Why do we need a house roof

Roof - plan and build

Roof shapes

Mansard roof, hipped roof, gable roof, flat roof: the differences between these and other roof shapes are sometimes serious and influence the overall appearance of a building. The shape of the roof also determines how the roof can be used. On a flat roof, for example, there is space for a roof terrace, but due to the lack of an incline, solar systems need a support frame. And a Mediterranean tent roof does not allow the expansion of the attic, the installation of dormers or the installation of a roof terrace.

Anyone who wants to expand the roof and use it as living space needs a certain height and, above all, light. This is ensured by roof windows or dormer windows. Roof loggia or roof terrace provide free space at a lofty height.

Roof structure and insulation

The roof structure should also be carefully considered. A rafter roof is common, a purlin roof is only needed for more complex roofs or large dormers. A distinction is also made between cold roof and warm roof.

The roof structure also includes a possible roof insulation. This is mandatory if the roof is to be used as living space. If you want to save money and don't need the space, you can also insulate the top floor ceiling instead of the roof. The attic can then at best be used as a storage room.

When planning the roof, it makes sense to keep the future in mind. Even if the current financial resources do not allow the optimal solution and the client wants to save something - in a few years it may look different. It is good if the roof is then at least prepared, because if purlins have to be drawn in due to dormers, for example, it can be expensive. It would be better to take the future condition into account and, for example, install above-rafter insulation, even if the top floor remains undeveloped for a few years.


When it comes to roofing, optics and price are decisive criteria. But here, too, the development plan can thwart the client's bill: Not all materials or colors are always allowed. In addition to the standard clay tiles, you can also cover your roof with slate, which in turn is standard in some areas or is even required in the development plan. Metal, concrete or plastics as well as various coatings are also options. In addition to appearance and price, the materials also differ in terms of their maintenance requirements and their lifespan.

Another alternative are green roofs, i.e. planted roofs - which in turn have certain requirements on the roof structure. Such a roof has to carry a higher weight, with roof pitches of more than ten degrees safety devices are required to prevent the green roof from slipping off. The roof structure and the final construction must also be designed to be root-proof.

If you want to use your roof as a support surface for photovoltaic systems or solar thermal systems, you don't have to worry too much about the color and shape of the roofing and can use inexpensive standard tiles - provided the development plan allows it. Alternatives would be solar tiles with integrated solar cells.

Roof decorations

Roof decorations have been around since ancient times. Back then, people decorated their roofs to please the gods. Elaborately designed decorations also indicated the homeowner's origin or occupation. In the 19th century, farmers decorated their houses with animal figures, each with a specific symbolism. The ridge rooster, as a rooster on the roof, was supposed to protect the house from fire. It was also a symbol of fertility and was placed as soon as the first son was born in the house. A horse, on the other hand, symbolized strength and freedom, an owl was supposed to protect against burglars.

Today, roof decorations are more an expression of personal individuality and in most cases a purely decorative element. If the figure is mounted directly on the roof tiles, for example at the ridge connection or termination, it should be attached by the roofer. Other figures can be attached with a wire or screwed or glued on. Homeowners who are not afraid of heights can do this themselves. But be careful: if the roof decoration is blown off the roof in the wind, the owner is liable for any damage that may result. Decorative elements should therefore be attached in a weatherproof manner.


Roof extension and use

In order to use the attic afterwards, the roof must be well insulated, the attic must be expanded from the inside and, of course, sufficient space must be available. To ensure this, dormers can be installed. Skylights are much cheaper, but they don't add to the living space. The most expensive and complex solution for creating living space is to add storeys to the roof, for example to raise the knee, to reduce the roof pitch or to gain an entire floor.

With all of this, the question arises as to how the newly created space should be used. Fitting a bathroom or kitchen in particular on the slope can be challenging. The impractical sloping roof is often contrasted with a charm of its own.

Roof renovation and maintenance

After 20 or 30 years, the roof often doesn't look so nice anymore. Then it's time to clean it up and, if necessary, apply a roof coating to protect it from moss, lichen and water. The less time-consuming renovation work also includes, for example, replacing the gutter.

A well-maintained roof can survive 80 years and more. But at some point the time has come to cover every house again. At the same time, the roof of an old building can be insulated or a skylight or dormer built in.

That's how much a roof costs

The roof often accounts for eight to ten percent of the cost of a new building. However, the exact costs depend on the effort and the materials used. A mansard roof with dormers, turrets, roof garden and golden roof tiles is of course more expensive than an undeveloped gable roof with standard tiles.

For the building owner, however, the prices of different roof variants are often only visible as surcharges within an overall invoice. Depending on the building partner, these surcharges can vary greatly, depending on the house and which roof shapes are offered as standard. The roof is only billed as an individual component if the client himself awards it as an individual service, for example if he organizes the building of a house on his own or if he has the roof of an old building renewed.

The following sample calculations show how different the costs for a roof can be and give a rough guide for personal calculations. However, the actual price can vary widely. The best thing to do is to get offers from different companies to builders and then choose.

120 m² roof area, standard pitched roof without dormers, without skylights, with floor area insulation in-house, simple roofing.

  • Roof structure 12,000 euros
  • Cheap coverage: 4,000 euros
  • Insulation (material only): 1,500 euros
  • Standard pipes and gutter: 1,000 euros

Total: 18,500 euros

120 m² roof area, hipped roof with two large dormers, purlin roof, slate roofing.

  • Roof structure 12,000 euros
  • Two dormers 9,000 euros
  • Slate cover 10,000 euros
  • Insulation 7,000 euros
  • Standard pipes and gutter: 1,200 euros

Total: 39,200 euros

120 m² roof area, standard pitched roof, two roof windows, above-rafter insulation, simple roofing.

  • Roof structure 12,000 euros
  • Cheap coverage: 4,000 euros
  • Two skylights: 1,200 euros
  • Insulation: 6,000 euros
  • Standard pipes and gutter: 1,000 euros

Total: 24,200 euros

100 m² flat roof as inverted roof, staircase, roof terrace and intensive greenery

  • Flat roof as an inverted roof: 12,000 euros
  • Rise: 5,000 euros
  • Intensive green roof garden: 6,000 euros

Total: 23,000 euros

Many builders need a bank or other lender to finance a house or a new roof. Often, however, the building project can also be funded. The KfW Bank in particular has interesting programs on offer for builders.

Matthias Dittmann

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