This Help Center article is a summary of the official Earthaus Faswall® Block Wall System Guide. Download the full Faswall® Block Wall System Guide (PDF).

Overview

The Earthaus BUILD Pozzolanic Hydraulic Lime (PHL) Plaster System is designed for Faswall® Block construction. It is standardized but versatile for unique project needs.

Key Properties:

High-plasticity lime + pumice pozzolan for workability, adhesion, and durability.
Breathable plaster system: allows Faswall to release moisture.
Slow, steady curing supports flexibility during early structural movement.

Exterior System (Faswall Walls):

Layer	Product	Thickness	Coverage
Scratch Coat	PHL Binder	3/8" (1 coat)	65 ft²
Brown Coat	PHL Binder	3/8" (1 coat)	75 ft²
Finish Option 1	Lime Stucco Coarse	1/4" (1 coat)	50 ft²
Finish Option 2	Lime Stucco Fine	1/8" (1 coat)	100 ft²
Sealer (optional)	Breathable Sealer	–	TBD

Interior System (Faswall Walls):

Layer	Product	Thickness	Coverage
Scratch Coat	PHL Binder	1/4" (1 coat)	100 ft²
Brown Coat	PHL Binder	3/8" (1 coat)	75 ft²
Finish Option 1	Sand Finish	1/8" (1 coat)	100 ft²
Finish Option 2	Stone Finish	1/16" (1 coat)	250 ft²
Sealer (optional)	Olive Oil Soap Sealer	–	700 ft²

Substrate Preparation

Inspect the Walls — The surface must be clean, dry, and free of debris. Repair cracks before plastering.
Dampen Before Plastering — Pre-dampen with light mist coats; the goal is darkened but not saturated.
Plaster Stops & Lath — Protect dissimilar materials with felt paper plus expanded metal lath. Recommended: embed fiberglass reinforcing mesh in the brown coat to reduce cracking.
Protect Surrounding Areas — Mask off windows, doors, and non-plaster surfaces.

PHL Binder Installation Over Faswall

Scratch Coat:

Thickness: 3/8". Score horizontally 1/4" deep while wet. Must fully cover the Faswall.
Cure 10 days before the brown coat.

Brown Coat:

Thickness: 3/8". Cure 10 days before the finish coat.

Sand Aggregate (Mandatory):

Scratch coat: 1 bag PHL Binder + 3 × 5-gal buckets sand.
Brown coat: 1 bag PHL Binder + 5 × 5-gal buckets sand.

Applying the Finish Coat

After the brown coat has cured (10 days), apply your selected finish from the system table above:

Exterior finishes (Lime Stucco Coarse or Fine): see the Lime Stucco — Application Guide.
Interior finishes (Sand or Stone): see the Interior Sand & Stone Finishes application guide.

Pigment color and optional sealer are listed in the system table above.

Calculate How Much You Need

Estimate the materials for your project with the Earthaus calculators:

PHL Binder (scratch & brown coats): PHL Binder Calculator — select your wall system in the calculator.
Exterior finish: Lime Stucco Fine Calculator or Lime Stucco Coarse Calculator.
Interior finish: BUILD Sand Finish Calculator or BUILD Stone Calculator.

Technical Support

Product questions: email support@earthausplaster.com
Technical consultation: Earthaus technical consultation