Sandhurst BlindsJohannesburg
A Sandhurst house on its north-west slope in late afternoon, a wide sunscreen roller blind half lowered across the double-volume glazing while the garden and the distant ridge stay visible through the weave

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The Sandhurst Slope & Sightline Papers

A field study of the light on a north-west facing suburb: where the sun goes through the year, what it does to each elevation, and what we would fit where — with the honest catch beside every recommendation.

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  • Written for this slope, every figure sourced at the foot
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  • Child-safe controls as standard

Where to start

A suburb built to face its view — and the view faces the afternoon

Sandhurst sits on a north-western slope, which is why the houses here look the way they do: living wings, terraces and pools turned outward, toward the city and the far line of the Magaliesberg. A lovely arrangement, carrying one consequence nobody puts in the brochure — on this slope the view and the hot half of the day occupy the same quarter of the compass. The glass that was built to hold the view is, hour for hour, the glass carrying the load.

The second thing worth knowing is that there is no single Sandhurst house. Most of the suburb went up between 1940 and 1970 — steel-framed windows set deep in the wall, generous eaves, rooms built by people who did not expect to air-condition them. Alongside those, often on the same street, stand the rebuilds: frameless glass, double-volume voids, four-metre sliders with nothing above them at all. Those two houses want opposite specifications, and the older one usually needs less than its owner assumes.

So the useful unit here is not the house. It is the window, its aspect, and whatever is already standing above it.

The light here

Twenty-six degrees south, seventeen hundred metres up

Sandhurst has no weather station of its own. Every figure below is Johannesburg's, and every one of them is sourced at the foot of this page.

Solar noon sits due north — about 86° up in December, about 40° in June N E W S The afternoon arc Sunset swings 243° in December → 295° in June 52° of low sun raking the western half The morning arc Sunrise swings 118° → 69° Cool air: glare rather than heat On a north-west slope the view wall and the hot wall tend to be the same wall.
  • Afternoon sun, December to June
  • Morning sun
  • The main glazing, turned north-west

  1. Almost overhead in December, low and due north in June

    At the December solstice the midday sun stands about 86° above the horizon, within four degrees of vertical; in June it drops to about 40°, due north, and stays there through the middle of the day. One window, two entirely different problems, six months apart.

  2. The afternoon sun rakes a 52° arc

    Summer sunset falls on a bearing of about 243°, twenty-seven degrees south of due west; winter sunset is about 295°, twenty-five degrees north of it. The setting sun sweeps that 52° arc through the whole western half of the house — and by then it is low. No eave, no slab and no overhang stops a ray arriving almost horizontally.

  3. Mornings are the mild half of the day

    Midsummer sunrise is on a bearing of about 118°; in June it swings to 69°. East glass takes hours of low sun, but the air and the building fabric are still cool, so an east room is a glare-and-waking problem rather than a heat one. A study of Highveld sun paths says it plainly: the afternoons run far hotter than the mornings.

  4. Storms and hail arrive in the same hour as the heat

    October to April brings hot days followed by afternoon thundershowers; May to September, dry sunny days and cold nights. January averages a daily maximum of 25.6 °C and roughly 713 mm of rain falls in a year. A satellite catalogue of fourteen years of convective storms found South African hail concentrated along the Highveld, most frequent from mid-November through February and clustered in the afternoon — the same hour the west glass is at its worst and, on a working day, the same hour the house is empty. Anything mounted outside the glass has to be able to get itself in without you.

  5. Altitude buys you extra ultraviolet

    The city sits at about 1,753 m, and the World Health Organization puts the effect simply: UV rises roughly 10 per cent for every 1,000 m of altitude. That is a fading argument, not a health one — it takes the colour out of a rug, a timber floor, a sofa arm, and eventually out of the blind itself.

External aluminium venetian blinds mounted outside the glazing of a modern steel-and-glass Sandhurst house, wide slats tilted against the low afternoon sun

A low sun is a sideways problem.

A blind that only travels up and down has one answer to a three-o'clock sun: cover the window and lose the room. Something that tilts, or that stands outside the glass, has a better one.

Elevation by elevation

Five different problems, and one of them is not a wall

Walk the house once with the compass on your phone, at about four o'clock in February. On this slope, aspect changes the answer more than what the room is used for.

  1. North — solve it with geometry before you spend

    At 86° the December noon sun barely reaches into a north room; at 40° in June it reaches several metres. That is why an eave, a first-floor slab or a deep veranda does so much work here — and why blacking a north wall out permanently throws away the best free heating in the house. Check what the building already does before buying anything for it.

  2. West and north-west — where the money belongs

    This is the view side, and the 52° arc lands squarely on it. Low sun arrives under the eave, so overhead projections do very little. If there is one elevation in a Sandhurst house worth spending properly on, it is this one — and the answer usually sits outside the glass rather than behind it.

  3. East — the same geometry, half the penalty

    An east room takes the mirror image, early, while the air is still cool. Glare on a screen and waking at first light matter more here than heat. Bedrooms are a blockout conversation; a breakfast room usually is not, because there the sun is the entire point.

  4. South — the quiet side

    Because midsummer sunrise and sunset both sit south of the east–west line, a south wall catches a slice of low sun early and late in December and almost none in winter — the flattest-lit, coolest rooms in the house. Sometimes the honest recommendation for a south window is to spend nothing on it.

  5. The double-volume void — its own elevation

    A void is not a tall window; it behaves like a chimney. Heat gathers at the top, the glass up there is unreachable, and a blind nobody can operate stays in one position for a decade. Anything above about three metres is a motor conversation before it is a fabric one.

What we would fit, and why

The reasoning — and the honest catch with each

Nothing here is right everywhere, and each one costs you something — so the catch is written beside it. Press Add to my window list and it carries down to the form at the foot of this page.

Sunscreen & blockout roller blinds

Best on: view-side living rooms · bedrooms

Why here. A 3–5% openness sunscreen cuts glare and much of the ultraviolet while the lawn, the trees and the far ridge stay visible through it. Blockout does the opposite job on one flat sheet — no folds, no slats, just darkness where people sleep.

The catch. Sunscreen reverses after dark, so a view-facing bedroom usually wants both fabrics on one bracket. And blockout is only as dark as its edges: inside a reveal, a light line down each side unless side channels are specified.

Day & night blinds

Best on: street-side rooms · guest suites

Why here. Alternating sheer and solid bands slide past each other, so one blind goes from open view to eye-level privacy without being raised.

The catch. Never a true blockout, and the banding is a strong horizontal pattern — often the wrong texture against 1960s joinery. Hold a sample up in the room first.

Timber venetian blind in a mid-century Sandhurst living room, its horizontal wooden slats tilted so stripes of low afternoon sun fall across the parquet floor

Venetian blinds, timber or aluminium

Best on: studies and older steel-framed rooms · aluminium in kitchens and bathrooms

Why here. Low afternoon sun is a sideways problem and a tilting slat answers it sideways: close the angle and the beam stops while the room stays bright and the window stays open. A roller has one move; a slat has two. Timber also sits comfortably with the steel frames and parquet of the older houses.

The catch. It stacks deeper than a roller, eating more glass when raised — noticeable on a short window. Timber dislikes steam, so wet rooms get aluminium. And every slat collects Highveld dust.

Cellular honeycomb blinds

Best on: gables, skylights, single glazing you will not replace

Why here. The fabric folds into hexagonal cells holding still air against the glass. Against original single panes under a high ceiling, that trapped air is the least invasive comfort upgrade going — the window itself is untouched.

The catch. Wrong side of the glass for summer heat. Against a hard west sun an external product beats it outright, because a cellular blind only slows heat already through the pane.

Vertical & panel blinds

Best on: four-metre sliders and glass-walled rooms

Why here. Rotating vanes or wide gliding panels cover a very wide opening edge to edge and stack clear of the glass, so the door still works.

The catch. Vanes swing in the draught through an open slider, and a panel blind needs wall to stack onto. Where a living wing runs to a corner there is none — and one wide roller is the better answer.

A blockout roller blind dropping from a slim recessed slot in the ceiling of a double-volume Sandhurst window bay, one flat sheet with no visible hardware, garden beyond the lower glazing

Concealed blind boxes

Best on: renovations and new work, before the ceiling closes

Why here. Fabric drops from a slot in the ceiling and the hardware disappears. On the frameless glass of the newer Sandhurst houses it is usually the only detail that does not argue with the architecture.

The catch. It is decided at drawing stage. Retrofitting means a slim surface cassette — no longer invisible — or opening a ceiling. If a renovation is coming, have this conversation early.

Wide aluminium external venetian slats outside a contemporary facade at dusk, throwing shadow bands across the glazing

External venetian blinds & roller shutters

Best on: the hard west and north-west glass, and anything with no overhang

Why here. Both stop the sun outside the glass, and that is not a small difference. The US Department of Energy's guidance is blunt: exterior attachments block sunlight before it passes through the window and are typically more effective at reducing solar heat gain. An interior blockout kills glare instantly, but the pane behind it still heats and radiates into the evening. External venetians tilt, so the view survives them; roller shutters close right down into a compact headbox.

The catch. In relative terms, the dearest answers here. They need a wind strategy through hail season, they nearly always want a motor, and — the specifically Sandhurst part — they alter the outside of a building. Read the next chapter first.

Shading, not security. Our roller shutters are specified for sun, heat, glare and daytime privacy on the outside of the glass. They are not security-rated shutters — that is a different product, quoted on request.

A folding-arm awning extended over a paved Sandhurst terrace on articulated arms with no posts on the paving, a Highveld thunderstorm building over the garden behind it

Folding-arm awnings & zip screens

Best on: the terrace, the pool side, a covered patio

Why here. An awning shades a terrace with nothing standing in the middle of it — which is why it beats a fixed structure where you still want the June sun back. A zip screen does a different job: mesh under tension in side channels, holding its shape in wind while you still see the garden.

The catch. This is the Highveld from October to March. Wind and hail ratings are engineering limits, not marketing, and an awning caught open in a November storm does not survive it. On an exposed elevation we would rather quote a motor and wind sensor than a cheaper manual awning.

Motorisation & automation

Best on: double-volume glass, long west runs, everything outdoors

Why here. A four-metre blind nobody can reach stays in one position for years. One keypad, remote or app runs a whole elevation — on a schedule, or on a sun sensor that manages the west glass while the house is empty. It also removes cords entirely, the safest answer in a child's room.

The catch. Motors need power, and a cable route that does not chase a wall or open a ceiling is a real question in a 1950s house. Battery motors trade that for a charging routine somebody has to remember.

Not sure which of these is yours?

Best on: most houses, honestly

Why here. Plenty of windows in any house need nothing at all, and the difficulty is telling which. That judgement gets made standing in the room at the hour that hurts — which is what the free measure is for.

The catch. None, beyond an hour of your time.

Optional

Want these Papers marked up for your own house?

Tell us which rooms or elevations are the problem and we will send this back with notes against your actual aspects — what we would start with, and what we would leave alone. No visit involved, no obligation.

We use these details only to send you the marked-up Papers and, if you ask for it, to arrange a consultation call-back (POPIA). No marketing lists, and never shared with a third party.

Before anything goes on the outside

Age, booms and the rules that live outside your glass

Most of Sandhurst was built between 1940 and 1970, which puts a good share of the original houses either side of a line that matters. Section 34(1) of the National Heritage Resources Act 25 of 1999 says no person may alter or demolish any structure, or part of a structure, older than sixty years without a permit from the relevant provincial heritage resources authority — and the protection is triggered by age alone, whether or not a building appears on any register. Some Sandhurst houses are over that line and some are not; it is an address-by-address question.

That draws a clean line through everything above. A blind fitted inside a room changes neither the structure nor how the house reads from the street. Anything mounted outside — external venetians, roller shutters, an awning cassette bolted to a wall, face-fixed guide channels — is an exterior alteration. We fit blinds; we are not heritage practitioners, so we will not tell you what the answer is for your address. We raise it at the measure and design the interior specification so you have a good option either way.

Where a home is in a cluster or an apartment scheme, a second rulebook applies: under the prescribed conduct rules of the Sectional Titles Schemes Management Act, the trustees' written consent is needed before an owner changes the external appearance of a section or drills into common property. Better asked before an order than after.

One last Sandhurst note, and it is logistics rather than law. This was effectively Sandton's pioneering suburb for road closure, and its closed roads generally belong to the properties adjoining them — so a boom, a guardhouse and a long driveway change how a delivery of four-metre tubes gets planned. Tell us at the measure and we plan around it.

The honest limit of any guide

Five things only a tape measure at the window can settle

Everything above narrows the field. These five decide it — and all five are exactly what the free measure is for.

  1. True reveal depth, and whether the opening is square

    Depth decides whether an inside mount is possible at all, which decides how much light escapes past a blockout. Sixty-year-old masonry settles and reveals vary wall to wall inside one room, so every opening gets measured in three places.

  2. What the frame is made of, and what it will carry

    Original steel casements, timber, modern aluminium and frameless glass each take a fixing differently, and some take none at all — in which case we mount to the surrounding masonry. A decision made with a hand on the frame.

  3. How exposed that elevation really is

    Anything external lives or dies on wind exposure through hail season. A terrace tucked behind a wing and one thrown open to the west down the slope are different specifications — sometimes different products entirely.

  4. Where the power for a motor can actually go

    Motorising a double-volume run is simple in principle and fiddly in practice: the cable has to arrive without chasing a wall or opening a ceiling. Sometimes a roof void solves it, sometimes a bulkhead, sometimes a battery motor.

  5. What the eaves, the trees and the wall are already doing

    A fair share of the shade on this slope is already free. Knowing which windows need nothing at all is worth as much as knowing which do — a judgement made standing in the room at four o'clock in February, not read off a plan.

Two ways forward

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Both start on the one short form below.

Recommended

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Open the window list

The close

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One short form. Want a budget range too? Add rough window sizes underneath — entirely optional, and nobody will chase you for it.

What you are interested in (anything you added above is already ticked)
Optional: add rough window sizes for a budget range

Rough really is fine — a tape across the outside of the frame is enough, and we will send a budget range by the next working day. If measuring is not your idea of a Saturday, skip this entirely: the free measure gives you exact per-window pricing anyway.

Your window list — room, width, drop, mount and product for each window
Room Width (mm) Drop (mm) Inside or outside the reveal Product Remove

Nothing on the list yet — and that is completely fine.

Your details are used only to arrange this consultation call-back and, if you have added sizes, to send your budget range. They are never shared with any third party (POPIA).

Sources

Where the numbers on this page come from

Every sun-path, climate, suburb and legal figure above is taken from the following. Sandhurst has no weather station of its own, so all climate figures are Johannesburg-wide and the solar angles are calculated for Johannesburg. Where something could not be verified, we left it out rather than round it into a sentence.

Two honest caveats. The 46%/14% research quoted by the US Department of Energy is for insect screens, not for any product we fit — we cite it for direction and scale, and publish no performance figure of our own. And the road-closure and area descriptions above come from property professionals writing about the suburb, not from a municipal register; we treat them as local context, never as a rule about your address.

Reading this from a neighbouring window? The same reasoning applies across Hyde Park, Atholl, Illovo, Dunkeld and Inanda — it is the housing stock and the exposure that change.