Presentation On Basement Waterproofing-1
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Simplifying design and construction Alan Tovey, Director The Basement Information Centre
Simplifying design and construction
Grades of construction Construction options Design and waterproofing issues Basement Approved Document – 2004 Other Available information
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994) Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994) Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994)
British Cement Association National House-Building Council
2000 The Building Regulations 1991
Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk
Basements for dwellings
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994) Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk Pending Approved Document additions: -- Plain Masonry and Plain In-situ Conc. Retaining Walls due for Public Comment Feb 2005
Grades and types of construction
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type B - BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 Type C ventilated (+ vapour control)
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type B - BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 Type C ventilated (+ vapour control)
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type Type BB -- BS8110 BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 8007 Type C ventilated (+ vapour control) (+ vapour control)
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type Type BB -- BS8110 BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 8007 Type C ventilated (+ vapour control) (+ vapour control)
2 Minimum for garages 3 Minimum for accommodation
Approved Document Basements for dwellings
Wall construction types - BS8102 Total reliance on waterproofing
Structure provides main water resistance
Structure provides some water resistance with internal drainage system
WALL TYPE A
WALL TYPE B
WALL TYPE C
(Masonry)
(Insitu concrete)
( concrete – new build) (masonry – existing)
TYPE A STRUCTURES ( Tanked protection ) External waterproofing
Sandwich waterproofing
Internal waterproofing
TYPE B STRUCTURES ( Structurally integral protection )
External or internal waterstop as reqd
Crystallization, hydrophilic or injected waterstop
?
Kickered construction
Kickerless construction
TYPE C STRUCTURES ( Drained protection )
Preformed cavity floor and wall drain system
Drainage sump with pumped outlet
Part C – Resistance to moisture AD – Basement for dwellings 2004
British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
Generally water-proofing recommendations same: as in 1997 version except Type C now with full sump
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE
Variable
See Note 2 CONSTRUCTION
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE Permanently below
Variable
See Note 2 CONSTRUCTION
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE
Variable Period ?
See Note 2 CONSTRUCTION
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE
Variable
See Note 2 CONSTRUCTION
Permanently above
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Construction options
TYPICAL RANGE OF CONSTRUCTION METHODS Reinforcement
Restraining ties
Reinforcement
Expanded polystyrene formwork system In-situ concrete infill In-situ concrete infill Reinforcement
In-situ concrete
EPS formwork
Wall ties
Masonry
Reinforcement
Precast concrete
Types of construction Masonry Basement Walls
Filled hollow blocks Plan view Key items • Strength of units • Reinforcement - Vert and Horiz • Compaction ?? • Waterproofing details Water proofing
Running bond may offset cores
Cores not parallel
Cross section
Filled cavity block wall Plan view
British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
Water proofing
Key items • Strength of units. • Reinforcement - Vert and Horiz. • Compaction – easier ( 100mm continuous cavity ) • Waterproofing details
Cross section
Types of construction - contd Pre-cast and PC insulated
Pre-cast/insitu hybrid walls
Expanded Polystyrene Formwork
Poured In-Situ Basement Wall
Pre-Cast Concrete Wall
Pre-cast/insitu hybrid walls
Expanded Polystyrene Formwork
Expanded Polystyrene Formwork
Poured In-Situ Basement Wall
Design and Water proofing issues
Design Considerations Structure Waterproofing Repair
WATERPROOFING DESIGN PRINCIPLES Decide on basement usage Gather site information Decide on form of construction Decide on form of waterproofing
Approved Document Fig 2A.1 Determining appropriate form of basement construction and waterproofing British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
9 Stages
Determining appropriate form of basement construction and waterproofing
Proposed development
Site survey
Basement use Environmental requirements Geology Water table Topography Soil drainage
Design considerations
No Is Construction buildable?
Yes SOLUTION
Basement Construction Type A/B/C
Selection of Waterproofing system
House type and Foundation design
External drainage Ground level Geocomposite drainage sheet Basement structure Percolating ground water External or internal waterproofing as appropriate
Perimeter drain (fin or land drain to discharge water to down side)
If external drained used to control conditions >> Make rodable
General principles External or internal waterproofing as appropriate
Basement structure
Generally waterproofing to basement to be continuous Adequate details must be provided for junction, etc Details and construction should be as simple as possible
External or internal waterproofing as appropriate? Basement structure
Continuity seems simple But essential to consider with structure
Waterproofing Details Assumed continuity!!??
Foundation details Type A structure - strip foundation External or internal waterproofing
External or internal waterproofing
Discontinuity between slab and wall
Slab built-in
Foundation details Type A structure - piled foundation Internal waterproofing
?
Difficult to achieve external waterproofing
Interaction of water proofing with structure
Structural design - Waterproofing
Ultimately won’t fail but serviceability conditions may affect waterproofing
Simple design of section
Design structure in three dimensions
Cross section
Bending moments in structure
Design structure in three dimensions
Cross section
Bending moments in structure
Corner moments sometimes over looked
Plan
British Cement Association
Continuity of horizontal reinforcement in masonry walls (Figure 3A.3, AD Basements)
National House-Building Council
The Building Regulations 1991
Basements for dwellings
Horizontal reinforcement = 0.5 As along wall and around corners
Plan view Main vertical reinforcement
Similar detail provided for insitu walls (Fig 3B.2)
Cross section
Insitu concrete options
Corbel details? Ties required!
Construction?
Large section but easy to concrete
Waterproofing details?
Comment - Need to consider construction abilities/difficulties
Design in three dimensions - waterproofing Drawing is simple in two dimensions But structures are three dimensional !! Waterproofing membrane shown following thickened profile
Cross section
Design in three dimensions - waterproofing Drawing is simple in two dimensions But structures are three dimensional !! Waterproofing membrane shown following thickened profile
Cross section
Membrane likely to require preformed sections to cater for mitre
Comment: If not catered for can lead to construction defects
Plan view at corner
Design in three dimensions - waterproofing Drawing is simple in two dimensions But structures are three dimensional !!
Waterproofing membrane
OK here Cross section
Simpler square corner no mitre
Comment: Design can help waterproofing
Plan view at corner
Ensure compatibility between waterproofing and structure Stress and crack width controlled by reinforcement. Likely to be compatible with most waterproofing membranes.
. . . . .
Reinforced wall
In an unreinforced wall, crack width is uncontrolled. May exceed strain capacity of some waterproofing membranes.
Un-reinforced wall Comment: Structural behaviour can affect selection of waterproofing
Can basement be investigated and repaired? Example 1 May influence redesign and choice of waterproofing. Internal/External?
Structure designed for water-resistance (Type B)
Can basement be investigated and repaired? Example 1 May influence redesign and choice of waterproofing. Internal/External?
Structure designed for water-resistance (Type B)
Can basement be investigated and repaired? Example 1 May influence redesign and choice of waterproofing. Internal/External?
Structure designed for water-resistance (Type B)
Can basement be investigated and repaired? Example 2
Example 1 May influence redesign and choice of waterproofing. Internal/External?
?
?
Plan Structure designed for water-resistance (Type B)
Basement under part of area of house
Other Design Issues British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
The new Approved Document – Basements for dwellings Amended to deal with B Regs 2000
British Cement Association National House-Building Council
The Building Regulations 1991 2000 B
Basements for dwellings
a m e s
rits B o a N
e C h lH a n
to ia c C g n
n o c u
il
e h T
i u B
g in d l
e R
la g u
n io t
te n
rs fo
e w d
m to n e s u
lin g
o s A -B ild u
s
9 1 s
1 9
Covers A, B, C, E, F, H, K, L, N, J and Vehicle access As for AD 1991 + Plus Part M
Contents
B Regs part
Site preparation and resistance to moisture
C
Structure
A
Fire safety
B
Conservation of fuel and power
L
Ventilation
F
Resistance to the passage of sound
E
Contents
Contd
B Regs part
Stairs, ramps and guards
K
Glazing - materials and protection
N
Drainage and waste disposal
H
Heat producing appliances
J
Vehicle access
Significant guidance on: Site preparation and resistance to moisture Structure Conservation of fuel and power
‘Site preparation and resistance to moisture’ Gives Guidance on: Subsoil drainage Obtaining water- resistance
‘Structure’ Gives Guidance on: Masonry retaining walls In-situ concrete retaining walls Foundations - plain and reinforced
Masonry retaining walls Table 3A.2 AD - Basements: Minimum masonry strength and reinforcement for 2.7 m propped retaining wall
Foundation type
Strip
Soil type (well drained)
Clay Granular
2.7 m
Vertical load (kN/m) up to
Moment taken at base of wall (kN/m)
Block comp. strength (N/mm2)
70
17
7
20
530
12
7
20
340
Brick comp. strength (N/mm2)
Area of reinfment As (mm2/m)
Table in AD also covers raft foundation and different vertical load Similar tables for 2.1 m and 1.6 m cantilevered walls 2.1 and 1.6 m
Insitu concrete retaining walls Table 3B.1 Minimum reinforcement for 2.7 m propped in-situ concrete retaining wall Foundation type
Strip
Soil type (well drained)
Clay Granular
Vertical load (kN/m) up to
70
Moment taken at base of wall (kN/m)
2.7 m Area of reinforcement As (mm2/m) Wall thickness (mm)
200
300
17
420
390*
12
290
390*
Table in AD also covers raft foundation and different vertical load Similar tables for 2.1 m and 1.6 m cantilevered walls 2.1 and 1.6 m
Centre line of retaining wall
British Cement Association National House-Building Council
The Building Regulations 1991
Retained ground
Basement
Basements for dwellings
Foundation requirements for strip foundation 200 mm min.
(a)
(b)
Cover 40 mm
Width of foundation (a)+(b)
Centre line of retaining wall C
Reinforcement as paragraph 3B.3.4
Retained ground
Requirement for raft foundation
Internal wall Basement Reinforcement as paragraph 3C.5.3 Reinforcement as paragraph 3C.5.1
T (to be not less than 200 mm 1200 mm minimum Foundation should extend past centreline of retaining wall by a distance equal to 2T, where T is the thickness of the foundation
Cover 20 mm
= C = 1200 mm minimum Cover 40 mm Reinforcement as paragraph 3C.5.2
‘Conservation of fuel and power’ Gives Guidance on: General requirements Tables for wall insulation thickness Tables for floor insulation thickness Calculation procedures Only in AD – Basements for dwellings
Not included in AD L1
Simplifying design and construction Available information, Inc AD Basement s Grades of construction , Construction options
Design and waterproofing issues Structure Waterproofing Repair
Adopt simple details
Approved Document – 2004 Simplifies design for walls, and foundations and aids reliability
And so to the finished project
By simplifying the design
Building into the Basement
Simplifying design and construction
Grades of construction Construction options Design and waterproofing issues Basement Approved Document – 2004 Other Available information
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994) Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994) Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994)
British Cement Association National House-Building Council
2000 The Building Regulations 1991
Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk
Basements for dwellings
Available Information - Publications Basement 1 - Benefits and costs (1991, 1999, 2005) Basement 2 - Design Guide – Soil pressures and masonry (1991) Basement 3 - Thermal insulation (1993) Basement 4 – Layout Design Example (1994) Waterproofing Design Guide (1994) Waterproofing Site Guide (1994) Waterproofing existing structures (BSWA, 2005) Approved Document – (1997, 2004) Basement Land use (2) (1998) Others on Website www.basements.org.uk Pending Approved Document additions: -- Plain Masonry and Plain In-situ Conc. Retaining Walls due for Public Comment Feb 2005
Grades and types of construction
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type B - BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 Type C ventilated (+ vapour control)
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type B - BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 Type C ventilated (+ vapour control)
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type Type BB -- BS8110 BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 8007 Type C ventilated (+ vapour control) (+ vapour control)
Table 1 (BS 8102) Guide to level of protection to suit basement use Grade
Basement usage
Performance level
Form of construction
1
Car parking: plant rooms (excluding electrical equipment); workshops
Some seepage and damp patches tolerable
Type Type BB -- BS8110 BS8110
2
Workshops and plant rooms requiring drier environment; retail storage areas
No water penetration but moisture vapour tolerable
Type A
Ventilated residential and working areas including offices, restaurants etc., leisure centres
Dry environment
Type A
3
Type B - BS 8007
Type B - BS 8007 Type C
4
Archives and stores requiring controlled environment
Totally dry environment
Type A Type B - BS 800 8007 Type C ventilated (+ vapour control) (+ vapour control)
2 Minimum for garages 3 Minimum for accommodation
Approved Document Basements for dwellings
Wall construction types - BS8102 Total reliance on waterproofing
Structure provides main water resistance
Structure provides some water resistance with internal drainage system
WALL TYPE A
WALL TYPE B
WALL TYPE C
(Masonry)
(Insitu concrete)
( concrete – new build) (masonry – existing)
TYPE A STRUCTURES ( Tanked protection ) External waterproofing
Sandwich waterproofing
Internal waterproofing
TYPE B STRUCTURES ( Structurally integral protection )
External or internal waterstop as reqd
Crystallization, hydrophilic or injected waterstop
?
Kickered construction
Kickerless construction
TYPE C STRUCTURES ( Drained protection )
Preformed cavity floor and wall drain system
Drainage sump with pumped outlet
Part C – Resistance to moisture AD – Basement for dwellings 2004
British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
Generally water-proofing recommendations same: as in 1997 version except Type C now with full sump
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE
Variable
See Note 2 CONSTRUCTION
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE Permanently below
Variable
See Note 2 CONSTRUCTION
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE
Variable Period ?
See Note 2 CONSTRUCTION
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Fig 2A.4 Acceptability of construction types Water table
Type B
Type A Waterproofing
Plus drainage
BS 8110
Plus Wproofing
Type C
BS 8007
Plus Wproofing
BS 8110 BS 8007 Plus moisture barrier
Low ACCEPTABLE
Variable
See Note 2 CONSTRUCTION
Permanently above
High
Not recommended
Note 1
Note 1
Decreasing risk Notes
1. In high water table seek manufacturer’s advise 2. Some constructions may be suitable depending on conditions
From : Approved Document – Basements for Dwellings
Construction options
TYPICAL RANGE OF CONSTRUCTION METHODS Reinforcement
Restraining ties
Reinforcement
Expanded polystyrene formwork system In-situ concrete infill In-situ concrete infill Reinforcement
In-situ concrete
EPS formwork
Wall ties
Masonry
Reinforcement
Precast concrete
Types of construction Masonry Basement Walls
Filled hollow blocks Plan view Key items • Strength of units • Reinforcement - Vert and Horiz • Compaction ?? • Waterproofing details Water proofing
Running bond may offset cores
Cores not parallel
Cross section
Filled cavity block wall Plan view
British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
Water proofing
Key items • Strength of units. • Reinforcement - Vert and Horiz. • Compaction – easier ( 100mm continuous cavity ) • Waterproofing details
Cross section
Types of construction - contd Pre-cast and PC insulated
Pre-cast/insitu hybrid walls
Expanded Polystyrene Formwork
Poured In-Situ Basement Wall
Pre-Cast Concrete Wall
Pre-cast/insitu hybrid walls
Expanded Polystyrene Formwork
Expanded Polystyrene Formwork
Poured In-Situ Basement Wall
Design and Water proofing issues
Design Considerations Structure Waterproofing Repair
WATERPROOFING DESIGN PRINCIPLES Decide on basement usage Gather site information Decide on form of construction Decide on form of waterproofing
Approved Document Fig 2A.1 Determining appropriate form of basement construction and waterproofing British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
9 Stages
Determining appropriate form of basement construction and waterproofing
Proposed development
Site survey
Basement use Environmental requirements Geology Water table Topography Soil drainage
Design considerations
No Is Construction buildable?
Yes SOLUTION
Basement Construction Type A/B/C
Selection of Waterproofing system
House type and Foundation design
External drainage Ground level Geocomposite drainage sheet Basement structure Percolating ground water External or internal waterproofing as appropriate
Perimeter drain (fin or land drain to discharge water to down side)
If external drained used to control conditions >> Make rodable
General principles External or internal waterproofing as appropriate
Basement structure
Generally waterproofing to basement to be continuous Adequate details must be provided for junction, etc Details and construction should be as simple as possible
External or internal waterproofing as appropriate? Basement structure
Continuity seems simple But essential to consider with structure
Waterproofing Details Assumed continuity!!??
Foundation details Type A structure - strip foundation External or internal waterproofing
External or internal waterproofing
Discontinuity between slab and wall
Slab built-in
Foundation details Type A structure - piled foundation Internal waterproofing
?
Difficult to achieve external waterproofing
Interaction of water proofing with structure
Structural design - Waterproofing
Ultimately won’t fail but serviceability conditions may affect waterproofing
Simple design of section
Design structure in three dimensions
Cross section
Bending moments in structure
Design structure in three dimensions
Cross section
Bending moments in structure
Corner moments sometimes over looked
Plan
British Cement Association
Continuity of horizontal reinforcement in masonry walls (Figure 3A.3, AD Basements)
National House-Building Council
The Building Regulations 1991
Basements for dwellings
Horizontal reinforcement = 0.5 As along wall and around corners
Plan view Main vertical reinforcement
Similar detail provided for insitu walls (Fig 3B.2)
Cross section
Insitu concrete options
Corbel details? Ties required!
Construction?
Large section but easy to concrete
Waterproofing details?
Comment - Need to consider construction abilities/difficulties
Design in three dimensions - waterproofing Drawing is simple in two dimensions But structures are three dimensional !! Waterproofing membrane shown following thickened profile
Cross section
Design in three dimensions - waterproofing Drawing is simple in two dimensions But structures are three dimensional !! Waterproofing membrane shown following thickened profile
Cross section
Membrane likely to require preformed sections to cater for mitre
Comment: If not catered for can lead to construction defects
Plan view at corner
Design in three dimensions - waterproofing Drawing is simple in two dimensions But structures are three dimensional !!
Waterproofing membrane
OK here Cross section
Simpler square corner no mitre
Comment: Design can help waterproofing
Plan view at corner
Ensure compatibility between waterproofing and structure Stress and crack width controlled by reinforcement. Likely to be compatible with most waterproofing membranes.
. . . . .
Reinforced wall
In an unreinforced wall, crack width is uncontrolled. May exceed strain capacity of some waterproofing membranes.
Un-reinforced wall Comment: Structural behaviour can affect selection of waterproofing
Can basement be investigated and repaired? Example 1 May influence redesign and choice of waterproofing. Internal/External?
Structure designed for water-resistance (Type B)
Can basement be investigated and repaired? Example 1 May influence redesign and choice of waterproofing. Internal/External?
Structure designed for water-resistance (Type B)
Can basement be investigated and repaired? Example 1 May influence redesign and choice of waterproofing. Internal/External?
Structure designed for water-resistance (Type B)
Can basement be investigated and repaired? Example 2
Example 1 May influence redesign and choice of waterproofing. Internal/External?
?
?
Plan Structure designed for water-resistance (Type B)
Basement under part of area of house
Other Design Issues British Cement Association National House-Building Council
The Building Regulations 1991
Basements for dwellings
The new Approved Document – Basements for dwellings Amended to deal with B Regs 2000
British Cement Association National House-Building Council
The Building Regulations 1991 2000 B
Basements for dwellings
a m e s
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e C h lH a n
to ia c C g n
n o c u
il
e h T
i u B
g in d l
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Covers A, B, C, E, F, H, K, L, N, J and Vehicle access As for AD 1991 + Plus Part M
Contents
B Regs part
Site preparation and resistance to moisture
C
Structure
A
Fire safety
B
Conservation of fuel and power
L
Ventilation
F
Resistance to the passage of sound
E
Contents
Contd
B Regs part
Stairs, ramps and guards
K
Glazing - materials and protection
N
Drainage and waste disposal
H
Heat producing appliances
J
Vehicle access
Significant guidance on: Site preparation and resistance to moisture Structure Conservation of fuel and power
‘Site preparation and resistance to moisture’ Gives Guidance on: Subsoil drainage Obtaining water- resistance
‘Structure’ Gives Guidance on: Masonry retaining walls In-situ concrete retaining walls Foundations - plain and reinforced
Masonry retaining walls Table 3A.2 AD - Basements: Minimum masonry strength and reinforcement for 2.7 m propped retaining wall
Foundation type
Strip
Soil type (well drained)
Clay Granular
2.7 m
Vertical load (kN/m) up to
Moment taken at base of wall (kN/m)
Block comp. strength (N/mm2)
70
17
7
20
530
12
7
20
340
Brick comp. strength (N/mm2)
Area of reinfment As (mm2/m)
Table in AD also covers raft foundation and different vertical load Similar tables for 2.1 m and 1.6 m cantilevered walls 2.1 and 1.6 m
Insitu concrete retaining walls Table 3B.1 Minimum reinforcement for 2.7 m propped in-situ concrete retaining wall Foundation type
Strip
Soil type (well drained)
Clay Granular
Vertical load (kN/m) up to
70
Moment taken at base of wall (kN/m)
2.7 m Area of reinforcement As (mm2/m) Wall thickness (mm)
200
300
17
420
390*
12
290
390*
Table in AD also covers raft foundation and different vertical load Similar tables for 2.1 m and 1.6 m cantilevered walls 2.1 and 1.6 m
Centre line of retaining wall
British Cement Association National House-Building Council
The Building Regulations 1991
Retained ground
Basement
Basements for dwellings
Foundation requirements for strip foundation 200 mm min.
(a)
(b)
Cover 40 mm
Width of foundation (a)+(b)
Centre line of retaining wall C
Reinforcement as paragraph 3B.3.4
Retained ground
Requirement for raft foundation
Internal wall Basement Reinforcement as paragraph 3C.5.3 Reinforcement as paragraph 3C.5.1
T (to be not less than 200 mm 1200 mm minimum Foundation should extend past centreline of retaining wall by a distance equal to 2T, where T is the thickness of the foundation
Cover 20 mm
= C = 1200 mm minimum Cover 40 mm Reinforcement as paragraph 3C.5.2
‘Conservation of fuel and power’ Gives Guidance on: General requirements Tables for wall insulation thickness Tables for floor insulation thickness Calculation procedures Only in AD – Basements for dwellings
Not included in AD L1
Simplifying design and construction Available information, Inc AD Basement s Grades of construction , Construction options
Design and waterproofing issues Structure Waterproofing Repair
Adopt simple details
Approved Document – 2004 Simplifies design for walls, and foundations and aids reliability
And so to the finished project
By simplifying the design
Building into the Basement
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