In England and Wales a waterproof underlay is laid
across the trusses and held down by the roofing or tile
battens. In Scotland there is a requirement for sarking
boarding beneath this underlay with counter battens
beneath the roofing battens.
Roofs can be either tiled or slated. However,
these two alternatives encompass many different choices with
tiles being divided and subdivided into clay or concrete,
plain or profiled and slates being divided into stone, metamorphic
and man made.
Key Points
1
A slate roof should have
every slate nailed at least once.
2
Tiled
roofs will require nailing according to the exposure
rating and the manufacturer's recommendations. Make
sure this is done.
3
Pay
close attention to areas such as verge tiles are properly
fixed and pointed in to the undercloaking and that all
ridge tiles are properly bedded
4
Make
sure that all lead soakers, valleys cavity trays and
flashings are in properly, especially around chimneys
and roof abutments.
5
The
plumber and the bricklayer may need to be on hand with
the tiler to attend the lead and point it in.
6
Check that the roof is properly
ventilated in combination with the correct form of insulation.
7
If coloured mortar is required
make sure you have it on site.
8
As soon as the tilers have
finished, paint the facia and fix the guttering prior
to the scaffolding coming down.
9
Make sure that the guttering
is the correct size and profile. In Scotland you will
need high capacity guttering.
Types of Tiles
Interlocking concrete tiles are perhaps
the most cost effective of the roof coverings. These are
large tiles that cover around ten to the metre. They are
laid as a single lap, side by side with the grooves on
the underside of the one tile resting within those on
the upper side of the preceding tile.
Plain tiles come in both concrete and
clay forms with the hand made clay tiles being the most
expensive. The coverage rate is around sixty to the square
metre so there is a consequent increase in labour. Additionally
as the tiles are laid double or treble lapped (i.e. each
tile has part of up to two other tiles beneath it) there
is a great deal more battening needed and the weight on
the roof is significantly increased. Plain tiles are often
used for tile hanging.
Pantiles are usually made from clay. Traditionally,
they are single lapped with the downward roll of each
tile simply rolling over the upward roll of the preceding
tile. Modern alternatives in both clay and concrete often
emulate the look of the pantile whilst using the technology
of the interlocking tile.
Types of Slate
Slates vary from region to region. They are usually laid
treble lapped with each slate nailed to the batten. These
days, slates are imported from places as far away as China,
Spain and Canada. Additionally there are many man made slates
on the
market made from either fibre and cement or moulded with a
mixture of slate dust and glass fibre resin. Some of these
combine with the technology of the interlocking tile in order
to create a slate effect single lapped roof.
Perhaps the most expensive mainstream roofing option is to
use stone slates. These are enormously heavy slabs of natural
stone laid in slightly different patterns from region to region.
They are most commonly seen in areas such as the Cotswolds
and the Pennines. They are very expensive to both buy and
lay. Once again man has stepped in to copy them and there
are now acceptable concrete moulded imitations. However, these
copies are by no means cheap.
In Scotland all roofs must be covered with a rigid sarking
board over which the underslating felt is laid with a counter
batten beneath the roofing battens. If a breathable membrane
slating / sarking felt is used then the need for ventilation
at the ridge or soffit may be negated so long as there is
a counter batten creating clear space below and above the
membrane.