Innovative Smart Wood Structures

What is Kielsteg?

Whati s Kielsteg


Kielsteg Element Detail Cantilevered projections

Projecting roofs are frequently demanded for industrial and commercial buildings. KIELSTEG can be used to make cantilevered projecting roofs up to ten metres deep.

Kielsteg Element Detail Wide spans for roofs and structural floors

Creation of low-profile load-bearing structures spanning spaces up to 27 metres as single-span beam structure and up to 35 metres as continuous beam structure.

Kielsteg Element Cambered single-span elements

KIELSTEG elements can be made optionally cambered upwards along their length, with corresponding effects on the serviceability limit state.


Kielsteg Dachkonstruktion

economically efficient structural floors and roofs from 5 to 27 metres clear span

… the wide clear spans ensure flexible use of the building

aesthetically attractive underside makes suspended ceilings unnecessary

fire resistance class up to REI 60 without additional constructive measures

… high degree of prefabrication, therefore quick construction

cantilevered projecting roofs up to 10 metres

… environmentally friendly, sustainable, carbon-negative building method

… a personal contribution towards the use of natural resources and responsibility for

the coming generations


Kielsteg Dachkonstruktion

Use: Structural floors and roofs
Internal structure: Repeating cellular structure with upper and lower flanges of spruce timber connected by webs of plywood or OSB
Wood: Spruce
Surface: Industrial quality/Visible quality (one side); planed and untreated
Dimensions Width: 1,200 mm

Laid width: 1,165 mm

Thickness: 280 mm to 800 mm
Length: 5.00 m to 35.00 m
Fire resistance class: Fire retarding REI 30 is the standard fire resistance class for all KIELSTEG

Highly fire retardant/REI 60 is possible from KSE 280 upwards

Long edges: Edges are rebated to overlap/join neighbouring KIELSTEG elements
Service class: Service classes 1 and 2
Bonding: MUF glue of emissions class E1
Moisture content: On delivery: 12±3%
Dimensional changes: (humidity-dependet) Longitudinal: 0.01% per 1% change in wood moisture content
Lateral: 0.24% per 1% change in wood moisture content
Thickness: insignificant


Raw Materials


For the zones of the element under compression and tension, finger-jointed spruce timber of the strength class C24 is used.


Webs of 3-ply, 4 mm spruce and pine plywood form the interior cellular structure of the elements of thicknesses 280 mm to 330 mm.


OSB3 sheets of thicknesses 8 mm, 10 mm and 12 mm form the interior cellular structure of the elements of thicknesses 485 mm to 800 mm.

Holz Detail Kielsteg Detail Kielsteg Detail


Kielsteg Element Detail

German Approval

The DIBt (Deutsches Institut für Bautechnik) is the German approval body for construction products and types of construction. The national technical approval (allgemeine bauaufsichtliche Zulassung) regulates the manufacturing and use of KIELSTEG elements.

Deutsches Institut für Bautechnik Logo

PEFC, the Program for the Endorsement of Forest Certification Schemes, is a certification and labelling program for products derived from ecologically, economically and socially sustainable forestry. When customers buy products with the PEFC label, they can be sure that their purchase supports the use of wood produced under environmentally friendly conditions.


Schweighofer Preisverleihung

Schweighofer Preis Schweighofer Preis 2013

Innovation award for the European forest-based sector

Inventum Inventum 2014

The prize of the Austrian Patent Office for the best patent of the year 2013

Materialpreis materialPREIS 2015

First prize in the category ‘wood and wood materials’, awarded by the materials agency raumPROBE

Kielsteg GmbH | Reininghausstraße 13a | 8020 Graz, Austria | Tel.: +43 (0) 316 269 7881 | Mail: | Legal Notice