Trade Window and Door Sourcing and Fenestration Procurement
Direct trade window and door procurement enables building contractors, residential developers, and self-builders across London and Surrey to secure high-specification fenestration systems manufactured by established UK and European extruders without retail intermediary markups. Window Fitters Ltd bridges the operational gap between factory extrusion plants and physical construction sites, providing technical takeoffs, opening deduction calibration, scheduled A-frame deliveries, and optional installation by directly employed glazier teams.
Unlike traditional builders merchants or desk-bound trade counters staffed by order clerks with no on-site fitting experience, our trade sourcing is managed by qualified fenestration surveyors. Every window schedule, architectural drawing, and bill of quantities submitted to our estimating team is checked for structural expansion clearances, wind load resistance, glass handling weights, and statutory compliance with UK Building Regulations before fabrication commences. Contractors can choose between supply-only deliveries, sourced trade supply paired with professional installation, or complete supply and installation packages.
EXTRUDER SOURCING
Spectus, Cortizo, Smart
Direct trade sourcing across Spectus, Rehau, Cortizo, Smart Systems, and Senior Architectural.
PROCUREMENT ROUTES
Three Flexible Pathways
Dedicated glazier teams, sourced trade supply with installation, or complete supply and installation packages.
TECHNICAL LOGISTICS
A-Frame Stillage Delivery
Floor-by-floor site sequencing, timed kerbside drops, and crane offloading for heavy glass units.
SURVEY VERIFICATION
Pre-Fabrication Checks
Laser aperture checks, deduction calibration, and Approved Document L compliance audits.
Extruder Sourcing Partnerships and Systems Matrix
We source certified fenestration systems from the UK and Europe's established extruders and profile systems houses, manufactured to precise project specifications:
| Extruder / Systems House | Core Profile Systems | Technical Engineering Specifications | Thermal and Security Compliance | Typical Project Application |
|---|---|---|---|---|
| Spectus Window Systems | Elite 70 bevelled and ovolo casements, Vertical Sliding Sash, reversible commercial windows. | 70 mm frame depth, 5-chambered profile core, recycled composite thermal inserts, galvanized steel reinforcing. | Whole-window Uw 1.2 W/m²K; WER Band A+; PAS 24 security certified; BS 6375 weather tightness. | Residential housing developments, social housing refurbishments, Victorian sash replacements. |
| Cortizo Aluminium | Cor Vision and Cor Vision Plus minimalist sliding doors, Cor 70 Hidden Sash, Cor 80 Industrial. | Ultra-slim 20 mm central interlock sightlines, glazed panels up to 400 kg, concealed perimeter outer frames. | Whole-window Uw from 0.9 to 1.3 W/m²K; RC2/PAS 24 security; Class 4 air permeability to EN 12207. | Architectural luxury extensions, panoramic glass elevations, high-end residential renovations. |
| Smart Systems | Alitherm 300/600/800 casements, Visofold 1000/6000 bifold doors, Smart Wall commercial screens. | Extruded aluminium alloy 6063-T6, polyamide thermal breaks, Qualicoat marine-grade polyester powder coating. | Whole-window Uw 1.4 W/m²K; PAS 24:2016 security; Document L compliant; Document Q compliant. | Domestic rear extensions, bifold replacements, retail shopfronts, low-rise commercial facades. |
| Rehau Polymer | Rehau Total70C and Total70S, Rio flush sash casements, Calibre multi-fold doors. | Virgin polymer uPVC formulation, 70 mm multi-chamber extrusion, integrated weatherseal gaskets. | Whole-window Uw 1.2 W/m²K; WER Band A; Secured by Design accreditation; BS 8213-4 compliant. | Suburban residential refits, heritage conservation cottage upgrades, apartment blocks. |
| Senior Architectural Systems | SF52 curtain walling, Ali VU slimline casements, SPW501 commercial doors and screens. | Enhanced thermal isolator clips, 52 mm sightline stick curtain wall grid, heavy-duty concealed closers. | CWCT certified to 600 Pa water tightness; whole-system Uw from 0.9 W/m²K; UKCA certified. | Schools, commercial office developments, medical facilities, multi-storey glazed atriums. |
| Origin Global | OB-49 and OB-72 bifolding doors, OS-20 and OS-29 sliding doors, OW-70 slim casements. | Aerospace-grade prime aluminium billet, finger-safe compression gaskets, 8-point multi-point locking. | Whole-window Uw 1.1 to 1.3 W/m²K; PAS 24 and Secured by Design; 20-year manufacturer guarantee. | Prime residential refurbishments, luxury garden rooms, homeowner-specified architect builds. |
| Solidor Entrance Systems | Solid timber core composite doors, Traditional and Italia luxury entrance collections. | 48 mm cross-laminated solid hardwood core, thermo-plastic skins, Ultion 3-star anti-snap euro cylinders. | Doorset Ud 1.3 W/m²K; PAS 24 certified; Document Q tested; Part M low threshold compliant. | Domestic front entrance doors, property portfolio entrance upgrades, housing schemes. |
Explore our profile comparisons in our window profile systems comparison, inspect aluminium systems in our aluminium windows guide, and discover energy performance ratings in our Window Energy Ratings guide.
Technical Takeoffs, Survey Handover, and Site Logistics
Ordering directly through trade suppliers often fails because factory order clerks lack site installation experience. Window Fitters Ltd bridges this gap by combining trade account purchasing power with seasoned fenestration surveying through a structured 4-stage procurement workflow:
STAGE 1Aperture Deduction Calibration and Thermal Movement Allowances
Thermal expansion rates vary dramatically across fenestration materials. Standard white uPVC expands at 0.06 mm per metre per °C, requiring a 10 mm total deduction (5 mm per side). Dark foiled uPVC profiles (such as Anthracite Grey or Black Ash) absorb higher solar radiation, demanding a 15 mm total perimeter allowance. Architectural aluminium profiles require 10 mm to 12 mm expansion clearances. Our surveying team calculates precise structural deductions, ensuring frames do not distort during hot summer months or bind against masonry reveals.
STAGE 2Laser Survey Verification and Structural Deflection Analysis
For large structural openings, such as 4-pane sliding patio doors or 5-leaf bifolding doors, a simple tape measure is inadequate. We deploy calibrated optical laser levels to assess opening cross-corner diagonals, level tolerances, and lintel deflections. When spans exceed 3 metres, we verify structural beam live loads to specify overhead expansion clearance couplers, preventing ceiling loads from transferring directly onto the sliding door track.
STAGE 3A-Frame Stillage Delivery and Floor-by-Floor Site Staging
Damaged frames and scratched glass cause disastrous site delays. Our trade deliveries arrive vertically racked on dedicated timber or steel A-frame transport stillages, strapped with protective rubber cushions. We coordinate delivery timing with your on-site trade program, providing kerbside drop-offs or arranging mechanical crane offloads for heavy sealed glass units weighing up to 250 kg, placing materials directly onto staging decks or ground-floor distribution points.
STAGE 4Trade Accounts, Estimating Takeoffs, and Commercial Terms
We work directly from architectural elevations, window schedules, and bill of quantities spreadsheets. Our estimating department provides transparent itemized quotations breaking down profile costs, glazing specifications, delivery logistics, and optional installation labour. Established building contractors and commercial clients benefit from dedicated trade account facilities, flexible stage payments, and direct manufacturer warranties.
The Contractor Difference: Practical Installation Foresight
Factory sales representatives rarely understand how external wall insulation (EWI), projecting stone cills, or internal plaster finishes affect window fitting. Because our primary business is installation, we inspect practical detailing such as frame add-on depths for internal plaster returns, trickle vent canopy clearances behind structural brick overhangs, and sub-cill projections before placing factory orders.
Review our commercial agreements on our contracts page, explore B2B subcontracting on our B2B contracting page, and examine regulatory details in our UK Building Regulations guide.
Three Flexible Trade Procurement Pathways
Because Window Fitters Ltd combines direct factory trade accounts with directly employed installation teams, we offer three clear procurement models tailored to your project structure and budget:
| Procurement Pathway | Sourcing and Procurement Scope | Installation Scope and Deliverables | Warranty and Client Suitability |
|---|---|---|---|
| Dedicated Glazier Teams (Labour-Only / Installation-Only) | Client or main contractor procures windows, doors, and glass directly from their chosen trade fabricator or supplier. | Our CSCS-carded glazier teams handle aperture verification, mechanical fixing to BS 8213-4, toe-and-heel glazing, perimeter foaming, and weathersealing on fixed day rates or per-unit rates. | Workmanship installation warranty; ideal for developers, general builders, and carpenters with existing supplier trade accounts. |
| Sourced Trade Supply with Installation | Window Fitters Ltd conducts detailed site laser surveys, calculates opening deductions, and orders frames directly from established extruders at trade rates. | Complete site logistics coordination, A-frame delivery, old frame extraction, licensed waste carrier disposal (CBDL650268), professional fitting to BS 8213-4, and silicone finishing. | Combined manufacturer product warranties plus our direct installation warranty; ideal for property owners and builders avoiding retail markups. |
| Complete Supply and Installation Package | Single-point complete package project management including initial fenestration survey, CAD scheduling, Building Control coordination, and custom extrusion orders. | Full glazier deployment, dust protection, structural bay post propping (Approved Document A), complete fitting, perimeter insulation, Building Control certification, and final sign-off. | Comprehensive 10-year guarantee covering both product integrity and site installation; ideal for prime domestic refits and commercial contracts. |
Compare procurement models in our supply and fit vs supply only guide, check our glazier day rates on our labour-only page, and review typical project investments in our window cost guide.
Indicative Trade Procurement and Installation Rates Matrix
Representative trade supply and contractor installation pricing across popular domestic and commercial fenestration systems:
| Product Format and System Specification | Trade Supply-Only Unit Rate | Labour-Only Fitting Rate | Sourced Supply + Fit Package |
|---|---|---|---|
| Spectus / Rehau White uPVC Casement (A-Rated, 1200 x 1200 mm) | £195 to £280 per window | £35 to £65 per aperture | £320 to £540 per window |
| Spectus Vertical Sliding Sash (White uPVC, Run-Through Horns) | £380 to £540 per window | £70 to £110 per aperture | £550 to £780 per window |
| Smart Alitherm 300 Aluminium Casement (Polyester Powder Coated) | £360 to £520 per window | £45 to £75 per aperture | £520 to £750 per window |
| Smart Visofold 1000 3-Pane Aluminium Bifold Door (3000 x 2100 mm) | £1,750 to £2,400 per doorset | £180 to £270 per doorset | £2,350 to £3,200 per doorset |
| Cortizo Cor Vision Minimalist Sliding Patio Door (2-Track, 2-Pane) | £2,800 to £4,200 per screen | £280 to £450 per screen | £3,600 to £5,400 per screen |
| Solidor Composite Entrance Doorset (48 mm Solid Core, PAS 24) | £680 to £980 per doorset | £150 to £250 per doorset | £980 to £1,450 per doorset |
| Dedicated 2-Man Glazier Team Day Rate (CSCS Certified) | Not applicable | £540 to £580 per day | Consumables pack: £45 to £65/day |
For detailed domestic cost guides, read our 3-bed house window replacement cost guide, see door fitting options in our door installation guide, and request a trade quotation on our quote request page.
Professional Installation Sequence to BS 8213-4:2016
Whether fitting client-supplied frames or our own trade-sourced packages, our installation teams follow a rigorous 5-stage installation sequence:
- Site Laser Survey and Aperture Preparation: We inspect the structural reveal with optical laser levels, verifying plumb, squareness, and lintel structural bearing under Approved Document A. Old frames are removed without masonry spalling, and debris is cleared.
- Sub-Cill Alignment and Thermal Barrier Bedding: External sub-cills are bedded on continuous silicone barriers and mechanically secured. EPDM waterproof membranes are integrated where required to prevent moisture ingress under the threshold.
- Frame Setting, Shimming, and Mechanical Anchoring: Frames are positioned on non-compressible setting blocks, maintaining consistent 5 mm perimeter expansion gaps. Fixings are driven 150 mm from frame corners and at maximum 600 mm centres in accordance with BS 8213-4 code of practice.
- Toe-and-Heel Glazing and Hardware Calibration: Insulated glass units are packed diagonally using stepped bridge packers from bottom hinge pivots to upper locking corners. Multi-point espagnolettes and shootbolt keeps are aligned to ensure effortless operation and airtight gasket compression.
- Perimeter Polyurethane Insulation and Neutral-Cure Weathersealing: The perimeter expansion gap is filled with low-expansion elastic polyurethane foam to eliminate thermal bridging. The external boundary is sealed with high-grade neutral-cure silicone, and trickle vents are tested to confirm Approved Document F background airflow.
Inspect our installation workforce qualifications on our installers page, explore our full company history on our about Window Fitters Ltd page, and discover our general services on our glazing company hub.
Specialist Contractor Capabilities and Trade Accreditations
Window Fitters Ltd operates as a fully certified fenestration contractor across Greater London, Surrey, and the South East from our registered office at 139 Wentworth Road, Croydon, CR0 3HZ via Croydon HQ travel-time tiers (<15m local at £540/day, 15-45m extended at £580/day, >45m outer Surrey with half-day minimum). Under Director and Head Window Fitter Marian Gheorghe, our operations are protected by 5,000,000 pounds Commercial Public Liability and 10,000,000 pounds Employers Liability insurance. Every directly employed installer holds valid CSCS cards and fenestration craft competencies. All supplied systems comply with Approved Document L (Conservation of fuel and power) achieving whole-window Uw values of 1.4 W/m²K or lower, Approved Document F for background trickle ventilation (minimum 8,000 mm² equivalent area for habitable rooms), Approved Document B for emergency fire egress, Approved Document Q and PAS 24 for intruder resistance, and Approved Document K with BS EN 12600 safety glass below 800 mm. We are an Environment Agency registered waste carrier (CBDL650268), ensuring all extracted timber, metal, and glass frames are transferred to licensed UK recycling facilities.
Frequently Asked Questions About Trade Window and Door Supply
Clear trade answers to common questions regarding fenestration sourcing, lead times, and contractor installation options:
Which profile systems and extrusion manufacturers do you source for trade clients? +
We source leading UK and European fenestration systems including Cortizo, Smart Systems, Spectus, Rehau, Senior Architectural Systems, Origin Global, and Solidor composite doors. All systems are procured directly from certified fabricators to exact technical cutting schedules, complete with factory CE/UKCA marking and manufacturer Declarations of Performance.
How does Window Fitters Ltd differ from an impersonal builder merchant or trade counter? +
Unlike traditional trade counters staffed by sales personnel who do not visit construction sites, Window Fitters Ltd is first and foremost a specialist glazing installation contractor. Every window schedule and architectural takeoff submitted to us is vetted by experienced fenestration surveyors. We inspect opening deductions, thermal compliance, glass unit weights, and structural drainage before extrusion commences, preventing costly site remakes.
Can building contractors and developers purchase windows on a supply-only basis? +
Yes. We provide supply-only procurement for main building contractors, property developers, and independent carpenters who retain their own on-site installation labour. We supply frames manufactured to approved CAD schedules, delivered on sequenced A-frame stillages with complete manufacturer documentation, fixing brackets, and technical setting drawings.
What are the standard manufacturing and delivery lead times for trade window orders? +
Standard white uPVC casements and composite entrance doors typically require a lead time of 2 to 3 weeks from survey sign-off. Coloured foil uPVC, flush sash profiles, and architectural aluminium systems such as Smart Alitherm or Cortizo sliding doors require 3 to 4 weeks. Specialist dual-colour extrusions or structural curtain walling require 5 to 7 weeks.
How are delivery logistics managed on congested London and Surrey job sites? +
We coordinate site deliveries to match your construction sequence. Frames and heavy glass units arrive loaded on protective timber or steel A-frame stillages, preventing transit distortion and scratch damage. For restricted residential sites across Greater London, we arrange timed kerbside drops or Hiab crane offloading, delivering materials directly to designated ground-floor staging zones.
Can trade clients hire your dedicated glazier teams to install client-sourced windows? +
Yes. Through our dedicated glazier teams and labour-only subcontracting options, contractors and homeowners who have already purchased windows elsewhere can hire our directly employed, CSCS-certified installers. We operate on fixed day rates or per-unit rates, providing precision laser alignment, mechanical fixing to BS 8213-4, and weatherproofing backed by a written workmanship warranty.
Author & Technical Reviewer: Marian Gheorghe
Head Installer & CEO, Window Fitters Ltd
Marian Gheorghe is the Active Director and Team Leader Installer at Window Fitters Ltd. With over 15 years of hands-on experience, he oversees technical safety and UK Building Regulations compliance for all residential and commercial glazing contracts.
Ready to discuss your project?
Window Fitters Ltd provides window and door installations across London and Surrey for residential, trade, and commercial projects.
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Verified Google & MyBuilder Reviews
"Stunning Sash Windows in Croydon"
"Marian and his team replaced our old Victorian sash windows. They were clean, fast, and the double glazing has completely blocked out the street noise. Highly recommended!"
"Excellent Bifold Doors in Bromley"
"Installed beautiful grey aluminium bifold doors for our new kitchen extension. Smooth gliding mechanism and great insulation. The best quote we got in Kent."
"Perfect Front Door Upgrade in Sutton"
"Very happy with our new composite door installation. Excellent lock security and high-quality GRP slab finish. Fast half-day fitting and no mess left behind."