Piece obtained by pressure or extrusion, drying and firing of a clay paste, used for creating an element of water-tightness for the roof.
Upper covering of a building that protects it from the actions of weather.
Field of Roof:
The angled planes that define the roof.
Maximum pitch:
Trajectory that describes the free fall of water on the field of roof.
The edges of the roof below the overhang which prevents the rainwater collecting on the roof running down the vertical wall.
Right side of slope:
The right side of the field of roof when looking forward from the eaves.
Left side of slope:
The left side of the field of roof when looking forward from the eaves.
Valley rafter:
The meeting point for the roof slopes and where the rainwater gathers
The sloping line that forms the meeting point between two areas of roof, and from which the rainwater is distributed towards both sides of the roof.
The horizontal line resulting from the meeting point of the roof (gable roof), or roof with a vertical plane (one-sided, inclined roof).
Lateral edge:
Lateral finish to the part of the roof which is not protected by any element above it.
The facing wall which is bounded by the roof.
Structural base:
Its function is to provide stability to the whole roof as well as to form the slope.
The element on which the roof is laid, it resists the action of wind and the weight of snow. It may be continuous or discontinuous:
- When it is continuous, it is defined as a roof panel and can be made of long ceramic, thin-walled hollow bricks (rasillones) finished in mortar or concrete, fibre cement boards, panels made of various materials, etc.
- Discontinuous support consists of laths, profiles, etc.
Element which is parallel to the line of maximum roof pitch and which supports the purlins.
Element which is perpendicular to the maximum pitch of the roof, and which support the slats. In certain cases they can function as battens.
Slat or rafter:
Element which is parallel to the maximum pitch of the roof which supports the battens.
Element which supports the roof tiles.
The process of joining the roof material to the support. Depending on the pitch, nails, screws, hooks, staples, water-resistant mortars or specific adhesives can be used for this purpose.
Ventilation tile:
Piece which allows a current of air both beneath the tiles and the roof, preventing the possible formation of water condensation.
Piece which secures the water-tightness throughout the length of the roof’s hip and ridge line.
End ridge piece:
Piece used to finish the end of the hip line, playing an important aesthetic role, as well as guaranteeing water-tightness in the joint with the eaves.
Double ridge piece:
Piece which allows a change of direction to the tongue and groove of the ridge piece in order to finish off the hip with the final ridge piece at its edges.
Three-way ridge:
Piece which secures water-tightness and run-off at the meeting point of the ridge and two hips. The roof needs to adapt to the angles between the ridge and the hips for which it has been designed.
The piece used to close up the gap left by the flat part of the tile below the ridge. The plug is placed along the length of the entire ridges and hips.
Ridge plug:
Es la pieza que rellena el hueco que deja la teja mixta en su parte plana bajo el caballete. Se coloca a lo largo de las cumbreras y limatesas.
Chimney support:
Piece of equal or multiple dimensions in relation to the tile, whose function is to support the chimney.
Piece that combines with the chimney base, determines the aesthetics and functionality of air escape.
Chimney stack:
Piece that combines with the chimney base, determines the aesthetics and functionality of air escape.
Eave roof tile:
Piece which forms the line of the eaves. Situated some 15 cm above the façade at the top of the first line of roof tiles. Its purpose is to prevent damp and stains. The eave roof tiles are installed next to each other ensuring a perfect fit under the rows of tiles above them.
Lateral finish:
Piece which ensures wind and water-tightness throughout the length of the gable edges.
For mixed tiles, using the lateral finish of overlapping under the roof tiles is recommended. This piece is used for both right and left.
For flat roof tiles using the angular lateral finish on the tile is recommended.
Half tile:
Tile with the flat part cut away, for complementing the lateral finish.
Transverse half tile:
Piece with reduced length to facilitate the joint with the ridge.
Double tile:
Tile with two curved parts and two flat parts, for complementing the lateral finish.
Glass tile:
Clear glass component for exterior use with equal or multiple dimensions to the tile, to ensure the passage of light in order to illuminate spaces under the roof.
Component made of metal or galvanised steel used to finish roof joints with mouldable waterproof strips.
Mouldable waterproof flashing:
Flexible waterproof strip which adapts to the curvature of the tiles in order to finish the joints.
Ventilated eave:
Piece which allows ventilation through the eave and prevents the entry of birds or rodents under the tiles. It is shaped like a comb to allow the passage of air in order to ventilate the roof.
Bird stop:
Piece which allows the ventilation of the roof.


  • determining the pitch:

     To guarantee a good performance of the roof, one should keep the minimum recommendations in mind, which have been established based on the length of the roof and climatic conditions of the location; as shown in the table. For roof gradients which are below that recommended, a waterproof barrier should be used to guarantee the water-tightness of the roof.

     To determine the pitch, you will need to keep 3 parameters in mind:

    • 1.- 1. The areas in which the territory is divided based on rainfall, wind action, weight of snow, etc., The NTE-QTT guidelines have a map, which is reproduced below, with the Spanish territory divided into three areas: 1, 2 and 3.

    • 2.- 2. Apart from these three areas, it is useful to have in mind the climatic effects which may result from local conditions in each area, allowing for the differentiation in each area of three sites:

        - Protected site: this may be the base of a depression surrounded by hills and protected from the wind in all directions.

        - Normal site: flat land or plateau with gradients of little importance.

        - Exposed site: areas which are very exposed to the wind. Close to the sea, in a strip of some 5 km, above cliffs, islands or narrow peninsulas. Inland, they could be narrow valleys with strong wind currents and on hilltops.

    • 3.- 3. To select the correct roof pitch, keep its length in mind, selecting between roofs of:

        - 0 – 6,50 m.

        - 6,50 – 9, 50 m.

        - 9,50 – 12 m.

        - + 12 m will require a specific evaluation by the manufacturer.

  • distance between battens:

    The distance recommended between battens by HDR is:

      - Mixed tile = 387 mm

      - Western tile = 420 mm with +- 45 mm of the transverse length.

      - Marseille tile = 379 mm with +- 45 mm of the longitudinal length.

      - Moneo tile = 370 mm

    Any of these distances can be checked by following the process below, being understood as between the maximum and minimum placement distance.

    The average values for assembly, according to the following outline are:

      - Take 12 tiles randomly from the consignment supplied

      - Place them on a flat surface, fitting them together and stretching them out in order to ascertain the maximum placing distance by measuring from the first to the eleventh tile.

      - Then join the tiles by fitting them together at the maximum point allowed and make a new line which corresponds to the minimum placing distance between the first and the eleventh tile.

      - After this, continue to join the tiles by fixing them together at the maximum point allowed and create a new line which corresponds to the minimum placement distance between the first and eleventh tile.

  • pitches:

      - Pitch 1: less than 25 %. Pitch not advisable

      - Pitch 2: between 25%-80 %. As a minimum, use attachment level A.

      - Pitch 3: between 80%-100%. As a minimum, use attachment level B.

      - Pitch 4: between 100%-173%. Use attachment level C.

  • attachment:

    The slope of a roof will determine the level of attachment required for the tiles. On eaves, laterals, ridge lines, hips, rafters, vertical unions and other specific points, all pieces should be fixed, and always avoid using supported piece which have not been fixed.

      A: Attach all tiles onto battens using nails, self-tapping screws, hooks, etc.

      B: Attach tiles in proportions of at least one to five in a regular pattern on the battens using nails, self-tapping screws, hooks, etc.

      C: Place the tiles on the battens (their slipping off should be prevented by strap hangers).

      D: Not recommended.

recommendations for receiving tiles on site:

At their arrival on site, ceramic tiles should comply with the conditions specified in the current regulations. In this case, UNE-EN 1304.

The specific technical instructions that the tiles should meet when they are received on construction sites, the trial methods for determining their characteristics and the general procedure for their reception on site.

A series of recommendations for their reception on site are cited below:

  -The reception of materials should be carried out by the site managers or by a delegated and duly authorised person.

  -The dispatch note and the packaging should contain the name of the manufacturer and their commercial logo, as well as the Type (curved, mixed or flat), their Nominal Dimensions and, if they possess it, the AENOR trademark.

  -If required, the supplier will provide the site management with two factory samples taken at random before the start of the supply process. One of these should be sent to the laboratory in order to verify that it complies with the specifications provided, while the other sample should remain on site to be used as a reference when receiving the different consignments.

  -The samples should be packaged in a way that facilitates their storage and guarantees that they will not be altered in any way. Each sample should be labelled so that it can be correctly identified, including: the manufacturer’s name, the tile designation, the name of the worksite, the consignment number and the date of receipt of the sample.

  -The site management may substitute the previous trials by the provision of trials certificates which have carried out by AENOR.

  -When the materials arrive on site, the management should check that: the tiles have arrived in good condition, the material is identifiable according to the specifications on the delivery note and on the packaging, and the products correspond to the accepted comparison sample. If these checks are satisfactory, the site management can accept the consignment or order control trials, otherwise, the site management should reject the consignment straight away.

  -Control trials should be carried out in laboratories which are appropriately accredited for materials made from fired clay.

  -When the tiles supplied are covered by the AENOR trademark, the site management will be able to simplify reception of the consignment by doing away with the control trials.

  -The samples used to carry out the control trials should be taken at random in the presence of the manufacturer, and be representative of the consignment received at the site.

  -It is recommended that there are various representative tiles with the range of tones available on site, which will serve to check that the consignment is within this range. The template pieces and those used for colour comparison should be thoroughly clean and dry.

  -Any anomaly detected in the tiles supplied should always be communicated to the manufacturer before the tiles are used in the building work.


In general terms, clay tiles are supplied to worksites as compact packages within supporting structures to facilitate the loading operations in the factory, transportation and unloading at the worksite.

Their storage near the work site should be on flat, clean and mud-free areas, in order to avoid irregular distribution of weight and, in case of rain, so that the tiles are not stained with earth or other materials. Stacking should be no higher than two pallets.

Tiles should be stored in places where there is no handling of products, such as: lime, cement, plaster, paint, or where any facings take place, to avoid staining the tiles and spoiling their initial appearance. Handling components on worksites should guarantee the integrity of the tiles and avoid knocks, scuffs, tips, drops, etc.

storage in the roof area:

In the roof area, the material should be distributed in a way that avoids overloading the amounts permitted on the boards. It is essential to place the loads on the support elements of the board.

The stored material should be placed on a balanced and stable space, whatever the gradient, in order to avoid any slipping, and should be propped with blocks.

After their placement on site, the tiles should be distributed over the roof in groups of 6 to 10 units, obtaining in this way a logical distribution of the load and facilitating the work of the roofer.

cutting the pieces:

Normally, during the making of the roof, it will be necessary to cut some pieces, whether to adapt them to the layout or to find a resolution for specific points.

Tiles should be cut with the appropriate tool, in a place with the required safety conditions for the worker.

Basic recommendations to keep in mind during the roof build:

micro-ventilation system

  • Ventilation is the differentiating element in controlling the hygrothermic behaviour of the roof.

  • The degree of ventilation is, and should be, decisive in maintaining the humidity content below saturation point, to avoid the appearance of construction pathologies.

  • There should always be a space between the roof support panel and the tiles to allow the circulation of air under these. Place the metallic ventilated eave within the first row of the eaves and on the rafters to facilitate the entry of air.

  • The rafters, hips and laterals should not be made solid with mortar. Use aluminium self-adhesive bands on the hips, and nails and screws on the laterals. Place metal support pieces on the batten on which the ridge is fixed with screws or clips. For convenience, use ridge plugs between the tile and the ridge.

  • On the ridge plug (if one is used) and the tile, place the perforated aluminium adhesive strip to facilitate the escape of air from the ridge.

  • Place a minimum of one ventilation tile every ten metres.

  • Always observe the minimum recommended pitch according to the length of the roof section and the geographical location of the roof.

  • Our tiles are used in various countries and they are manufactured according to the most demanding European quality directives. They are subjected to strict quality controls which allows us to provide a 35 year guarantee against any manufacturing defects or damage caused by frost, as long as recommendations are followed for laying the tiles in dry conditions, that the tiles are not made water-resistant and that the Guidelines of the Spanish Technical Building Code and the UNE Regulations 136020 for Ceramic Tiles are observed.

  • Our 35 year guarantee only covers the replacement of manufactured tiles and not their placement.

specific joints

  • Ridge:

    -On the ridge line, it is necessary to use pieces of ridge tiles with an attachment system to finish off.

    -The tiles on the last longitudinal line which meets the ridge batten should be attached.

    -After this, the waterproof laminate should be placed on the ridge batten and the butt tile which connects to the roof sections, in order to close up the built joint with finishing piece which will secure the total water-resistance of the unit, with overlay pieces of ≥ 5cm. (The ridge piece should be laid in the opposite direction to the dominant winds in the area). A special piece for ventilation of the ridge can also be installed.

  • Hip:

    The hip line will have the same instructions as the ridge line, having the water-resistant and ventilation layer on the support, finish this joint with special pieces both in the joint with the ridge and in the eaves gutter.

  • Rafter:

    The rafter line is a critical point for the roof, as it is the meeting point which collects the rainwater from the roof sections, for which reason its water-tightness needs to be ensured and snow accumulation needs to be avoided. It should be built from the bottom to the top of the roof and always overlapping the material which forms the water collection channel with at least a 10cm overlap. These components should be attached to both roof sections and should have a projection or elevation at their finished edges to avoid the entry of water through the roof where they are attached. Overlapping should take place both in the ridge area and in the eaves gutter, finishing these areas off with special pieces. There should be a minimum of 15 cm separation between the opposing tiles of each roof section, flowing into the channel, cutting the pieces in parallel to the axis of the rafter. Fix all the tiles to both sides of the rafter.

    Note: If mortar is used, this should be water-resistant and use the least required, always leaving space for micro ventilation



All our tiles are subject to UNE regulations with obligatory compliance and which are included in the UNE 136020 or UNE 1304 tile regulations. Therefore, the UNE regulations are obligatory in nature, and specify the compliance values for each of the tile characteristics to ensure the quality of the product and of the building in which they are used.

Due to the obligatory compliance, all our tiles carry the EC standard for ceramic products.

EThe EC standard is an obligatory standard that indicates product compliance to the essential requirements of the Directive for Construction Products (89/106/EEC) relating to them, as well as compliance with the specifications of the harmonised regulations which apply to them.

The EC standard for a product is an essential condition for its commercialisation within any State of the European Union.

Responsibility for a product to be in possession of the EC standard rests with the product manufacturer.

To obtain the EC standard, the following tasks need to be completed:

  - Carry out the initial type trials.

  - Definition, development and implementation of the Manufacturing Process Control (MPC)

  - Trials for the samples taken from the factory in accordance with the trial plans established in the MCP.

  - MCP Certification and monitoring of this.

  - EC declaration of conformity.

  - EC product standard.

The trials should be carried out by a Member State Trials Laboratory which is registered to carry out this work.

The EC standard should appear on the packaging and on a sheet which should include additional information referring to the product properties.

There are other product standards, also of a voluntary nature, that guarantee the quality of the product possessing this distinction. The most important product standard is the N Standard from AENOR.

The requirements for the N Standard are the points indicated in Annex V of the Standards Regulations RP 34.00, which entail a series of controls both in the production and in the manufacture of the piece.

The control of the final product is subject to internal control by the manufacturer and external control which needs to be carried out by accredited laboratories.

To obtain the N standard, an external audit of the quality system carried out by an accredited body must be successfully passed, as well as a further production inspection every six months.

To obtain the AENOR N standard, all our tiles have undergone a control process and have been manufactured according to a quality system which is periodically audited.

All manufactured products and the quality control system for the manufacture of roofs with clay tiles comply with all Spanish regulations, and due to this, we possess the N standard.

All manufactured products comply with the legal requirements of the European Directives 89/106/EEC (and the later modifications in Directive 93/68/EEC) for “Construction Products" and, due to this, we possess the EC standard.

We have a firmly-established quality control system which involves employees and managers at all levels on a daily basis, with the objective of improving the product, safety in production and taking the maximum amount of care of the environment.

Our technical development department and our own laboratories work daily on projects whose aim is to offer innovative products and improve the characteristics (colour, finish, resistance, ease of attachment, etc.) of existing tiles.

Both companies possess the Integrated Environmental Authorisation, which certifies that they comply with all the environmental requirements stipulated by current legislation and the company has a commitment to the Environment.

Prevention and Environment regulations ISO 9001, OSHAS 18001 and ISO 14001.

As our products are certified by both standards, such as the EC and the N standards, there are certain pathologies which may arise due to poor worksite practices.


The pathology of buildings is the area of construction that studies defects and construction problems appearing in buildings during or after they have been built: its causes, evolution and symptoms.

As its upper covering, one of the roles that the roof of a building should comply with is the protection of the building’s interior against atmospheric agents.

Any failure in the roof, whether in the planning stage, during construction or during maintenance, will allow the entry of water and the consequent appearance of cracks caused by damp in the building interior.

The most common causes allowing the entry of water into the building interior are filtration or through any of the components that make up the roof.

The most frequent errors in clay tiled, pitched roofs are the roof designs not having enough pitch, or a lack of overlap length between the tiles. Rainwater aided by wind action can travel over the roof pitch and penetrate the overlap between tiles.

Another common error is that the roof pitch is too great for the type of tile used, or for the tile placing system chosen, and this can cause the tile slippage, leaving roof areas without the necessary overlap between tiles to keep rainwater out.

It is also a mistake to have a section without enough gutters or downpipes where torrential rain will cause the rainwater to run down the interior of the building or soak the surface of its façade.

An inadequate design or build of the roof joints with the rafters, meeting points with wall coverings and other “specific points” are the areas where the majority of roof failures are produced.

Another frequent error is to fill eaves, ridges and other areas of major exposure to atmospheric agents with mortar.

Another of the most common errors is the use of grip mortars containing an excessive amount of cement as their shrinkage may create cracks in the tile.

Insufficient tile overhang over the guttering is another failure when laying a roof.

In order to foresee all the above causes of poor roofing work, it is necessary to carry out a series of measures, both at the planning stage and in the building stage, as well as during the useful life of the roof. These measures are aimed to guarantee the water-tightness of the building.

When designing pitched roofs, keep in mind the recommendations established in the current regulations relating to gradient, overlapping of tiles, etc., in accordance to the rainfall zone that the building is located in, as well as the recommendations made by Hermanos Díaz Redondo.

During the build, ensure the correct tile layout, paying particular attention to the treatment of specific points of the roof, such as joints with vertical components, rafters, guttering, eaves, etc.,

The surface of the tile overhanging guttering, eaves and gables should be of an adequate length to avoid the run-off of rainwater onto the wall coverings.

Always consider the possible incompatibilities which exist between the different waterproofing materials.

Anticipate and prepare exits and access points to the roof in order to carry out repairs and maintenance work. This should consist of an annual cleaning of gutters, down pipes and water collection pipes.



Clay tiles do not need any special maintenance, as their qualities remain unaltered over time.

Nonetheless, in order for the combination of roof components to do their job correctly, a minimum amount of maintenance is required. Below is some advice which, along with the rest of the recommendations in the current manual, will guarantee the water-tightness of the roof.

- The roof should only be accessed when carrying out maintenance work.

- When making inspections of the roof, move around areas where the tiles are fixed. This will avoid any displacement or breakage of tiles.

- Use anti-slip footwear when moving around the roof, and always use a safety hook. Any movement should be made along the roof. Where this is not possible, walk on the backs of the tiles.

- On the roof, there is a series of specific anchorage points for antennae and similar objects which, if possible, should be situated close to the roof access. This will avoid causing breakages by having to walk over the tiles.

- Rainwater evacuation systems, such as guttering and rafters, should be kept clean and monitored, particularly in areas where there may be an accumulation of leaves, litter, soil, etc.

- Periodic inspections should be carried out of any particular roof points where membranes or waterproof flashing have been used to cover joints, and their condition should be checked.

- Periodic removal should be carried out of moss and lichens appearing in the joints along the shaded areas of the roof.

- A curative or preventive FUNGICIDE treatment for the removal of lichens, mildew and moss should be carried out on wall coverings. On no account is the application of waterproofing or other silicone-based products recommended, as they can reduce the durability of the product.

- The products we recommend for the removal of lichens, mildew and mosses are:

  Anti Moss Henkel AM 2900

  Moss and lichen cleaner ESLO

  Anti moss STARWAX

- Keep all gaps free of obstacles both in the entry and escape of air, thereby allowing for adequate ventilation.

- Maintenance work should be done by specialists who are trained to carry out roof repairs and replacement of parts.

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