What is a Cavity Wall? Purpose, Advantage and Disadvantage

What is a Cavity Wall?

It is a hollow wall in which there are two separate walls to form a single wall with some space and cavity between them. This wall is also known as a hollow wall. It is formed by an outer skin or an inner skin of masonry separated by a cavity but connected by metal ties. These skins are called leaves or wythes. The masonry can be formed by bricks, blocks, or stones. The minimum thickness of the cavity is 2 inches.

Cavity wall

Cavity Wall Tie

A cavity wall tie is an element used to tie the internal and external walls of a cavity wall. Generally, ties are made up of steel, iron, or plastic. Ties are designed to lock into the mortar. Ties are set down in the cavity wall during construction. It is selected after checking the type of masonry such as cavity width.

Cavity wall ties

Purpose of Cavity Wall

  • To resist the entry of moisture into the house.
  • Help in maintaining the thermal insulation.
  • Acts as a cushion for absorbing sound.
  • Prevention of efflorescence of brickwork or concrete.

 

Advantages of Cavity Wall

  • Cheaper than solid walls.
  • Cavity walls are fire-resistant.
  • Reduce the risk of moisture condensation.
  • Gives protection against efflorescence.
  • Gives good thermal insulation, keeping the house cool in summer and warm in winter.
  • Offer a good sound insulation property as a result it can reduce the effect of external sound.
  • Reduce the cooling cost of the house.
  • Least interruption to install.
  • Reduce the weight of the foundation.

 

Disadvantages of Cavity Wall

  • Heat and cold pass-over problems.
  • Metal ties used in the wall may face corrosion problems.
  • There is no way of refilling the holes in the insulation.
  • Highly skilled labours and masons are required.
  • Standard supervision is required during construction.
  • A vertical damp proof course is necessary.
  • The thickness of insulation is restricted by the width of the cavity.
  • Possibility of unfilled air pockets, causing cold spots, which attract condensation.

 

 

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