K.J. INSTITUTE OF TECHNOLOGY

CAVITY WALL -:PREPARED BY:- PATEL HARSH (130640106089) PATEL JAIMISH (130640106090) PATEL KAPISH (130640106091) PATEL KISHAN (130640106092) PATEL PRANALI (130640106095)

Cavity wall:- A cavity wall or hollow wall consists of two separate walls, called leaves or skins, with a cavity or a gap of 5 to 10 cm between them. Two leaves of a cavity wall may be of equal thickness or unequal thickness. In case of non load bearing walls the two leaves of cavity are made of equal thickness. In case of load bearing walls the internal leaf may be made thicker than the external leaf to meet the structural requirements.

Advantages of cavity wall:- 1. The direct moisture cannot travel inside the building, as there is no direct contact between the inner and outer leaves. 2. The cavity between the two leaves is full of air which is bad conductor of heat. Hence transmission of heat from external face to the inside the room is very much reduced. Cavity walls have about 25% greater heat insulating value than the solid walls.

3. They have good sound insulation property. 4.They are economical. 5. The nuisance of efflorescence is very much reduced. 6. Loads on foundations are reduced because of lesser solid thickness.

Brick cavity walls:- A cavity wall is constructed of two leaves – inner leaf and outer leaf with a hollow space of 5 to 10 cm in between. The outer wall is generally ½ brick (10 cm) thickness and the inner wall may be ½ brick or 1 brick thickness. However, if heavier loads are to be supported, the thickness of inner leaf can be increased in the multiple of half brick thickness.

Precautions during cavity wall construction:- 1. The contact between the inner leaf and the outer leaf should be the least. 2. The half brick thick leaf of cavity wall should be constructed with stretcher bond. 3. The D.P.C. should be laid separately for both leaves. 4. The bottom most horizontal D.P.C. should be laid atleast 150 mm above the bottom of the cavity.

5. Wall ties should be strong and rust proof. 6. The bottom of cavity should be well-ventilated by use of air bricks or ducts. 7. To prevent the entry of moisture, the bottom of cavity should be kept 150 mm above the outside ground level. 8.The cavity wall should be properly drained by providing weep holes immediately below the main horizontal D.P.C. 9. Wall should be constructed with greater care so that mortar droppings or brick rubbish etc. do not fall inside the cavity.

10. Special attention should be pid to see that the rats, vermins or mosquitos do not find access to the cavity. 11. The doors or window jambs should be build solid by means of headers which should be either of precast concrete slab or brick headers. The lintel should cover full width of the wall and the bearing of lintel should be sufficiently strong and solid. 12. The top of cavity may be built of atleast two solid courses of bricks. 13. Two leaves of the wall should be raised simultaneously and uniformly. The position of wall ties should be predetermined so as have uniform spacing, preferably in centers.

REFRANCE http://en.wikipedia.org Information From: BUILDING CONSTRUCTION Author: Dr. R. P. Rethaliya ATUL PRAKASHAN