How to Write a Specification for Aluminum Windows

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A good aluminum window specification defines the system, profile type, glazing build-up, opening types, finish, performance requirements and installation scope in clear, measurable terms. It should also state the submittal documents and tolerances the supplier must provide before manufacture. Writing it this way lets tenders be compared fairly and reduces variations on site.

Define the Scope and Window Schedule

Start by stating exactly what the package includes: supply, fabrication, delivery, installation, sealing and cleaning. Attach a window schedule that lists each mark, location, overall size, opening type and quantity. Clear marks help the factory, the site team and the quantity surveyor refer to the same unit without confusion.

Window mark and floor level
Overall width and height
Opening type (fixed, sliding, casement, tilt and turn)
Quantity per mark

Specify the Aluminum Profile System

Name the profile system or describe its required characteristics: frame and sash depth, wall thickness of the extrusions, thermal break type and profile alloy. Ask the tenderer to confirm the system in their submittal rather than accepting a generic description. Where a thermal break is required, state its minimum width and the material used, since these affect both insulation and condensation risk.

Set Out Glazing and Infill Requirements

Describe the glazing build-up for each window type, including glass type, thickness, coatings, gas filling and spacer type. Separate requirements for safety glass, acoustic glass and solar control where they apply. Specify glazing bead profile and gasket type so that the glazing method is fixed in advance and not left to the supplier's standard practice.

Define Hardware, Accessories and Operation

List the hardware by function: hinges, locks, handles, stays, espagnolettes and any security or restrictor devices. Require that hardware be rated for the weight and size of each sash and that the operating force meets the limits stated in the specification. Include drainage, weatherstripping and insect screen requirements, as these are often omitted and then added as variations.

Set Performance and Testing Requirements

Performance should be written as requirements the supplier must demonstrate, not as vague claims. Typical items are air permeability, water tightness, wind load resistance and thermal transmittance of the completed window. Ask for test reports from an accredited laboratory for a comparable system. Exact numerical classes should be taken from the project's design criteria and the relevant Israeli standards, and checked with the engineer.

Finish, Submittals and Installation Requirements

State the surface finish in full: anodized or powder-coated, the colour reference system, the minimum coating thickness and the required colour tolerance between batches. Require shop drawings, samples and a sealing and fixing method statement before fabrication starts. Finally, describe installation: fixing method, perimeter sealing, protection during works, cleaning on completion and the defects period. Clear submittal and installation clauses are what make a tender comparable and a handover smooth.

Frequently asked questions

Should I specify a brand of aluminum profile?

It is usually better to specify the performance and the system characteristics rather than a single brand. This keeps the tender open to suitable alternatives while still guaranteeing quality. Require the tenderer to name the proposed system and provide test evidence.

What is the most important item to include in the specification?

The window schedule and the performance requirements are the most important, because they define what is being built and how it must perform. Without them, tenders are difficult to compare and variations are likely.

Do I need to specify finish colours in detail?

Yes, name the colour reference, the finish type and the minimum coating thickness. Also state how colour consistency across batches will be controlled, so that all windows on the project match.

Who should check the exact performance values?

The project engineer should confirm the exact numerical values against the design criteria and the applicable Israeli standards. The specification writer then transfers those confirmed values into the tender documents.

Common mistakes to avoid

A common mistake is leaving performance, glazing and finish unspecified and relying on the supplier's standard practice. This leads to unequal tenders and disputes on site.

Our recommendation

Attach a complete window schedule and require a submittal package before manufacture, including shop drawings, test reports and samples. This single step prevents most mismatches between what was tendered and what is delivered.

Summary

A clear aluminum window specification covers scope, profile system, glazing, hardware, performance, finish and installation, all written as measurable requirements. Good specifications make tenders comparable and protect the project during construction.

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