Civil Engineering Reference
In-Depth Information
Note: unless otherwise specified, always fit timber with the greater dimension
vertical. So in this case the bearer would be fitted with the 100 mm vertical, making the
horizontal width of the top of the bearer 75 mm.
F8 refers to the stress grade or strength of the type of timber that is required
OBHW refers to the type of timber. In this example: Ordinary Building Hardwood.
@1.8 crs refers to the position of each bearer relative to the neighbouring bearer.
The crs is short for centres. This means that the measurement of 1.8 metres is to be
measured from the horizontal centre of each bearer. An easier way to measure this is from
the common side of each bearer. That is, if you measure from the northern side of the
first bearer to the northern side of the next bearer it will give you the same result as
measuring from centre to centre on each bearer, and is much easier (see Figure 3.1).
centres
=
common edge
Figure 3.1
The centres and common edge are the same measurement
Stumps distance
The distance between the stumps is detailed in the timber specification schedule. Having
established the position of the rows of stumps we now need to find the position of each
stump along the rows of stumps. Again this may be on the cross section drawing but it is
unlikely. The cross section drawing will only detail the position of the rows of the stumps
or, the distance between the stumps along the rows as it is a two-dimensional drawing.
Refer to the timber specification schedule where you should find a description of the
stumps and their spacing. Care should be taken when gaining this information, as there
are often different spacings for the stumps in different positions within the building to
support differing building loads. For example, the outside walls of a straw bale house are
likely to have stumps every metre whereas the stumps supporting only the floor on the
inside of the house may be at 1.5 metres or even greater. If you are unable to find the
details on the stump spacings in the timber specification schedule, which is likely if you
are using concrete stumps, you will need to refer to the details supplied by your engineer.
The stump spacing details in the specification schedule should read something like this:
Stumps 100 × 100 F7 Cypress Pine @ 1.5 crs.
Again 100 × 100 refers to the dimensions of the stump.
F7 refers to the strength or stress grade of the timber.
Cypress Pine is obviously the type of timber.
@1.5 crs refers to the spacing of the stumps.
On occasions you may find that the term spacings is used rather than centres (crs). In this
instance the measurement refers to the actual gap between the timber.
During the process of fitting the stumps you are going to need to put all the dirt that
comes out of the stump holes back into the hole. There is nothing more frustrating than
trying to separate the dirt from long grass and sticks that happen to be on the building
