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A parge coat is a thin layer of mortar applied to masonry surfaces like concrete or brick. It’s used to improve the appearance, strength, and durability of the underlying material. A parge coat, or parging coat, is applied as a smooth or textured cement plaster over an exterior or interior masonry wall. The purpose is to seal gaps, fill holes, and level out imperfections for better moisture resistance and energy efficiency. It creates a protective barrier and refined finished surface.

Historical Significance 

Pargeting developed centuries ago as a decorative and protective treatment for European architecture. Craftsmen hand-carved intricate plaster reliefs, contributing fine details to Tudor timber framing and half-timbered styles. Medieval churches and English manor homes prominently showcased the artistry of pargeted exteriors. Revival movements like arts and crafts borrowed their ornate flourishes. This traditional building method endures preserving heritage structures with sensitive restoration.

Materials And Application 

Traditional parge coats use a cement-based mortar mix. Modern formulations may incorporate latex binders, fibers, or pigments. For exterior use, the mix is reinforced with a galvanized metal lath to add strength. The application requires surface preparation, such as scraping and wire brushing loose material. A bonding agent is often applied before the base “scratch coat.” This is finished with a float or trowel to the desired texture. Skilled masons use tools and wood forms to achieve precise edges and details.

Benefits Of A Parge Coat

A parge coat provides several key benefits for enhancing masonry surfaces:

  1. Improved Durability: The hardened cementitious matrix is highly durable and resistant to weathering. It protects the substrate from UV damage, temperature extremes, water infiltration, and other environmental stresses that can degrade masonry over time.
  2. Enhanced Moisture Resistance: By seamlessly sealing cracks, joints, and small holes, a parge coat acts as a moisture barrier. This prevents damp issues like efflorescence and spalling. It also improves the thermal insulation properties of walls for greater energy efficiency.
  3. Increased Fire Resistance: The non-combustible cement base adds an additional layer of protection against fire. It helps maintain the structural integrity of walls in the event of a fire.
  4. Aesthetic Appeal: A well-applied parge coat creates a smooth, seamless surface for a refined appearance. It can also highlight natural textures like a stone finish. Pigments allow custom colorization to match architectural styles.
  5. Acoustic Performance: Sealing air gaps and cracks dampens exterior sound transmission for improved occupant comfort
  6. Substrate Reinforcement: The weight of a parge coat counteracts stresses on masonry from shrinking, swelling, or movement. It strengthens weak or damaged substrate areas prone to cracking.
  7. Low Maintenance: With its durable composition and sealed surface, a parge coat requires minimal ongoing upkeep compared to other finishes like paint.


Types Of Parge Coats

Traditional parge coats rely on plain cement mixes troweled smoothly. Modern varieties feature polymer-modified blends and specialty additives for characteristics like increased flexibility or vapor permeability. Exterior applications require durable formulations that are resistant to weathering. Interior parge coats focus on non-toxicity and aesthetics, like replicating a stucco appearance indoors. Decorative parging incorporates artistic textures, carvings, and color schemes.

Considerations For Using A Parge Coat 

Proper surface preparation is essential for adhesion. Cracks or defects must be repaired first. The weather during application and curing also matters – heat accelerates drying, while rain or freezing can damage unfinished coats. Costs vary based on material choices and detailed finishes. Labor is intensive, requiring skilled tradesmen. Completing this type of project correctly maintains the integrity of walls for decades of service.


Maintenance And Repair

Regular inspections check for cracks from shifting foundations or water damage. Touch-ups preserve the protective barrier. Minor repairs re-apply a thin coat; extensive damage may need scraping and re-parging larger sections. Proper preparation and compatible products extend the coat’s lifespan.

Advantages Over Other Finishes

Compared to paint, a parge coat adheres directly without needing subsequent re-application. Its thickness and density also outperform paint as a moisture-resistant barrier. Stucco has a similar rugged appearance but lacks the reinforcement and durability of a cement-based parge coat. With skilled application, parging produces long-lasting, low-maintenance finishes suitable for most climates and structures.

Applications Of A Parge Coat

Common uses include patching cracks and holes in basement walls, sealing chimneys, and covering foundations that extend above grade. Parge coats strengthen retaining walls and shelter uncovered building exteriors from weathering. Inside, they reinforce walls of tile or stone ornamentation. Historic replica projects prefer the authentic look of traditionally parged interiors. Contemporary styles feature smooth or textured parge coats as well.


With proper application, a parge coat creates a durable, weather-resistant, and aesthetically pleasing finish for masonry. The cementitious formulation strengthens surfaces while sealing out moisture for enhanced durability. Whether used decoratively or functionally, it protects exterior and interior structural elements as a long-lasting enhancement. Consultation with skilled craftspeople ensures correct installation and maximized benefits from this historically significant technique.

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