Did you know that in Australian summers, a staggering 87% of the heat entering our homes comes through our windows?

In winter, draughty sash windows are one of the biggest sources of heat loss in older homes. If you have double hung sash windows chances are they rattle, let in cold air, and make your heating and cooling work twice as hard.

The good news is you don't need to replace them. To draught proof a sash window properly is a genuine DIY job that can be done in a few hours, and the difference in comfort, noise and energy bills is immediate.

With proper draught proofing and care, traditional sash windows can actually outperform modern replacements.

There's a common misconception that old windows are inefficient and should simply be replaced. But many historic sash windows have stood the test of time and can be just as effective as modern alternatives once properly sealed.

Draught proofing is one of the most effective and affordable upgrades you can make. Many homeowners spend thousands on double or triple glazing, yet neglect to seal the gaps around their windows, rendering that investment far less effective.

• Dramatically reduced heat loss in winter and heat gain in summer
• Lower energy bills
• Eliminates rattling and outside noise
• Keeps out smoke, dust and insects
• Preserves your heritage windows
• Best ROI for home thermal efficiency

The correct approach for a double hung sash window uses replacement timber beading fitted with a brush pile seal - importantly with a central plastic fin, not foam tape or stick-on strips, which deteriorate quickly, look unsightly, and simply don't perform. Lock and Latch's draught proofing system is simply a series of brush piles that entirely seal the perimeter of the sash window. The process involves taking off the existing stop / staff and parting beads and replacing them with Draught Seal Stop / Staff and Parting Beads.

Why brush seals instead of foam?

Double hung sash windows slide, they don't compress. Foam and rubber seals are designed for casement windows and doors where the surface closes against the seal.

On a sliding sash, a compression seal wears away every time the window moves. Brush pile bristles flex with the sliding motion, creating a lasting draught barrier without wearing down. Brush pile also adapts better to uneven gaps, making it far more effective for older windows where frames may not be perfectly square.

A proper brush pile beading system seals the entire perimeter of your sash windows — including the top of the top sash, meeting rails, lower rail of the bottom sash, parting bead, and staff bead — creating a complete barrier against draughts. It comes pre-assembled with the brush pile seal already fitted, so there's no fiddly separate installation.

It is very important to draught proof the parting bead. This is the trim of timber that separates both sashes vertically and often gets overlooked when draught sealing the sash window. It is imperative that the sash window is entirely sealed, even a small gap can make a massive reduction in the performance, let alone 3mm, the whole length of the box itself, which is what will happen if the parting bead is not draught proofed.

Lock and Latch stock a complete range of draught seal beading specifically for Australian double hung sash windows — available in the sizes and profiles needed for most homes.

Everything you need to draught proof a sash window is listed below

• Draught seal stop / staff bead — seals the gap between the sash and the frame on the sides
• Draught seal parting bead — seals the gap running vertically each side between the sashes
• Meeting Rail carrier with pile — for the meeting rails - where the two sashes "meet" horizontally in the middle of the window

All of the above comes in a handy kit which includes enough material for one window up to 2 metres high and 1 metre wide:

• DIY Draught Seal Kit for One Double Hung Sash Window (22mm Stop Bead)
• DIY Draught Seal Kit for One Double Hung Sash Window (30mm Stop Bead

• A knife
• A tape measure
• A hammer and pry bar (to remove the old beading)
• Mitre saw or hand saw
• Nail gun or hammer and panel pins
• Sandpaper

👉 Shop our complete DIY Draught Seal Kit

Step 1 — Measure Up (Measure Twice, Cut Once!)

• Getting your measurements right is the first step to a successful draught proof sash window installation. Here's exactly how to do it.
• Before removing anything, note the width of your existing stop bead.
• Standard sizes of Stop / Staff Beads are: 22mm x 18mm and 30mm x 18mm

How to calculate Stop / Staff Bead

• Measure the height of the window frame and multiply by 2 (left side + right side)
• Measure the width of the window frame and multiply by 2 (top + bottom)
• Add all four measurements together
• Add at least 100mm to each individual length to allow for mitre cuts

For example, if your window is 900mm wide x 1200mm tall:

• Height x 2 = 2400mm + 100mm allowance = 2500mm
• Width x 2 = 1800mm + 100mm allowance = 1900mm
• Total stop bead needed = approximately 4400mm (4.4 metres)

How to calculate Parting Bead:

• Measure vertically from the window sill to the head (top) of the frame
• Multiply by 2, as parting bead is needed on both sides of the window
• Add 100mm per length for cutting allowance

Using the same example window (1200mm tall):

• 1200mm x 2 = 2400mm + 200mm allowance = approximately 2600mm (2.6 metres)

• Tip: If you have multiple windows, measure each one individually — windows in older homes often vary in size, even in the same room.
• Not sure? Our beading calculator guide has the full breakdown, or call us on 02 7228 0625 and we'll help you work out exactly what you need before you order.

Step 2 — Remove the Old Stop Bead

The stop bead (also called staff bead) runs vertically down both sides of the window frame and holds the lower sash in place. You need to remove it to access the sash. Removing the stop bead carefully ensures you don't damage the frame as you draught proof your sash window

• Start by running a knife around the edge of the beading to cut through the paint. Then use a flat pry bar or chisel to lever the stop bead off the frame.
• Top tip! Start in the middle and then work out towards the ends, the bead is more flexible in the middle.
• Once removed, the lower sash can be tilted or lifted out of the frame
• Keep the old bead as a reference for sizing your replacement.

Step 3 — Remove the Bottom Sash

• With the stop bead removed, carefully lift the lower sash out of the frame and set it aside. This gives you access to the parting bead channel.

Step 4 — Remove the Parting Bead

The parting bead sits in a groove in the centre of the frame and separates the upper and lower sashes vertically and at the top (head).

• Use your knife around as much as the parting bead as possible to loosen any paint, then use the chisel or flat pry bar to lever the bead out of groove of the frame.
• Do this all the way around the frame making sure you remove the parting bead at the top of the sash also.
• Use a flat chisel or pry bar to lever it out
• Work carefully as the channel is narrow

Important: Don't skip this step. The parting bead separates the sashes vertically and must be sealed completely to avoid significant heat loss. Skipping it compromises the effectiveness of the whole draught proofing sytem.

Step 5 — Remove the Top Sash

With both sashes removed you now have full access to every part of the window. This is the ideal time to:

• Assess the window for any rot and repair using a timber epoxy repair system before proceeding
• Weigh and rebalance your sashes to ensure they are correctly weighted and sliding freely. See our guide here.
• Remove sash weights and re-hang if required - change weights if required
• Replace pulleys if required
• Scrape back the frames and release any excess paint build-up

Step 6 — Seal the Meeting Rail

The meeting rail (the horizontal point at which the top and bottom sashes meet in the middle) also need sealing.

• This product features a self-adhesive PVC carrier with a pre-inserted polypropylene brush pile and twin central fin. The fin enhances the sealing capability by forming a continuous barrier against air and water infiltration.
• Ensure that all surfaces are clean, dry, and free from debris before application.
  
• Use an 8.0mm straight router bit to create a 3.5mm deep groove for a flush fit.
• Recommended: Apply a small amount of mitre glue or superglue at the ends of the channel to prevent brush pile movement over time.
• Install a pile and brush carrier routed into the meeting rail on the bottom sash — these come in 1-metre lengths, which is generally enough for most windows

Step 7 — Re-Install the new cords with correct weights

Step 8 — Install the New Parting Bead

Draught seal parting bead from Lock and Latch comes pre-fitted with a brush pile seal on one side.

• Start with the top parting bead at the head. Measure horizontally between the frame and add a few mm to this as you want the bead to go all the way across the head of the window.
• It is recommended to pre-drill your holes in the beads before nailing.
• Then fix the parting bead in position and nail in (40mm nails recommended)
• Re-install the top sash
• Next, measure up for the side parting beads. Measure from the sill up to the parting bead you have just installed in the step above.
• Cut your pieces for the left and right side then cut each piece in half at the meeting rail.
• Make a pencil mark at the halfway point and cut.
• Top tip! Apply a small amount of superglue or mitre fix glue to the top and the bottom between the plastic and the brush of each parting bead to stop the pile moving and seal the ends.
• Pre dill holes in the parting bead and nail into place
• On the bottom half of the window install the parting bead so that the pile faces inwards.
• On the top half of the window switch the bead over so that the pile faces outwards. This will cushion the sashes and eliminate the gaps.
• The brush pile seal faces the sashes, not the frame

Step 9 — Reinstall the Bottom Sash

• With the new parting bead in place, re-install the bottom sash.
• The sashes should slide smoothly — the brush pile seal creates gentle resistance but shouldn't bind.

Step 10 — Install the New Stop Bead

The stop bead runs vertically down both sides of the frame and holds the lower sash in place while sealing the gap between the sash and the frame.

• Cut the draught seal stop bead to length
• Position it so the brush pile seal makes contact with the face of the lower sash
• Pin it in place with a nail gun or hammer and panel pins
• The sash should still slide freely — if it's too tight, move the bead back slightly
• Our Stop / Staff Beads have a brush seal with a central plastic fin running through the middle. It is this fin that forms the seal so it's important that the fin makes contact with the sash

Step 11 — Test and Adjust

• Open and close both sashes to check they slide smoothly.
• There should be gentle resistance from the brush pile seals but no binding or sticking.
• If a sash is too tight, loosen the stop bead slightly and reposition.
• Run your hand around the edges of the closed window on a cold day. Your draught proof sash window is now complete — you should feel no air movement at all

Step 11 — Paint and Finish

• The draught seal timber beading comes pre-undercoated, but will need finishing coats to match your windows.
• Lightly sand and fill any nail holes first. Take care not to get paint on the brush pile seals.

How Long Will This Take?

Allow around 3–4 hours per window for your first attempt. Once you've done one, subsequent windows go much faster. 

Do I Need a Tradesperson?

No — this is can be a DIY job with basic tools. We provide phone support from qualified carpenters to assist you through the process, 

That being said, if your frames are damaged or you have a large number of windows, a professional installer can handle repairs and installation at the same time.

When Should You NOT Draught Proof?

If your windows are in very poor condition — rotting timber, broken cords or severely damaged frames — we recommend repairing these issues first. Trying to draught proof a window in bad structural shape won't give you good results and could make future repairs harder.

Need to repair rotten timber first? See our guide to epoxy timber repair for a step by step walkthrough.

Will draught proofing my sash windows make them hard to open?

No, actually the opposite! When installed correctly, brush pile seals create gentle resistance but the sashes still slide freely and now have a brush instead of wood against wood, enabling smoother operation. The seal compresses slightly as the sash moves past it. 

Will I be able to see the beading once installed?

No. When the window is closed it's completely invisible. When open, only neat draught seals protrude slightly — a clean, integrated finish with no unsightly strips.

Can I draught proof my sash windows without removing them?

Not properly. To do the job correctly you need to remove the stop bead and sashes to access the parting bead channel. Stick-on solutions that don't require removal won't seal the window properly and won't last.  

Can this beading be used on casement windows or doors?

No — this system is designed specifically for double hung sash windows. For doors and casement windows, see our weatherseal range. 

How much does it cost?

Materials for one double hung window typically cost between $115 and $180 depending on size. Compare that to replacement windows and the ongoing energy savings — it's exceptional value.

How long does it last?

Our draught seal beading uses FSC-certified timber and high-quality brush pile seals. When properly installed and timber is maintained, it will last for many years.

Can I see the product before purchasing?

Yes — you can order samples or visit our warehouse in Warriewood, NSW 2102. Contact us to arrange a visit.

Ready to Get Started?

We supply everything you need to draught proof your double hung sash windows and provide expert advice on phone or email.

Not sure what you need? Call us on 02 7228 0625 or email sales@lockandlatch.com and we'll help you work it out.