Accessories (for roofs)

Complementary pieces for roofing.


Formed through the disaggregation of feldspar rock that becomes malleable when wet. Argil can be found near riverbeds, often forming banks along the margins. Argil can be white, red, gray and brown. It is composed mostly of hydrated alumina sillicata - - Al2O3 · 2 SiO2 · 2 H2O, has low cristallinity and minute dimensions (particles under 2 µm in diameter). Mineralogically, its main components are quartz, illite, caulinite, anatase, hematite and feldspar.


Same as fracture.

Clay tiles

Products for non-continuous application on inclined roofs and wall linings, made by standardizing processes (extrusion and/ or pressing), drying and baking prepared argil, with or without additives.

Construction products

Products to be used or applied permanently in construction projects.


of composing elements (roof tiles and accessories)


Structural defect that consists of a gap with a more or less regular shape affecting the thickness of the piece and is visible to the naked eye.

Distance between laths or gauge

Length of the exposed part of a roof tile or accessory, measured longitudinally.


Edge of a roof along the outer part of a protruding roof slope, made of roof tiles


Edges of a roof along the outer part of a roof slope, projecting beyond the side of a building and composed of accessory pieces.

Effect of ice

This term refers to the wear caused on roofing pieces by successive frost-defrost cycles.


Type of coating, permeable or impermeable, or the material used therefore.


Production process.


Crack with a more or less regular shape that does not affect the whole thickness of a piece.

Fixation orifice

Open or easily pierced orifice for the fixation of a product on the support structure.


Structural defect that consists on the breaking of a product into two or more fragments.


Space under a roof slope

Gutter / Joist

Concave, open piece, usually made of metal, through which liquids run, placed horizontally along the eaves of a roof to drain rainwater, thus avoiding infiltrations.


Property of materials relating to their capacity to absorb water. Ceramic materials are less hygroscopic than concrete or mortar.


Secondary structural piece of a roof arranged in a perpendicular line in relation to the highest inclination of a roof slope, where coating elements are supported.


When used in relation to flat or fitting roof tiles, the value of linearity is given by the deviation in a straight line as measured from the roof tile brim, both longitudinally and transversally.
For Canudo roof tiles, linearity is given by the deviation in a straight line as measured along the generating line at the bottom of a roof tile’s concave end.

Mechanical resistance to flexion

This test is conducted by applying an increasing force on a roof tile until it breaks. The value registered at the breaking point indicates the flexion of the roof tile.

Outeiro da Cabeça

Village located 18 Km from Torres Vedras.
The village covers an area of 5,7 Km2 and has a population of 932 inhabitants. Its main economical activities revolve around red clay ceramic industries (roof tiles and bricks) and agriculture.


 PDM: Municipal Master Plans (Portuguese).


Fixation orifice that is not fully pierced through.

Recommended overlap

Roof tile length that must be overlapped to the next roof tile.

Roofing functional demands

Minimum criteria to be met by a roof. The proper performance of any roof depends on three main factors: correct conception at the project stage, good individual performance of clay pieces and their correct application on the roof.

Roof slopes

Where joists are placed.

Roof tile fixation

Use of nails, screws, metal hooks or any other auxiliary fixation mechanisms that prevent pieces from moving.

Roof tile gap

Gauge or distance between laths.


Also known as pitch or roof surface; any flat surface of an inclined roof.


Surface defect over 7mm on average, consisting of a fraction of the material, separated from the ceramic body on the visible side of the product.

Support spindle

Relief at the underside of a roof tile or accessory allowing its fixation on the support structure, generally consisting of laths.


Colour shade variation on the same make of pieces.

Transversal profiles

This term is applied to Canudo roof tiles and refers to the width of its internal edges.

Underside roof tile ventilation

Also known as micro-ventilation; this refers to the circulation of air near the underside of a roof tile. Aids in the drying of absorbed rainwater and eliminating water vapour from inside a building, which could otherwise condensate on the underside of the roof tile; also aids in the conservation of the lath work, when it is made of wood. Improves roof tile resistance to the effect of ice.


Air circulation process.


In this context, the term relates to the capacity of a roof to completely prevent the entry of water. Impermeability of the clay material used and total roof coverage must be ensured, as well as the correct inclination of the roof. Wind and rain, which in conjunction can provoke ascending water movement along the roof surface, are a serious challenge to the watertight qualities of a roof.

Technical Support

General Principles of Roof Maintenance

To guarantee its proper working condition, any roof should be regularly maintained. Preventive maintenance is the best guarantee of durability of a roof.

Before approaching maintenance itself, it is important to refer two relevant aspects that are fundamental in the maintenance process:

  • Maintenance planning should begin while still at the project phase. The designer should foresee and plan suitable access and circulation conditions on the roof.
  • Once the planning of these conditions is complete, the builder should execute them accordingly.

Not complying with the above conditions is often the reason why basic maintenance activities are not conducted.

Inspecting the roof upon completion

Once roofing operations are completed, a thorough inspection and cleanup of the whole roof must be carried out and any external elements should be removed.

It is common to find leftover mortar scattered through the roof surface that will later settle into water draining areas. Any leftover paper, wood, cabling and other items (usually used by bricklayers, painters and electricians for protection or to carry out other tasks) should also be removed upon inspection, as their presence is detrimental to roof performance.

Roof maintenance and conservation activities should be seen as an investment as they will effectively prolong the whole house’s longevity.

Who should conduct maintenance/conservation work and how?

Roof maintenance/ conservation work should be conducted by specialized professionals only; although the task is apparently simple, it should be carried out in compliance with safety regulations.

Moving and walking on a roof should be object of special care and the following aspects must be taken in consideration:

  • Workers must be fully aware of the risks associated with this type of work;
  • Before starting, risks should be carefully assessed. All work at height must be minutely planned, so as to reduce risks to a minimum;
  • Preventive measures in case of fall should be taken. These should consider both collective and individual safety. The should also be put in place before starting the work;
  • Roof access should be provided only for conservation and maintenance work;
  • Do not move or walk on the roof surface when wet;
  • Do not move loads over 120 kg on the roof surface;

When planning any repair, restoration or roof removal operations, comply with the following procedures regarding the removal and storing of any material removed from the roof.

Directive 92/57/EEC establishes the minimum safety and health instructions applicable to temporary or mobile construction sites.
Regarding work on roofs, this directive states, in annex I:

14. Work on roofs:

14.1. Where necessary to avert a risk or where the height or the slope exceed values set by the Member States, collective preventive measures must be taken to prevent workers, and tools or other objects or materials, from falling.

14.2. Where workers have to work on or near a roof or any other surface made of fragile materials through which it is possible to fall, preventive measures must be taken to ensure that they do not inadvertently walk on the surface made of fragile materials, or fall to the ground.

Roof inspection conducted by the owner

While roof maintenance should be conducted by specialized professionals, the owner may conduct preliminary inspections. However, the basic safety principles stated above should be strictly followed.

If the owner does not have the necessary safety equipment, professional personnel should be called in.

Basic roof inspection operations should be conducted once a year (preferably before the start of the rain season): 

  • Unclog ventilation points.
  • Inspect all water drainage systems and remove any sediment that might block adequate water flow.
  • Clean all gutters and gutter-pipes.
  • Check the condition of insulation elements, mainly near chimneys, gutters and joists.

A thorough washing and cleanup of the roof should be conducted every three years, to remove all debris, vegetation and moss that might degrade the clay pieces and verify whether any pieces are broken or damaged, in which case they should be replaced.

If the condition of the roof is verifiably good, the work is done. Otherwise, move on to the next stage.

Maintenance/Conservation conducted by a specialized professional

After the roof is inspected, it is advisable that a specialized professional conduct any maintenance/ conservation work deemed necessary.

When choosing the specialized professional to conduct the work, always ask for a detailed budget of the work to be conducted, how it will be processed and for work completion warranty.

The specialized professional should describe the work to be conducted accurately but it should be kept in mind that unforseen situations might arise (such as damaged structures or other roofing problems). It is expected that the specialized professional conducts an inspection of the roof prior to the start of works, and it is recommended that photographic records of any anomalies found be kept.

Roof maintenance operations might entail the following stages:

Removal of all and any type of vegetation and sediment accumulated by action of wind and other elements, by means of pressure washing;

  • Elimination of any snow residues that may block roof air vents;
  • Repair of insulating elements, namely around chimneys, gutters, joists, etc.
  • Should a deformation of the roof surface be noticed, the affected area should be raised and the situation assessed. A specialized technician, who will estimate the situation and plan any necessary interventions, should conduct this assessment;
  • Replace all damaged elements (roof tiles, accessories or other). It is advisable to keep spare pieces for this.
  • The roof should not have any applications that pierce it or impede water draining, such as antennas or solar panels, which must be placed on special structures, nor should any element overload the roof or its structure;
  • Functional or structural characteristics cannot be changed, nor the shape of the roof surface, including gutter-pipes and the ridge, except if a specialized technician advises it in the face of a functional or structural deficiency found on the roof;
  • Never apply chemical products on the roof that are not specifically advised by the maker.

If the roof tiles of a roof have any added hydrofuge or impermeabilizing product, it will be necessary to replace it periodically. However, Toreense advises the use of natural roof tiles, which can perfectly guarantee the functionality of a roof.