The
NF norm is a document of recommendation. It
is an auto-declaration that is the sole responsibility of the
manufacturer.
No controls or supervision are effected by a certificating organisation.
In France it is forbidden to offer for sale a product which
does not conform to the NF/EN norm in force. The manufacturer
must be able to provide proof of conformity to the norm if inspected. Certain manufacturers judge these
demands to be too minimalist and submit themselves to more demanding
procedures in order to obtain the NF mark or an ISO certificate.
The
NF mark is one of the national marks of standardisation provided
by the decree no 84-74 of 26 January 1984 laying down its statutes.
It provides for a certification of products through article
L 115-27 of the law no. 94 442 of 3 June 1994.
Its object is to testify to the conformity of products to the
relevant norms in the conditions defined by the rules of application
as laid down by AFNOR. The essential difference between the
norm and the NF mark lies in the fact that the manufacturer
whose products bear the NF mark regularly undergoes controls
made by outside laboratories looking at the quality of his products.
For the control of products, the NF mark relies on the provisions
of the National, European or International norms in force in
terms of quality assurance.
The NF mark is the exclusive property of AFNOR. It should be
noted that AFNOR delivers to tile manufacturers attestations
of the right to use the NF mark which authorises them to affix
the mark NF to their products and associated accessories. An
example: BS EN 1304 would apply to the UK.
Certain
national regulations of the Member States of the European Community
have been harmonised on the basis of common texts: these are
the European directives.
These directives fix the minimum
demands in terms of health and safety, protection of
the consumer and the environment. The CE marking attests to
this conformity. It is stamped onto the tile by the manufacturer.
The CE marking can coexist with other marks of quality certification.
It
is the mark of certification of systems delivered by AFAQ (Association
Francaise d’Assurance Qualite)/French Association of Quality
Insurance. It defines the procedures for ensuring product quality. The production sites certified
by AFAQ fulfil all the demands of the ISO 9002 norm and have
systems in place to improve both the products and the services.
Clay
tiles are products of natural manufacture (clay, water, fire)
which gives them a natural red colour after firing. This
does not change with time.
Manufacturers propose a range of colours adapted to each region
and in harmony with the environment.
The colours of these products are usually produced from natural
oxides applied by dusting or spraying with liquefied oxide and
this is done prior to firing. In this case, the tile, which
has been dried beforehand, absorbs this oxide which becomes
stable once it has been fired.
A roof can have various different shades which make it look
like a roof of old tiles or a Provencal roof. The principle
remains the same, the only difference being that these colours
are obtained by the application of different oxides.
The
clay tile has several advantages.
• It is strong and durable
• It is non-combustible
• It is resistant to acid rain
• It mellows and matures with age
• It is adaptable to all environments
How do you prevent small animals entering the roof space?
Certain
tiles with a pronounced relief make it easier for birds and
rodents to get in. This can be avoided by interposing
plastic combs fillers under the first row of tiles or accessories
(also plastic) complementing the shape of the tile.
You can also find, for certain tiles, a clay accessory which
acts as a “sparrow grille”.
It stops birds getting under the roof whilst allowing for the
ventilation of the underside of the tiles.
We advise you to approach a specialist roofing contractor who
will determine the best solution for your particular roof.
What should you do about the infiltration of powdery snow?
This
happens quite frequently, whatever the model of tile.
The regulations make it clear that this protection cannot be
provided by the tiles alone and that
it is necessary to install a membrane under the roof.
(e.g. felting)
This membrane is normally installed at the time of construction
on the underside of the tiles. This protection can if necessary
be moved to the floor of the roof space if this is not used.
This is often done when the roof is already in position and
cannot be removed in order to insert the membrane.
If the infiltration is only slight or occasional, we advise
cleaning the roof space and regular checks. If it happens frequently,
you should call on a professional to install a membrane under
the felt under the roof. He will be able to advise of the most
appropriate solution.
These
algae do not affect the quality of the tiles nor their durability.
It is advisable to clean your roof:
• either mechanically (power-washing?)
• or chemically.
It is often necessary to use both methods in order to obtain
a satisfactory result, (no solution being completely effective
in a site that is prone to moss growth).
A roofing contractor is best placed to identify the problem
and carry out the work.
You
may notice slight dampness on the underside of the tiles the
first time it rains after installation. In this case, it is
quite normal and should not last. This damp can also be due to:
• poor maintenance of the roof allowing the
accumulation of organic debris where the tiles fit together
(leaves…)
• water getting in around a particular feature
(chimney, skylight, sloping ridge/valley?)
• a roof pitch that is not suited to the
type of tile used.
A common problem is condensation, particularly when membranes
are used. Ventilation is mandatory in most countries. Check
with the local building regulations or contact Imerys Roof Tiles
technical department.
It
is essential to consider two important parameters:
• the general look of the roof (form
of the product).
• the different technical criteria which
are imperative.
The latter are numerous and demand a very
detailed study of the roof:
• The roof timbers must
be able to support the weight of the tiles (remember that new
tiles may be much heavier).
• Extra weight due to snow
must be included in weight calculations.
• The pitch of the roof
must be appropriate to the tile you have chosen.
• The geographical situation
(zone and exposition) must be determined precisely.
• The type of insulation
used must be adapted to current requirements.
• Ventilation of the roof
must conform to the latest regulations in force.
• The length of the side
of the roof must not exceed on the horizontal that imposed
by building
regulations with respect to the product newly installed.
We advise you to approach a roofing specialist who will carry
out a study with the help of a tile manufacturer if necessary.
Extending your house: which tiles should you choose?
An
extension is similar to a new building. So the load- bearing
structure as well as the obligatory technical questions must
be studied and considered by a roofing specialist. The proposed
extension should be conform to regulations in force. The choice
of tile generally depends on the type already used.
We advise you to approach a firm which will prepare a study
of the extension.
The tiles on your roof are no longer made. What should you do?
Tiles
have a life span of over 30 years.
However, their manufacture may not last that long. If for whatever
reason you have only a few tiles to change (partial recovering
of the roof):
• you must check with a roofer or building
supplies merchant if a current model will match your old tiles. You will
easily be able to identify the manufacturer and model of your
tile by looking at the details on the underside of the tile.
• If there is no chance of recent models
being compatible with your old tiles, we advise you to remove
the tiles so as to reconstruct a complete section of roof with
your old tiles. Keep the remaining tiles religiously in case
of further alterations
• Then recover the stripped side with new
tiles as close as possible in shape and colour to your old tiles.
The
norms
What is the NF/EN norm?
