Level 3 (Springfield Roofing)

Question 1

Is there any guidance for steep pitch roofs?

Answer 1

BS 5534 - Slating & Tiling of pitched roof

BS 8000- Workmanship on building sites. Code of practice for slating and tiling of roofs and claddings

Question 2

What else is covered in BS 5534?

Answer 2

Rain and wind resistance, along with durability, thermal insulation, the control of condensation, fire resistance, sound, environment, and health and safety issues are also covered.

Question 3

What does BS 8000 cover in relation to roofs?

Answer 3

The laying and fixing of clay tiles, concrete tiles, natural slates and fibre cement slates, as well as their associated fixings and accessories.

Question 4

What pitch should my roof be?

Answer 4

Roof pitches traditionally range from 12.5° (anything less is considered a flat roof) up to 75°.

Question 5

What does ‘Minimum Roof Pitch’ Mean?

Answer 5

Lowest angle at which a roof can be designed so the roof covering remains watertight.

Question 6

What is The Golden Ratio?

Answer 6

(a ratio of about 1:1.62) simply acts as a benchmark against which any architect that finds a design unsatisfactory

Question 7

What is the minimum pitch for slate or clay tiles?

Answer 7

35 degrees.

Question 8

How does the pitch of a roof affect the surface run off?

Answer 8

The lower the pitch, the greater the amount of water that the roof slope will collect and discharge.

Question 9

Where is rainwater drainage covered in Building Regulations?

Answer 9

Building Regulations Part H3- basic provisions for adequate disposal of rainwater from roofs

Question 10

What are the factors for a given roof drainage system?

Answer 10

use of the building, its projected lifespan and its geographical location.

Question 11

What British standard is used to calculate rainwater?

Answer 11

BS 12056-3:2000, and the National Annex for the UK.

Question 12

What are the calculation factors?

Answer 12

Rainfall intensity
The attenuation effect
Type of outlet
Vertical surfaces
Return periods

Question 13

What is rainfall intensity?

Answer 13

The rate at which rain lands is known as rainfall intensity, and this forms the basis of rainwater outlet design. The unit of rainfall intensity is litres per second per square metre (l/s/m2). Under BS EN 12056, the design must be assessed against the time it takes for a peak summer downpour of two minutes’ duration to run off roof surfaces into outlets

Question 14

What is the attenuation effect?

Answer 14

When water falls on a roof it is channelled in a particular direction – this is the “collection” stage.

Question 15

How does the Type of outlet effect drainage?

Answer 15

Horizontal or parapet type outlets act like a weir, and therefore flow rates are much lower than with vertical or sump type drains.

Question 16

How can vertical surfaces affect drainage?

Answer 16

Another factor that is often ignored is the run-off from vertical surfaces or facades above and adjoining a flat roof. BS EN 12056 requires that 50% of the vertical surface, up to a maximum height of 10m from the roof, be included in the roof area to be drained.

Question 17

Return periods

Answer 17

A return period is the likelihood of a storm of a similar intensity returning within that period of time. BS EN 12056 gives four categories (1-4) of risk.