Beams size calculator

Beams

Spacing m

Span m

Permanent load kg/m2

Imposed load kg/m2

Service class

Appropriate I beam

  • 240
  • 300
  • 350
  • 400
  • 450

Rafters

Spacing m

Span m

Permanent load kg/m2

Snow load kg/m2

Pitch α °

Service class

Appropriate I beam

  • 240
  • 300
  • 350
  • 400
  • 450

SIA I-beams produce laminated I-type wood (double-T) beams. These beams have proved to be an irreplaceable construction material for building construction in North America and gradually have started to conquer also the European market.

In order to correctly calculate the necessary amount of beams we have developed a calculator, which will help you quickly and easily calculate the spacing and type of the beam depending on the span and load.

How to use the calculator:

  1. Enter the span length. For the floor beams it is the furthest distance between the walls on which the beams rest on. For the rafters it is the horizontal distance (projection of support places, typically the distance between the axis) between the support places of beams (the actual beam is longer than this projection, meaning – the bigger the angle – the longer the beam).
  2. For the rafters enter the roof pitch.
  3. Enter the spacing. Spacing is the distance (on center) between two adjacent beams.
  4. Permanent loads may be changed. According to the standard EN 1991, permanent loads are taken according to self-weight of floor/ceiling/roof assembly.
  5. Imposed loads may be changed. According to EN 1991 the imposed loads are chosen according to category of use. Imposed load of 200 kg/m2 may be used on floors for rooms in residential buildings and houses, characteristic snow loads are taken according to EN 1991-1-3/NA.2.3. In Riga it will be 125 kg/m2.
    *Section calculator has been developed taking into account the partial factors according to EN 1990 “Basis Of Structural Design” which are: for permanent loads – 1.35 and for imposed loads – 1.5. For the section calculator enter only characteristic loads – without partial factors.
    *Loads to be used will depend on each situation individually.
  6. When all the cells are filled, you may view the results. Below the calculator you can find the table with our beams. The beams which may be used are marked in green, and in red – those of which either load carrying capacity or allowable deflections do not correspond the parameters you entered. In order to change the result we recommend changing the beam spacing.