Commercial Interior
Paint Specification Guide

Getting the paint specification right on a commercial project matters more than most people realise. An under-specified system — wrong primer, too few coats, inadequate preparation — will fail early, look poor at handover, and create liability. An over-specified system wastes budget. This guide provides a working technical reference to help surveyors and FMs write specifications that are both technically sound and commercially proportionate.

It covers interior works. For external or structural coatings, corrosion protection systems or specialist industrial finishes, separate references apply.

1. Surface Preparation

Surface preparation determines the outcome more than any other single factor in a paint system. Paint applied to a poorly prepared substrate will fail regardless of product quality. The specification should describe the required preparation standard as precisely as the paint system itself.

Existing painted surfaces — sound condition

• Wash down all surfaces with sugar soap solution; rinse and allow to dry fully
• Fill all cracks, holes and surface defects with appropriate filler; sand flush when cured
• Abrade any areas of high gloss finish to provide key
• Spot prime any bare areas with appropriate primer before full coats
• Where staining (watermarks, nicotine, marker pen) is present, apply stain-blocking primer to affected areas before finishing coats

Existing painted surfaces — poor condition (flaking, peeling, heavily stained)

• Strip back loose and defective material; scrape and sand to a sound substrate
• Fill, prime and make good all repaired areas
• Full stain-blocking primer coat over all surfaces where contamination is present
• Assess whether a full strip and re-skim is required before redecorating — this is a plastering scope item, not a decorating one

New plaster — walls and ceilings

• Allow minimum 28 days cure time before painting (longer for thick coats or in low-temperature conditions)
• Test moisture content where programme is critical — target below 5% before coating
• Apply mist coat as first coat: trade emulsion thinned 10–20% with clean water, or proprietary mist coat product — do not use neat vinyl silk or soft sheen as first coat on new plaster
• Allow mist coat to dry fully before finishing coats

New plasterboard — unsealed

• Apply plasterboard primer/sealer before finishing coats — unsealed plasterboard absorbs moisture unevenly, causing patchiness and joint shadowing through the finish
• Ensure all joint tape and filler is flush and sanded before priming

Timber — doors, skirting, architrave

• Sand all surfaces to remove nibs and provide key; vacuum and wipe down with tack cloth
• Apply knotting compound to any exposed resinous knots before priming
• For MDF: apply MDF primer/sealer to all cut edges and faces — MDF is highly absorbent and will telegraph texture without a sealing primer
• For softwood: apply wood primer or equivalent before undercoat
• Apply undercoat before finishing coats where colour change requires it, or as part of a full specification system

Metal — radiators, pipework, steelwork

• Degrease thoroughly; abrade to remove any surface rust or scale
• Apply compatible metal primer — zinc phosphate primer is the standard for structural steelwork; for radiators and pipework, use a heat-resistant primer where surface temperatures may exceed 80°C
• Do not apply standard emulsion or oil-based finishes to surfaces that will reach high temperatures — use heat-resistant enamel

2. Paint Systems by Substrate

The following are standard specification systems for commercial interior decorating. Product types are described generically — the specification should reference named products or an approved equivalent.

3. Sheen Level Selection

Sheen level affects durability, cleanability, and how much it highlights surface imperfections. Specifying the wrong sheen for the location is one of the most common errors in commercial decorating — a high-sheen finish in a space with poor plasterwork will show every defect; too flat a finish in a high-traffic corridor will mark and scuff within months.

4. VOC Compliance in Commercial Environments

VOC (Volatile Organic Compound) limits for decorative paints are set under EU Directive 2004/42/CE (retained in UK law). Phase 2 limits have applied since 2010. All compliant products sold in the UK must display their VOC content on the tin.

Occupied environments — additional requirements

Where decorating is carried out in a live or part-occupied office, VOC compliance alone is not sufficient. The specification should additionally require:

• Low-VOC or near-zero-VOC products — specify ≤10 g/l where practicable; most leading trade ranges now offer ultra-low-VOC options at no significant cost premium
• COSHH assessment — a contractor working in an occupied space must hold a site-specific COSHH assessment covering all products in use
• Adequate ventilation — specify that all areas being decorated are ventilated during application and for the drying period; clarify whether this is the contractor's responsibility to arrange or the client's
• Work outside core hours — where products with higher VOC content are unavoidable (e.g. specialist primers), specify application outside occupied hours with a defined dwell period before reoccupation
• Product data sheets at handover — require the contractor to provide TDS and SDS documents for all products used, particularly if the building holds a BREEAM or WELL certification

5. Coat Counts — Quick Reference

The following coat counts represent standard commercial practice. They are minima, not targets — complex colour changes, poor substrate condition or high-specification finishes may all require additional coats.

6. The Dilapidations Standard

Where painting works are specified as part of a schedule of dilapidations, the governing standard is almost always described as "good and substantial repair and in good decorative order" — or a close variant. This phrase is a legal standard, not a construction specification, and understanding the difference matters.

What "good decorative order" means in practice

It does not require a perfect or as-new finish. It requires a standard that a reasonable incoming tenant would find acceptable — typically described as:

• All painted surfaces even in colour, without visible patchwork, shadows or uneven coverage
• No visible staining, scuffs, marks or damage showing through the finish
• Surfaces properly prepared — not painted over unrepaired defects
• Colour consistent with original lease specification or, where altered, returned to a neutral landlord-approved finish
• Joinery finished to the same standard as the walls — not left in a lesser condition because it was "harder to access"

Fair wear and tear

Leases typically exclude fair wear and tear from the tenant's obligations. In practice, a building surveyor assessing a dilapidations schedule will consider the age of the premises and the original state of decoration — a tenant vacating after 10 years is not expected to deliver the same standard as one leaving after 2 years. The RICS guidance on dilapidations (the Dilapidations Protocol) requires both parties' surveyors to act reasonably and proportionately.

When a schedule of condition applies

Where the lease was entered into with a schedule of condition attached, this document defines the baseline — the tenant's obligation is to return the premises in no worse a condition than recorded at the start. This can significantly limit the decorating liability, particularly in buildings that were already in partial disrepair at lease commencement.

Reinstatement of tenant alterations

Where a tenant has applied a branded colour scheme, painted over a landlord-specified neutral finish, or used non-standard products (such as specialist coatings, anti-graffiti finishes or textured paint systems), the schedule will typically require reinstatement to the original specification. This is distinct from routine redecoration and often involves stripping and full preparation before recoating — it should be specified and priced accordingly, not assumed to be covered by a standard 2-coat repaint rate.

7. Writing the Specification

A complete paint specification for commercial decorating works should include the following elements. The level of detail required increases with project complexity and value — a routine dilapidations redecoration can be covered in a few pages; a full refurbishment specification may reference NBS clause M60 in full.

Minimum required elements

• Substrate description: What is being painted and its current condition (e.g. "existing painted plasterboard walls, sound condition, minor filling required")
• Preparation method: Wash, fill, sand, prime — described specifically for each substrate
• Paint system: Primer type (if applicable), undercoat (if applicable), number of finishing coats, product type or equivalent
• Sheen level: State clearly — not "as existing" unless the existing condition and sheen level have been confirmed
• Colour reference: BS 4800 number, RAL code, NCS reference, or manufacturer's colour name and range. "White" is not a specification
• VOC requirements: State maximum VOC limit in g/l if applicable, particularly for occupied environments
• Special requirements: Anti-mould additive for wet areas, fire-retardant coating where required, anti-graffiti topcoat for ground-level external surfaces
• Coverage and spreading rate: For large areas, specify minimum wet film thickness or spreading rate — this prevents contractors cutting coverage to save material
• Access and protection: Responsibility for masking, sheeting and protection of adjacent surfaces and furniture
• Inspection hold point: State whether an inspection is required after preparation and before application of finishing coats (recommended on higher-value projects)
• Documentation at handover: Product data sheets, colour references, any VOC certificates or COSHH assessments