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Constructing your Roof
The roof protects your home from the elements and
gives it a distinctive style |
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Options for Contructing your Roof
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Key Points |
1 |
Check that the wallplates
are level and properly tied down with strings. |
2 |
Check
that the roof is properly ventilated with all soffit
or facia vents fitted. |
3 |
Never
cut a pre-fabricated truss. |
4 |
Always
use the proper fixings. |
5 |
Always
ensure that the roof trusses are properly braced both
structurally and in accordance with the drawings and
temporarily during erection, especially in windy conditions. |
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Constructing the roof on site is time consuming and therefore
costly and many houses these days are built with a pre-fabricated
trussed roof. These trusses come in two basic forms; those
which are simply deigned to act as the support for the roof
covering and those, attic trusses, where the roof void can
be occupied. Timber
Frame companies almost always include the complete pre-fabricated
roof within their package. Those building traditionally
have to order their roof separately and can choose between
ordering a complete pre-fabricated roof or just the trusses
with the ancillary timber being purchased separately.
The more complex a roof is, the more expensive it will
be. Occupying the roof space by the use of attic trusses
or a cut and pitch roof will increase the overall costs
of the roof construction. However, this is a very good and
relatively inexpensive way of providing extra space within
the home.
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Roof Types
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- Flat roofs are often
considered as potentially high maintenance areas and in
design terms they have fallen out of favour. However, they
still have their place. A flat roof can have a concrete
or timber deck. In previous times most flat roofs were constructed
as ‘cold roofs' where the insulation was beneath the
decking. This is now banned in Scotland and frowned upon
in the rest of the UK and instead, roofs are usually built
with the insulation on top of the decking beneath the waterproofing.
The traditional waterproofing is two or three layers of
felt laid onto hot bitumen, finished off with a layer of
protective chippings. Modern alternatives use four layers
of glass reinforced polyester bonded permanently to each
other and the decking, with no joints or seams.
- 'Cut and Pitch' roofs
are constructed on site from loose sawn lumber delivered
to site. This style of roof is sometimes referred to as
a purlin and spar roof because the construction usually
takes the form of timber or steel purlins spanning between
gable walls supporting rafters or spars between the wallplate
and the ridge. Such a roof has to be designed by an expert
who will calculate the various sizes of timber needed to
perform the many different functions such as purlins, rafters,
ceiling tiles, collar ties, hip
and valley trees.
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Insulating your Roof
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All roofs must be insulated. A cold roof has the insulation
at ceiling joist level and, unless a breathable membrane underlay
is used,
the roof void must be ventilated by the use of proprietary
soffit, eaves and ridge ventilation in order to prevent condensation.
A warm roof has the insulation directly below the roof covering
making condensation unlikely, it does not require ventilation. |
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