Natural Hydraulic Lime (NHL) Internal Plaster - Breathable, Faster Gain Coatings for Historic Interiors

We specialise in internal plastering using Natural Hydraulic Lime (NHL) for historic and listed buildings. NHL combines the breathability and flexibility of lime with earlier strength gain and improved early moisture tolerance, making it ideal where quicker programme, moderate exposure or better bond to damp substrates is required. Our conservation led practice matches correct NHL grade and mix design with traditional hand application to protect original fabric and deliver durable, sympathetic finishes.

What we do

• Survey substrates and existing finishes to determine condition and compatibility.
• Specify appropriate NHL grade, aggregate grading and coat build (scratch, floating and finishing coats).
• Consolidate and reattach loose plaster, install backing and finish coats, reinstate mouldings and cornices, and match textures and tooling.
• Produce trial panels and control curing to ensure correct set, carbonation and finish.
• Finish with compatible breathable decoration such as limewash or mineral paints.

Why use NHL for internal plastering

• Faster early strength: Useful for cooler or wetter conditions and tighter programmes.
• Breathable and flexible: Allows vapour movement and accommodates minor substrate movement without brittle failure.
• Improved early moisture tolerance: Better resistance to temporary wetting and damp substrates than fat lime.
• Conservation compatible when correctly specified: Performs well with many historic substrates while avoiding cementitious incompatibility.

Key benefits

• Tailored performance: Selectable grades (e.g. NHL2, NHL3.5, NHL5) to balance workability, strength and permeability for each situation.
• Durable finishes: Correct coat build and curing produce resilient plasters that cope with thermal and structural movement.
• Conservation sensitive: Retains decorative detail, matching textures, tool marks and breathable finishes.
• Practical for refurbishment: Enables quicker redecoration or occupation without compromising material compatibility.

Conservation & specification protocol

• Survey & testing: Record substrate type, adhesion, moisture/salt profile and decorative stratigraphy to select the correct NHL grade.
• Trial panels: Mock‑ups of mixes, textures and finishes for client or conservation officer approval.
• Minimum intervention: Prioritise consolidation and like‑for‑like repair; remove incompatible materials selectively.
• Documentation: Provide mix recipes, coat build, curing guidance, photographic records and sample approvals.

Typical workflow

• Condition survey — record substrate, adhesion, salts, lath/boarding and decorative features.
• Specification — choose NHL grade, aggregates, coat build and any reinforcement.
• Trials — produce sample panels for texture, colour and finish sign‑off.
• Preparation — protect adjacent fabric, remove unstable material and consolidate substrate.
• Application — apply backing and finish coats in stages; respect recommended thicknesses and curing times.
• Finishing — apply limewash or breathable paints once appropriate.
• Handover — supply photographic records, mix formulations, curing and maintenance advice.

Why choose us

• Technical expertise: Skilled plasterers experienced with NHL systems and conservation best practice.
• Material integrity: Correct NHL selection, tested mixes and traditional workmanship to safeguard heritage fabric.
• Complete service: From forensic survey and trial panels to sympathetic execution and full documentation.