Which Glass Do I Need?

The definitive decision guide for trade customers — find your application below, see the build-up we’d recommend, and jump straight through to the full product spec. Still not sure? The comparison tables and quote team have you covered.

How this guide works

Find Your Glass By Application

The right specification depends on the problem you’re solving — privacy, noise, heat, safety or a heritage look — not on the glass on its own. Below we’ve grouped the applications trade customers ask about most, with the build-up we’d recommend for each and a link through to the full product page. If your project spans more than one category (most extensions and renovations do), use the master comparison table further down or send us the brief directly and we’ll spec it for you.

It’s worth resisting the urge to default to the cheapest build-up across a whole job. A window schedule mixing a bathroom, a street-facing bedroom and a south lounge genuinely needs three different specs to perform properly — pricing them all the same as a single “standard” unit usually means one or two rooms underperform once fitted. Spec each opening against its actual application and the quote comes back accurate first time, without a change order once the client notices condensation, glare or road noise after move-in.

Decision path

Match Your Application

Quick Match

What's the Main Problem?

Tap the problem you're solving — we'll jump you straight to the matching application below.

Bathrooms & Wet Rooms

Privacy is the driver, not thermal performance. Obscure or patterned glass at Privacy Level 3-5 blocks the view while keeping daylight, and any pane under 800mm from finished floor level should be toughened as standard. For shared-wall bathrooms and en-suites we’ll usually specify a Stippolyte or similar heavy-obscure inner leaf paired with a standard Low-E outer. View obscure & patterned glass →

Street-Facing & Noisy Bedrooms

Standard double glazing knocks down some noise, but for a busy road, flight path or shared party wall you need an acoustic laminated build. The interlayer damps sound frequencies a plain air gap can’t touch, typically taking a unit from the low 30s dB into the 36-50+ dB range depending on glass thickness and cavity width. Best paired with trickle-vent acoustic seals for the full benefit. View acoustic glass →

South-Facing Lounges & Conservatories

Large south-facing glazing is the classic overheating complaint — great in January, unbearable in July. A solar control coating reflects a meaningful share of solar heat gain before it enters the room while still passing visible light, which is exactly what Building Regs Part O is pushing new and refurbished glazing towards. Combine with Low-E for year-round comfort rather than choosing one or the other. View solar control glass →

North-Facing Rooms & All-Year Comfort

North-facing glazing rarely overheats, so the priority flips to retaining heat rather than rejecting it. A Low-E coated inner pane with argon fill is our usual recommendation here — it reflects room-side heat back inside while still letting daylight through, cutting heat loss through the glass without any change to appearance. This is the specification we default to across most residential projects unless another factor overrides it. View Low-E energy glass →

Doors & Low-Level Glazing

Any glazing in a door, alongside a door, or below 800mm in a critical location falls under the safety glazing guidance in BS 6262 and Building Regs Approved Document K. That means toughened or laminated glass — toughened breaks into small, blunt granules rather than sharp shards, while laminated holds together on impact. Full-glass doors typically pair a toughened outer with a laminated inner for both safety and a degree of security. View toughened safety glass → | View laminated safety glass →

Conservatory & Orangery Roofs

Roof glazing takes the overheating problem from the lounge scenario above and multiplies it — direct overhead sun with nowhere for the heat to go. We combine a solar control coating with a self-cleaning outer surface, which uses sunlight to break down organic dirt so rain sheets it off rather than streaking. Saves a ladder trip and keeps the roof performing as specified rather than fouled with grime. View solar control glass → | View self-cleaning glass →

Heritage & Conservation Properties

Listed buildings and conservation areas often restrict the visible depth of a sealed unit to keep original slim glazing bars and sightlines intact. Our heritage slim-fit units step the cavity down to as little as 8-12mm overall while still sealing as a genuine double-glazed unit, giving planners and conservation officers a like-for-like profile without asking the homeowner to sacrifice thermal performance entirely. View heritage slim-fit units →

Commercial Shopfronts & Offices

Ground-floor commercial glazing carries three risks in one elevation: pedestrian-level impact safety, solar overheating on west-facing frontages, and street noise. We spec toughened glass wherever the pane falls within a door, side panel or below 800mm — the same critical-location rule as any low-level glazing — paired with a solar control coating on west and south elevations to cut the g-value from around 0.83 on clear float down to 0.25-0.40, and an acoustic laminated build on street-facing units, where 36-38 dB Rw covers most busy roads. Units run up to 6000 × 3210mm with a silicone secondary seal for structural glazing. View commercial units → | View solar control glass → | View acoustic glass →

Compare at a glance

Glass Types Side By Side

A quick reference across the glass types above — what each one solves, the build-up it usually sits in, and how it compares on cost relative to a standard Low-E unit. These are relative bands, not quoted prices; every project is quoted individually against the actual sizes and spec.

Glass Type	Solves	Typical Build-Up	Relative Cost
Standard Low-E	General heat retention, everyday glazing	4-20-4 Low-E Argon	Low
Obscure / Patterned	Privacy without losing light	4-20-4 with obscure inner leaf	Low-Medium
Toughened Safety	Impact safety in doors & low-level panes	Toughened outer/inner, Low-E Argon	Medium
Laminated Safety	Impact safety plus security & sound	Laminated pane within the DGU	Medium
Acoustic Laminated	Traffic, flight path & party-wall noise	Acoustic laminate outer, wide cavity	Medium-High
Solar Control	Overheating on south-facing & roof glazing	Solar coated outer, Low-E inner	Medium-High
Self-Cleaning	Grime build-up on hard-to-reach glazing	Self-cleaning outer surface treatment	Medium
Heritage Slim-Fit	Listed/conservation sightline restrictions	Stepped 8-12mm slim cavity	Medium-High

Full reference

Specification Reference By Scenario

For a faster like-for-like lookup against a specific scenario, use the full reference table below — this is the build-up we’d start from before adjusting for your exact sizes and site conditions.

Application	Recommended Spec	Key Notes
Standard window (residential)	4-20-4 Low-E Argon WE (28mm)	U-value 0.9. CSU standard.
Bathroom window	4-20-4 Low-E + Stippolyte inner	Privacy Level 4. Toughen if <800mm.
Front door (full glass)	T4-20-T6.8L Low-E Argon	Toughened both. Laminated inner for security.
Bifold / patio door	4-20-4 Low-E Argon + integral blinds	Toughened. Blinds for privacy.
Sash window	4-6-4 heritage slim	Slim cavity suits period frames.
Rooflight / skylight	T6-16-6.8L Low-E Argon	Tough outer + lam inner MANDATORY.
South-facing large window	6 Suncool 66/33-16-4 Low-E	Solar control essential. Part O.
Near busy road (noise)	6.8L Acoustic-20-6 Low-E Argon	36+ dB. Optiphon/Stadip Silence.
Juliet balcony	10mm toughened (top rail) or 13.5mm+ T/Lam	1.5mm interlayer. Min 1100mm. BS 6180.
Stair balustrade	10mm toughened (with handrail)	Laminated where frameless. BS 6180.
Kitchen splashback	6mm toughened Lacobel T	White/black/grey back-paint or digital print. Heat resistant.
Shower screen	8-10mm toughened clear/frosted	Polished edges.
Fire door	EI 30 Pyrostop / Contraflam	Approved framing required.
Glass floor	T10+T10+13.5L SentryGlas	Anti-slip. Engineer sign-off.
Conservation area	4-6-4 Low-E Argon heritage	Slim profile. Restoration glass.

Not on the list?

Describe your application and we’ll recommend the right spec and quote it. Tel: 020 8574 9342 — Email: sales@csultd.co.uk

Still Not Sure Which Spec?

Two quick options if your project doesn’t map cleanly onto the tables above. Try the glass selector quiz on our homepage for a guided recommendation in under a minute, or go straight to Get a Trade Quote and describe the application in the notes — our team will confirm the right build-up as part of the quote, usually returned within 2 business hours (Mon-Fri, 8am-5pm).

Still Not Sure Which Spec?

Tell us the application and we’ll recommend the right glass and quote it — within 2 business hours (Mon-Fri, 8am-5pm).

020 8574 9342 sales@csultd.co.uk Get a Trade Quote →