Roof windows retrofitted - prices & costs for installation

• A short overview
• An open word about cheap skylights
• Costs with existing roof opening
  • Other costs
  • Roof window costs
• Costs with the roof closed
  • Legal framework
• Clear thing for artisans: large skylights
• The supreme discipline: dormers
• Be smart and secure funding

The skylight is a quick and easy solution to convert unused roof space into a bright living or working area. How expensive that will be depends on your wishes. The range of window shapes and window sizes is huge. But the investment is far from complete with the purchase of the window. Here we show you the costs that you have to expect for replacing or rebuilding a roof window.

A short overview

The following costs arise when installing a skylight:

• Disposal of rubble and the old window
• Purchase price of the new window
• Insulating material for inside and outside
• Covering material for interior
• Labor costs for the craftsman
  • alternatively: costs for tools and work material
• possibly costs for the construction engineer
• If applicable, follow-up costs for construction defects that are only discovered during installation
• In addition there are the avoidable follow-up costs
  • Structural damage due to penetrating water
  • high energy costs due to wrong or missing insulation
  • Legal costs, fines and dismantling costs in legal disputes with neighbors or authorities

An open word about cheap skylights

We do not want to advertise but we would advise you to pay attention to brand quality when buying a skylight. Some DIY stores offer skylights for well under 100 euros including mechanics and installation kit. Ask yourself: how long should such a window be able to withstand a cloudburst or a snowstorm ">

Costs with existing roof opening

The easiest way to build a new window into a roof is to replace it with an existing one. On many attics, for example, there are still old, single-glazed skylights. Upgrading these rudimentary components to real windows is quick and easy. Since they count as skylights, you have neither construction law nor static important things to consider if you perform an exchange here. The old light hatch is usually made of galvanized sheet metal, which the scrap collector likes to collect free of charge. The situation is different when you replace an old skylight. With only one window, the disposal costs are negligible. For a complete roof truss with a number of old windows, real disposal costs are incurred: a guideline for the disposal of mixed waste is approx. 25 euros per 100 kilograms.

Other costs

The trade now offers a wide selection of complete installation kits for small skylights. If you choose a window of approximately the same size, you will already have a viable solution starting at around 480 euros . These small windows on the roof slope are relatively easy to install. The important thing is that you choose a size that will keep you within a rafter width. If you thoroughly inform yourself in advance and follow the installation instructions carefully, you will also save on expensive structural damage or energy losses.

For tools and materials you have to expect the following costs:

• Window: from 480 euros
• Carpenter hammer: 30 euros
• Rubber mallet: 15 euros
• Rent for jigsaw and grinder: approx. 10 Euro per device and day
• Screws, angles and nails: about 20 euros
• Buy cordless screwdriver (something you always have in the house): about 150 euros
• Work clothes and personal protective equipment: approx. 50 Euro
• Drainage film: about 40 euros
• Disposal costs: about 25 euros per 100 kilograms

For outsourcing: about 250 to 350 euros as a wage from a specialist

Tip: If you buy a new cordless screwdriver, take a device with a second battery. You can not afford to interrupt your work because of failing tools during installation. Once the roof is open, it must go fast so it does not rain in your house.

If you want to have a real window that not only replaces the light hatch, but enhances the whole roof, you need to dimension a little larger.

Roof window costs

The cost varies a bit from the window type and material. At a brand manufacturer, you will find the following prices for the cheapest variants:

• 55 × 98 cm for 478, - Euro
• 55 × 118 cm for 502, - Euro
• 66 × 118 cm for 568, - Euro
• 66 × 140 cm for 598, - Euro
• 78 × 98 cm for 544, - Euro
• 78 × 118 cm for 598, - Euro
• 78 × 140 cm for 646, - Euro
• 78 × 160 cm for 724, - Euro

The prices vary depending on the degree of insulation, frame material and mechanics. Triple insulated windows are about 10-20% more expensive than double insulated windows. For that they are eligible .

Since rafters are usually about 75-85 cm apart, they are on the safe side with this window width. Before buying in your attic, measure exactly the rafter width on your roof again.

Tip: If you want to rebuild a house or put on a new roof truss, put the rafters apart as far as possible. In retrospect, this gives you the greatest possible freedom of choice for retrofitted skylights.

Costs with the roof closed

Building a simple, spar-width skylight into a closed roof is more of a challenge than you might think. The disposal costs for building rubble are comparable to the replacement of an old window. The biggest danger with the installation of a small roof window, however, is to produce a serious construction error due to the incorrect installation. An elaborate roof renovation including replacement of unusable insulation and shuttering can easily cost several thousand euros. Therefore, you should be sure of your cause, or hire a craftsman. You save all costs for tools and protective clothing. Installation for a window by a craftsman varies depending on the type of cover and other factors.

New, standardized and not insulated tiled roofs are easy to equip with a window. Old, insulated roof trusses with a slate roof, on the other hand, are also a challenge for the carpenter's journeyman and more a matter for the master. In the best case, the installation of the roof window succeeds already for 300 euros . But it can also cost more than 1000 euros depending on the effort.

Legal framework

But beware: The installation of a roof window in a closed roof is a structural change of the building. It is not necessarily subject to approval, but you must report the project to the relevant building authority. There may be local building codes that restrict the installation of the skylight. The official jargon speaks in this case of a "change of the building". As soon as the installation of the skylight is classified as a "substantial change of the building", fines of 100 Euro or more are possible. The fine levels vary depending on the state. In NRW, for example, they start at 400 euros. In addition, the demolition costs and the depreciation on the investments made are then due.

It is also advisable to arrange the installation of the windows with your neighbor. You can see the window from an exposed location on his property. Bear in mind that some people may feel disturbed by this and take this into account with an open discussion.

Clear thing for artisans: large skylights

So far, we have only spoken about small, sparrenbreite roof windows. If you think of a generously dimensioned roof window, please refrain from the idea of ​​wanting to install it yourself. A roof window, which requires the cutting of a rafter, must be installed by a master. The installation costs are much higher and can be up to 2000 euros. In terms of price, however, the large windows are not much more expensive than the smaller windows that fit into a rafter space. A 134 x 140 cm window is, depending on the material and degree of isolation at about 850 to 1300 euros.

The supreme discipline: dormers

A skylight creates light. A dormer creates additional space. With the installation of a dormer they increase the area with which they can stand under one roof. This is a significant added value whose investment should be worth considering. Installing a dormer is undoubtedly the job of a master craftsman . There are now prefabricated dormers, which are heaved in one piece on the roof. This saves a lot of time, but on the whole is not necessarily cheaper than an individually built-in installation. In any case, you need a rental crane for the prefabricated dormer, which costs from about 100 euros per hour. The cheapest dormers start at about 2700 euros and reach up to 6000 euros. In addition, you can still expect up to 3500 euros for installation.

But you will receive a significant added value for your roof. The installation of dormers must also be checked by building law! The local building regulations exactly specify the type and shape of skylights. Informing before means saving unnecessary costs.

The following example costs are intended to illustrate the investment volume of a dormer window:

"Big dormer"

• Dimensions approx. 1.50 height x 4.20 m length - 6.000 EUR
• Installation costs - 3.400 EUR
• Transport costs - 950 EUR
• Connection of the loft extension - 2, 000 EUR
• Total price 12, 350 EUR

"Little dormer"

• Dimensions approx. 1.30 m high x 1.40 m long - 3.200 EUR
• Installation costs - 2, 800 EUR
• Transport costs - 650 EUR
• Connection of the loft extension - 2, 000 EUR
• Total price 8.650 EUR

These prices are for a simple dormer. If you want a more elaborate construction, this will have a corresponding impact on the construction costs.

Be smart and secure funding

You can counteract the high costs of installing a skylight by applying for funding from KfW. This is available as a grant or as a low-interest loan. For example, triple-glazed windows are subsidized by up to 25%. This can help to get the best possible solution at a reasonable price. More information can be found on the websites of KfW and your energy consultant. More information on funding can be found here: Energy-efficient renovation (KfW)

Tips for quick readers:

• narrow windows save the structural engineer.
• Clarifying construction projects with neighbors saves expensive litigation
• Rent a power tool instead of buying
• Obtain local building codes
• Observe the monument protection
• isolate correctly
• Consultants and experts consult.
• Obtain subsidies