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City & Guilds Construction

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PowerPoint presentationFloor boarding and calculations

Unit 202: Principles of building construction,

information and communication



Aims and objectives

Aim:

• Introduce learners to floor boarding and calculations.

Objectives:

• Identify components of a timber floor.

• Describe each component of a suspended timber floor.

• Calculate the linear quantity of floor boarding to cover an irregular

shaped area.

• Calculate additional quantities of wastage using percentages.



Flooring

Much of the terminology used for timber floors and for timber flat roofs

is the same, and many of the principles used in their construction are

also the same. Therefore by learning about either one, you can find out

much about the other.

A floor is defined as a level surface area within a construction suitable

for, and capable of supporting, the load it is designed to carry.

The design will depend on the type of building – eg a house for living

purposes, a factory for industrial use, a warehouse for storage use, or a

shop. The floors may be constructed from timber, concrete or other

materials, but only timber floors are dealt with in this section.



Terminology

Wall plate: Bedded on top of the support walls, and to which the joist

ends are fixed. Cross-section size usually 100mm x 50mm, but may

differ according to specification.

Wall bearer: As wall plates, but fixed to a wall face by bolts or other

means. Cross-section size as specified to the suit span of the joist.

DPC: Damp Proof Course – a brickwork material through which

moisture cannot pass.

Air brick: Honeycombed brick through which air can pass.

Joist hanger: A metal frame (or shoe) fixed into a wall (or to a

supporting joist), for supporting the end of a joist. Size to suit joist

section size.



Terminology

Strap anchor: A metal bar fixed to a joist and to a supporting wall to

prevent lateral floor/wall movement.

Bridging joist: Spanning the shortest distance from support wall to

support wall, and the support for the floor board. Cross-section size

determined by span and loading.

Trimming joist: Fixed in the same direction as a bridging joist, but at one or both ends of an opening supporting the trimmer joist, and the edges of the decking. Cross-section as the bridging joist but thicker, or double joists may be used.

Trimmed joist: Fixed in the same direction as the bridging joist, but cut (trimmed) shorter to allow for an opening to be formed in the floor. Cross-section size the same as bridging joist.



Terminology

Trimmer joist: Fixed (usually at right-angles to the bridging joists) at

the side of an opening to support the ends of the trimmed joists, and

the edge of the decking. Cross-section as the bridging joist but thicker,

or double joists may be used.

Struts: Fixed in rows between joists and at right-angles to bridging

joists, to restrict buckling of the joists. The position and number of rows

will depend on the joist span.

Noggings: Fixed between joists to support joints in decking material

(eg floorboard trap, roof decking joints).

Decking: Sheet materials or boarding used for covering a floor or roof

surface area.



Suspended timber flooring



Calculating for sheet flooring

Flooring is calculated in m2.

• To calculate the area, the formula is length x width.

• Sheet flooring is approximately 900mm wide x 1800mm long =

approximately 1.62m2.

For example:

• If you have a room 4.3m x 6.4m, the area = 27.53m2.

• Now divide the room floor area by the sheet flooring area.

• 27.53m2 / 1.62m2 = 16.9 = 17 sheets of flooring.



Calculating for floor boards

The formula for floor boards is similar to that for sheet flooring.

Floor board widths vary depending on the supplier, but are generally

150mm wide x 5m long, which is the size we will use.

Flooring is laid across the joists (the length of the room).

If you have a room 4.3m (L) x 6.4 (W) the area = 27.53m2.

= 4.3m / 150mm = 28.6

= 28.6 x 6.4 = 183.5m

= 183.5m / 5m = 36.693 lengths of floor board

= 37 lengths of floor boards at 5m long.



Calculating for wastage

Wastage is generally calculated at 15%. This ensures that there is sufficient

flooring, as in some circumstances flooring has to be cut and wastage is

inevitable. We will calculate for the previous two flooring calculations.

Sheet flooring:

27.53m2 / 1.62m2 = 16.9 = 17 sheets of flooring

17 x 15% = 2.55 = 3 sheets

17 + 3 = 20 sheets

Floor boards:

183.5m / 5m = 36.693 = 37 lengths of floor board

37 x 15% = 5.55 = 6 lengths

37 + 6 = 43 lengths



Any questions?

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