What survives here?

Nearly non-absorbent, which solves staining and freeze-thaw in one move.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.

A wash once a year

Ask the supplier: What is the slip classification, wet, and how is it being laid: pedestals, sand or mortar?

Slip rating is measured on a clean sample; algae and frost change the real answer more than the rating does.

Drains, forgives, crunches, and travels indoors on everybody's shoes.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: What size and shape is the aggregate, and is there an edge to keep it where it belongs?

Angular gravel stays put and hurts underfoot; rounded gravel is kinder and migrates.

Durable in every way except the one people notice: it gets extremely hot.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: What is the absorption rate, and is it rated for freeze-thaw where you are?

Durability and touch temperature are separate questions, and dark stone answers them very differently.

Cooler underfoot, and it shows every drop of red wine.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

Oiling or repainting each year

Ask the supplier: Is it sealed, and what does resealing involve once it has been down a few years?

Pale paving lowers surface temperature and raises the radiant load on a person standing on it. Both are real.

Does everything adequately and nothing beautifully, which is often exactly right.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: Is the mix air-entrained for freeze-thaw, and what is the plan for control joints?

Concrete cracks. The question is whether it cracks where somebody decided it would.

Ages well, grips well, and moves with the ground rather than fighting it.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: Is this a paving brick rated for your freeze-thaw exposure, or a facing brick?

Facing bricks sold as paving are the most common cause of spalled terraces in cold climates.

Invisible until it is filthy, and it does nothing for wind noise.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Staining: Tannin from leaves, sunscreen and red wine are the three that actually mark outdoor surfaces.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.

A wash once a year

Ask the supplier: What is the edge detail, and how will it be cleaned on the outside face?

Glass blocks wind without blocking view, and it also blocks the breeze you wanted in July.

Excellent until the wrong grade meets salt, and then it stains like anything else.

• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Corrosion: Corrosion usually starts at a fixing, a cut edge or a foot, not in the middle of a panel.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.

A wash once a year

Ask the supplier: Is it 304 or 316? Within a few miles of salt water that difference is the whole decision.

Tea staining on coastal stainless is cosmetic corrosion and is very common in grade 304.

Light, rust-proof, and entirely dependent on the quality of its coating.

• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.

A wash once a year

Ask the supplier: Is the powder coat rated to AAMA 2604 or 2605, and is the substrate marine-grade?

Aluminium does not rust, but a scratched coating in salt air still corrodes underneath and lifts.

It is meant to rust, and the whole question is whether the rust ever stabilises where you are putting it.

• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Corrosion: Corrosion usually starts at a fixing, a cut edge or a foot, not in the middle of a panel.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Slow drying: This family gives water back quickly, which is most of the battle here.

Nothing to do

Ask the supplier: Is this a genuine weathering grade, and what does the datasheet say about wet-dry cycling and about run-off staining?

Weathering steel depends on repeated drying and sufficiently low chloride exposure to develop a protective patina. Persistent wetness, coastal salt, detailing and runoff can defeat that behavior; structural suitability remains an engineering/specification question.

Sacrificial zinc doing a quiet job for twenty years, then not.

• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Corrosion: Corrosion usually starts at a fixing, a cut edge or a foot, not in the middle of a panel.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.

A wash once a year

Ask the supplier: Is it hot-dip galvanised or electroplated? The difference in service life is measured in decades.

Any cut or drilled edge is unprotected steel unless it was treated afterwards.

Handsome and heavy, and it starts rusting from the first chip.

• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Corrosion: Corrosion usually starts at a fixing, a cut edge or a foot, not in the middle of a panel.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.

Oiling or repainting each year

Ask the supplier: What is under the powder coat, and is there a primer or a galvanised layer beneath it?

Rust starts where the coating is broken, which is almost always at the feet.

Beautiful, permanent-feeling, and a repainting commitment forever.

• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.
• Corrosion: Corrosion usually starts at a fixing, a cut edge or a foot, not in the middle of a panel.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.

Oiling or repainting each year

Ask the supplier: How was it finished, and what is the recommended repainting interval here?

Cast iron in freeze-thaw conditions can crack where water sits in a hollow section.

Genuinely weatherproof, and honest about being plastic.

• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: Is it ultraviolet-stabilised, and what does the fade warranty say in years?

Cheap resin embrittles from the inside; it looks fine until it snaps at a joint.

Only as good as the fibre it is woven from, and it hides a steel frame that can rust.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: What is the frame made of, and is the weave HDPE or PVC?

PVC weave goes brittle years before HDPE does, and both look identical when new.

The only seat fabric that is genuinely dry an hour after rain.

• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: What holds the sling to the frame, and can that fixing be replaced when the fabric goes?

Sling fabric usually outlives the stitching and the frame fixings holding it.

The colour is in the fibre rather than on it, which is why these survive sun that ruins everything else.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.

A wash once a year

Ask the supplier: Is the colour solution-dyed through the fibre, and what colour-fastness rating is stated?

Mildew grows on what lands on the fabric, not on the fibre. A shaded acrylic cushion still goes green.

Cheaper than acrylic, and the difference shows up in the third summer rather than the first.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.

A wash once a year · assumes it comes in for the winter

Ask the supplier: Is this solution-dyed or piece-dyed, and does the warranty cover fading or only failure?

The gap between a good and a poor outdoor polyester is wider than the gap between polyester and acrylic.

Beautiful indoors. Outdoors it is a consumable.

• Slow drying: This family holds water, and holding water in a slow-drying spot is what actually destroys outdoor things.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.

Taking in and putting out each season · assumes it comes in for the winter

Ask the supplier: Has this been treated for exterior use, or is it an indoor fabric being sold outdoors?

Treated natural fabrics exist and behave far better. The treatment, not the fibre, is what to ask about.

No splinters and no annual oiling, in exchange for a surface that gets extremely hot.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Salt air: Salt air changes which metals and which grades of metal are viable, not just how often you wash them.

A wash once a year

Ask the supplier: Is it capped, what is the surface temperature rise in direct sun, and what is the expansion gap?

Composite boards move with temperature considerably more than timber, and badly gapped installs buckle.

Convincing at three metres, and it moves more than the fixings expect.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.

A wash once a year

Ask the supplier: What expansion allowance is required per metre, and how are the fixings slotted?

Most composite screen failures are movement failures, not material failures.

Forgiving underfoot and unforgiving in sun: it is the hottest surface most gardens will ever have.

• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.

A wash once a year

Ask the supplier: What surface temperature has this been measured at in full sun, and what is the critical fall height at the depth being quoted?

Impact attenuation and heat are separate specifications. Field research has measured dark wet-pour rubber and synthetic playground surfaces at burn-relevant temperatures in sun, but actual temperature depends on material, colour, climate and shade.

Dimensionally calm, indifferent to sun, and very fond of soaking up whatever lands on it.

• Slow drying: This family holds water, and holding water in a slow-drying spot is what actually destroys outdoor things.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.

A wash once a year

Ask the supplier: Is this sheet specified for direct exterior weather exposure, what edge/cut treatment is required, and what freeze-thaw or wet-service performance does the actual product document?

Exterior fiber-cement sheet performance is product- and installation-specific. The family label cannot establish edge treatment, joint detailing, freeze-thaw durability or warranty conditions.

Comfortable, quick-drying, and it holds dirt in the braid.

• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Ultraviolet breakdown: Fading is cosmetic; degradation is the fibre or the polymer itself giving up.

A wash once a year

Ask the supplier: What is the rope core, and can a strand be re-tensioned or replaced?

The rope usually outlasts the frame's fixing points, which is where these fail.

An indoor material with an outdoor photograph.

• Slow drying: This family holds water, and holding water in a slow-drying spot is what actually destroys outdoor things.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.

Taking in and putting out each season

Ask the supplier: Is this natural fibre or a synthetic rope made to look like one?

Natural rope loses strength invisibly as it weathers, which matters when it is holding a seat.

Cooked rather than treated, so it moves less and rots slower, at the cost of some strength.

• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Slow drying: This family gives water back quickly, which is most of the battle here.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.

Oiling or repainting each year

Ask the supplier: What modification class is it, and what does the warranty actually cover?

Modification classes differ by process and producer far more than the category name suggests.

Silvering is not decay. Most teak that fails outdoors failed at its joints, not its surface.

• Slow drying: This family gives water back quickly, which is most of the battle here.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.

A wash once a year

Ask the supplier: Where is the timber from, and are the joints mortised or held with metal fixings that will corrode?

Behaviour here depends more on grade and joinery than on species.

Naturally durable, dimensionally calm, and softer than people expect.

• Slow drying: This family holds water, and holding water in a slow-drying spot is what actually destroys outdoor things.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.

Oiling or repainting each year

Ask the supplier: Is this heartwood or sapwood? The durability claim only applies to heartwood.

Durability ratings describe the heartwood of mature trees, and much of what is sold is neither.

The workhorse. It lasts because of what is in it, not because of what it is.

• Slow drying: This family holds water, and holding water in a slow-drying spot is what actually destroys outdoor things.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.

Oiling or repainting each year

Ask the supplier: What use category is the treatment rated to, and is it approved for ground contact?

Cut ends lose the treatment. Whether they were sealed on site matters more than the grade.

Fine for a season, and a maintenance project after that.

• Slow drying: This family holds water, and holding water in a slow-drying spot is what actually destroys outdoor things.
• Wetting: Soaked here, things take about 16.6 hours to dry on an average day.
• Mildew and algae: Anything that stays damp grows something, whatever it is made of.
• Ultraviolet: This spot takes about 1.04 MJ per square metre a day of ultraviolet in its harshest month.

Taking in and putting out each season

Ask the supplier: Is there any treatment at all, and what is the intended service life?

Untreated softwood in ground contact can fail in three years, or last fifteen if it stays dry.