| Supplier documentation | Request product specifications, installation instructions, finish details, warranty terms, and evidence of applicable testing. | Compare equivalent window sizes, opening styles, glass types, and hardware—not headline prices alone. | Clear documentation makes it easier to verify performance, maintain the windows, and resolve warranty issues. |
| Thermal performance | Check the whole-window U-factor and solar heat gain coefficient (SHGC) for the specified frame and glazing combination. | Values depend on the complete window assembly, glass, frame, and test method. Compare ratings from the same system where possible. | Thermally improved frames and suitable glazing can reduce heat transfer; the best specification depends on climate and building design. |
| Weather performance | Ask for air leakage, water penetration, and structural performance results relevant to the project’s location and exposure. | Do not assume one rating suits every building. Wind exposure, building height, and local code requirements affect the specification. | Appropriate performance and correct installation help reduce drafts and water-intrusion risks. |
| Colonial grid design | Confirm grid pattern, bar dimensions, finish, and whether bars are applied to the glass, placed between panes, or are part of the glazing system. | More complex patterns and custom layouts can add fabrication cost and may affect cleaning or glass replacement. | Choose a design that meets the desired appearance while keeping future cleaning and repair practical. |
| Opening style and hardware | Compare fixed, casement, awning, and sliding configurations, including locks, hinges, rollers, and insect-screen options. | Operable windows generally involve more hardware than fixed units; the number and type of openings influence the quote. | Durable, replaceable hardware can extend serviceability. Confirm that replacement parts will be available. |
| Glazing and safety | Specify single or insulating glass units, low-emissivity coatings, laminated or toughened glass where required, and safety glazing locations. | Additional panes, coatings, and safety glass usually increase initial cost. Requirements vary by climate, building use, and local regulations. | Choose glazing for the project’s energy, comfort, noise, and safety needs rather than selecting on price alone. |
| Installed cost | Compare itemized quotes for frames, glass, colonial bars, hardware, delivery, removal of old windows, installation, and finishing work. | There is no reliable universal price: dimensions, quantity, access, local labor rates, specification, and site conditions all affect cost. | A complete installed quote helps avoid comparing a supply-only price with a fully installed package. |
| Finish and corrosion exposure | Ask for the coating or anodizing specification, care instructions, and suitability for the project’s environment. | Coastal or industrial exposure can require more careful finish selection and cleaning than sheltered inland conditions. | Aluminium forms a natural oxide layer, but suitable finishes and routine care help preserve appearance and protect exposed surfaces. |
| Routine maintenance | Follow the supplier’s care guide: clean frames and glass, clear drainage paths, inspect seals, and check moving hardware. | Cleaning frequency depends on pollution, salt exposure, weather, and the manufacturer’s instructions. Keep weep holes and tracks free of debris. | Regular inspection can identify blocked drainage, worn seals, or stiff hardware before they lead to larger problems. |
| Warranty and service | Read separate terms for frames, finishes, glass, hardware, and installation; check exclusions and claim procedures. | Coverage periods and conditions vary by supplier and product. Confirm what maintenance is required to keep coverage valid. | Accessible service and clearly defined responsibilities matter if adjustment, repair, or replacement is needed later. |
| Installation quality | Confirm who measures and installs the windows, how openings are sealed, and how the units are fixed and drained. | Installation scope should be stated in the quote. A well-rated product can underperform if incorrectly measured or installed. | Correct installation supports weather resistance, smooth operation, and the expected service life of the assembly. |
| Whole-life comparison | Compare the purchase and installation price with expected maintenance, energy performance, repairability, and replacement needs. | Use project-specific assumptions; energy savings and payback depend on climate, existing windows, energy prices, and building use. | The lowest initial quote is not necessarily the lowest-cost choice over time. Balance specification, workmanship, maintenance, and service support. |