Finishing slopes of plastic windows - all the subtleties and rules

Gusevsky Andrey Anatolyevich

Trimmed slopes

Today we’ll talk about decorating window slopes. Many do not attach much importance to this most important component of the finish, but in vain.
Probably many had to deal with this problem: they removed the old, wooden windows and installed new, plastic ones in their place. At first everything was just wonderful, the windows are beautiful, they open and close easily, do not require annual sealing, and fit well into the interior.

Mold on the slopes - not a cause, a consequence

But a short period of time passes, and you notice that mold begins to form on the slopes, especially in the corners.

Slope mold

The acquisition and use of various modern household chemicals does not give a result. After a short period, the mold appears again.
So what is the reason?
And it is quite commonplace: the interior of the slopes of the plastic windows was finished incorrectly, with gross violations. In this case, the appearance of mold is not a cause, but a consequence.

Consequences - visible and not visible

Understanding that many people are concerned about the issue of eliminating this problem with their own hands, today we will consider it in detail, and here's why. Solving the issue of how to get rid of mold on the slopes of plastic windows will help to understand at the same time that technology slope finishes for plastic windows, different from finishing for wooden windows.
This understanding will allow you to avoid mistakes in the future. It is always easier to warn than to correct.
First, let's talk about the formation of mold itself.

Our reference - Mold is a widespread microorganism in nature. Its second name is fungus.
Being actually microscopic fungi, mold, like all fungi, has spores. If the mold itself can only spoil the appearance of the room, its spores are very harmful to the human body.
Settling indoors, they multiply and can cause: eczema, bronchial asthma, dermatitis, thrush, allergies and a large number of different diseases.

Ventilation - as one of the components

The cause of its occurrence is moisture and poor ventilation.
Many may have a question - before installing plastic windows, everything was fine, but problems arose only after installing them. And here ventilation, ventilation, we did not touch?
In this case, it may just be in ventilation. Your old wooden windows were far from ideal.
Various microcracks allowed air to freely ventilate the room. Even seasonal sealing allowed enough air to penetrate into it.
Unlike wooden windows, plastic windows are airtight. So, the way out of this situation is the constant ventilation of the room.
We could still draw your attention to the window sills. As you probably know, in the old panel houses they were quite small in width and this is no accident.
Their size allowed warm air from heating radiators to circulate freely.

Window sills - deceitful beauty

When installing plastic windows, many are installing new window sills. As a rule, they try to install as wide as possible.
Of course, this is beautiful and you can decorate the window by installing pots with flowers or other interior attributes on them. In this case, to restore ventilation it is enough to drill several holes in the windowsill.
Thus, ventilation will be restored.

Window sill vents

Slotted valves - half the solution

Another solution is to install special slotted valves on the windows. They are widely represented in the market and have manual or automatic control.
We could consider this issue in more detail, but the topic of our article today is slopes, let’s talk about them.

Moisture - the second term

The second factor in the occurrence of mold is moisture. This is a topic just for our article.
Moisture formation in the corners of the slopes of plastic windows can only be in one case - the technology for finishing the slopes of plastic windows is incorrect.

Correct slopes - we solve the problem radically

• Take a specific case: Panel multi-storey building, after replacing wooden windows with plastic, mold began to form on the slopes.
• Attempts to remove did not solve the problem; it formed again and again, gradually moving to the walls.

Bridges of cold - “nailing with a computer”

Moisture can form on slopes only if there are cold bridges. Cold air, colliding with the warm air of the room, forms condensation, moisture.
It becomes clear that the whole reason is in the cold slopes. On many resources they give “practical advice” - to establish a vapor barrier, to sheathe the slopes not just with drywall, but with a sandwich, etc. etc.
What can be said about this? On the one hand, some tips may solve the problem, but another question begs, why "fence the garden"?
It is clear that if someone advises to mount a heating system in the slopes, using the example of a warm floor, this solution will save from mold. But we must understand that the price of individual materials is quite high, and the saying begs to hammer nails with a computer suggests itself - perhaps, but expensive!

Determining the cause - stage one

But to the point:

• First you need to determine how we have installed the plastic window.
• Everyone knows that a simple wooden window is much wider than a plastic one.
• It is important to understand that the formation of condensate on the slopes is greatly affected by the thermal conductivity of the building wall.
• The thicker the wall and the slope of the wall, the higher the thermal conductivity.

Any window has two slopes, internal and external. It is important to know that the window box of a wooden window is much thicker than a plastic one.
The window itself is set based on the calculation of the wall thickness of the building. The middle of the thickness of the window and the wall should match.
Thus, the window is installed exactly in the middle, this is no accident.

Scheme of the installed wooden window

This installation allows you to position the center of the axis of the window at the same distance from the outer and inner part of the wall. Accordingly, slopes are made on both sides of the window.

First inspection - first mistakes

What do plastic window installers do?

Dismantling scheme

They remove the internal slopes, leaving the external ones, and then insert the plastic window right next to them. But we already know that the window box of a plastic window is much thinner than a wooden one.
Thus, the center axis of the box and the center axis of the wall do not match. If earlier the center of the wall axis was in the center of the window axis, now it is inside the room.

Plastic window installation diagram with old exterior slopes

The first mistake entails the second

What happens next:

• Inside they make slopes.
• If we assume that the center of the axis of the wall is the freezing point, then it becomes clear that now it is located just under the internal slopes.
• Accordingly, the slope simply can not be warm.
• In addition to this, a wide window sill is installed in the formed deep opening. Everything, condensation on the slopes is provided to you.

It would be correct to set the window as shown in the figure below.

Proper window installation

The window is correctly installed or not, in any case, it is necessary to completely remove the internal slopes.

Our advice - if you find that the window is installed with an offset, we recommend that you make the correct installation. In this case, the guarantee against moisture and condensation will be full.

But what if there is no way to dismantle and then install a plastic window?

What they forgot to pay attention to - external slopes

Let's pay attention to how the slopes are finished on the plastic windows from the outside. We repeat, usually installers do not touch the external slopes when dismantling the old window.
Regardless of the accuracy of dismantling, cracks and chips are formed on them.

Chips on the external slopes

• By inserting a new plastic window, the existing gap between the wall and the window is foamed.
• A small amount of foam protrudes from the outside through cracks and chips.
• There is no slope outside, but only inside.

The owners of the upper floors are especially guilty of this. From far away it is not visible and good.

Slope int. You can see the foam - this is wrong

But you need to know that under the influence of ultraviolet rays, the foam begins to break down. Over time, sufficient pores are formed in it to penetrate moisture and cold.

Destruction of foam under the influence of sunlight and weather

Freezing in the winter, the moisture which has got inside, aggravates the situation even more.
As a result, the main slope directly becomes the internal slope itself. Hence the cold, condensation, moisture.

Correction of the situation - external slopes

So:

• We removed the completely internal slopes.
• The same should be done in areas outside where foam is visible.
• We remove the damaged foam and re-foam.

Our advice - before starting work, remove all existing paint from the slopes.

• Do not forget to take off the tides. Most likely there are also enough pores and cracks. Everything needs to be foamed.
• Get tile glue from a hardware store. With its help it is very good to close up all cracks and chips outside.

When to finish puttying?

• The rule should be like this: nowhere on the outside should there be more than one open area of ​​foam. This is the main technology for finishing slopes on plastic windows.
  Nothing more, just the quality and compliance with elementary rules for the use of materials.

Our advice - when filling gaps with foam, use a special gun. Foam for pistols is better and work, therefore, much more convenient.

Finishing - internal work

After that, you can do the internal slopes.
Everything is simpler here. We cut off the excess foam and carry out the slope according to all the rules.
Today we will not touch on how to make slopes, but in this case, this is not particularly important, we have completed the main task.
If you installed plastic windows, the technology for finishing slopes cannot be performed without following the above tips. Otherwise, problems cannot be avoided.

Do you change windows? - do it right

Let's summarize all of the above:

• When installing plastic windows, make sure that they are correctly positioned relative to the central axis of the wall.

Our reference - this advice does not apply to buildings with external finishes made using various insulation.

• After installing the windows, pay particular attention to the external slopes.
• Protruding outside foam is the very first sign of future trouble.

Get to know the different kinds window decoration and slopes, you can read the relevant articles on our website or by watching the corresponding video.
Good luck to you!