How to Prepare a BOQ and Material Specification Package for Premium Facade Projects

Poorly prepared Bills of Quantities and material specifications are one of the leading causes of cost overruns and material substitution on Vietnamese construction projects. When a BOQ is vague, contractors substitute cheaper alternatives. When specifications are incomplete, suppliers quote different products and comparison becomes impossible.

This guide walks you through the complete process of preparing a BOQ and specification package that protects design intent and enables accurate competitive tendering.

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Why This Matters More Than You Think

In Vietnam's construction market, a facade material BOQ that simply says "HPL cladding" will receive quotes for products ranging from $15/m² to $85/m². The contractor will award to the lowest price — which may be a domestic product with no test certifications, no warranty, and a colour that shifts within two years.

A properly specified BOQ with exact brand references, technical minimums, and approved-equivalent clauses enables you to:

• Receive genuinely comparable quotations
• Defend design intent during value engineering
• Create a clear basis for quality inspection during installation
• Protect yourself (and your client) from liability for premature material failure

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Step 1: Facade Area Take-Off

Before writing a single specification, you need accurate area quantities. Common mistakes:

Surface Area Calculation

Gross facade area = Building perimeter × Building height
Less: Window openings
Less: Door openings  
Less: Reveals and soffits (measure separately — different unit rate)
= Net cladding area

Waste Factor

Always add waste factor to net area:

Panel Format	Recommended Waste Factor
Large format (>1200mm)	8–12%
Standard format (600–1200mm)	10–15%
Complex facades with angles/curves	15–25%

Additional Items to Quantify Separately

Item	Unit	Notes
Primary structure (steel RHS/SHS)	kg or tonne	Structural engineer to specify
Aluminium subframe (rails + brackets)	m² or lineal m	Depends on system
Insulation (if required)	m²	Specify R-value
Airtight membrane	m²	If rainscreen system
Starter/closer trim	lineal m	Perimeter of cladding area
Corner trims	lineal m	External corners
Window surrounds	lineal m	Reveals around each opening
Sealant (joints between panels)	lineal m	Calculate from panel grid layout

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Step 2: Writing the Material Specification

This is the most critical document. A good material specification has four parts:

Part A: Performance Requirements

State the minimum technical performance the material must achieve. This defines the floor — any compliant product must meet or exceed these:

EXTERIOR FACADE CLADDING — PERFORMANCE REQUIREMENTS

2.1 Fire Classification
    Minimum: Class B-s2,d0 per EN 13501-1
    For buildings > 28m height: Class A2-s1,d0 per EN 13501-1

2.2 Weather Resistance
    Minimum UV resistance: 2,000 hours per EN ISO 4892-2
    Maximum moisture expansion: 0.2% per EN ISO 1604

2.3 Structural
    Minimum flexural strength: 13 MPa per EN 12467
    Wind load resistance: calculated per TCVN 2737 for project location

2.4 Finish
    Colour fastness: ΔE ≤ 2.0 after 2,000 hours UV exposure
    Surface: Factory-finished, no site painting required
    Warranty: Minimum 10 years for panel and surface finish

Part B: Proprietary Specifications (Basis of Design)

Name the specific product your design is based on. This eliminates ambiguity:

2.5 Basis of Design
    Specified product: FunderMax Max Compact Exterior NT
    Colour reference: F516012 (Slate Grey)
    Thickness: 8mm
    Surface: Matte
    Supplier: HIASHI (info@hiashi.vn)

Part C: Approved Equivalents Clause

Allows competition while maintaining technical integrity:

2.6 Approved Equivalents
    Substitutions from the specified product will only be considered 
    if the contractor submits, no later than [DATE], a written 
    submission including:
    a) Full product technical data sheet
    b) EN 13501-1 fire test certificate (valid, third-party laboratory)
    c) EN ISO 4892-2 UV test certificate
    d) Colour sample for architect approval
    e) Written warranty terms
    
    The architect's decision on equivalents is final and non-negotiable.
    No substitution will be approved after contract award.

Part D: Installation Requirements

2.7 Installation
    Installation shall comply with the manufacturer's published 
    installation guide. Subframe design shall be submitted to the 
    structural engineer of record for review before fabrication.
    
    Fasteners: Minimum SS316 stainless steel
    Joint sealant: Silicone, minimum 25% movement capacity
    Drainage cavity: Minimum 20mm drained and ventilated cavity 
                     behind cladding panels
    
    Installer shall have completed manufacturer's authorised 
    installer training program.

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Step 3: BOQ Format

Structure your BOQ as follows:

Item	Description	Unit	Qty	Unit Rate	Amount
A. FACADE CLADDING
A1	HPL compact exterior panel, 8mm, FunderMax Max Compact Exterior NT, colour F516012, including all fixing accessories	m²	2,450
A2	Aluminium horizontal rail, 150×40mm, anodised silver, including adjustable wall brackets at 600mm centres	m	8,200
A3	Corner trim, extruded aluminium, L-profile 50×50mm, anodised silver	m	340
A4	Window surround trim, extruded aluminium, U-profile 20×50×20mm	m	890
A5	Silicone joint sealant, grey, 8mm wide joints	m	12,400
A6	EPDM backing rod, 8mm diameter	m	12,400

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Step 4: Supporting Documents to Include

A complete tender package for facade materials should include:

Document	Purpose
Facade drawings (1:100 and 1:20 details)	Show panel layout, joint pattern, corner details
Panel layout drawing	Numbered panel positions — enables accurate take-off verification
Colour and finish schedule	Specific colour codes, any special finishes by zone
Subframe drawing (schematic)	Bracket spacing, rail centres, fixing centres
Sample requirements	Size, quantity, and deadline for architect approval
Programme dates	Material delivery window, installation start and completion

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Step 5: What to Request from Suppliers

When issuing an RFQ to facade material suppliers (including HIASHI), request:

• ✅ Priced BOQ based on your quantities
• ✅ Lead time from purchase order to site delivery (Vietnam import lead times: 6–14 weeks for European materials)
• ✅ Minimum order quantity (MOQ) — important for small projects
• ✅ Copy of current fire test certificate
• ✅ Copy of UV test certificate
• ✅ Sample delivery (physical, minimum A4 size)
• ✅ Warranty document (signed, on company letterhead)
• ✅ Reference project list in Vietnam (if any)
• ✅ Installation contractor recommendations

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HIASHI's BOQ Support Service

HIASHI provides free quantity take-off verification and specification writing support for projects specifying our partner brands. Send your floor plan and facade elevation drawings to info@hiashi.vn, and our technical team will:

1. Calculate net facade area and waste quantities
2. Prepare a detailed BOQ with our products priced
3. Provide sample material within Vietnam for architect approval
4. Coordinate technical submittals for permit applications

Submit Project Drawings for BOQ Support →

Ask HIASHI AI for Specification Help →