National Insulation Dispatch installs TrustMark-certified thermal insulation to reduce heat loss, lower energy bills, and meet Building Regulations Part L. We survey existing insulation depth and U-values, specify compliant materials (mineral wool, PIR board, blown fibre), install to achieve target U-values (loft 0.16, walls 0.28, floors 0.22)—then certify for ECO4 grants that can cover 100% of costs for qualifying households earning under £31,000.
Survey week 1. ECO4 application week 2. Materials arrive week 3. Loft installed day 1 (4-6 hours). Cavity walls day 2-3. Certificate issued week 4.
TrustMark required for ECO4 funding (government-approved installer scheme). Typical loft insulation (270mm mineral wool, 50m² coverage) costs £600-800 installed, saves £350/year on heating bills. Cavity wall insulation (100m², blown beads) £1,200-1,500, saves £450/year. Solid wall external (EWI, 90m²) £9,000-12,000, saves £550/year. Materials: mineral wool (Knauf/Superglass) £3-4/m² for loft, PIR boards (Celotex/Kingspan) £25-30/m² for solid wall. Building Regs Part L compliance certificate issued on completion. ECO4 grants cover full cost if household income under £31,000 or on benefits (Pension Credit, Universal Credit, Child Benefit with income under threshold).
From loft top-up to full external wall systems
Most cost-effective upgrade: 270mm mineral wool in loft achieves U-value 0.16 (Part L requirement, down from typical 0.40 with 100mm existing). Cost: £600-800 for 50m² loft (£12-16/m² installed). Materials: mineral wool rolls (Knauf Earthwool 100mm + 170mm cross-layer, or blown fibre Superglass for awkward spaces). Installation: clear loft boarding/stored items, lay breathable membrane over joists, roll first layer between joists, second layer perpendicular across joists to eliminate cold bridging. Saves £350/year on heating (based on detached house, gas heating, 3-bed 150m²). Payback: 2-3 years. Loft hatch: insulated cover required (adds £80), achieves U-value 0.25. Condensation risk: ensure 50mm ventilation gap at eaves (cross-flow ventilation prevents moisture buildup under roof—critical in modern airtight homes). Lights: downlighters need fire hoods (£15 each) to maintain insulation coverage without fire risk. ECO4 eligible: free if household income under £31,000 (application takes 3-4 weeks, we handle full process).
Standard wall construction (1930s-1990s) has 50-100mm cavity between inner/outer brick skins—filling this with insulation achieves U-value 0.28 (Part L requirement). Cost: £1,200-1,500 for 100m² wall area (typical semi-detached). Materials: blown mineral wool or EPS beads (expanded polystyrene), injected through 12mm holes drilled in outer brick skin every 1m. Installation: scaffold not required (drill from ground level or ladder for upstairs), holes drilled in mortar joints (less visible), cavity filled top-to-bottom via hose, holes plugged with matching mortar/brick dust. Time: 1 day for typical house. Saves £450/year on heating. Payback: 3 years. Guarantee: 25 years against defects (CIGA-backed—Cavity Insulation Guarantee Agency). Suitability checks: borescope survey confirms cavity is clear (no debris blocking), walls are sound (no cracks/damp), cavity width minimum 50mm. Not suitable for: exposed coastal locations (driving rain risk), solid wall pre-1930s properties (no cavity). ECO4 eligible: free for qualifying households.
Solid wall properties (pre-1930s, no cavity) lose heat rapidly—external insulation wraps house in thermal envelope. Cost: £9,000-12,000 for 90m² wall area (£100-130/m² installed). System: 100-150mm PIR/EPS boards fixed to existing wall with adhesive + mechanical fixings, covered with reinforced basecoat mesh, finished with silicone/acrylic render (20+ colors available) or brick-effect cladding. Achieves U-value 0.18-0.22 (better than Part L minimum 0.28). Installation: full scaffold required (£1,500-2,000), takes 2-3 weeks for typical house. Saves £550/year on heating (solid wall properties have highest heat loss). Payback: 16-20 years (but transforms appearance + adds property value £15-20k). Benefits beyond thermal: weather protection (render seals cracks), eliminates cold bridging (insulation continuous over whole facade), no internal space lost (vs internal insulation which loses 100mm room depth). Planning: may need permission in conservation areas or if changes appearance significantly. ECO4 eligible: grants cover £6,000-10,000 of cost for qualifying households (remainder £2-6k self-funded).
Energy Company Obligation (ECO4) scheme requires energy companies to fund insulation for low-income households. Eligibility: household income under £31,000/year OR receiving means-tested benefits (Pension Credit, Universal Credit, Child Tax Credit, Income Support, ESA income-related, JSA income-based). Grant covers: full cost of loft insulation (£600-800), cavity wall (£1,200-1,500), or partial cost of solid wall EWI (£6,000-10,000 toward £9-12k total). Application process: (1) We assess property and confirm suitable measures, (2) submit application to ECO4 scheme administrator with household income proof, (3) approval takes 3-4 weeks, (4) installation scheduled within 8 weeks, (5) independent inspection verifies work quality, (6) certificate issued. No repayment required—it's a grant, not a loan. Installer must be TrustMark-certified (we are). Typical measures: loft + cavity wall both covered if property qualifies. Time from application to completion: 8-12 weeks. Only one ECO4 claim per property (can't re-apply once installed). We handle full application process—you provide income proof (P60/benefits letter), we do the rest.
Building Regulations Part L sets minimum thermal performance (U-values) for insulation upgrades. Required U-values: loft 0.16 W/m²K, walls 0.28, floors 0.22 (lower = better insulation). We calculate existing U-values via survey (measure insulation depth, identify materials, check for gaps), design upgrade to meet/exceed Part L, install specified materials, then issue compliance certificate for Building Control. Typical existing U-values: loft with 100mm insulation 0.40 (needs 270mm to reach 0.16), uninsulated cavity wall 1.50 (needs cavity fill to reach 0.28), solid brick wall 2.10 (needs 100mm EWI to reach 0.22). Materials thermal conductivity (λ): mineral wool 0.035-0.044, PIR board 0.022-0.023 (better insulator, thinner for same U-value), EPS 0.030-0.038. Calculation formula: U = 1 / (Rsi + R1 + R2... + Rso), where R = thickness / λ. Example: 270mm mineral wool (λ 0.044) = R 6.14, plus plasterboard/air layers = total R 6.5 = U-value 0.15 (meets 0.16 requirement). We provide full calculations for Building Control approval (required for notifiable work—loft over 50m² or any wall insulation). Certificate issued on completion confirms compliance.
Suspended timber floors (common in pre-1970s houses) lose significant heat through uninsulated void below. Insulation fitted between joists achieves U-value 0.22 (Part L requirement). Two approaches: (1) From below (if accessible crawl space)—fix insulation boards between joists from underneath using netting/battens. Cost: £15-20/m² (£750-1,000 for 50m² ground floor). (2) From above (lifting floorboards)—fit rigid PIR boards between joists, replace boards. Cost: £25-30/m² (more disruptive but better for inaccessible voids). Materials: 100mm PIR board (Celotex/Kingspan) achieves U-value 0.18, or mineral wool batts 150mm for U-value 0.22. Ventilation critical: underfloor void must remain ventilated (airbricks/vents in external walls prevent timber rot)—insulation fits snug between joists but doesn't block airflow. Saves £150-200/year (smaller saving than loft/walls but eliminates cold feet/drafts). Solid concrete floors: harder to insulate (need to lift floor, add insulation layer, re-screed—costs £50-70/m², rarely cost-effective unless full refurb). ECO4 eligible: underfloor insulation covered for qualifying households.
Required for ECO4 grants and Building Regs compliance
Tell us your property type and current heating bills