HQL - Dimensioning of floor joists
Table 1 Maximum span for floor joists (A) at a given joist dimension and agiven joist distance (B) for
housing. Figures in brackets apply to light industrial buildings.
Dimension
in mm:
45 x 145
45 x 170
45 x 195
45x220
45 x 245
45x270
45 x 295
58 x 145
58 x 170
58 x 195
58 x 220
58*245
58 x 270
58x295
Joist distance, center to center in m (B)
0,3
0,4
0,5
0,6
0,8
1,0
3,40 (2,85)
4,00(335)
4,60 (3,85)
5,20(4,40)
5,85 (4,90)
6,45(5,40)
7,00 (5,90)
3,70 (3,10)
4,35 (3,65)
5,05 (4,20)
5,70 (4,80)
6,35 (5,35)
7,00 (5,90)
7,65 (6,45)
3,10 (2,55)
3,65 (3,05)
4,20 (3,50)
4,75 (3,95)
5,30 (4,45)
5,85 (4,90)
6,45 (5,35)
335 (2,80)
3,95 (3,30)
4,55 (3,85)
5,15 (4,35)
5,75 (4,85)
6,35 (5,35)
6,95 (5,85)
2,85 (2,40)
3,35 (2,80)
3,85 (3,25)
4,40 (3,70)
4,90 (4,10)
5,40(4,55)
5,90 (4,95)
3,10 (2,60)
3,65 (3,05)
4,20(3,55)
4,80 (4,00)
5,35 (4,50)
5,90 (4,95)
6,45(5,40)
2,65 (2,25)
3,15 (2,65)
3,65 (3,05)
4,10(3,45)
4,60 (3,85)
5,10(4,25)
5,55 (4,65)
2,90(2,45)
3,45 (2,90)
3,95(3,35)
4,50 (3,75)
5,00(4,20)
5,55 (4,65)
6,05 (5,10)
2,40 (2,00)
2,85 (2,40)
3,30 (2,75)
3,75(3,15)
4,15 (3,50)
4,60 (3,85)
5,05 (4,25)
2,65 (2,20)
3,10 (2,60)
3,60 (3,00)
4,05 (3,40)
4,55 (3,80)
5,00 (4,20)
5,50 (4,60)
2,25(1,85)
2,65(2,20)
3,05 (2,55)
3,45 (2,90)
3,85 (3,25)
4,25(3,60)
4,65 (3,95)
2,45 (2,05)
2,90 (2,40)
3,35(2,80)
3,75 (3,15)
4,20(3,55)
4,65 (3,90)
5,10(4,30)
Example
Wanted: Floor span of 5.5 m in a single family house.
According to the table the following possibilities fulfill this requirement:
45 x 245 mm joist center to center distance 0.3 m, or
58 x 270 mm joist, center to center distance 0.6 m
HQL-floor joists may be used as
floor partition in dwellings,
offices and in larger assembly
buildings. .
The maximum span of the floor
joists of different dimensions and
distances is stated in table 1.
DESIGN ASSUMPTIONS
Table 1 distinguishes between two
load combinations: Housing: Load
in dwellings, hereunder apartments
and single family houses, habitable
and
non-habitable
attics
corresponding to an imposed load of
1.50 kN/m2 and a load from light
internal walls of 0.5 kN/m2. Apart
from dead load of the joists also a
dead load from the floor and ceiling
construction of maximum 05
kN/m2 is included Light industrial
buildings:
: Load in offices,
laboratories class rooms and rooms
used
for
asimilar
purpose
corresponding to an imposed load
of 2.50 kN/m2 and a load from
light internal walls of 0.5 kN/m2.
The floor joists are dimensioned
assuming they are simply
supported and the calculations
have been carried out according to
normal safety class and moisture
class I.
The values in the table
guarantee sufficient load capacity
and a maximum deflection of
1/500 of the span at an imposed
load of 1.50 kN/m2 and 1/300 of
the span for dead load + usual
imposed load + (0.75 kN/m2).