We supply and fit triple glazing in Clerkenwell, with made-to-measure windows that use three panes of glass in place of two. This page is for homeowners who want the warmest, quietest windows they can get. You will learn how triple glazed units are made, which frames we use, how we fit them and what drives the cost.
All our work is signed off under FENSA and comes with a 10-year guarantee. For the full range of styles, see our double glazing windows page, or go back to our double glazing home page.
What Triple Glazing Is
A triple glazed unit has three panes of glass with two sealed gaps between them. Each gap is filled with argon or krypton gas, which slows heat far more than air. The panes are held apart by warm edge spacers and sealed round the edge, so the unit acts as one piece.
Most units are 36mm to 44mm thick, against about 28mm for a standard double unit. Two of the panes carry a low-E coating. This thin layer lets light through but bounces heat back into the room.
The result is a centre-pane U-value of about 0.5 to 0.8 W/m²K. A good double unit is about 1.1 to 1.4 W/m²K, and single glass sits near 5.6. A lower number means less heat lost.
Is Triple Glazing Right for You?
Triple glazing costs more and weighs more than double glazing, so it is not the right call for every home. It makes most sense in a well-insulated house, on a cold or exposed side, or near a busy road. Our guide to double vs triple glazing sets out the pros and cons in full, so you can decide before the survey.
Frames That Take Triple Glazing
A triple unit is heavier and thicker than a double one, so the frame has to be built for it. We fit triple glazing in:
- uPVC: deep, multi-chamber profiles with steel inside them carry the weight well. They are the most common choice. See our uPVC double glazing page for frame details.
- Aluminium: modern frames with a thermal break between the inner and outer parts. Slim sight lines let in plenty of light. Our aluminium double glazing page covers the range.
- Timber and alu-clad timber: deep wood frames with an aluminium skin outside for low upkeep.
Most styles can be triple glazed, including casements, tilt and turn windows, and many sliders and doors. Very slim period frames and some sash windows may not take the extra depth. We check this when we measure.
Glass Options for Triple Glazed Units
You can tune the glass to suit each room:
- Acoustic glass: a laminated pane with a sound-damping layer, for rooms facing a busy road or rail line.
- Toughened safety glass: needed in doors, low panes and near stairs.
- Laminated glass: holds together if broken, which adds security.
- Obscure glass: patterned panes for bathrooms and side windows.
- Solar control glass: cuts glare and heat on south and west faces.
- Self-cleaning glass: a coating that helps rain wash dirt away.
Triple glazing also keeps the inner pane warmer. That means less condensation on the glass in cold weather and less of a cold spot when you sit near the window.
How We Fit Triple Glazed Windows
The extra weight of a triple unit means fitting care is key. If the frame is not packed and fixed well, the sash can drop over time.
- We remove the old window and check the opening, sill and lintel.
- We set the new frame on firm load-bearing packers so it sits level and square.
- We fix it into the wall with frame screws at set spacings.
- We glaze the unit with packers under it, so the weight goes into the frame, not the hinges.
- We adjust the sash so it opens and locks with a light touch.
- We seal the gaps and finish with trims and silicone inside and out.
Most homes take one or two days, the same as double glazing. The full process from survey to after-care is on our how we work page.
Building Regulations and Planning
Building Regulations Part L sets a limit of 1.4 W/m²K for a whole replacement window, or band B or better. Triple glazing beats that easily, so it is a good choice if you want to go well past the minimum. All other rules still apply: safety glass in risky spots, fire escape sizes in bedrooms, and trickle vents where the old windows had them.
As FENSA members we self-certify the work and send you a certificate. Planning permission is rarely needed for like-for-like windows on a house. Listed buildings and some conservation areas have stricter rules, and the deeper frames may not be allowed on a period front. We check this at the survey.
What Drives the Cost of Triple Glazing
We do not publish fixed prices, as each window is made for its own opening. These are the main things that change the cost:
- Size: larger panes use more glass and need stronger frames.
- Frame: uPVC costs least, aluminium and timber cost more.
- Gas fill: krypton costs more than argon but works better in thin gaps.
- Glass type: acoustic, laminated, solar control or self-cleaning panes.
- Style: tilt and turn and sliders cost more than simple casements.
- Colour: two-tone and custom finishes.
- The opening: sill, lintel or reveal repairs, and access on upper floors.
To see how window costs build up in general, read our double glazing prices page. Every job gets a written, fixed quote after a free survey, with the payment stages set out in it. You can ask for your quote here.
Looking After Triple Glazed Windows
Triple glazed windows need no more care than double ones.
- Clean the glass and frames with warm, soapy water.
- Keep the drain slots at the base of the frame clear.
- Oil hinges and locks once a year.
- If a sash starts to drop or catch, call us. A small hinge tweak fixes it.
If you ever see mist between the panes, a seal has failed. We can replace the unit without changing the frame.
Frequently Asked Questions
How long does triple glazing last?
A well-made triple glazed unit should last for decades. The edge seal is the part that ages, so good spacers and a sound fit matter most. The frame often outlasts the glass. If a unit ever fails, you will see mist between the panes. We can swap the sealed unit on its own and keep your frame in place.
Does triple glazing make a home more secure?
Three panes are harder to break through than two, which slows a burglar down. Real security comes from the whole window, though: multi-point locks, internal beads and strong hinges. We can add laminated glass, which holds together when struck. All our windows are fitted with locking handles, and ground floor units can have extra key locks.
Can triple glazing go in a listed building?
It is rare. Listed building consent is needed for any change to the windows, and triple glazed units are deep, which makes the frames bulkier than the originals. Councils often prefer repair, slim double glazing or secondary glazing on listed homes. We can advise on what your council is likely to accept and help with the details they ask for.
Is triple glazing a greener choice?
It cuts heat loss more than any other glazing, so you burn less fuel to keep warm. uPVC frames can be recycled at the end of their life, and timber frames from certified forests are renewable. Aluminium is easy to recycle too. Ask us for frames with recycled content or certified timber if that matters to you.
What upkeep does triple glazing need?
Very little. Clean the glass and frames with warm, soapy water a few times a year. Keep the drain slots clear and oil the hinges and locks once a year. Because the units are heavy, check that the sash still closes with a light touch. If it starts to drop or rub, we can adjust it for you.
