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How to Fit Gapseal for Sash Windows

Gapseal is perfect to fill the gaps around your sash windows. Its unique design and the application tool ensure that your gaps can be sealed without causing damage to the window or frame. It is designed to address difficult gaps of varying thickness and in areas where windows either cannot be opened or have to slide up and down within a frame.

Step 1 - Preparation

Before fitting Gapseal you need to ensure that the gap between the window and the frame is clean and free from dirt and debris which can be removed using the applicator provided or an appropriate tool such as an old credit card, a blunt knife or a screwdriver.

When removing debris from around windows, care should be taken to avoid injury from old, damaged windows and frames.

Step 2 - Starting the Application

Using the applicator provided push the end of the Gapseal into the gap at the end of the window frame. Continue to push the Gapseal into the first 1-2 inches of the window gap to ensure that the seal is firmly in place.

To make the first part of the installation easier the end of the Gapseal strip can be carefully trimmed into a point using a pair of scissors, this will allow the end of the seal to be pushed into the window gap easily.

Step 3 - Fitting the Seal

After you have fitted Gapseal into the first 1 - 2 inches of the gap and the end is firmly in place, stretch the windows seal as much as necessary to push it into the gap without using excessive force. The resistance against the applicator should feel comfortable and not too strained.

Work a short section at a time! Repeat this process over the length of the window gap. The ideal depth is 2-3 mm below the surface of the window frame.

Step 4 - Cutting to Size

After you have fitted Gapseal to the full window and are reaching the end of the gap, the final length of the gap should be measured and the sealant trimmed with about one inch surplus length.

This is done to ensure a good fit during the final stage of installation and to prevent gaps being created at a later stage. Gapseal can easily be cut to size with household scissors.

Step 5 - Finishing the Application

Once Gapseal has been trimmed to size, use the applicator supplied or an appropriate tool such as an old credit card or a screwdriver to push the sealant into the remaining window gap.

This will ensure a snug fit and create an effective seal between the window and the frame. This fitting method should be applied to each window that you would like to seal against cold draughts.

Safety Tip - Avoid Injury Risks

The application tool is extremely effective for installing the sash window sealant because of its specially designed shape.

It is however important to remember that excessive use of force can result in injury. To eliminate the risk of injury, never work the applicator toward your face and always maintain a safe distance between the applicator and your leading hand. The applicator should be stored in a safe place away from children.

Important: When installing Gapseal in rooms with open fires or a gas fire, please ensure that a sufficient flow of air to the fire remains. Without sufficient air flow there is a risk of carbon monoxide poisoning. You can increase air flow to the fire without cooling down the room by installing shuttable air inlets in the floor directly next to the fire.

Our Customers Love Gapseal

4.5 / 5 Stars

Read reviews from 162 customers who've installed Gapseal to eliminate draughty windows and make their homes warmer.

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Gapseal 10m Pack

Suitable for 2 - 7mm gaps
More than 20 in stock Expected dispatch: 27th Aug

£13.99 inc VAT

£11.66 ex VAT

Additional Application Tool

Do I need another applicator?
More than 20 in stock Expected dispatch: 27th Aug

£2.29 inc VAT

£1.91 ex VAT

Sub Total:

£0.00 inc VAT

£0.00 ex VAT

FREE Economy Delivery

All UK orders are shipped FREE of charge and delivered in 2-3 working days by Hermes as standard.

Please Note: Deliveries to islands and remote locations can take an additional 1-2 days to be delivered.

Next Working Day Delivery

Orders can be upgraded to next working day delivery for
£4.50 inc VAT and will be delivered by Hermes.

Next Working Day Delivery

Orders can be upgraded to next working day delivery for
£4.50 inc VAT and will be delivered by DHL.

International Delivery

We offer an international shipping service for customers looking to buy Gapseal from outside of the UK.

If you are interested in an international delivery please contact our international sales team for a shipping quote.

Image Gallery

An excellent collection of images showing sash window gaps that have been sealed using Gapseal sash window gap filler.

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