How to make a bay window roof and rafter system

How to make a bay window roof and rafter system How to make a bay window on the roof with your own hands

Bay windows are part of the room , which will go beyond the facade plane. The fashion for such architectural solutions has not disappeared since the Middle Ages.

But making a bay window on the roof is difficult even for an experienced builder, and the main secret of construction is experience and knowledge about the features and types of construction, as well as construction methods.

Let's see how to make a bay window on the roof.

General information

Advantages and disadvantages of a roof with a bay window

According to external data, a bay window is very similar to a balcony or terrace.

But structurally, it is part of a house with capital-type walls. Depending on the project, it is capable of occupying several floors, having a trapezoid, semicircle, rectangle or other polyhedron at the base.

Bay window roofs have many advantages:

  • How to make a bay window roof and rafter system Beautiful appearance ...

  • Excellent resistance to strong wind gusts - will be provided by the absence of a roof gable.
  • The streamlined shape makes the roof structure above the bay window reliably protected from various types of precipitation.
  • Lightweight insulation process.
  • Possibility to use the under-roof space as a room for domestic needs or living.
  • Possibility to use complex design solutions when arranging space under the roof.

  • An additional type of protection for the load-bearing walls above the bay window due to the large roof overhang.
  • Reducing the load on the base and its more even distribution due to the absence of a roof gable.

The bay window roofing structure has many advantages, but there are also certain disadvantages:

  • The complexity of the installation work - the mistakes made are difficult to correct, and they greatly reduce the reliability of the architecture element and negate its advantages.
  • Erection of a roof on a bay window requires a large investment of finance - the design and construction work is quite difficult and expensive.
  • Increased heat loss.

Let's consider what types of bay window structures are.

Types and types of bay window structures

A bay window may differ in size and shape, and they can vary in area. Builders and designers can give the bay window almost all possible shapes.

The most popular are:

  1. Trapezium - the side parts adjoin the facade at different angles, except for the straight one. The center-type window is usually larger than the ones located on the sides.

  2. Venetian type of bay window, that is, a semicircle. It will give the appearance of the house smooth lines. It looks great both from the street and inside. Turrets located at the corners of the building can be attributed to this type.
  3. Rectangle - can be made by joining the sides to the facade at an angle of 90 degrees.

    The interior has the usual parameters, but it doesn't look so interesting.

  4. Triangle - Not as popular as other construction varieties. But it all looks very original.

There are also more complex forms of geometry, and they will determine not just the appearance of the building, but also the interior of the room.


Acquaintance, calculations, estimates

Rafter roofing house system with a bay window

The device of the bay window rafter system is made of a ridge beam, and also rafters with different purposes.

How to make a bay window on the roof with your own hands? Since roof slopes can have different angles of inclination, there are several types of rafters, the main ones of which are:

  • Intermediate central - they are attached to each end of the ridge bar, 3 pieces.
  • Oblique (that is, corner) rafters - serving as the main bearing structural parts, are located at the corners of the frame, and also have the smallest slope compared to intermediate rafters.
  • Intermediate - located from the harness to the ridge, between the central rafters.

When installing the roof rafter system, the following is additionally mounted:

  • Ridge-type purlins - crossbars that are horizontally directed and create support for corner and central rafters.
  • Short (that is, external) rafters are structural elements that are attached to the corner rafters and strapping, and also have the same slope.

  • Mauerlat is a beam that is attached to the top of the walls from the outside and evenly distributes the rafter load, which serves as a base, that is, a connecting frame link between the walls and the roof.
  • A brace is a support for the legs of rafters with large spans, and also makes it possible to cover more spans and at the same time save the sections of the main beams.

Consider how to calculate the total area.

How to calculate the area of ​​a bay window

To measure the area of ​​a bay window, you need to use the following tools:

  • A ruler - at least an accurate measuring device that gives a large error.
  • Construction tape - suitable for measuring small areas.

  • Laser rangefinder is a tool that shows the most accurate measurement result, and also makes it possible to carry out work without the help of a partner.

The main problem when calculating the bay window area will be its complex shape, rounded or beveled. If it is not a triangle or a rectangle, but a more complex polygon, it is important to divide it into several simple shapes. The next steps are:

  • Measure all sides.
  • Make drawings, mark the received data on it.

  • Using the calculation formulas, perform calculations for ordinary shapes.

Let's consider a step-by-step algorithm.

Making a bay window with your own hands

The first stage of the bay window construction process is making a project, as well as planning a form. In certain cases, additional paperwork is required.If you build structures, and this will go in parallel with the house, then there is no need for them.

if an extension of a bay window is made to a building that has been in operation for some time, it is important to amend the project and get a destruction for the extension.

Laying the base

The structure of the foundation for the bay window structure is similar to the base of the building. A monolithic tape is suitable, and there are stages of construction. The foundation is in great need of shrinkage, after which it will be possible to process with materials for waterproofing.

How to build a bay window

If you build a bay window with your own hands, it is not recommended to do everything above one floor with your own hands.

the most suitable materials are aerated concrete or bricks, and the masonry has many features that are important to consider:

  1. For internal walls, you can use gas silicate blocks, or aerated concrete.
  2. For exterior masonry, it is best to use high quality facing bricks.
  3. With the simultaneous use of both aerated concrete and bricks, it is required to correctly calculate the load on the base.
  4. Thermal insulation should be in the middle layer, and it can be mineral wool or other, much more modern spray-on materials.
  5. It is required to provide waterproofing - membrane type film or other similar solutions.

  6. The walls of the building and the bay window must be of a monolithic type. This makes it possible to avoid problems during the operational process.

We should also talk about the roof above the bay window.

Roof above the bay window

The main rule when applied is that the roof must fit correctly into the main roofing style. In practice, you can find several types of roofing over the bay window.

The simplest version of the roof over the bay window is to make an extension of the roof of the main building. Its shape will depend on how the bay window is made (trapezoidal, semicircular, triangular or rectangular).

Roofing varieties over the bay window

The most popular types of roofs above the bay windows can be distinguished:

  • Hip - it is made in buildings with an oblong roof, it has ridge and four slopes, two of them are triangles in shape, and two are trapezoids.
  • Hip-roof - used for bay windows with a small area, and also makes the building look like a tower, and also has a large number of faces.
  • Multi-gable - a complex roofing structure of a bay window roof with valleys and gables, a type of pitched roof with two or more gables, elements of a gable type with ridge.

  • Decorative - it is equipped with additional structures, for example, the same towers.

The main criterion when choosing a type of roof over a bay window is to perform its own functions.Most often, you can meet the roof of a one-story house with a bay window, which is the simplest in terms of construction. It will not require large material and labor costs.

Scheme of the rafter roofing system above the bay window

Dimensions, exact location of each frame element and section - all this is provided by the rafter system scheme.

Moreover, the rafter system drawings include the following characteristics:

  • Roof height.
  • Span width.
  • The angle of inclination of each slope.
  • Skate run dimensions.
  • Structural strengthening methods.

  • Features of fixing structural elements.

The photo shows a diagram of the rafter system on the bay window of the hip roof.

How to make a roof with your own hands

When installing the roof truss system and bay window, the same materials are usually used as for the main roof. In addition, to make the roof of a house with a bay window, the following materials are required:

  • Purlins.
  • Galvanized iron.

  • Roof type beams.
  • Self-tapping screws, screws and nails.

Working steps:

  1. How to make a bay window roof and rafter system The initial working step will be the preparation of the belt for reinforcement ...

    This beam support, which also makes the masonry much stronger. The belt material will be reinforced mesh and concrete.

  2. Next, it is important to start installing the truss beams, here they use timber and boards, which are connected by means of screws and self-tapping screws. It is important to cut them with small gaps, which are removed after the beams have been fixed.
  3. Before starting the installation of the rafters, check the angle of the roof slope.

    The rafters need to be adjusted on the ground, and after lifting they are sewn on the roof ridge using metal plates and self-tapping screws, and also attached to the rafter type beams.

  4. After the rafter system, it is required to cover it with waterproofing material and make a crate.
  5. Now you can proceed to the most difficult installation stage, and they also install valleys using different gutters. Bottom bars are required to evacuate snow and water. The upper bar will serve as a decorative function, and also perfectly hide flaws.

    They are attached to the end board, and the joints are also treated with a sealant.

  6. At the final stage, the roof above the bay window needs to be insulated and hemmed.

Now there are some useful things for novice craftsmen.

Recommendations and useful tips

Experienced craftsmen advise you to pay attention to the following points:

  • Before the final choice of the size and type of roof Above the bay window, create a smaller 3D model.
  • All lumber that is used in the construction of the roof must be treated with an antiseptic.

  • The waterproofing film must be at least two layers so that the sealant can be placed close to it.
  • The waterproofing film should allow water vapor to pass through as much as possible.
  • Valleys should be of galvanized type, because the requirements for their moisture resistance and corrosion resistance are the highest.

Following these tips will help you get things right.


Building a reliable, beautiful roof and bay window with skillful hands will give the whole building a beautiful appearance.

Making a bay window on the roof means increasing the internal area, as well as transforming the premises into more spacious and bright ones. In the designs of the bay window, excellent recreation areas and winter gardens, comfortable rooms for children are created.


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