natural Oil): Outdoor Defense Oil

Best (Mostly) Natural Option if You Want Lots of Stain Colors: Rubio Monocoat Hybrid Exterior

Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.