Aluminium Windows and Doors for South African Homes

Two quotes for the same window opening can differ by half, and both sellers will tell you they’re using aluminium. Aluminium windows prices are quoted per opening rather than per square metre of house, so the only fair comparison is line by line. The gap is in the profile system, the glass, the hardware and the seals, and none of it is visible in a photo of a finished house.

We install aluminium windows and doors alongside our awning and shade work across Gauteng and KwaZulu-Natal, and this is what we explain to clients before they compare prices.

Why aluminium took over from steel and timber

Steel windows rust and need painting, and in coastal KZN they rust from the inside out where you can’t see it. Timber windows look good until the first rainy season finds a bad seal, after which they swell, stick and need maintenance every few years. Aluminium doesn’t absorb water, doesn’t rust, and holds a powder-coated finish for a long time with almost no attention.

It’s also strong for its weight, which allows bigger openings and wider glass panels without a heavy frame. That’s the reason sliding doors got so big in South African homes: aluminium is what made a four-panel opening to a patio normal rather than a structural drama. Aluminium sliding doors are the default patio door here now, and because aluminium doors in South Africa use the same profile ranges as the windows, a house specified from one range looks coherent inside and out.

The trade-off is heat conduction. Aluminium conducts temperature, so a poorly specified window becomes a cold bridge in winter. That’s what thermal breaks are for in colder regions, and it’s a spec conversation rather than a reason to avoid the material.

What you’re actually buying

The profile system. The wall thickness of the extrusion and the design of the chambers inside it decide how strong the frame is and how well it drains. Cheap profiles look the same on the shelf and dent, twist or leak within a few years. Ask which system is being quoted and compare like with like.

The glass. Single glazing is standard and fine for most of the country. Laminated glass holds together when broken, which matters for security and for large panels. Toughened glass is stronger but shatters into small pieces when it fails. Double glazing helps with heat and noise, and it’s worth it on a west-facing bedroom or a house on a busy road.

The hardware. Hinges, handles, friction stays, rollers and locks are where cheap installations give themselves away. A good frame with poor rollers means a heavy door you fight for years. Stainless hardware is the difference between a coastal installation that lasts and one that needs replacing.

The seals and drainage. Rubber gaskets, brush seals and weatherstripping stop water and dust. Weep holes and drainage slots let water out that gets in anyway. Missing or blocked drainage is the most common cause of a window that “leaks” while the glass is perfectly sealed.

The finish. Powder coating gives the widest colour choice and a finish that resists chipping. Anodising is more resistant to salt and abrasion but limits you to a few metallic tones. In coastal areas the coating grade matters more than the colour.

Window and door types and where each one belongs

Type	Best used for	Airflow	Watch out for
Sliding window	Living areas, wide openings	Half the opening only	Roller and track wear
Casement or side-hung	Bedrooms, kitchens	Full opening when pushed out	Wind catch and hinge load
Top-hung or awning window	Bathrooms, above furniture	Ventilation with rain cover	Limited clear opening
Tilt and turn	Where space is tight	Two modes from one sash	More hardware to service
Sliding or stacker door	Patio and garden access	Large clear opening	Track needs cleaning
Folding door	Entertainment areas	Almost fully open	Needs a track and clear space

Coastal KwaZulu-Natal versus the Highveld

On the coast, from Umhlanga and Ballito down to the Bluff and Amanzimtoti, salt is the deciding factor. It attacks fixings, handles and any bare metal edge, and it gets into drainage slots and stays there. Stainless hardware, a coating rated for coastal exposure, and a habit of rinsing the frames a few times a year will keep aluminium frames looking new for a long time.

Inland, the issues are UV and temperature swing. Powder coat fades in hard Gauteng sun, and black frames on a west-facing wall get properly hot, which puts thermal expansion into the seals and gaskets. In the hail belt, laminated glass on large panels is worth considering, and so is window protection if a west wall is exposed.

Dust is the other Highveld problem. Aluminium sliding tracks collect fine dust and grit, and a door that slides beautifully in January starts grinding by September if the track never gets cleaned. A brush seal and a periodic vacuum of the track solve almost all of it.

Glass, heat and where the sun hits

Glass specification matters most on the north and west elevations. West windows take the full afternoon sun load, which is where a shading solution does more work than a glass upgrade ever will.

Consider the combination rather than the individual products. A west-facing room with a big aluminium window needs something over the glass or over the patio outside it. An external solution, such as an awning or a roll-down blind, stops the heat before it reaches the glass, and it works far better than a blind mounted inside the window. If the opening above the window is solid, there’s usually a way to fit an external system; if it isn’t, internal blinds are the fallback.

Shading also cuts glare on the screens people work from all day, which is a practical reason many clients in Johannesburg and Durban North add external shading at the same time as replacing windows.

Installation: what the process actually involves

Every job starts with a measurement visit, and it’s a mistake to skip it. Openings in older houses are rarely square. Plaster thickness varies, some walls are out of level by more than you’d expect, and a frame has to be ordered to the real opening, not the dimension on a plan drawn decades ago.

Manufacture follows, usually on a lead time you should confirm in writing. Then removal of the old frames. On steel windows this can be messy: the frame may be set into the plaster and brickwork, and making good afterwards is part of the job, not an extra nobody discussed.

Installation is fixed, sealed, and squared, with drainage left clear and the frame anchored to the structure. Finally the making good, which is where the finish quality shows. What you should ask before ordering is whether plastering and painting around the new frames is included, because that’s the part most quotes leave out.

Retrofits and older South African homes

Older Johannesburg and Pretoria houses often have steel windows set into face brick, and older Durban homes frequently have timber frames softened by humidity. Both can be replaced with aluminium, and both involve slightly different work. Steel frames need careful cutting out, and timber frames sometimes reveal rot in the reveal that has to be treated before a new frame goes in.

Where an extension is being built, ordering aluminium windows and doors at frame stage lets the builder set the openings to suit, which is cheaper than cutting brick later. And it’s worth checking building regulation requirements around glazing at that point, since compliance certificates for glazing are commonly requested during plan approval and sign-off.

Replacing a patio door is a good moment to look at the shading on that opening too. A large sliding door facing west is the single biggest heat gain in most homes, and pairing the new door with external shade keeps the room usable in summer.

Mistakes we see on quotes

Comparing total prices without comparing what’s on the frame: profile series, glass type, hardware brand, and whether installation and making good are included.

Ignoring which way the door slides. A sliding door that stacks on the wrong side blocks the wall where the braai or the plug point is, and it’s fixed once it’s manufactured.

Choosing black profiles on a west elevation for looks, then discovering the frame is uncomfortably hot to touch and the seals age faster.

Skipping the weep holes or letting the installer seal them shut with silicone. Water then has nowhere to go, and the first complaint is a leak that isn’t a leak.

And leaving drainage and paving to be sorted after installation, when the door needs a finished level to open onto.

We supply and install aluminium windows and doors as part of the same range as our awnings and shade structures, which means we can sort the frame and the shading over it in one visit rather than two trades blaming each other. Ask Forever Awnings for a site measure.

Frequently asked questions

What changes the price of aluminium windows and doors?

The profile system and its wall thickness set much of the cost, followed by the glass specification. A large opening with laminated or double glazing costs far more than the same area in single-glazed small windows. Hardware quality, coastal or anodised finishes, and the size and number of panels all move the number. Installation, removal of old frames and making good the plaster are separate line items worth checking, because some quotes silently exclude them.

Do aluminium windows work on the KZN coast?

They’re the material of choice on the coast, provided the hardware is stainless and the finish suits salt exposure. Aluminium itself doesn’t rust, but cheap fixings and handles do, and once corrosion starts at a fixing the frame’s weather sealing suffers. Rinsing the frames a few times a year keeps the salt from building up in drainage slots and tracks.

How long does installation take?

Manufacture usually takes longer than installation, so ask for a lead time in writing before you commit. Fitting itself is quick for a straightforward replacement window. A whole-house retrofit, or replacing steel frames set into brickwork, takes longer because removal, making good and drying times all have to be worked into the schedule. Weather matters when openings are left exposed at night.

Should I choose laminated or toughened glass?

Laminated glass holds together in the frame when it breaks, which is why it’s common on larger panels, low-level glazing and doors. Toughened glass is stronger in everyday use and fails into small blunt pieces, but it can’t be cut or drilled afterwards. On large west-facing panels in the hail belt, laminated is usually the better of the two answers.

Written by the team at Forever Awnings. We’ve supplied and installed aluminium windows, doors, awnings and shade structures across Gauteng and KwaZulu-Natal for more than two decades, and we quote the whole job, including the parts other people leave out.