Triple glazed insulated glass unit showing three panes, spacer bars and sealed cavities
Triple glazed insulated glass unit showing three panes, spacer bars and sealed cavities

Triple Glazed Window Unit - Standard

£200.00
 per 
  • Estimated lead time: 6 weeks
  • Energy Rating (A–G): —
  • Building Reg Compliance: Part L 2021 Compliant
  • Warranty Period: 15 years
  • Installation Required: Yes
💾
You have a saved configuration

Last saved: Just now

1
Where's it going?
Choose installation type
Safety glass required
Building Regulations require toughened glass for doors. This will be automatically applied.
2
Size & Thickness
Enter your measurements
Min: 300mm Max: 4000mm
Width must be between 300mm and 4000mm
Min: 300mm Max: 4000mm
Height must be between 300mm and 4000mm
Please check your dimensions - we can manufacture glass between 300mm and 4000mm
Large panel - please call for availability
1.68 m² coverage area
💡 Select size to see thickness recommendation.
3
Glass Selection
Choose your glass type

Safety glass that holds together when broken - required for overhead glazing

4
Privacy & Style
Customise your glass appearance
Glass Privacy Level
Spacer Bar Colour
Same price regardless of spacer type
Traditional grid pattern (£12 per bar)
🚫 Georgian bars are only available with clear glass
Bars: 2 × £50.0 = £100.0
Traditional leaded glass effect between panes
5
Extras & Cutouts
Optional additions
Catflap Cutout
Professional cutout for cat/dog flap installation
+£25
Argon Gas Fill
Enhanced insulation - improves U-value by ~15%
+15%
Toughened Glass
5x stronger - required for safety-critical areas
+15%
Your Price
£164.22
inc. VAT
10-Year Warranty Free UK Delivery Secure Checkout
1200mm × 1400mm Pilkington K Glass 24mm

📋 Request a Quote

We'll create a saved quote and email it to you

Your Details

Quote Summary

Dimensions 1200 × 1400mm
Glass Type Pilkington K Glass
Options 20mm, Clear, Black spacer
Estimated Price £164.22 inc. VAT

You'll receive the quote by email within minutes

Description

Triple Glazed Window Unit — Residential Casement Windows

The casement window — side-hung or top-hung — is the most common window type in UK homes. Our Triple Glazed Window Unit is engineered to fit the frame profiles used by leading casement window manufacturers, delivering U-values from 0.7 to 0.9 W/m²K in the most popular window format.

Whether you're replacing failed sealed units in existing casement frames or specifying new windows for a renovation, our triple-glazed units drop straight into most modern uPVC, aluminium, and timber casement systems. The result: a step-change in thermal and acoustic performance without changing your window style.

Specification

Our standard triple-glazed window units are available in 28mm, 32mm, and 36mm overall thickness to suit different frame systems. All units include Low-E coating and argon gas fill as standard.

  • U-value: 0.7–0.9 W/m²K (depending on build-up)
  • Thickness options: 28mm, 32mm, 36mm
  • Low-E coating: Included as standard
  • Gas fill: Argon (90%+)
  • Glass options: Clear, obscure, tinted, solar control

Compatible with most modern window frame systems including uPVC, aluminium, timber, and composite. Custom sizes manufactured to order.

Manufactured to BS EN 1279 at our Bristol facility. FENSA registered, 10-year warranty, nationwide delivery.

Use our glass configurator to specify your frame system, dimensions, and glass preferences for instant pricing.

Material

Glass Composition

Three panes of 4mm float glass with Low-E coating and argon gas fill as standard. The overall thickness depends on cavity width: 28mm (8mm cavities), 32mm (10mm cavities), or 36mm (12mm cavities). Wider cavities deliver better thermal and acoustic performance.

Low-E coating position: soft-coat on surface 5 (28mm single-coating option) or surfaces 3 and 5 (32mm and 36mm double-coating option). Double coating delivers the lowest U-values.

Warm-edge or aluminium spacer bars available. Warm-edge spacers are recommended for living spaces where edge condensation would be noticeable — they maintain a warmer inner-pane perimeter temperature, reducing moisture risk.

Care

Cleaning & Maintenance

Your triple glazed window unit requires minimal ongoing maintenance to deliver decades of reliable performance. Regular cleaning keeps glass looking its best and helps identify any issues early.

Routine Cleaning

Clean both faces of the sealed unit using warm water with a small amount of washing-up liquid and a soft, lint-free cloth or sponge. Avoid abrasive cleaners, scouring pads, or razor blades, which can damage coatings and seals. Rinse thoroughly with clean water and dry with a chamois or microfibre cloth to prevent water spots.

Seal & Spacer Bar Inspection

Inspect the perimeter seal every 6–12 months. Look for cracking, peeling, or gaps in the secondary sealant (typically black polysulphide or silicone). If you notice internal condensation between the panes, this indicates seal failure — contact Pane Relief for a warranty assessment.

Frame & Drainage

Keep drainage slots in the window frame clear of debris. Blocked drainage channels allow water to pool against the sealed unit edge, which accelerates seal degradation. A pipe cleaner or compressed air clears most blockages.

Installation

Installation Guide

Correct installation is critical to the long-term performance of your triple glazed window unit. These guidelines cover standard rebated-frame glazing — always refer to the frame manufacturer's instructions for system-specific requirements.

Preparation

Inspect the unit on delivery. Check for chips, cracks, or seal damage before removing protective film. Verify dimensions match the frame rebate with 3–5mm clearance on all sides. Ensure the frame rebate is clean, dry, and free from old putty or sealant residue.

Setting Blocks & Packers

Place two setting blocks (minimum 50mm wide) at the quarter points of the bottom rail — approximately 50mm from each corner. Use 5mm flat packers for side and top clearance. Setting blocks must be load-bearing nylon or HDPE, not timber, which can swell and crack the glass.

Glazing & Sealing

Apply a continuous bead of neutral-cure silicone sealant to the back of the glazing bead before pressing into position. Do not use acid-cure silicone, which attacks the spacer bar sealant. Ensure the glazing bead is fully seated with no gaps — water ingress behind the bead is the most common cause of premature seal failure.

Drainage

Verify that frame drainage slots (minimum two per unit, positioned at the lowest point of the rebate) are clear and functional. The sealed unit must never sit in standing water.

Window-Specific Notes

Verify frame compatibility before ordering — check the frame manufacturer's maximum glazing thickness specification. Most modern triple-glazing frame profiles accept 28–44mm, but older frames designed for double glazing may only accommodate 24–28mm. For sash windows, check the balance system weight rating against the triple-glazed unit weight (approximately 30% heavier than double glazing of the same dimensions).

Warranty

10-Year Manufacturer's Warranty

Every triple glazed window unit from Pane Relief is backed by our comprehensive 10-year manufacturer's warranty, covering seal integrity, gas retention, and coating performance. Our BS EN 1279-certified manufacturing process ensures each unit meets the highest quality standards.

The warranty covers: internal condensation caused by seal failure, visible coating degradation, and argon or krypton gas leakage beyond acceptable levels. Normal wear, external condensation (a sign the unit is working efficiently), and damage from incorrect installation or handling are excluded.

To make a claim, contact our Bristol team with your order reference and date of purchase. We aim to inspect and resolve all warranty claims within 14 working days. For installations carried out by FENSA-registered installers, we can process claims directly — no third-party paperwork required.

Shipping & Returns
  • Free shipping on orders over £250
  • Standard delivery within 2–5 business days
  • Easy 30-day returns
  • Return items in original condition for a full refund

Standard delivery within 2–5 business days

Return items in original condition for a full refund

Need a Custom Size?

Use our glass configurator to specify exact dimensions, gas fills, coatings, and more — with instant trade pricing.

Configure Your Unit

Frequently Asked Questions

Everything you need to know about this product before ordering.

  • Our insulated glass units achieve U-values as low as 1.0 W/m²K with argon gas fill and low-emissivity coatings. The exact U-value depends on your chosen glass specification, spacer bar type, and gas fill. We can provide a detailed thermal calculation for your specific configuration on request.

  • Yes, we manufacture bespoke units to your exact specifications. Simply provide the width, height, and glass configuration you need. There is no minimum order quantity for custom sizes, and we can accommodate most non-standard shapes including arched, circular, and raked units.

  • Standard units ship within 2–3 weeks from order confirmation. Custom specifications such as toughened, laminated, or triple-glazed units may take 3–4 weeks depending on glass availability. We will confirm the exact lead time when we process your order.

  • We supply direct to trade — our units are designed for professional installation by qualified glaziers and window fitters. Each unit ships with fitting instructions and gasket recommendations. If you need installation support, we can recommend approved installers in your area.

Sealed Unit Replacement

How to Replace a Sealed Unit

Follow these steps for a professional sealed unit replacement. Always wear protective gloves and eyewear when handling glass.

1

Measure the Opening

Measure the width and height of the glass (not the frame) in at least three places. Take the smallest measurement and deduct 2mm for clearance. This gives you your order size.

2

Remove the Beading

Starting with the longest bead, insert a stiff putty knife or glazing chisel into the gap between bead and frame. Gently lever outward. For uPVC, the bead will unclip. For timber, carefully prise the pinned bead away.

Number each bead as you remove it so they go back in the correct position.
3

Remove the Old Unit

Using suction cups, carefully lift the failed sealed unit out of the frame. Tilt the top edge toward you first, then lift clear. Have a second person assist with larger units.

Always wear cut-resistant gloves and safety glasses when handling glass.
4

Clean the Frame Rebate

Remove any old sealant, dirt, or glazing tape from the rebate using a scraper and white spirit. The rebate must be clean and dry for the new unit to sit properly and for sealant to adhere.

5

Position the Packers

Place setting blocks at the quarter and three-quarter points along the bottom of the frame. These support the weight of the glass and ensure even distribution. Use 5mm packers for standard units.

6

Insert the New Sealed Unit

Lower the new unit into the frame, resting it on the packers. Push the unit back into the rebate until it sits square. Check that the gap is even all around — adjust packers if needed.

7

Refit the Beading

Starting with the shortest bead, press each one firmly back into position. For uPVC, tap with a rubber mallet until it clicks home. For timber, pin back in place. Ensure all beads are flush with the frame.

8

Check & Finish

Use a spirit level to confirm the unit is sitting level. Check all four edges for even gaps. Clean the glass with a soft cloth. The new unit should operate smoothly within the window.

Tools & Materials Needed
Tape measureGlazing chisel or stiff putty knifeSuction cupsSetting blocks / packersLow-modulus silicone sealantSealant gunCloth and white spiritSafety glovesSafety glasses

Not confident doing this yourself? We offer professional installation across Bristol and the South West.

Need Help? Contact Us

Trade Support

How We Help Trade Customers

Bulk Trade Pricing

Volume discounts on all insulated glass units. The more you order, the more you save.

View trade pricing

Technical Support

Our glazing experts are on hand to help with specifications, Building Regs compliance, and installation advice.

Call 0117 330 3057

Reliable Delivery

Nationwide delivery direct to site. Careful packaging ensures your units arrive in perfect condition.

Delivery information

Ready to order?

Get Your Trade Quote Today

Fast specification-led pricing for insulated glass units. No middlemen, direct to your site.