Over the years, draught-proofing timber windows have become something of a speciality for the JLM Property Maintenance team. Whether we’re doing battle with winter draughts blowing in from Torbay or making local heritage properties more comfortable, there are various ways to draught-proof your casement or sliding sash windows. Read on to learn more…

Your windows could be elegantly understated casements or the gorgeous box sash windows beloved of Georgian, Victorian and Edwardian architects. Whatever their provenance, windows’ provenance – their ‘air permeability’ – allows heat out, cold air in, raises energy bills and costs you, the property owner, money. What’s more, draughts are uncomfortable, rattling windows are annoying and poorly fitting windows may be more vulnerable to damage. Furthermore, gaps that let in draughts can also make windows less secure.

How do you draught-proof a window?

Back to basics for a moment: most windows feature opening parts and a fixed part. For casement windows, they’re the opening part of the window and the window frame respectively. For sash windows, one or both sashes move relative to each other within a fixed sash box (or sash case). You get draughts when the gap between the fixed and opening parts of the window – a small gap is essential – isn’t sealed well enough to stop air movement into and out of your property.

Plastic perimeter seals or brush pile

To draught-proof windows, we add or replace suitable draught-proofing. It could be flexible perimeter sealing, such as Schlegel’s BS644/BBA-approved Aquamac weatherseals. Or alternatively, it could be polypropylene brush-pile or brushes set directly into the joinery or secured by brush carriers fitted in skilfully routed grooves. Occasionally, draught-proofing may consist of self-adhesive weather stripping applied to the surface of window parts. We rarely use the latter as it is more of a DIY solution. Properly fitted draught excluders give far better long-term performance. As with so much in life, with draught-proofing, you get what you pay for.

Does draught-proofing sash windows work?

Call them sash windows, box sashes or vertical sliders, timber sash windows are among the most drought-prone window types. Working in and around South Devon, we usually find traditional single-glazed sashes to be the worst offenders. They may have been less rattly when they were installed with the 3mm air gap needed to allow relative movement of the sashes. But with time’s passing and the weather’s ravages, those sashes probably rattle remorselessly nowadays.

How do I stop my sash windows from rattling?

So how do we draught-proof sliding sashes to help them keep heat in, cold out and reduce rattles when the wind blows? Various draught-proofing methods are available. They range from correctly-sized sash brushes (it’s not a case of one size fits all) or, bristles, to durable plastic perimeter seals from leading brands such as Schlegel.

You could also take the ultimate step of renewing your old sash windows with slimline double-glazed units featuring built-in draught-proofing. It’s a great way to update all aspects of your windows, including draught proofing, security, thermal efficiency and soundproofing – but it’s often not necessary. If we can solve your draught problem without recommending full sash replacement, we’ll always do so. You’ll be amazed at what’s possible.

New or replacement weatherproofing

Draught proofing sliding sashes typically involves adding new or replacement weatherproofing to staff beads, parting beads between upper and lower sashes, bottom rails and top (‘head’) rails.

Because our sister company is a FENSA-approved specialist bespoke joinery business, we can take care of everything in house. If possible, we’ll install draught-proofing on-site. However, if adding correctly routed perimeter seals or brushes is needed for your windows, we’ll take the sashes to our workshop. That way, our team can do everything required in a properly equipped environment.

By the way, because of our experience with heritage properties, you can rest assured that we’ll always use draught-proofing methods that are in sympathy with your windows.

Draught proofing windows during refurbishment

A time may come in a window’s life when skilled refurbishment or restoration is needed. This typically involves joinery repairs, maintenance or upgraded window hardware, and installation of improved security. With the sashes removed from their box and in the workshop, it’s also the perfect time to improve the draught-proofing.

Windows painted shut?

We’re sometimes asked to refurbish timber sash windows that have been silicone sealed or painted shut. It’s a drastic DIY draught-proofing solution, but not one we’d ever recommend. It works – in a way – but it doesn’t look great. It can encourage moisture damage too. And it defeats the purpose of having lovely sliding sashes, which enable various opening combinations to manage airflow.

If your timber sash windows are painted shut, we can often restore them to their original glory with full functionality. At the same time, we can also install suitable plastic or brush draught-proofing. Not only will this remain largely hidden, but we’ll fit it in such a way that your windows keep their authentic sash window look.

Draught proofing casement windows

As mentioned above, it’s usually timber vertical sliders that present the greatest draught-proofing challenge. That said, we sort out draughty casement windows too.

It’s often a simpler task, but the principles are similar. We’ll refurbish or replace existing draught-proofing or add new draught-proofing. This could consist of high-performance EPDM rubber ‘P’ or ‘E’ strip, compression seals, or bristle strip sealing between the casement and the window frame.

Learn more about window draught proofing

Whether it’s your timber casement windows or your timber sliding sashes that are letting in draughts, we can help draught proof them as a standalone project or part of more extensive window refurbishment or restoration.

Call today on 07595 387211 or contact us