Wood Build Norway. New opportunities with web joist floor constructions. Contribution from SINTEF Building & Infrastructure. Anders Homb June 2013

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1 Contribution from SINTEF Building & Infrastructure Wood Build Norway New opportunities with web joist floor constructions Anders Homb June 2013 Technology for a better society 1

2 Objective, new opportunities Comfort criteria Span width Sound insulation Duct installations Examples Technology for a better society 2

3 Background Timber beam constructions - limited span width - major use of beams with wooden cross sections - major use in family houses and 2-3 storey residiential buildings Recent years - development of new criteria - increased span with possible - development and increased interest of new beam solutions - development of wooden buildings above 3-4 storyes Technology for a better society 3

4 Timber beam floors Increasing market share - ordinary gluelam beams (GB) - web joist beams (WJ) - K-beam (gluelam type) - I-beam Beam hight - GB and WJ beamse no limitations - K-beam and I-beams: up to 300 / 400 mm respectively Technology for a better society 4

5 Span with new criteria Floor Vibration Criteria Evalution of methods and application of Canadian method (Hu & Shi) in Norway - combination of: point load deflection and the lowest natural frequency of the floor (calculated) Example from SINTEF Building and Infrastructure Building Detail sheet: Timber floor construction Gluelam beams Beam dimension (mm) 48 x x x x 300 Span width (m) beam c/c 600 mm 3,1 4,4 3,4 4,8 Other assumptions: Design guide Technology for a better society 5

6 Web joist floor constructions, span width Single span width From SINTEF Building Research design guide Example with 22 mm chipboard, without transversal stiffener Beam hight (mm) Span width (m) beam c/c 600 mm 4,6 5,1 5,6 6,0 6,4 Other assumptions: Design guide Technology for a better society 6

7 Web joist floor constructions, span width Single span width Maximum transversal stiffener 22 mm chipboard Beam hight (mm) Span width (m) beam c/c 600 mm 5,2 5,8 6,4 7,0 7,5 Other assumptions: Design guide Technology for a better society 7

8 Web joist floor constructions, span width Double span width Continous beam on center support - results from a research project - calculations: positive effect (on deflection and natural frequencies) - measurements: small or none effect of the center support (on the Comfort Criteria) Technology for a better society 8

9 Web joist floor constructions, acoustics Sound insulation properties, three solutions measured 1) Concrete layer at the sub floor on transversal stiffeners Airborne sound insulation: R w + C db (pilot building) Impact sound insulation: L n,w + C i, db (pilot building) 48 db (residential building) Fulfill Sound Class B (NS 8175) Technology for a better society 9

10 Web joist floor constructions, acoustics 2) Wood infill between beams on transversal stiffeners Airborne sound insulation: R w + C db (pilot building) 62 db limited / 60 db normal flanking transmission (residential building) Impact sound insulation: L n,w + C i, db (pilot building) 51dB limited / db normal flanking transmission (residential building) Solution fulfill Recommendation with limited flanking transmission Other solutions fullfill minimum requirement, Class C (NS 8175) Technology for a better society 10

11 Web joist floor constructions, acoustics 3) Ordinary floor solution without transversal stiffeners Airborne sound insulation: R w + C db (pilot building) 62 db limited flanking transmission (residential building) Impact sound insulation: L n,w + C i, db (pilot building) db limited flanking transmission (residential building) Solution fulfill minimum requirement, Class C (NS 8175) Technology for a better society 11

12 Web joist floor constructions, ducts HVAC ducts etc. in the beam construction Free transmission path in the open web joist Single family houses no limitations Residential building limitations regarding fire resistance and sound insulation Technology for a better society 12

13 Web joist floor constructions, ducts Residential buildings Ducts penetrating ceiling NOT recommended Ducts penetrating floor construction possible solution - fire resistance: minimum insulation thickness required below the ducts - sound insulation: stiff connections to the upper floor must be avoided Technology for a better society 13

14 Web joist floor constructions, ducts Single family house Example Sound proof solution Example Technology for a better society 14

15 Wood Joist Floor Constructions Project example Husnes beam hight 650 mm - 11,7 m free span width - transversal stiffeners Technology for a better society 15

16 Wood Joist Floor Constructions Project examples Skiptvedt - apartments, two timber floors - Engeneering & production: JATAK Klosterhaugen - apartments, one timber floor - Engeneering: Godhavn - Production: Støren Treindustri Technology for a better society 16

17 Wood Joist Floor Constructions Project example Siriskjær, apartments - up to three timber floors - Engeneering, JATAK Technology for a better society 17

18 Summary, new possibilities Increased span width possible - preferable solutions with transversal stiffeners Sound insulation properties - Solutions fulfilling recommendations and better available Integration of ducts - free transmission paths and solutions fulfilling fire resistance and acoustics possible Project examples & documentation - available Technology for a better society 18

19 More information Floor Vibration Criteria - Project Report 8 (2007) Deflection calculations - evalution of methods and calculations - Project Report 37 (2009) Floor vibration & deflection measurements - measurements and analysis of beam solutions - Project Report 49 (2009) Web joist floor constructions - Solutions and details - Project Report 103 (in progress 2013) Project Reports can be downloaded from (in norwegian) Technology for a better society 19