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How to Remove a Window Sill – Manual for Do-it-yourself Enthusiasts

Anyone who wants to install new aluminium, uPVC or natural stone window sills, has to first remove the old models. But there is no need for professional help. This manual will help you to plan and perform the professional removal of the sill. It will list all necessary tools, guide you through all steps and point out the important factors. Removing the window will be as easy as a walk in the park. Besides this manual, you will also need a few tools for the removal. No matter if you want to remove aluminium, uPVC or natural stone window sills, the proper equipment is absolutely necessary. You should make sure to have the following equipment:


  • Cover sheets or foil
  • A new sill; if applicable


  • Crowbar
  • Hammer
  • Chisel
  • Rip saw
  • Spatula
  • Impact drill
  • Cordless screwdriver

Aluminium or uPVC sills can usually be removed by one person. Natural stone models are very heavy, however, and require a helping hand. This can prevent furniture, laminate and tiles from being damaged.

1. Preparation

You will have to prepare the old construction component before the actual removal. If furniture, tiles or laminate are in the closer surrounding, they should be covered with either a sheet or foil.

Window sills are sometimes plastered into the masonry. The plaster can fall of while removing an aluminium, uPVC or natural component and can dirty furniture, tiles and laminate. Especially when working with a crowbar or chisel, take care, as flying fragments may damage the frame. This is why it is recommended to cover the frame as well.

You should re-measure the dimensions of the old window sill and compare it with the new one before removing it. This will ensure that the installation process can be performed smoothly (Fig. 1).

2. How to remove an outer Window Sill

The outer components are usually made of aluminium and are attached to the frame with screws. You will therefore only need a cordless screwdriver and the appropriate bits for this task.

  • Open the casement. You will be able to work properly on the outer sill from the inside.
  • Unscrew all screws with the cordless screwdriver (Fig. 2a).
  • If your sill is plastered into the wall, you have to use the crowbar and chisel it out carefully. Please be careful not to damage the plaster and the insulation beneath (Fig. 2b and Fig. 2c).
  • You can now remove it easily. Mineral wool is often used to bed many models. You can either use them again or recycle them together with the old construction element (Fig. 2d).

3. How to remove an inner Window Sill

A sill that is mounted inside is also usually not sealed in the wall - unless it is a natural stone model. The common models are just attached to the plaster and the removal should not be a problem.

  • Inner attached ones made of aluminium, uPVC or stone are often additionally connected under the plaster with angles. Use the cordless screwdriver to remove the screws from the angles (Fig. 3a).
  • Uncover the angle under the plaster, so you can remove the respective screws as well. Be careful and do not damage the wall. This will prevent unnecessary renovations (Fig. 3b).
  • You can now use the crowbar to remove the window sill. The more careful and precise you work, the less renovation work that will have to be done afterwards (Fig. 3c).

No matter if you remove the element outside or inside, this manual will help you perform the removal without complications. You can then restore the old components and re-install them on another window or in your winter garden.

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