load bearing elements part5

Traditional BuildingLoad bearing Walls

Part 5

February, 2012 John Fox, College of North West London Slide 1

Requirements For Lbw

Strength & stabilityWeather protectionGood thermal protectionFire protectionDurability

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Load bearing Walls

L.B.W have 2 primary functions;To support the loads of suspended

floorsTo support roofs

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Load bearing walls

A wall plate is fixed to the top of the wall

The weight load is transferred to the wall plate and then laterally through the brickwork

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Load bearing walls

Suspended floors – on a typical domestic house, wooden joists are either built into the wall or supported by joist hangers, which in turn are built into the brickwork

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External load bearing walls

The 2 most common materials used in walling for domestic construction are:

BricksBlocks

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Bricks

Majority of bricks are made from clayPlaced into plastic mouldsFired in a kiln

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Bricks

Bricks can be classified into 3 categories;

Commons- used for general work which will be covered in render

Facing brick- used where the brickwork face well be exposed

Engineering brick- These are dense bricks with high compressive strength used for manholes, retaining walls etc.

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Blocks

These are classified into 2 types;Concrete- also known as dense

blocks. Ideal for load bearing or party walls

because of their densityGood sound insulation valueGood conductors of heat- not

suitable for cavity work

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Blocks

Lightweight blocks- made form lightweight aggregates

Generally used for internal skin on cavity work

Light and easy to useGood thermal values

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Mortar

Mortar is the material that is used to bind the bricks & blocks together.

Functions;Good workabilityAdequate bond strengthResistance to water penetrationResilience of thermal movement to

masonry

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Mortar

Mix proportions;Soft sand- provides the ‘bulk’ of the

mixCement- acts as the binder and

chemically reacts, hydration, with sand & water. As a result the mortar hardens.

Lime- adds to the adhesion of the mortar

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Loads on brickwork

Brick walls have to be bonded in order to spread the load

Most common type of bond is stretcher bond

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Loadings over window openings

There are 4 common methods of building over window and door openings;

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Window openings

Flat gauged arch- found more in high quality Victorian homes

Segmental arch- found in low quality Victorian housing

Wooden lintel- used mainly on Edwardian cheap housing

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Loadings over windows

On most housing projects today, catnic lintels are used

Constructed of hard steelInsulation incorporated into the

lintel to prevent ‘cold spot’All catnics marked with safe

working loads

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