| 1. Compare visible frame profiles | Ask for the visible width of the head, sill, jambs, and interlocking meeting stiles—not just a marketing description such as “slim.” | Request dimensioned elevations showing each sightline in millimetres. Compare the same locations and number of panels across quotes. | Frame widths differ by position and configuration. A narrow outer frame does not necessarily mean a narrow meeting stile. |
| 2. Check frame depth and panel size | Compare the frame’s installation depth, panel dimensions, and the maximum panel weight permitted by the system. | Confirm that the proposed panel size and glass build-up fall within the manufacturer’s published limits for that configuration. | Large glass panels are heavy. Suitable frame depth, reinforcement, and hardware help support the panels and keep them operating correctly. |
| 3. Look for a thermal break | Check whether the aluminum frame separates its exterior and interior metal sections with a low-conductivity thermal barrier. | Request the whole-door U-factor or U-value for the specified size, glazing, and configuration. Compare results using the same rating method and units. | Aluminum conducts heat readily. A thermal break can reduce heat transfer through the frame, but performance depends on the complete door assembly. |
| 4. Match the glazing to the climate | Compare glass type, pane count, low-emissivity coating, gas fill, spacer, and glass thickness. | Ask for the glazing make-up and rated whole-door thermal performance. For noise concerns, request an acoustic rating for the complete door where available. | Glazing affects heat loss, solar gain, condensation risk, and sound reduction. Frame sightlines alone do not indicate overall performance. |
| 5. Inspect the sill and water-management details | Compare the sill height, drainage paths, weather seals, and whether the track is designed for the site’s exposure. | Review the installation drawings and test data for air leakage, water penetration, and structural performance under the relevant local standard. | Low-profile sills can improve access but still need suitable drainage and weather protection. Site exposure and installation affect results. |
| 6. Evaluate rollers, locks, and operation | Check roller capacity, adjustment access, locking points, replacement-part availability, and the method for removing panels for service. | Confirm that the hardware is rated for the specified panel weight and that the installed door will be tested or adjusted after installation. | Quality hardware supports smooth movement and secure closing. Heavy panels may require more robust rollers and careful adjustment. |
| 7. Verify the installed opening and warranty scope | Compare the finished clear opening, fixed-panel arrangement, thresholds, installation tolerances, and coverage for frames, glass, and hardware. | Request a project-specific drawing showing panel positions and clear passage width. Read the warranty for maintenance requirements and exclusions. | Panel configuration and installation can change the usable opening. Clear documentation helps align the quoted product with the finished result. |