EXTERNAL FEATURE DEFINITIONS
The definitions below are for features
found on the outside of a building.
Party Structures Defined - Party Wall Act Etc. 1996
A
structure which both parties enjoy the use of or benefit from. An
example of this would be where both parties gain support from a
wall or utilise a chimney or chimneys.
Any work to party structures, such as party walls or party
chimney stacks, require agreement under the Party Wall Act. We
would be more than happy to offer you help and advice in this
matter.
Tile on Edge Defined
A tile sitting sideways,
bedded in cement mortar which has been utilised as a flashing. Due to the cement mortar it is bedded
in being brittle and prone to cracking, this is not an ideal material. We
would always recommend the use of lead flashings.
Flaunchings Defined
A low, wide cement mortar fillet surrounding the flue terminal
on top of the chimney stack to throw off rainwater.
Flashings Defined
Flashings prevent dampness from
entering the property, usually at junctions where materials change. Such
a junction is the one between the chimney and the roof.
Spalling Defined
Spalling occurs to brick or stone
when water penetrates the surface and via freezing and thawing
starts to cause deterioration to the surface. This in turn allows
further water penetration and the surface breaks up further. This
ultimately can lead to water damage or structural damage to the
area.
Re-Pointing Defined
Re-pointing is carried out
where the existing mortar has failed and broken away to stop damp
penetration and further deterioration. The
mortar should be raked out to approximately 20mm and then replaced
with a mortar of a similar type, therefore, stopping damp occurring.
Capping Defined
Capping is a practice used when
chimneys are no longer in use to prevent moisture from entering
the structure in the form of rainwater via the chimney. This usually involves the closing
of the chimney with a tile or slab positioned across. It
should include vents to allow air circulation.
Parapet Walls Defined
These walls are usually
above the roof line and often sit on the boundary of the property. Due
to their position they are relatively exposed and suffer from deterioration
due to the elements.
Blinding Defined
This is where a mortar is used to bed the slate or tile.
Polycarbonate Defined
Transparent, extremely tough
plastic sheet, used for security glazing. It may also be an insulating light panel, double
walled or triple walled, or 10 or 16mm thick. It is not
a fire hazard as it has low ignitability and low flame spread,
and releases little heat and little smoke if burnt. It can
be coated to resist damage from ultraviolet.
Flashband Defined
Flashband is a sticky backed felt which is best used for temporary
repairs only.
Proprietary Flashings Defined
These are typically
supplied by the manufacturer of the roof covering and will be specially
made to fit the profile of the roof covering. Typically
they are aluminium.
Cement Fillets/Cement Flashings
This is where cement has been used to cover up or fill the junctions
between two areas, for example between a roof and a wall to help
prevent dampness. Cement is a brittle material and prone to cracking
which in turn allows dampness into the structure. We would always
recommend they are replaced with lead.
Torching Defined
Usually lime mortar dabs (but
can be moss) which the slates sit upon. These are used to
reduce the wind traveling through the building therefore reducing
the risk of wind damage.
Nail Sickness Defined
The weakening of the fixing
nails to slates or tiles due to the nails which fix them to the
battens rusting. This is normally
attributed to problems with slate roofs.
Lead Tingles or Lead Slaps Defined
These are strips of lead usually about 25mm wide which are used
to secure slates where they have slipped.
Turnerising Defined
"Turnerising" is a process used usually when roofs have started
to deteriorate or leak and it involves the covering of a roof with
a mesh and coating in bitumen. It is almost impossible to
economically save or re-use materials which have been treated in
this manner.
Nibbed Clay Tiles Defined
A nibbed tile is one which has raised areas known as nibs, usually
two in number, at the top of the tile to enable the tile to be
fixed to the roof batten which, in turn, fixes to the roof structure.
Blinding Defined
This is where a mortar is used to bed the slate or tile.
Polycarbonate Defined
Transparent, extremely tough
plastic sheet, used for security glazing. It may also be an insulating light panel, double
walled or triple walled, or 10 or 16mm thick. It is not
a fire hazard as it has low ignitability and low flame spread,
and releases little heat and little smoke if burnt. It can
be coated to resist damage from ultraviolet.
Flashband Defined
Flashband is a sticky backed felt which is best used for temporary
repairs only.
Proprietary Flashings Defined
These are typically
supplied by the manufacturer of the roof covering and will be specially
made to fit the profile of the roof covering. Typically
they are aluminium.
Delamination Defined
This occurs in sedimentary
and metamorphic rocks such as slate which are built up of layers. It
simply refers to the layers breaking down.
Sarking Felt/Underfelt Defined
This is the felt
that sits between the roof covering and the timber battens and
forms an additional protective layer to stop the wind lifting the
roof and to stop the elements from penetrating the structure. This
was first used in the late 1940's/early 1950's and is a requirement
for current Building Regulations.
Close Boarding Defined
These are timbers positioned
on the common rafters which are butt jointed together. They
add to the wind resistance and water-tightness of the roof together
with the overall structural integrity of the roof. Usually this
type of roof does not have an underfelt, this can lead to problems
if the roof is not cross-battened as wet rot will occur to the
underside of the timbers. This is very difficult to identify.
Feather Edge Boarding Defined
These are timbers positioned on the common rafters which form
the slope of the roof. These timbers are butted together but they
are cut at an angle, or feather edged, to give a lip for the nibs
of the tiles to sit upon.
Fire Walls Defined
Fire walls help prevent the spread of fire through roofs and are
a relatively recent Building Regulation requirement .
Purlins Defined
The purlin is the horizontal timber member usually running from
gable end to gable end and parallel with the walls which supports
the jack or common rafters (the angled rafters forming the slope
to the roof).
Ridge Board Defined
The ridge board forms the
apex of the roof and usually denotes that the roof was constructed
on site and joins the jack rafters or common rafters together. These
are the rafters that form the slope to the pitch of the roof.
Common Rafters Defined
The rafters form the slope to which the battens are secured and
in turn the roof covering is also secured too.
Couple Roof Defined
A traditional pitched roof with rafters and no tie beam, used
for short spans up to 3m, assuming standard joist centres.
Close-Couple Roof Defined
This is a traditional framed roof with common rafters joined at
the wall-plate level with a tie beam, also used for ceiling joists,
used for spans up to about four metres, assuming standard joist
centres.
King Post Truss Defined
A traditional timber roof truss with a vertical post from the
apex to the centre of the bottom tie beam, suitable for spans up
to about 11m, but like the queen-post truss not now used for new
work in Britain.
Prefabricated Truss Defined
This is a roof truss
made in a factory using gang nails at the joints, it is then transported
to the site and normally lifted into place. This type of
construction has been used for about the past 30 to 40 years.
Wall Plates Defined
Wall plates are the horizontal
members normally timber, although they sometimes can be metal RSJ's,
fixed to the top of the wall within the roof space. They
hold the common rafters from the roof in place but can be susceptible
to dampness.
Battens Defined
A small section, normally of timber, to which sheet materials,
slates and roof tiles are fixed.
Wind Bracing Defined
These are timbers fixed across the roof structure to stop movement
when it is windy.
Surcharging Defined
This term is usually used in relation to valley gutters and is
where there is too much rain for the valley gutter to cope with.
Cornice Defined
This is the top course of bricks where the house meets the roof.
Efflorescence Defined
This is where salts appear
on the surface of the brickwork in a white dust or crystal formation
Lime Mortar Defined
mix used to bed bricks upon;
its characteristics being that it flexes and moves with the structure. It
was used up to the War years.
Cement Mortar Defined
sand cement mix used commonly in brick houses from about the
First World War onwards and is relatively strong and brittle and
therefore does not allow much movement.
Re-Pointing Defined
Re-pointing is carried out where the existing
mortar has failed and broken away to stop damp penetration and
further deterioration. The
mortar should be raked out to approximately 20mm and then replaced
with a mortar of a similar type, therefore, stopping damp occurring.
Engineering Brick Defined
A clay brick of high
compressive strength and low absorption, eg Staffordshire blue
bricks and some reds. Class A bricks
are stronger than 70 N/mm² and have an absorption below 4.5%. Class
B have a 50 N/mm² compressive strength and maximum 7% water
absorption.
Fletton Brick Defined
A low cost pale red brick made from Oxford
clay with traces of coal that burn during firing, saving energy. It
is pressed like many clay bricks and can be sand faced, pigmented,
or textured for use as facings.
Bonding Timbers Defined
These are timbers used in construction of walls usually using
a lime mortar construction. Bonding timbers are used horizontally
and add strength to the wall enabling additional lifts of brickwork.
Render Defined
A sand and cement external coating applied in two or three coats
or layers.
Bell-Mouths Defined
A bell-mouth is a curve at the base of a wall which throws the
water away from the structure therefore preventing dampness.
Pier Defined
This can be the load bearing brickwork in a wall between openings,
or a short buttress on one or both sides of a wall, bonded to it
for stability.
Cavity Wall Ties Defined
A fastener across a
cavity wall to hold the two leaves together. Usually
made of stainless or galvanised steel wire or strip, sometimes
plastic, and has a twist or bend near the middle to form a drip
so that water cannot pass. Wall ties are built into the
brickwork bed joints as work proceeds and may have a large plastics
washer to hold cavity insulation in place.
Recessed Joint Defined
A mortar joint set back
about 6mm from the face of the wall, either a raked-out joint or
one made by tooling. It is used for
brickwork, and for stonework to prevent flushing, and is strongly
shadowed.
London Clay in General
This property stands on
London Clay as with the majority of properties in London. It is therefore more susceptible than most should
drains leak or trees be allowed to overgrow etc. It is not
unusual to have some settlement in London properties and from our
inspection of the walls we have found nothing unusual.
Influencing Distance Defined
This is the distance in which a tree may be able to cause damage
to the subject property.
Over Lights Defined
This is a window above the
door allowing light into the hallway area.
Secondary Glazing Defined
This is where a secondary
window has been added, usually to prevent draughts. We would
also draw to your attention that these type of windows can be restrictive
in the case of the emergency when, for example, a fire has occurred
in the property.
Trickle Vents Defined
Small vents to the windows to allow air movement inside the property
to stop a build up of fumes or humidity.
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