Loft insulation - at what cost you have to expect for different insulation work

Depending on whether you use your attic as a storeroom or as a living space or whether you are renovating your roof, there are various options for insulation in the attic area. With which costs you have to expect for the different Dämmmaßnahmen, and which factors are thereby price-determining, you will learn in detail in our contribution including sample.

Cost comparison in the example

In order to be able to compare the costs of the individual insulation measures with each other in a more vivid and practical way, we compared the costs for different kinds of insulation in an example of a 120 m² single-family dwelling.

In our family house, we assumed the following conditions:

  • 120 m² floor area (10 x 12 m) = attic area
  • simple saddle roof with 180 m² roof area, without dormers, rafters in the roof area 12%
  • Wooden beam ceiling with 20 cm beam height, 8 cm beam width and 60 cm beam spacing
Dämmarttotal costannotation
rafter15,618 EUR* while new roofing
Interim savings by craftsmen7,245 euros
Interim savings in self-construction2,760 EUR
Under rafters5,800 euros* additionally, at self-construction around 2.300 EUR additionally
only insulation of the top floor ceiling, not accessible2,947 euros* Loft is not used
only insulation of the uppermost floor ceiling and intermediate beam insulation, walkable6,240 EUR* Attic can be used as storage and storage room

All prices in the article are net prices


Note that our pricing example is just sample pricing. They are only intended to illustrate the cost differences that may arise with the different insulation measures on the basis of a concrete example. Depending on the individual circumstances of your house and price differences in the craft sector, the costs incurred there can be significantly different. In some cases, additional work on individual insulation measures may be required in your house, which can then lead to significantly higher prices.


According to the EnEV roof or top floor ceiling must be insulated. For the roof, a maximum heat transfer value of 0.20 W / (m · K) applies, which must be fulfilled. For the top floor, the thermal permeability should not exceed 0.24 W / (m · K).

Criteria for choosing the right insulation

To decide which insulation is right, first determine how to use your attic. If it is heated, the roof must be insulated. If the attic remains unheated, the (much cheaper) insulation of the top floor ceiling is sufficient. Detailed information on the floor slab insulation can be found here.

Walk-in or non-accessible floor slab insulation?

In a non-accessible insulation of the attic is lost after the insulation as a storage room and storage room. It makes sense, therefore, if you set from the outset on a walkable insulation in order to keep open for later additional uses on the attic. The difference in price between walkable and non-accessible floor slabs is in most cases not more than 20 - 25 EUR per m² of attic space, depending on the insulation material used.

On-roof insulation or under-roof insulation?

Here, the decision is easy: If you do not remove the roofing, for example because of a roof renovation, then neither roofing nor Aufsparrendämmung is economical. You can read more about the costs of both types of insulation here. Otherwise, in addition to the high costs of around EUR 70-90 per m² of roof area, they would have to bear the costs of covering the roof, renewing the battens and re-covering.

But if a roof renovation is pending anyway, the roof insulation is the most effective form of thermal insulation, which also relatively reliably precludes the risk of thermal bridges. Otherwise, the alternative is an inter-rafter insulation, if necessary with additional under-roof insulation, if necessary.

Basic cost overview

DämmungsartCost per m²
rafterabout 70 - 100 EUR per m² roof area
Custodial insulation Craftsmanapprox. 30 - 50 EUR per m², often additional under rafter insulation necessary
Interim savings in self-constructionapprox. 15 - 25 EUR per m², often under rafter insulation necessary
Underspread insulation craftsmanabout 30 - 40 EUR per m²
Sub-rafter insulation in self-constructionapprox. 15 - 25 EUR per m²
Ceiling, walkable, by Handwerksunternehmenapprox. 30 - 40 EUR per m² of attic space
Ceiling in self-constructionapprox. 20 - 30 EUR per m² of attic space

This table contains only rough guide values, which are intended as a guide. The total costs actually incurred by you may be significantly higher or lower.

Cost of possibly additional work required

Each of the mentioned types of insulation may require additional work. These costs can often range between 20 and 40 EUR per m². So leave enough room for your calculation if you are not sure what extra work might be needed.

Conservative factors

  • simple roof shapes and roof geometries (for example saddle roof)
  • already good thermal insulation ceiling construction
  • low rafters in the roof area (with intermediate rafter insulation)
  • large interior height for rafters (more than 140 mm)
  • Insulation is possible in self-construction

Increasing factors

  • Complicated or twisted roofs
  • Dormers, gutters and gutters in the roof (must be extra insulated with great effort)
  • Cavities in the roof area (blow-in insulation required)
  • high demands on heat protection (low U-value, efficiency or passive house standard)
  • Use of the highest quality materials, special designs
  • already existing damage to the roof (roof truss, rafters) which must be rehabilitated

Saving opportunities through self-construction or personal contribution

With some types of insulation, you can save a lot of money if you lend a hand. But you should at least have some skill and some basic knowledge.

Doing intermediate savings yourself

Making an intermediate savings by yourself can save a lot of money. If you make the insulation and the cladding as well as the vapor barrier, you save up to 20 EUR per m², with an additional under rafter insulation even up to 35 EUR per m². The prerequisite is that you can buy the insulation as cheap as the craftsman. Otherwise, the savings relativize again something.

Damp the floor itself

In most cases, you can also easily apply the insulation on the floor slab yourself. As a rule, you will save between 5 and 8 EUR per m² of insulation costs. But make sure that you insulate properly and do not create thermal bridges.

Take over additional work yourself

Any necessary additional work, such as the doubling of rafters if necessary, you can even easily take over, even if the insulation work by a craft business are running (recommended, because then the operation for all made mistakes in insulation and subsequent damage due to improper insulation in full liable).

Damm the roof yourself

By contrast, in-house services are not possible for rooftop and rafter insulation. Here all work has to be done by professional roofers.


As all insulation work is an energetic renovation of the house, there are several subsidies available for the roof and floor slab insulation, in addition you can assert a part of the costs for the income tax return. The costs and possibilities for depreciation you will also find out in detail in our general funding overview. If you are planning an attic conversion, you can also apply for subsidies for the entire work and use depreciation.

Tips & Tricks

Be sure to have your attic inspected by an energy consultant or other competent professional. So you can be sure that the thermal insulation is optimally planned and sufficient, but also not oversized. If you are a little above the required minimum, that's enough. Let the expert always calculate what costs pay for themselves and when, and so you can better estimate what makes sense for you. Passive house standard is not always automatically economically sensible.

Video Board: DIY: How To Easily Install Loft Insulation / Insulating Between Joists