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SAPS CALCULATIONS

 
 

U-VALUE - WALLS


SUMMARY OF BLOCK TYPES
USED IN THE TABLES
Block
 Thickness   LAMBDA VALUE
A
 100m Block @ 0.11 W/mK
B
 100m Block @ 0.15 W/mK
C
 100m Block @ 0.51 W/mK
D
 100m Block @ 1.13 W/mK

The tables below provide a quick and easy reference guide to the thickness of insulation required to meet the stated U-values for walls. All the solutions offered in this section are calculated using U-value calculation BS EN ISO 6946: 1997; are based on using butt edged insulation and are applicable for use with either stainless steel or galvanised wall ties.

Using a plaster finish to the internal wall, instead of a plasterboard finish as given in the examples below, will cause a slight increase in the insulation thickness required.		 
   

Full Fill Cavity
(102.5mm Facing brick outer skin, Insulation, 100mm Internal block, 12.5mm Plasterboard on dabs, Plaster skim)
U-Value 0.35
U-Value 0.30
U-Value 0.27
U-Value 0.25
MANUFACTURER
PRODUCT
LAMBDA
λ
BLOCK TYPE
A
B
C
D
BLOCK TYPE
A
B
C
D
BLOCK TYPE
A
B
C
D
BLOCK TYPE
A
B
C
D
 
Thickness MM
Thickness MM
Thickness MM
Thickness MM
BRITISH GYPSUM-ISOVER
ISOWOOL HI-CAV
0.033
60
75
75
85
       
75
85
100
100
       
100
100
-
-
       
100
-
-
-
       
KNAUF INSULATION
CROWN DRITHERM
PLUS CAVITY SLAB
0.036
-
-
-
85
       
75
85
-
100
       
-
100
-
-
       
100
-
-
-
       
CROWN DRITHERM
CAVITY SLAB
0.037
65
65
-
-
       
-
-
-
-
       
-
-
-
-
       
-
-
-
-
       
CROWN DRITHERM
CAVITY SLAB 34
0.034
-
 -
75
-
       
-
-
-
-
       
85
-
-
-
       
-
100
115
115
       

CROWN DRITHERM
CAVITY SLAB 32
0.032
-
-
-
-
       
-
-
85
-
       
-
-
100
100
       
-
-
-
-
       
ROCKWOOL
CAVITY WALL BATT
0.037
65
75
80
85
80
85
100
105
95
100
115
115
105
110
-
-
VENCEL RESIL
JABFILL
0.038
75
75
100
100
100
100
-
-
100
100
-
-
-
100
-
-

Partial Fill Cavity
(102.5mm Facing brick outer skin, 50mm Residual cavity, Insulation, 100mm Internal block, 12.5mm Plasterboard on dabs, Plaster skim)
U-Value 0.35
U-Value 0.30
U-Value 0.27
U-Value 0.25
MANUFACTURER
PRODUCT
LAMBDA
λ
BLOCK TYPE
A
B
C
D
BLOCK TYPE
A
B
C
D
BLOCK TYPE
A
B
C
D
BLOCK TYPE
A
B
C
D
Thickness MM
Thickness MM
Thickness MM
Thickness MM
BRITISH GYPSUM-ISOVER
ISOWOOL HI-CAV
0.031
35
40
65
65
       
50
70
-
-
       
75
-
-
-
       
-
-
-
-
       
CELOTEX
TUFF-R ™ZERO CW3000Z
0.023
30
30
40
45
       
40
45
50
55
       
45
50
60
60
       
55
60
65
70
       
DOW
WALLMATE CW-X
0.029
50
50
60
70
       
50
50
60
70
       
70
80
90
90
       
80
80
100
100
       
KINGSPAN
THERMAWALL TW50 ZERO ODP
0.023
25
25
30
40
       
60
70
80
80
       
45
45
60
60
       
50
60
65
70
       
KINGSPAN
KOOLTHERM K8 CAVITY BOARD
0.023 -0.021
25
30
35
40
       
35
40
50
50
       
40
45
50
60
       
45
50
60
65
       
KNAUF INSULATION
CROWN DRITHERM CAVITY SLAB
0.037
-
65
75
-
       
35
40
45
45
       
-
-
-
-
       
-
-
-
115
       
CROWN DRITHERM PLUS CAVITY SLAB
0.036
-
-
-
75
       
75
75
-
-
       
85
-
-
-
       
100
100
-
-
       
CROWN DRITHERM CAVITY SLAB 34
0.034
50
-
-
-
       
-
-
85
-
       
-
85
100
100
       
-
-
-
-
       
CROWN DRITHERM CAVITY SLAB 32
0.032
-
-
-
-
       
-
-
-
85
       
-
-
-
-
       
-
-
100
-
       
ROCKWOOL
HP PARTIAL FILL
0.034
-
-
-
-
70
75
85
-
80
85
100
-
90
95
-
-
VENCEL RESIL
JABWALL 70
0.038
55
 60
75
80
75
80
95
100
90
95
110
115
105
110
125
125

Timber Frame
90mm Timber Stud @ 600 centres
(Brick outer leaf, Cavity, Breather membrane, Sheathing board, Insulation, Vapour barrier, 12.5mm Plasterboard)
 
U-Value 0.35
U-Value 0.30
U-Value 0.27
U-Value 0.25
MANUFACTURER
PRODUCT
LAMBDA
λ
 CONSTRUCTION
Thickness MM
Thickness MM Thickness MM Thickness MM
BRITISH GYPSUM-ISOVER
ISOWOOL FRAME ROLL 032/BATT 032
0.032
 BETWEEN STUD
90 (*1)
CELOTEX
TUFF-RTM ZERO GA3000Z
0.023
 BETWEEN STUD
65
70 +
90 +
90 +
T-BREAKTMTB-3000
0.023
 IN FRONT OF STUD
-
12
12
20
KINGSPAN
ZERO ODP
0.023
 BETWEEN STUD
60
40 +
40 +
60 +
THERMAWALL TW55
   IN FRONT OF STUD
-
20
20
25
Calculations allow for 15% timber bridging detail

(*1) 0.32 U-Value is achieved if the breather membrane used is Tyvek Reflex or equivalent.
 

Timber Frame
140mm Timber Stud @600 centres
(Brick outer leaf, Cavity, Breather membrane,
Sheathing board, Insulation, Vapour barrier, 12.5mm Plasterboard)
     
U-Value
0.35
0.30
0.27
0.25
MANUFACTURER
PRODUCT
LAMBDA
λ
Thickness MM
BRITISH GYPSUM-ISOVER
ISOWOOL FRAME BATT HP 032
0.032
90
-
140 (*1)
140(*2)
ISOWOOL FRAME BATT 042
0.040
 - 140 - -
ISOWOOL FRAME ROLL 034/BATT34
0.034
 - - 140 140 (*5)
KNAUF INSULATION
CROWN TIMBER ROLL
0.032
90
-
140
-
CROWN TIMBER SLAB
0.032
90
-
-
-
CROWN FRAMETHERM ROLL 40
0.040
-
140
-
-
CROWN FRAMETHERM ROLL 35
0.035
-
-
-
140
ROCKWOOL
FLEXI
0.038
120
140
150 (*3)
150 (*4)
Calculations allow for 15% timber bridging detail

*1 - Isowool Frame Batt HP 032 (90mm & 50mm)
*2 - 0.24 U-value is achieved if the breather membrane used is Tyvek Reflex or equivalent.
*3 - 0.27 U-Value is achieved if 2 layers of plasterboard are used with a 150mm stud.
*4 - 0.25 U-Value is achieved if the breather membrane used is Tyvek Reflex or equivalent with a 150mm stud.
*5 - 0.25 U-Value is achieved if the breather membrane used is Tyvek Reflex or equivalent.
 

Timber Frame
90mm Timber Stud @600 centres
(Brick outer leaf, Cavity (unventilated), Breather membrane,
Sheathing board, Insulation, Vapour barrier, Laminate board)
     
U-Value
0.35
0.30
0.27
0.25
MANUFACTURER
PRODUCT
LAMBDA
λ
Thickness MM
KNAUF INSULATION
CROWN FRAMETHERM ROLL 38
0.038
-
90 + (25.5 - PL)
-
90 + (45.5 - PL)
CROWN TIMBER ROLL
0.032
-
-
90 + (30.5 - PL)
-
CROWN TIMBER SLAB
0.040
-
-
90 + (30.5 - PL)
-
Calculations allow for 15% timber bridging detail

PL = The insulation is used in conjunction with a Polyfoam Linerboard (thickness shown in brackets) to achieve the given U-values.
 

Clear Cavity - Dry Lining Solution
102mm Brick, 50mm Clear Cavity, 100mm Block, Thermal Laminate
     
U-Value 0.35
MANUFACTURER
PRODUCT
LAMBDA
λ
BLOCK TYPE
Thickness MM (Incl. 9.5mm plasterboard)
  A B C D
BRITISH GYPSUM
GYPROC THERMALINE SUPER
0.022-0.023
50
50
60
60
BRITISH GYPSUM
GYPROC THERMALINE PLUS
0.030
55
-
-
-
KNAUF DRYWALL
PHENOLIC LAMINATE
0.018-0.022
50
50
60
60
KNAUF DRYWALL
THERMAL LAMINATE PLUS
0.030
55
-
-
-
LAFARGE PLASTERBOARD
THERMALCHECK K
0.023 - 0.024
50
50
-
-
LAFARGE PLASTERBOARD
THERMALCHECK XP
0.030
55
-
-
-
         
 
U-Value 0.30
 
BLOCK TYPE
Thickness MM (Incl. 9.5mm plasterboard)
A
B
C
D
BRITISH GYPSUM
GYPROC THERMALINE SUPER
0.023
60
60
-
-
KNAUF DRYWALL
PHENOLIC LAMINATE
0.022
60
60
-
-
       
     
U-Value 0.27
     
BLOCK TYPE
Thickness MM (Incl. 9.5mm plasterboard)
     
A
B
C
D
BRITISH GYPSUM
GYPROC THERMALINE SUPER
0.024
65
-
-
-
KNAUF DRYWALL
PHENOLIC LAMINATE
0.022
65
-
-
-
 
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