Cover Image
close this bookRoof Structure Guide - Basics for the Design and Construction of Leightweight Sloped Roof Structures (SKAT, 1993, 144 p.)
close this folder1. Introduction
View the document1.1 Objectives of this guide
View the document1.2 Contents of this guide
View the document1.3 General remarks
View the document1.4 Definition of main terms

1.1 Objectives of this guide

The roof constitutes the most important part of a building and special care has to be taken in preparing it and its elements. The best available raw materials should be used and throughout the production process it should be kept in mind that a sub-standard and ill-designed roof may not only result in a defective roof, but may also lead to severe damage of the whole building.

In order to construct a reliable roof, not only must the cover material be of a high quality, but the entire roof structure and cover must function as a coherent system which is adapted to local conditions such as climate, available skill and materials. This guide therefore aims at facilitating the design of a suitable roof shape and adequate structure. It also provides guidelines on proper attention to details and on the construction and maintenance of the roof in a sound manner.


This guide is generally valid for sloped roofs which are covered by any kind of light and even material such as tiles or sheets. Emphasis is placed on basic and simple roof forms.

Target group

The guide is addressed to architects and engineers involved in the design of buildings and to builders, site engineers and overseers implementing construction.

Producers of roof-cover materials can also use the guide as a basis for advising their customers on the successful use of their products.

This guide can also be used as a teaching aid during training.

1.2 Contents of this guide

What you will find in this guide:

This guide provides information on how to design and build simple roof structures for lightweight and even (non-curved) roof cover materials. Although it was originally compiled as part of the FCR/MCR Toolkit series only, it is equally applicable in the case of other roof cover materials such as clay tiles, slates, sheets etc.

- In a popular rather than in a scientific way the principles of basic building statics are explained, providing a general understanding of the forces which occur in buildings and their implications on the structure.

- Various aspects that determine the design and shape of roofs are explained. These include climatic aspects and the interrelationship between the floor plan and roof shape.

- Principles of structural design are explained. A step-by-step approach explains how to develop the design of the structural elements.

Aspects of earthquake proof and storm proof construction are also included.

As timber is still a material which is widely-used in roof structures, it is dealt with in detail.

A handy method for sizing the main timber elements for simple roof structures is provided, taking into account the varying strength properties of different timber species. The method can be used where standard values are not available.

Other alternative materials for roof structures such as timber trusses, bamboo, pole timber, metal and concrete are dealt with briefly. For detailed information specialised literature or pro-fessional advice should be consulted.

- Finally, methods and practical hints for the construction process as well as maintenance are provided.

- The appendices contain conversion factors for roof slope measures, an extensive list of timber available in different regions with their main characteristics, tables for sizing structural timber (sawn timber and pole timber), and a list of selected literature.

What you will NOT find in this guide:

The guide is not a scientifically-comprehensive textbook, but is rather designed for practical application.

It does not focus on free and complicated forms in roof design which require a greater degree of expertise, skill and practical experience.

It also does not contain

- Information on production management

- Specifications with regard to costs and profit

- Information about particular problems in specific countries

- Truss-making

- Guidelines for the production of tiles

- Guidelines for quality control of tiles and the required tests

- Information about roof cover and its detailing

For information on these aspects please refer to the other toolkit elements in this series. (See Toolkit Overview on the front page)

1.3 General remarks

Validity of data

The material presented in this guide is based on general know-how and universal practice. It is up to the readers in each particular country to develop and apply corresponding solutions which are adapted to local practice and circumstances .

Responsibilities of the producer of roof-cover material

The reliability and functional value of the entire roof as a system as well as of its individual components such as the cover or structure, are of relevance for the house owner. The producer of cover materials should, therefore, not only be concerned about the high quality of his product, but also about the quality of the roof as a whole. If he constructs entire roofs as well as sells tiles, his responsibility is clearly defined. In the case where the roof is constructed by someone else, however, the producer should also take an interest in its design and construction. Although he can, naturally, not be held responsible for the structure and the laying of the cover, he should participate by advising and providing all necessary information.

Only if the roofs are properly functioning and long-lasting, will his products earn a good reputation and become a sustainable success.

1.4 Definition of main terms

1.4.1 Roof types

Gable roof, saddle roof or double-pitched roof

Single pitch roof or mono-pitched roof

Hipped roof

Pyramid roof

Shed roof

Broken pitched roof

Lean-too roof

Roof types

1.4.2 Structural elements

Structural elements 1

Structural elements 2

1.4.3 Roof cover related terms

Roof cover related terms