System Overview:
The Western Blended Products Conventional Exterior Stucco System is a traditional three-coat cement plaster wall assembly consisting of a scratch coat, brown coat, and finish coat installed over approved substrates and lath in accordance with ASTM standards and applicable building codes.

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The system utilizes factory-blended conventional basecoat products in conjunction with code-compliant weather-resistive barriers, metal lath, and compatible finish systems.

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The Conventional System complies with ASTM C926 and ASTM C1063 and may be installed using either:

• Standard three-coat application (scratch, brown, finish), or

• Scratch and double-back method in accordance with IBC Section 2512.8 (Alternate Method of Application).

The system is non-structural and functions as an exterior cement plaster cladding assembly.

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System Intent and Performance:
The Conventional Exterior Stucco System is engineered to:

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• Provide a nominal 3/4-inch cement plaster assembly applied in two basecoat lifts (scratch and brown).

• Comply with ASTM C926 for application of Portland cement-based plaster.

• Comply with ASTM C1063 for installation of lathing and accessories.

• Accommodate either standard scratch/brown sequencing or scratch and double-back method per IBC Section 2512.8.

• Support cementitious or acrylic finish systems.

• Permit optional incorporation of the Crack Resistant System (CRS) for enhanced crack resistance performance.

The system does not eliminate cracking caused by structural movement, substrate deflection, or improper control joint placement.

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When configured with the Crack Resistant System (CRS), the assembly incorporates a reinforced basecoat layer with embedded alkali-resistant mesh designed to enhance crack resistance characteristics and surface durability.

The Conventional System provides a code-recognized exterior plaster assembly adaptable to multiple wall configurations while maintaining compliance with applicable building codes and referenced ASTM standards.

The system is not structural and does not eliminate cracking resulting from structural movement.

System Components:
Basecoat Options:

• Insulite Lightweight Stucco (Sanded)

• Top Gun Premium Plaster Concentrate

• Top Gun Premium Plaster Sanded 

Nominal total basecoat thickness: 3/4 inch.
Maximum total plaster thickness shall not exceed 7/8 inch in accordance with conventional stucco code requirements.

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Weather-Resistive Barrier (WRB):

• Code-approved WRB installed in accordance with applicable building codes.

• Metal Lath & Accessories:

• Metal lath complying with ASTM C847.

• Installation in accordance with ASTM C1063.

• Control and expansion joints as required by code or project drawings.

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Exterior Finish Options:

• WBP Exterior Stucco Finish

• WBP Premium Acrylic Finish + PAF Primer

• Exterior Finish Coatings by approved WBP Manufacturers.

Premium Acrylic Finish assemblies requiring 7 & 10 year warranty tiers shall incorporate PAF Primer in accordance with WBP installation requirements.

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Optional Enhancement: Crack-Resistant System (CRS).

• The Crack Resistant System (CRS) consists of BPS Armor CRS reinforcing basecoat and alkali-resistant fiberglass mesh installed at a minimum 1/16-inch embedment thickness.

When incorporated into the Conventional Exterior System, CRS elevates the assembly to the reinforced warranty tier in accordance with the warranty schedule. CRS enhances crack resistance characteristics but is not structural reinforcement.

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Typical System Configuration:
A typical Conventional Exterior System assembly consists of:

• Approved structural substrate.

• Code-compliant weather-resistive barrier.

• Self-furred metal lath mechanically fastened in accordance with ASTM C1063.

• Scratch coat application.

• Brown coat application to achieve nominal 3/4-inch total thickness.

• Selected exterior finish coating.

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Alternate Method:
The scratch and double-back method may be used in accordance with IBC Section 2512.8.

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Substrate Requirements:
Substrates shall comply with applicable building codes and ASTM requirements. Permitted substrates may include:

• Concrete

• Masonry

• Wood structural panel wall sheathing

• Light-frame construction covered with gypsum board

• Other approved substrates in accordance with code.

Substrates shall be structurally sound, properly braced, and free of conditions that may adversely affect system performance.

 

Environmental Conditions:
Components shall not be installed when surface or ambient temperatures are below 40°F (4.4°C) or above 100°F (38°C).
All cementitious components require a minimum of forty-eight (48) hours moist curing. Extended curing may be required under conditions of heat, wind, or low humidity.
Protect installed materials from freezing, rapid drying, or inclement weather until adequately cured.

 

System Limitations:
The Conventional Exterior System:

• Is not structural.

• Does not eliminate cracking caused by structural movement.

• Requires proper control joint placement in accordance with ASTM C1063 or as specified by the project designer or architectural specification.

• Must be installed in accordance with ASTM C926, ASTM C1063 and WBP’s installation requirements.

• Requires installation by qualified applicators.

• System performance is dependent upon compliance with WBP installation guidelines and integration within approved stucco assemblies.

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Code and Standards:
The Conventional Exterior System shall be installed in accordance with:

• 2024, 2021, 2018 & 2015 International Building Code (IBC)

• 2024, 2021, 2018 & 2015 International Residential Code (IRC)

• ASTM C926 — Application of Portland Cement-Based Plaster

• ASTM C1063 — Installation of Lathing and Furring

• ASTM C847 — Metal Lath

• ASTM C144 — Aggregate for Masonry Mortar

• ASTM C897 — Aggregate for Job-Mixed Portland Cement-Based Plasters

• ASTM C150 — Portland Cement

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System Positioning:
The Conventional Exterior Stucco System provides a traditional three-coat cement plaster assembly designed for projects requiring ASTM-compliant scratch and brown construction.

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The system may be configured with premium basecoat options and the optional Crack Resistant System (CRS) to enhance crack resistance performance and extend warranty eligibility.

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Maximum warranty term for the Conventional Exterior Stucco System is ten (10) years.

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Western 1-Kote and Western One-Pass Systems provide extended warranty tiers where project conditions require higher-tier system configurations.

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Warranty Schedule Matrix:
The warranty schedule outlines the available warranty terms for the Conventional Exterior System based on basecoat selection, finish system configuration, and incorporation of the Crack Resistant System (CRS). 
Warranty duration is dependent upon compliance with WBP installation requirements and proper integration of system components as defined in this Technical Data Sheet applicable Codes and Standards.