Decision library
See the whole decision before you buy the object.
These are worked outdoor-space failures, not inspiration boards. Each case starts with the failure, names the evidence that would change the answer, tests reversible moves first, and keeps structural, drainage, electrical and legal boundaries visible.
Decision flow
The same five gates for every outdoor fix
- Diagnose. Name the failure. Not the product.
- Measure. Collect only what can change the answer.
- Test. Cheapest reversible move first.
- Re-run. Whole verdict, all seasons.
- Commit. Build once it has survived.
Gate four is the one people skip. A pergola that fixes five o'clock in July can close the space in February, and you only find that by running the whole year again rather than the hour you were annoyed about.
Opening the decision catalogue…
What the engine reasons with
The material and plant families behind every recommendation
Families rather than products, on purpose. A product name goes out of date and a family does not, and the question worth taking to a supplier is the same for everything in the group. Nothing here is a recommendation until your own geometry has had a say.
Materials
30 families| Family | Good for | Bad for | Ask the supplier |
|---|---|---|---|
| Solution-dyed acrylic textiletextile · annual-wash maintenance | Cushions and canopies in hard sun, Anything that will not be brought in | Deep shade, where what settles on it grows mildew | Is the colour solution-dyed through the fibre, and what colour-fastness rating is stated? |
| Outdoor polyester textiletextile · annual-wash maintenance | Covered terraces, Things you expect to replace | Unshaded south and west exposure | Is this solution-dyed or piece-dyed, and does the warranty cover fading or only failure? |
| Cotton, linen and untreated natural textiletextile · seasonal-work maintenance | A covered porch you carry things in from, Deliberately temporary summer dressing | Anything left out, Any spot that stays wet | Has this been treated for exterior use, or is it an indoor fabric being sold outdoors? |
| Sling and mesh fabrictextile · annual-wash maintenance | Places that stay wet, Anything that must be usable the morning after rain | Households with cats and dogs, where claws find the weave | What holds the sling to the frame, and can that fixing be replaced when the fabric goes? |
| Teaktimber · annual-wash maintenance | Left out all year, Coastal exposure | Anyone who wants it to stay the colour it arrived | Where is the timber from, and are the joints mortised or held with metal fixings that will corrode? |
| Western red cedar and redwoodtimber · annual-treatment maintenance | Screens, fences and cladding, Anywhere the silvered look is wanted | Ground contact, High-traffic decking that will dent | Is this heartwood or sapwood? The durability claim only applies to heartwood. |
| Thermally modified timbertimber · annual-treatment maintenance | Decking and cladding in wet climates, Places where movement has caused problems before | Anything structural, Ground contact | What modification class is it, and what does the warranty actually cover? |
| Pressure-treated softwoodtimber · annual-treatment maintenance | Structure, posts and ground contact, Anything you will paint or stain | Being left bare and expected to look good, Tables people eat from | What use category is the treatment rated to, and is it approved for ground contact? |
| Untreated softwoodtimber · seasonal-work maintenance | Temporary structures, Things you intend to replace | Ground contact, Anywhere it stays wet | Is there any treatment at all, and what is the intended service life? |
| Powder-coated aluminiummetal · annual-wash maintenance | Coastal sites, Frames that must not rust, Anything that gets moved | Dark finishes in strong sun, where it becomes too hot to touch | Is the powder coat rated to AAMA 2604 or 2605, and is the substrate marine-grade? |
| Stainless steelmetal · annual-wash maintenance | Fixings and fittings that must not fail, Kitchen and service surfaces | Coastal exposure in the wrong grade, Anywhere a hot surface will be touched | Is it 304 or 316? Within a few miles of salt water that difference is the whole decision. |
| Hot-dip galvanised steelmetal · annual-wash maintenance | Structure and posts, Anywhere strength matters more than looks | Coastal exposure, Anywhere cut or drilled on site without re-coating | Is it hot-dip galvanised or electroplated? The difference in service life is measured in decades. |
| Powder-coated mild steelmetal · annual-treatment maintenance | Dry climates, Furniture that stays under cover | Coastal sites, Anywhere it will be knocked or dragged | What is under the powder coat, and is there a primer or a galvanised layer beneath it? |
| Wrought and cast ironmetal · annual-treatment maintenance | Places where weight and permanence are the point | Coastal exposure, Anyone unwilling to repaint | How was it finished, and what is the recommended repainting interval here? |
| Exterior porcelain paverstone masonry · annual-wash maintenance | Freeze-thaw climates, Anywhere staining matters, Dining terraces | Anywhere the slip rating has not been checked | What is the slip classification, wet, and how is it being laid: pedestals, sand or mortar? |
| Dark natural stonestone masonry · annual-wash maintenance | Cool climates, Shaded terraces, Anywhere thermal mass into the evening is wanted | Hot sunny terraces used barefoot, Anywhere a dog lies down | What is the absorption rate, and is it rated for freeze-thaw where you are? |
| Pale natural stone and limestonestone masonry · annual-treatment maintenance | Hot climates, Where barefoot comfort matters | Under a dining table, Under trees that drop fruit or tannin | Is it sealed, and what does resealing involve once it has been down a few years? |
| Poured and precast concretestone masonry · annual-wash maintenance | Large areas, Anywhere a monolithic surface is wanted | Severe freeze-thaw without air entrainment, Anywhere staining is unacceptable | Is the mix air-entrained for freeze-thaw, and what is the plan for control joints? |
| Clay brick pavingstone masonry · annual-wash maintenance | Freeze-thaw climates with a rated paver, Anywhere grip matters | Furniture with narrow feet, which catches every joint | Is this a paving brick rated for your freeze-thaw exposure, or a facing brick? |
| Gravel and self-binding aggregatestone masonry · annual-wash maintenance | Places that must drain, Informal areas and paths | Dining chairs, Wheels and walking aids, Bare feet | What size and shape is the aggregate, and is there an edge to keep it where it belongs? |
| Composite and capped composite deckingcomposite · annual-wash maintenance | Anyone who will not maintain timber, Wet climates | Hot sunny decks used barefoot, Anywhere a dog lies in the sun | Is it capped, what is the surface temperature rise in direct sun, and what is the expansion gap? |
| Wood-plastic composite screeningcomposite · annual-wash maintenance | Screens and fences that must not be maintained | Long unbroken runs in strong sun | What expansion allowance is required per metre, and how are the fixings slotted? |
| HDPE and polypropylene resin furnitureplastic · annual-wash maintenance | Poolside and coastal, Anywhere it will be left out and hosed down | Windy roof terraces, where light furniture leaves | Is it ultraviolet-stabilised, and what does the fade warranty say in years? |
| Synthetic wicker and woven resinplastic · annual-wash maintenance | Covered terraces, Anywhere it will be brought in for winter | Full unshaded exposure, Coastal sites, where the hidden frame goes first | What is the frame made of, and is the weave HDPE or PVC? |
| Natural rattan, jute and untreated roperope weave · seasonal-work maintenance | A covered porch, Somewhere it comes in every night | Anywhere it will be rained on | Is this natural fibre or a synthetic rope made to look like one? |
| Braided outdoor rope seatingrope weave · annual-wash maintenance | Warm climates, Seating that must dry fast | Under trees that drop sap or berries, Cats | What is the rope core, and can a strand be re-tensioned or replaced? |
| Tempered glassglass · annual-wash maintenance | Balustrades where the view is everything, Wind screening without visual loss | Anywhere it will not be cleaned, Coastal sites, where salt etches it | What is the edge detail, and how will it be cleaned on the outside face? |
| Weathering steelmetal · none maintenance | Screens and planters in a climate with real wet and dry cycles, Anywhere the run-off has somewhere to go | Coastal salt air, where the patina never stabilises, Above pale paving, which it stains permanently, Anywhere small children lean on it in shorts | Is this a genuine weathering grade, and what does the datasheet say about wet-dry cycling and about run-off staining? |
| Fibre cement boardcomposite · annual-wash maintenance | Screens and cladding where movement matters more than colour, Shaded elevations that would warp timber | Unsealed edges in ground contact, Anywhere it will be splashed with anything that stains | 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? |
| Bonded rubber safety surfacingcomposite · annual-wash maintenance | Under play equipment where a fall is the risk being managed, Shaded or north-facing play areas | Unshaded play areas in hot climates, where it can burn bare feet, Anywhere a dog lies down in summer | What surface temperature has this been measured at in full sun, and what is the critical fall height at the depth being quoted? |
The last column is the point. A supplier who can answer it is selling you something they understand.
Plants
40 archetypes| Archetype | For | Mature | Years | Where it disappoints |
|---|---|---|---|---|
| Narrow upright evergreen screenevergreen | screening, structure | 3–8 m | 4 | Narrow forms lose their shape if the top is ever cut. Buy the mature height you want. |
| Broad evergreen hedgeevergreen | screening, wildlife | 1.5–4 m | 4 | A hedge kept below its natural width thins at the base, which is exactly where a seated sightline runs. |
| Deciduous hedge that holds its leavesdeciduous | screening, wildlife | 1.5–4 m | 3 | Winter screening is partial. If the problem is a winter sightline, this is not the answer. |
| Medium deciduous shade treedeciduous | shade, structure, wildlife | 7–14 m | 8 | Mature spread is the number that matters, and it is almost always larger than the space allowed. |
| Small ornamental treedeciduous | structure, seasonal colour, wildlife | 3–6 m | 5 | Many small trees resent reflected heat off a wall far more than they resent full sun. |
| Evergreen structural shrubevergreen · takes a container | structure, container | 0.6–2 m | 3 | Clipped evergreens in containers dry out from the root ball in, and the damage shows a season late. |
| Deep-shade foliage plantherbaceous · takes a container | ground cover, structure | 0.3–1.2 m | 2 | True deep shade is under three moles a day. Most plants sold as shade-tolerant want double that. |
| Part-shade perennialherbaceous · takes a container | ground cover, seasonal colour, wildlife | 0.4–1.2 m | 2 | These fail from dryness under a wall or a tree far more often than they fail from shade. |
| Full-sun perennialherbaceous · takes a container | seasonal colour, wildlife | 0.5–1.5 m | 2 | Below about eighteen moles a day these get leggy and flop, which reads as bad soil but is not. |
| Mediterranean sub-shrubevergreen · takes a container | structure, edible, container | 0.4–1.2 m | 2 | Wet feet in winter kills these more reliably than cold does. Drainage, not hardiness, is the question. |
| High-heat container herbannual · takes a container | edible, container | 0.2–0.8 m | 0 | A container against a sunlit wall can run twenty degrees above air temperature. That is a watering problem, not a light problem. |
| Shade-tolerant container herbherbaceous · takes a container | edible, container | 0.2–0.6 m | 0 | Below about eight moles a day these survive without ever being worth picking. |
| Fruiting vegetableannual · takes a container | edible, container | 0.5–2 m | 0 | Leaves grow at fifteen moles a day; fruit needs more than twenty. That gap is why people get plants and no crop. |
| Leafy salad cropannual · takes a container | edible, container | 0.15–0.4 m | 0 | In high heat these bolt. A spot that is too shady for tomatoes is often exactly right for these. |
| Wind-tolerant ornamental grassgrass · takes a container | structure, seasonal colour, container | 0.6–2 m | 2 | Grasses in containers on a windy terrace dry out faster than anything else on the plot. |
| Salt-tolerant coastal shrubevergreen | screening, structure, wildlife | 1–3 m | 3 | Salt tolerance is specific. A plant that shrugs off wind inland can still burn in a coastal gale. |
| Moisture-loving marginalherbaceous | structure, wildlife | 0.5–2 m | 2 | These want consistent moisture, not stagnant water. Standing water still needs solving. |
| Dry-shade ground coverevergreen | ground cover | 0.15–0.5 m | 3 | Everything struggles here for the first two years. Water through the establishment period or nothing works. |
| Evergreen climber on a supportclimber · takes a container | screening, structure | 2–6 m | 3 | The support carries the load, and most trellis sold for this is not fixed well enough to hold a wet mature climber. |
| Deciduous climber for seasonal shadeclimber · takes a container | shade, seasonal colour | 3–8 m | 3 | Wisteria in particular puts real load on a structure. Build for it before planting it. |
| Pollinator mix in full sunherbaceous | wildlife, seasonal colour | 0.3–1.2 m | 2 | Meadow mixes fail on rich soil and in part shade. Both are more common in gardens than people expect. |
| Fern for cool damp shadeherbaceous · takes a container | ground cover, structure | 0.3–1.2 m | 3 | Ferns burn in reflected heat off a pale wall even in a spot with very little direct sun. |
| Succulent and sedum groupevergreen · takes a container | ground cover, container | 0.05–0.4 m | 1 | Winter wet is the killer, not winter cold. In a wet climate these need overhead cover as much as drainage. |
| Espaliered fruit on a warm walldeciduous | edible, structure | 1.8–3 m | 4 | This needs pruning twice a year, forever. Skipped for two seasons it becomes a shrub against a wall. |
| Contained clumping bambooevergreen · takes a container | screening, container | 2–6 m | 3 | Only clumping species, and only with a root barrier. Running bamboo in a small garden is a decade-long regret. |
| Mixed native hedgedeciduous | screening, wildlife | 1.5–4 m | 4 | Mixed hedges take four years to be a screen and want cutting once a year to stay one. |
| Container specimen with clipped formevergreen · takes a container | structure, container | 0.6–2 m | 3 | Container specimens die from missed watering in a heat spell, which is a scheduling problem more than a plant one. |
| Seasonal container displayannual · takes a container | seasonal colour, container | 0.2–0.8 m | 0 | Daily watering in summer. If nobody will do that, this is a plan to buy plants and kill them. |
| Large evergreen screening shrubevergreen | screening, structure | 2.5–5 m | 3 | These reach the height quickly and then keep going. Plan the maintenance, not just the planting. |
| Shade-tolerant lawn or alternativegrass | ground cover | 0.05–0.1 m | 1 | Below about twelve moles a day, no grass mix holds. That is when a different ground cover is the answer, not more seed. |
| Alpine and scree plantsherbaceous · takes a container | ground cover, container, seasonal colour | 0.05–0.3 m | 2 | Almost nothing here is about temperature. Winter wet at the crown is what finishes them, so drainage beats hardiness every time. |
| Woodland spring ephemeralsherbaceous | ground cover, seasonal colour, wildlife | 0.1–0.4 m | 3 | A summer light reading tells you nothing about these. What matters is March and April, before the leaves are on. |
| Evergreen ground cover for shadeevergreen | ground cover, structure | 0.1–0.5 m | 3 | Slow to knit. Two seasons of weeding before it covers, and people give up in the first. |
| Rain garden and swale plantingherbaceous | ground cover, wildlife, seasonal colour | 0.4–1.5 m | 2 | The cycle is the point. Anything that only tolerates constant wet dies in the August between floods. |
| Prairie and steppe perennial matrixherbaceous | ground cover, wildlife, seasonal colour | 0.4–1.6 m | 3 | Rich soil and shade both make it flop. It is a group that is ruined by kindness. |
| Large-leaved subtropical foliageevergreen · takes a container | structure, container | 1.5–4 m | 3 | Wind tolerance near zero is not a detail. A single exposed afternoon turns the leaves to ribbons for the season. |
| Citrus in a containerevergreen · takes a container | edible, container, structure | 1–2.5 m | 3 | It is the winter that costs. Somewhere bright, frost-free and unheated is a harder brief than the summer position. |
| Soft fruit canesdeciduous | edible, wildlife | 1.2–2.2 m | 2 | Airflow matters more than the last few moles of light. A still corner gives mildew every year whatever else is right. |
| Sedum and extensive green-roof mattingevergreen · takes a container | ground cover | 0.05–0.15 m | 2 | It fails in shade, not in drought. Under an overhang or a parapet shadow it thins out and the substrate takes over. |
| Shade-tolerant screening shrubevergreen | screening, structure | 1.8–3.5 m | 4 | Everything that screens well in shade grows slowly in shade. Buy it closer to the size you want than you would in sun. |
Mature size is the size it becomes, not the size it is sold at, and the years column is how long you wait for the job it was planted to do. Both are the numbers people find out afterwards.
Use the library with the engine
The library teaches what deserves testing. The property model supplies the geometry, exposure and operating window. A scenario or matrix never changes a verdict by itself.