Civil Engineering Reference
In-Depth Information
Roof construction
There are two methods of constructing a roof on a straw bale house. The most common
today uses prefabricated roof trusses. The other alternative and original method is what is
known as stick framing, where the roof is constructed by cutting and assembling
individual pieces of timber to form the roof. To some degree this is a dying art, with
many of the newly trained carpenters having little knowledge or ability to perform this
task. This was never more evident than in recent conversation with a building surveyor.
The building surveyor's story
This is a true story about a building inspector's reservations regarding building stick
framed roofs. The pastor of the church we were attending at the time and personal friend
had purchased a house that was short on a bedroom. Prior to purchasing the house we
had discussions as to the cost of extending the house versus buying a bigger property and
it was clear that to extend the house was the most cost effective alternative. The house was
close to the church, and with the addition of a bedroom and ensuite, offered everything
they needed. They decided on an appropriate design for the extension and I set about
establishing an estimate for the cost of materials. To construct the roof and ceiling by
stick frame method was the cheaper alternative without compromising the design. The
plans were drawn up and submitted to the building surveyor for a building approval.
Not long after the plans were submitted, my friend rang me to say that the building
surveyor was having difficulty approving the plans, because he was unsure of how the
roof was going to be constructed as it was not a truss roof. Some time into the
conversation the inspector inquired as to the age of the person building the roof. When
he was told that I was about fifty years old he became a little more relaxed about the
situation, stating that given my age it was likely that I might know how to build a stick
frame roof.
Within the hour I had a phone call from the inspector asking how I would go about
the construction of the roof. The primary concern he had was that there were several
sections of the roof that had to be supported, but there was no wall below them on which
to transfer the weight. I explained to him that I would use what is known as a barrap on
each of the hips and possibly a scissors prop. He then felt even more comfortable with the
project and agreed to issue the permit on the basis of the information supplied. While he
at first appeared to be happy with the outcome of our conversation it was obvious he was
still a little concerned, as his parting comment was that I should read the instructions on
the box carefully before I fitted the barraps.
I think my response was something to the effect that if I had $10 for every barrap I
had fitted Jan and I would have a lovely holiday. Anyway, all was well with the inspector
and the building permit was issued the next day.
Once the walls and basic roof structure were assembled, it was time to measure and
order the barraps. They were not available locally so we organised for them to be picked
up in Melbourne. It wasn't until after the barraps were fitted when we were re-living the
discussions with the building inspector that it dawned on us that in fact there were no
instructions on the box. Obviously the manufacturers have more confidence in the ability
of tradespeople than the inspectors. This is by no means a slight against the building
