Download - 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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