Average cost of double glazing windows

Summary: How much do double glazing windows cost, average double glazing window installation costs and average double glazing window prices.

Costly heat loss occurs through all your property’s windows. Installing double glazing in your windows (basically two sheets of glass with a heat trapping gap between them) can mean a warmer and quieter home, lower heating bills, reduced condensation and a significant contribution to lowering your carbon emissions.

Average Cost

Factors to Consider

All window installations in England and Wales must comply with Building Regulations. To make the most of your new windows look for the Energy Saving Trust Recommended logo or the BFRC energy label; the most energy efficient windows are those rated A.

If you are planning to do the work yourself you will need building control approval from your local authority, which must be applied for before you start work. You will need to ensure that:

• There are adequate means of escape in case of fire from all rooms in your property (if this is not the case a fire safety window must be installed).
• Safety glass must be used in areas that are sensitive to collision.
• Adequate insulation levels must be achieved.
• Suitable support must be in place above the new window.

It is worth noting that to comply with the 1985 housing act, all rooms that you inhabit, must have glazing proportionate to at least 1/10th of the floor area of the room. This is to give natural light. To provide natural ventilation you must have an openable window of at least 1/20th the floor area of the room.

If you are dealing with a company make sure they are regulated by FENSA (Fenestration Self-Assessment Scheme) or the Glass and Glazing Federation. This counts for more than any of the other ‘memberships’ that may be quoted to you as it monitors all members and has standards of good practice. That being said a local one-man-band may be able to offer you as good a service, but a good idea is to get recommendations from friends and family who have used that person before, so that you know what you are getting.

If your home is a listed building or in a conservation area there may be restrictions on the type of window you can install. Check this out before you begin work.

The best companies are not always the biggest companies or the ones with the most advertising. Beware of salesmen who have artificially increased prices who can offer you amazing discounts if you sign up ‘now’. Ensure you know what you need and what you are getting before you sign anything.

Costs to consider

At the cheaper end of the market you can get hold of recycled PVC-U window frames. These may look great on the sample and seem to offer great value, however they do not keep their hard shiny coating and dirt and dust quickly creeps into these blemishes making the surface discoloured. Standard PVC-U usually comes in a white finish, but you can also get wood grain effect.

Your choice of frame material will affect the overall cost; frames can be in PVC-U, timber/ hardwood and aluminium, hardwood being the most expensive. You can also finish timber frames with a variety of stains, paints and treatments, all of which will incur additional cost.

Other costs to consider when fitting double glazing include:

• Trims and sealant.
• Choice of window handle.
• Hinges and pivots.
• Weather proofing and draught proofing.
• Sill for the outside of the house.
• Additional security features, e.g. bolts, keys or window restrictors.

The type of window you choose will affect the total price; the larger the pane of glass, the more expensive the window will be, much more so than the same area composed of multiple small windows.

It is imperative that the new window unit is well sealed, otherwise the gap between the panes of glass can be penetrated and a build-up of condensation can occur which cannot be removed. This may mean replacing the glass, although thankfully not necessarily the frame. Expanding foam is better for sealing than simply using thermal bridging.

Remember if the work is taking place more than three stories high, you will also have the additional cost of scaffolding.

Never remove an old window that can’t be replaced with a new window in the same day. If this does unfortunately happen and you are left windowless, you could end up with many more costs (in trying to temporarily cover the hole or putting right damage to your room), particularly if there is bad weather.

Well-fitted and good quality double glazing should last you around 20 years. It’s well worth spending time beforehand to plan the work carefully, to give you long years of trouble-free warmth and increased energy efficiency.