Basements

Question 1

What are the three main types of basement?

Answer 1

Retaining Wall and Raft
Box and Cellular Raft Basements
Piled Basements

Question 2

What is wall and raft basement construction?

Answer 2

• general method of basement construction

- raft slab forms basement floor and distributes load

Question 3

What is a piled basement?

Answer 3

Superstructure loads are carried to basement level via columns
Loads transferred from caps to piles

Question 4

What are the elements of a typical basement structure? Also talk through the method of construction.

Answer 4

Piles, retaining wall (secant or sheet), columns, Raft foundation, pile caps

Question 5

What are the three techniques to waterproof a basement?

Answer 5

Monolithic concrete

Mastic Asphalt Tanking (Internal & External)

Question 6

What is Mastic Asphalt Tanking?

Answer 6

Can be either internal or external

Continuous waterproof membrane to the base of the slab and walls

Question 7

What is external Mastic Asphalt Tanking?

Answer 7

Preferential method
Prevents ingress and protects the structure
Generally is sprayed on

Question 8

What is internal Mastic Asphalt Tanking?

Answer 8

Only adopted if external is not possible

Does not protect structure as external does

Question 9

What is top down / bottom up construction?

Answer 9

Top Down
The top-down method sees the top slab being constructed and then construction moves downwards to the base slab

Bottom up
Traditional technique of constructing underground structures starting from the bottom and working upwards