How to install a window sill if the window is already standing

Sometimes, due to damage, it is necessary to dismantle the old window sill and install a new one. Some people did not order a window sill along with plastic windows at one time, but later decided to install it. Now we will look at a step-by-step guide for installing a plastic window sill. Moreover, this work is quick and not complicated. You can do it yourself, saving money.

Let's start installing the window sill

The first thing you need to do is remove unnecessary things. For example, dismantle the previous window sill, and also use a hammer drill to hollow out grooves so that a new window sill can be inserted into them.


The depth of the grooves can vary depending on the length of the window sill, as well as how possible it is to make these grooves. Typically the window sill protrusion is 5–10 cm.
Next, measure the length of the window opening, taking into account the grooves. For this you will need a tape measure. Using this size, cut off the excess from the window sill using a jigsaw. To ensure that the angle you will cut is 90 degrees, use a pencil with a square.




After cutting off the excess, try on the window sill.

If it does not fit, then you need to use a hammer drill to clear the grooves a little. Please note that when taking measurements it is important to take into account the side plugs that are attached to the window sill.



Prepare construction foam by stirring it according to the instructions indicated on the can.

The window sill itself is attached to the outside of the window. First, you need to dismantle the ebbs, which are usually attached to self-tapping screws. Next, screw in several screws from the inside with an indentation of 30–40 cm to make marks. The screw should come out on the other side. Thus, on the outside you will already have holes into which you will screw the screws to secure the window sill.



When you screw the self-tapping screws into the window sill, immediately screw the ebb screws into the same holes in which they were secured.

When the window sill is installed with self-tapping screws and foam, it is necessary to repair the irregularities that were formed during installation. To do this, mix the required amount of putty to seal the seams. The main space of the side grooves can be sealed with mounting foam and then puttied to level the slopes.




Also in the lower part of the window sill, it is necessary to eliminate the gaps between the wall and the window sill using polyurethane foam and putty. Since the space between the window sill and the radiator may be small, this makes it difficult to seal uneven areas. Therefore, some install a special film to reflect heat, thus increasing heat transfer, as well as covering irregularities formed during the installation of the window sill.


When the putty dries, it must be rubbed with special sandpaper to level the surface and make it smooth.


Next, paint the slopes.It is best to paint the slopes completely, and not just those parts that you putty, since even the same color can differ and stand out against the general background. It is convenient to do this with a roller.

When you finish installing the window sill, remove the protective film. If you do not remove it for a long time, it will be much more difficult to do so later.

Why is it better to do this work yourself? For 1 linear meter, a master can estimate the work at 1000 rubles, depending on the area. Of course, in the capital, or in other large cities, this cost may be higher. But in fact, this work is simple and can be completed in just a couple of hours.