Aluminium, uPVC or timber: choosing the right windows
Window planning for South Africa
Comparing materials is rarely the first decision, although it is often treated that way when searching for windows. Replacing windows also involves planning facade views, opening directions, everyday ventilation, wall junctions and how rooms work together. Aluminium, uPVC and timber can each perform well when the frame, glazing, hardware and installation suit the building. The useful question is therefore not which material is universally best, but which priorities apply to this home, facade orientation and opening type. A townhouse with regular window lines, an older home with distinctive divisions and a new build with broad garden access each call for different choices. This guide helps you organise requirements, request quotations on a consistent basis and select frame material as part of the complete window project.
Start with the room brief, not the frame
A sound material choice begins with a window schedule. For each opening, record the room, approximate dimensions, facade orientation, preferred opening method and special conditions such as sloping roofs, deep reveals or floor-to-ceiling glazing. Add everyday use: is the room aired briefly in the morning, is a desk placed in front of the window, must the sash be easy to clean from inside, or is the opening regularly used as a passage? Also note where privacy, solar shading or a clear sill matters. This assessment separates essential functions from simple preferences. It also shows where repeated window types make sense and where an exceptional situation needs its own solution.
Then consider windows and doors as one connected building envelope. A fixed glazed panel beside an opening sash, a patio door and upper-floor windows should relate visually, but they do not serve the same purpose. For a bright area with no ventilation need, a fixed glazed window may be an appropriate category; material, glass build-up, frame sightline and junction must then be specified separately. In your schedule, mark function, proportion and operation first. Assign possible materials only in the second step. This avoids an early frame choice unnecessarily limiting later opening preferences, facade rhythm or furnishing. It also creates a clear basis for discussions with the supplier, design professional and installation contractor.
uPVC: choose pragmatically and specify details carefully
uPVC windows are often considered where an easy-care surface, a consistent appearance and an economically transparent overall plan are priorities. They can create a calm result across many regularly arranged openings. That does not mean every uPVC window looks alike. Visible frame widths, colour, surface texture, sash divisions, glazing bars and handles all strongly affect the result. Do not assess only a small colour sample. Review a drawing of the full unit and check its relationship with plaster, face brick, window sills and interior finishes. The internal and external faces may have different design requirements.
Do not compare quotations merely by the term “uPVC”; compare the complete construction described. Ask about sightline widths, possible unit sizes, opening limitations, drainage, colour on both sides and care instructions for the selected finish. In existing buildings, reveal depth, frame overlap and the appearance from the street or garden also matter. A single inward-opening window initially describes the opening direction and number of sashes, not a material or a particular performance level. Use such categories to clarify function, then request a written specification. Also check whether all regularly repeated windows will genuinely receive the same details. Small differences in handle height, divisions or frame sightlines quickly stand out on an ordered facade.
Aluminium: crisp design needs specific system planning
Aluminium can be the right direction where linear facades, large openings or a reduced frame appearance shape the design. Profile proportions are especially visible at entrances, wide glazed areas and transitions to the patio. Yet material alone does not establish a particular slimness or possible size. Both depend on the construction actually offered. Request dimensioned elevation drawings rather than perspective images alone. Ask to see how opening sashes, fixed lights, mullions and thresholds work together. A profile that appears understated as a single sample may become much more prominent across several divisions.
For a wide garden opening, decide the movement type before selecting material. A Patio Life lift-and-slide door is, for example, a possible product category for this transition; dimensions, material, threshold, glazing and hardware still need project-specific definition. Draw the open position on the floor plan and check handle placement, circulation routes, furniture and the connection to the outdoor area. Include neighbouring windows in the same elevation. Aluminium is then chosen not as an isolated accent, but as part of a coherent facade arrangement. Also consider the desired interior finish: a highly technical external appearance does not automatically create the right atmosphere for living rooms, bedrooms or workspaces.
Timber: treat finish and maintenance as planning tasks
Timber windows bring a visible, tactile material quality to interiors and facades. They suit homes where natural surfaces, traditional divisions or a warm internal appearance define the building. Timber can work equally well in contemporary architecture; profile, colour concept and window division are decisive. Do not treat the finish as an afterthought. Tone, opacity, visible grain and coordination with doors, floors, roof overhangs or facade surfaces belong in the sampling process. Compare samples in the light in which they will mainly be seen, and consider the inside and outside separately.
Maintenance needs cannot be described by one general figure. Weather exposure, building protection, coating, shading and use all interact. Request care and inspection guidance for the exact version selected, and establish which areas will remain accessible later. During sampling, look particularly at lower frame zones, junctions and surfaces exposed outdoors. For a facade with deliberately classic divisions, an historic-style outward-opening combination casement window can serve as a design reference. Whether this opening type, division and character suit the project should nevertheless be decided from a complete elevation. A historic impression does not arise from material alone, but from proportions, glazing-bar pattern, installation position and its relationship to other building elements.
Facade views reveal differences early
Material is experienced up close, while window divisions are seen mainly from a distance. Draw or photograph every facade and add window axes, sill heights, sash divisions and door openings. Check whether comparable rooms receive similar windows and whether a special format appears as an intended focal point or an accidental outlier. In a renovation, a straight-on photograph of the existing facade can help, with new divisions added at an approximate scale. Compare at least one calm option with a more subdivided one. This often makes material discussions more objective: sometimes the concern is not the material, but an unsuitable frame width or division.
Glazing bars need a clearly described role. Decorative bars and bars that divide the glass create different views and affect cleaning and glazing layout differently. State in the enquiry whether bars are wanted, how they should be arranged and whether all facade sides should be treated alike. Round, semicircular or angled openings also need an early drawing. A triangular or angled fixed-glazed window illustrates that special geometry and ventilation can be planned separately. Decide whether the distinctive outline should matter inside, outside or from both directions. The material choice should support this geometry without unintentionally dominating the wider facade or making neighbouring standard windows look like later additions.
Assess opening type and frame material together
A window is not only viewed; it is opened, used for ventilation and cleaned. Inward-opening sashes need clear space in front of the window, while outward-opening units must be coordinated with outdoor paths, planting and shading. Casement, tilt, pivot and reversible functions create different operating routines. Establish who will use the window, how often it will be opened and whether cleaning can be arranged safely and practically. A bathroom window may have different priorities from a large living-room window, even if both are to have the same colour. Handle height, window sills and curtains also belong in this assessment.
For wider openings, a double-sash unit can make sense where ventilation, views and cleaning benefit. A double inward-opening window is an example of this opening logic, but does not determine material or glazing. Have the opening area of both sashes shown on the floor plan. Check whether radiators, fittings, deep sills, furniture or planned insect screens obstruct operation. Also ask whether one sash will normally be enough and how the second sash is opened. Only once these routines work should aluminium, uPVC or timber be compared for that location. Otherwise, an attractive frame may be selected whose operation later proves impractical.
Compare technical data only on equal terms
Thermal performance, acoustic control, airtightness, solar gain and security hardware are characteristics of the planned unit and its installation, not blanket qualities of aluminium, uPVC or timber. A useful quotation comparison therefore needs matching starting data: identical opening sizes, sash divisions, glazing assumptions, operating types and installation conditions. Ask for data for the actual unit offered and what each value refers to. A small standard window, a wide moving sash and a multiply divided unit must not be placed side by side without context. Record differences in a separate comparison column rather than comparing only final prices.
Where the building has demanding energy objectives, windows, wall junctions, shading and the ventilation strategy should be considered together early. A outward-opening Passivhaus Super Low Uw window is a product-related designation, but it does not replace assessment of the specific configuration and whole project. Ask for the dimensions, glazing, frame version and assumptions underlying any stated performance. Have alternatives identified as such. Different glass or divisions may be sensible options, but they are no longer the same comparison basis. For Cape Town projects subject to building-plan review, assess the applicable SANS 10400-XA requirements, climatic location and project scope with the responsible qualified professionals. A product name should never be mistaken for an automatically suitable project solution.
Clarify installation and wall junctions before ordering
A carefully selected window performs its role only when measuring, fixing, sealing and the connection to the wall, reveal and sill are coordinated. Before ordering, discuss whether existing frames will be fully removed, which internal and external finishing work is included and how unexpected findings will be handled. Particularly in renovations, junction conditions can become visible behind linings or window sills that were not fully apparent beforehand. Record who assesses these locations, describes additional work and approves changes. A clear list of responsibilities is more useful than a broad phrase such as “installation included”.
Frame material also affects the visible joint and coordination with plaster, face brick, timber cladding or the window sill. A material sample shows colour and surface; a junction detail shows the actual installation situation. Ask how roller shutters, external blinds, awnings or insect screens will be accommodated if these components are planned. Also clarify protection for existing floors and internal surfaces, as well as the sequence of following trades. Roof windows, facade windows and floor-to-ceiling units each need their own junction assessment. Have details reviewed by the professionals responsible for the project. The material decision remains important, but cannot compensate for an unclear interface between window, wall and finishes.
Use consistency deliberately and design exceptions consciously
A home with the same frame material throughout can look calm and consistent, but this is not an end in itself. A special garden opening, roof window or entrance door can have different functional priorities from regularly repeated facade windows. The key is a recognisable hierarchy. Standard windows should follow a shared principle, while special transitions may deliberately stand out. When materials are combined, compare colour, sheen, frame sightline, sash division and handles in one view. A similar colour name does not guarantee the same effect on different surfaces. Sample relevant combinations side by side.
Divide the project mentally into repeated elements and justified special cases. For repeated windows, material, colour, sightline width and operating logic should be defined as clearly as possible. A different solution may be selected for special cases where it is visually and functionally understandable. Record the reason in your project schedule: for example, “wide garden access”, “special interior view” or “opening outside the normal window axis”. This short record supports later decisions and prevents arbitrary changes. Finally, review the full exterior elevation and a typical interior perspective. This shows whether the combination appears planned or simply consists of individually selected products.
Make quotations comparable with a fixed enquiry list
Request every quotation from the same window schedule. Each item should state the room, measurement basis, opening direction, sash division, material, internal and external colour, glazing-bar preference, glazing, hardware, accessories and installation scope. Ask for assumptions, exclusions and alternatives to be marked clearly. A lower overall price is not directly comparable where a different division, reduced installation scope or different glazing is intended. Create a table with the columns “required”, “offered”, “different” and “still to clarify”. Missing details become visible before they are carried into the order.
Before placing the order, also clarify site measurement, sampling, elevation approval, junction details and the planned sequence of delivery and installation. Windows and doors from Bloomcabin have a five-year guarantee. Subject to order confirmation, delivery takes four to six weeks. The programme should not replace specification checks. A single outward-opening patio door may look straightforward in an item schedule, but it affects circulation, the facade appearance and the exterior junction. Have individual doors shown together with neighbouring windows as well. Place the order only once opening directions, colours, divisions, accessories, installation work and identifiable alternatives are clearly separated in writing.
Frequently asked questions
Is aluminium always better for large windows?
No. Large units must be assessed as a specific construction of dimensions, divisions, glazing, opening type, hardware and installation. Aluminium can be attractive for clean, large-scale designs. Whether it suits the project is only shown by comparing the actual versions offered, with elevation drawings and clearly stated technical assumptions.
Are uPVC windows always easier to maintain than timber windows?
uPVC is often selected for its straightforward surface care. Timber requires conscious maintenance planning, whose extent depends on coating, weather exposure, building protection and use. A blanket ranking is therefore of little help. Ask for written cleaning, inspection and care guidance for every surface actually offered.
Can I combine timber windows with an aluminium sliding door?
This can work visually if the combination is planned deliberately. Compare sightline widths, colours, sheen levels, divisions and handles in a complete facade elevation. Decide which elements repeat and which component may provide an accent. Technical suitability must be checked against the specific constructions.
What matters most for windows in an older home?
Record existing openings, reveals, divisions, installation positions and the effect of the whole facade. Precise measurement, junction planning and room function follow. Historic-looking divisions are a design choice, not an automatic material requirement. Clarify the particular building’s requirements early with the responsible qualified professionals.
Must all my windows use the same material?
No. Consistency can calm the facade, but functional or architectural special cases may justify another solution. Define a clear principle for repeated windows and document exceptions. Colours, sightline widths, divisions and handles should be sampled together and checked in overall views across material types.
Next step
Aluminium, uPVC and timber do not form a general quality ranking. uPVC often suits an easy-care, consistent plan. Timber makes surface and maintenance conscious parts of the home. Aluminium can be interesting for clean lines and special formats. Still, make an initial selection only after preparing the window schedule, facade elevation and opening plan. Compare specific constructions under the same assumptions and clarify junctions and installation before ordering. Treating material, operation, design and installation as one connected project delivers a considered decision rather than a simple preference for a frame material.
