Roadstone

Thermal Liteblock System

RS.BRO-12 Rev 01 Oct ‘19

CONTENTS

01. Introduction

02. Nearly Zero Energy Buildings (NZEB)

03. What is the ROADSTONE THERMAL LITEBLOCK?
• Key features and benefits of the Roadstone Thermal Liteblock System

04. What is Thermal Bridging?

05. What is a Lambda (λ) value?

What is an R Value?
What is a U value?
What is a psi value?

06. What is a (y) factor?

07. What happens with U values and Y values in DEAP?

• What is the Energy Performance Coefficient (EPC)?

09. How do U values & Thermal Bridging affect the Energy Performance of a building?

10. The effects of Thermal Bridging

12. Comparison of specifications and BER results

13. Reducing the risk of Mould growth and surface condensation

14. Roadstone 13N Thermal Liteblock

16. Block Range

17. 3D Details

19. Sample Thermal Bridging Details

LOCATIONS

LOCATIONS
Cork Laois Locations
1. Ballygarvan Retail Outlet Locations
26. Ballyadams
2. Carrigtwohill
Limerick
3. Castlemore 12
27. Joseph Hogan’s
4. Classis
28. Gooig
5. Keim
6. Mallow Longford
7. Midleton 29. Moyne

Clare Mayo
8. Ballyquinn 30. Castlebar 13
11
9. Bunratty Meath
10. Ryans 31. Barley Hill
Donegal 32. Duleek
11. Ballintra 33. Mullaghcrone 36
12. Carndonagh 34. Slane 30 8
29 31
13. Laghey Offaly
38
Dublin 35. Tullamore
34
14. Belgard Central Roscommon
33
37 32
Dispatch / Belgard 36. Boyle
Weighbridge 37. Cam 5
18
15. Huntstown Finglas 6 15
38. Castlemine 19 35
16. Head Office, 4 14 16
Tallaght Tipperary 23
47
39. Ballyknockane 46 9
17. Swords, Feltrim 10 3
40. Killough
8
26
Galway Waterford
9

18. Two-Mile-Ditch 28
41. Cappagh 27
26 45
40 24
19. Kilchreest
Wexford
Kerry 42. Brownswood,
20 39 42
20. Ballyegan Enniscorthy. 43

21. Killarney 25
43. Kilmuckridge 6 7
22. Killorglin 44. Killinick 22 21
44
5 41
Kildare Wicklow 2
23. Allen, Naas 45. Arklow 3 4
2 7
1
1
Kilkenny 46. Dorans Pit
24. Bennettsbridge 47. Fassaroe, Bray
25. Kilmacow

RETAIL OUTLET LOCATIONS

Cork Kilkenny
1. Ballygarvan 7. Kilmacow
2. Classis
Mayo
Clare 8. Castlebar
3. Ryans
Wicklow
Dublin 9. Fassaroe, Bray
4. Belgard
5. Feltrim, Swords

Galway
2
6. Two-Mile-Ditch
1
INTRODUCTION
Thermal bridging is one of the key factors The following construction types have
been examined and thermally modelled:
which need to be addressed to improve energy
efficiency in the design and construction of ► Cavity wall - full fill insulation
new buildings. All thermal bridges must be (Table D1)
► Cavity Wall - partial fill insulation
minimised to reduce heat loss through cold
(Table D1)
bridging. All major junctions between building ► External Insulation on to masonry
elements (floors, walls, roofs, windows and walls (Table D2)
doors) must be built in compliance with the ► Internal insulation with twin-pot
cavity block (Table D6)
Acceptable Construction Details (ACDs).
The Roadstone Thermal Liteblock system combines the Roadstone
Thermal Liteblock with the Roadstone concrete block range, which
when used in accordance with the Acceptable Construction Details
(ACDs), achieves psi values equal to or better than the standards set
out in Technical Guidance Document (TGD) Part L 2019.

Roadstone has thermally modelled all relevant details in appendix

D of TGD L 2019. From this extensive research Roadstone are now
in a position to provide detail solutions that comply fully with psi
value requirements outlined in TGD L 2019- Appendix D.

Retain the heat with

Roadstone Thermal Liteblock

Fig. 1

Ground floor to external wall junction

using Roadstone Thermal Liteblock
NEARLY ZERO ENERGY BUILDINGS(NZEB) 2

Definition Of Nearly Zero Energy Buildings Directive 2010/31/EU Energy Performance Of Buildings:
“ ‘nearly zero energy building’ means a building that has a very high energy performance, as determined in accordance with Annex I. The nearly zero or very low
amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produces
on site or nearby’’
The NZEB standard as set out in TGD L 2017 Buildings other than dwellings applies to works from 1st January 2019 (subject to
transitional arrangements). For Public Sector bodies, NZEB applies from 31st December 2018.

Impacts of NZEB
TGD L 2019 Dwellings includes numerical indicators for NZEB which apply to works from 1st November 2019 (subject to
transitional arrangements). The numerical indicators provide Maximum Permitted Energy Performance Coefficient (MPEPC)
of 0.30 and Maximum Permitted Carbon Performance Coefficient ( MPCPC) of 0.35. Note: These indicators are relevant to
both Part L 2011 (with 2017 amendments) and Part L 2019.

Renewable Energy Requirement

Renewable Energy Ratio (RER) is the ratio of the primary energy from renewable energy technologies to total primary energy
as defined and calculated in DEAP. An RER of 0.2 represents 20% of the primary energy from renewable energy technologies
to total primary energy as defined and calculated in DEAP.

The nearly zero or very low amount of energy must be covered to a very significant extent by energy from renewable sources
including energy from renewable sources produced on site or nearby.

In order to achieve NZEB compliance, it means that buildings will require:

• Improved Fabric Efficiency: This will result in a larger footprint due to increased insulation thickness within external wall in
order to achieve the same internal floor area. It will also mean that deeper dig levels will be required to facilitate extra
floor insulation. In addition, windows with reduced U Values, in certain cases triple glazed windows, will be required to
achieve NZEB compliance. Low values of air permeability should also be targeted.
• Advanced Services and Lighting Specification: Heat sources e.g. Air Source Heat Pumps with improved efficiencies will
be a key element as well as 100% energy efficient lighting. Mechanical ventilation with high heat recovery efficiency may be
needed in certain cases to achieve NZEB compliance
• Renewable Energy Ratio of 20%: Increasing the number of highly efficient PV panels will also be a key element in
achieving compliance.

Benefits of Roadstone Thermal Liteblock regarding NZEB

• There is a significant benefit in targeting a y value (Thermal Bridging Factor) of 0.05 W/m²K and avoiding the use of the
penalising default y value of 0.15 W/m²K, or 0.08 W/m²K where all details are as per ACDs
• If details are bespoke, a y value of 0.15 W/m²K must be used: To avoid this penalty, bespoke details should be thermally
modelled by an approved NSAI Thermal Modeller . This needs to be part of the energy strategy at design
• Typical ACD’s, as well as a suite of bespoke junctions have been modelled with Roadstone Thermal Liteblocks (both 7.5N
and 13N) and enhanced psi values over TGDL 2017 have been achieved.
• These psi values, when inputted into a manual y value calculation, typically result in improved y values/Thermal Bridging
Factor (TBF) outputs. Using the calculated y value means that relaxing the U Values of building elements and windows, and
even reducing the efficiency of services and number of PV panels may be possible while still achieving NZEB compliance.
3 What is the
ROADSTONE THERMAL LITEBLOCK?
Roadstone Thermal Liteblock is manufactured in Ireland, achieving
thermal conductivity (Lambda λ) values of 0.33W/mK, using a special mix
which includes light weight aggregates. This mix produces a concrete
block with excellent insulation properties, while maintaining structural
strength and allowing for traditional construction methods to be used.

Energy efficient design begins with a Fabric First Approach, whereby the buildings shape,
orientation and thermal mass, with proper detailing, will save energy. This ensures that the
majority of the energy saving work is done by the building by having a high performance
fabric rather than relying completely on the addition of mechanical renewable energy systems.
The Roadstone Thermal Liteblock plays a key role in achieving good thermal efficiency in
the building fabric by providing a highly cost effective solution to achieve improved thermal
bridging performance, thus reducing cold bridging and allowing designers more flexibility
when generating a Part L compliant specification.

Key features and benefits of the

Roadstone Thermal Liteblock System
► The Roadstone Thermal Liteblock is required only in key locations in conjunction with the
Roadstone Concrete Block range.
► The thermal mass integrity of the building is maintained when using Roadstone Thermal
Liteblock in conjunction with the Roadstone Concrete Block range.
► The Roadstone Thermal Liteblock system is a very cost effective solution and can result in
significant savings in the overall build cost.
► Robust and durable concrete block available in both 7.5 N/mm2 and 13N/mm2 .
► Roadstone can provide Standard Construction Details* which are proven to comply
with the psi value requirements and facilitates ease of compliance with TGD L 2019.
► Roadstone Thermal Liteblock is unique in colour to enable traceability on site.
Photographic recording of the Thermal Liteblock built on site can then form evidence of
compliance for the Assigned Certifier, Architects, Engineers and BER assessors.
► Reduced Thermal Bridging resulting in reduced heat loss, and lower heating bills.
► Excellent thermal conductivity (Lambda λ) value of 0.33 W/mK which is a 300%
improvement when compared to standard blocks.
► CE marked– manufactured to the requirements of I.S. EN 771-3 to System 2+.
► Suits traditional construction methods familiar to Irish and UK designers and builders.
► Roadstone Thermal Liteblock is a concrete block and provides excellent adhesive
properties with traditional mortars and renders.
► Improved (y) factor calculations are achieved when using the
Roadstone Thermal Liteblock system.
► When a full building specific (y) factor calculation is carried out using the psi values
incorporating the Roadstone Thermal Liteblock, improved (y) factor as low as .03 can be
achieved.
► Compliant U values are achieved without having to provide a cavity in excess of 150mm.
 4

What are the benefits to using the Roadstone Thermal Liteblock

System in a low energy building, and what is the impact on the
Building Energy Rating (BER) results?

To demonstrate the benefits, we need to be clear on what thermal bridging is, and the difference
between U value, thermal conductivity (Lambda λ) value, psi (ᴪ) values and how psi (ᴪ) values
are used to calculate the overall (y) factor for a building. All of these parametres are used in the
Dwelling Energy Assessment Procedure (DEAP) in Ireland, to calculate the overall heat loss through
the building fabric.

What is Thermal Bridging?

Thermal bridging is a localised area of the building envelope where the heat flow is increased
in comparison with that of adjacent areas, due to junctions where insulation is not continuous.
Thermal bridges are weaknesses in the building envelope where thermal energy is transferred
at an increased rate compared to the surrounding area. Thermal Bridging is first measured by
calculating the psi(ᴪ) value of each junction (see below explanation for psi(ᴪ) value. The sum of
the psi(ᴪ) values are then multiplied by the lengths of the bridged junctions, these figures are then
used to calculate the overall Thermal Bridging Factor (y value) for any given building.

Thermal bridging occurs in 3 different ways:

1. Repeating (e.g. timber studs with insulation 3. Non-repeating (e.g. Junctions between
between, at fixed distance centres): floors and walls, walls and roofs, window
Because this type of bridging is constant, jambs and heads). Cold bridging at these
the effects of a repeating thermal bridge can junctions occurs where the insulation
be accounted for in a U value calculation. layer is interrupted by non-insulating
materials, and heat loss in these areas
2. Random (e.g. one off cold bridge due to can lead to reduced surface temperatures
penetration of the insulation layer, such as a causing interstitial and surface condensation
balcony support bracket, metre box etc). to occur.

Fig. 2

The first diagram shows a non-compliant eaves

THERMAL BRIDGE detail where the cavity is closed by a concrete block,
bridging the inner and outer leafs. This leads to cold
surfaces at the top of the inner leaf and can lead to
surface condensation. The second diagram shows a
typical floor and external walls junction, where the
inner leaf is bridging between the floor insulation and
the cavity wall insulation. The use of regular blocks in
this location can lead to cold surface temperatures,
surface condensation above and behind the skirting
board area.
THERMAL BRIDGE

REGULAR BLOCK
Fig 2 – Thermal Bridging
heat flow diagram
5
What is a Lambda (λ) value? What is an R Value?
THERMAL CONDUCTIVITY (W/mK) THERMAL RESISTANCE (m2 K/W)
A Lambda value (λ) is a measure of the rate of The R- Value is a measure of the resistance to
heat flow through a material (fig 3). It will vary heat flow of a given thickness of a material (fig 4)
with density, porosity, moisture content and or combination of materials, i.e. building plane
temperature of the material. The units of Thermal elements such as a wall, roof or floor.
Conductivity are expressed in watts per metre To calculate the Thermal Resistance (R) of a
of thickness per degree Kelvin of temperature material, divide the thickness (d) of material by its
difference from one side of the material to the lambda value (λ). d/ λ =R.
other. The lower the number, the less heat passes
through the material.

For example:
Standard Concrete block: λ = 1.33 (W/mk)
Roadstone Thermal Liteblock: λ = 0.33 (W/mk)

Fig. 3 Fig. 4

Lambda = heat flow Resistance = material’s

through material ability to resist heat flow.

What is a U value? (W/(m2K) What is a psi value? (W/mK)

The Thermal Transmittance (U value) relates to a The psi value (ᴪ) is the amount of heat (Watts)
building plane element (wall, roof, floor), and is a lost at a thermal bridge, for every linear metre
measure of the rate at which heat passes through (m) of that bridge, multiplied by the temperature
one square metre of all of the components difference between outside and inside (degrees
combined to make up that structure (fig. 5). The Kelvin (K)). The psi value represents the extra heat
U value is measured in W/m2K (Watts per square flow through the linear thermal bridge over and
metre Kelvin), where Kelvin (K) is the unit of above that through the adjoining plane elements.
temperature difference across the elements from The psi value figures for any given junction are
inside to outside. A U value = 1 divided by the sum multiplied by the lengths of those Junctions to
of all the thermal resistances of each component in calculate the buildings y factor. A psi value for a
the structure combined, i.e. 1 / Σ (R) = U. junction is calculated using 2D and 3D thermal
modelling, in accordance with various standards
such as BR497, BRE IP 1/06, I.S. EN ISO 6946
I.S. EN ISO 10211, I.S. EN ISO 13370 depending on
the junction type.

Fig. 5 Fig. 6

U value = Watts (W) of heat flow Psi = Heat flow (Watts) per metre
per m2 x temperature difference (K) (m) x Temperature Difference (K)
What is a (y) factor? 6

The DEAP calculation accounts for thermal bridging at junctions between elements and around
openings using a (y) factor. When linear thermal transmittance psiᴪ(ᴪ) values are available for
element junctions, the psi values can be multiplied by the lengths (l) of their respective junctions
(ᴪ
ᴪ X l), and the sum of all the (psi X l) figure is then divided by the total area of building envelope
containing thermal bridging, to calculate the (y). Roadstone can now provide details* and
corresponding psi values, in line with Paragraph 3 of Appendix K of the DEAP Manual below:

Fig. 7

DEAP MANUAL EXTRACT:

A default value of y = 0.15 W/m2K applies for all dwellings except for the following:

Paragraph 1
y = 0.08 W/m2K: for new dwellings whose details conform with “Limiting Thermal Bridging
and Air Infiltration – Acceptable Construction Details” (www.environ.ie ) as referenced
in Building Regulations 2008 and 2011 TGD L. This requires that the relevant drawings be
signed off by the developer, builder, site engineer or architect. The BER Assessor must retain the
relevant drawings, such as those from the Acceptable Construction Details and associated sign
off in support of thermal bridging factor entered.

Paragraph 3
Alternatively values of (Ψ) can be determined from the results of numerical modelling, or
they can be derived from measurement. If the junction detail is as recommended in Acceptable
Construction Details (ACDs), the Ψ-value associated with that junction can be taken from TGD
L 2011 Appendix D or from Introduction Document for Acceptable Construction Details or
other certified Ψ values.
7 What happens with
U values and Y values in DEAP? (Dwelling Energy Assessment Procedure)

When entering the dimensions of a building into DEAP the assessor measures and enters the
areas and U values for each plane element. DEAP calculates the total building fabric heat loss by
multiplying the area of each element by their U value, adding these all together to get the total
heat loss via plane elements.

The assessor then uses a (y) factor to account for the heat losses via thermal bridging. The (y)
factor is a fraction or percentage of the overall heat lost through the fabric, and takes into account
the total envelope area containing thermal bridges. See figure 8 showing areas for U values, and
lengths for psi values.

The total heat loss envelope area, heat loss through plane elements and cold bridging are all
combined to determine the total heat loss through the building fabric. The fabric heat loss figure,
along with all other parameters, are used to determine the overall energy efficiency of the building.

Fig. 8

psi Junction lengths

U Value Areas for walls

U Value Area for Roof (insulated at ceiling)

U Value Area for Door

U Value Area for Windows

U Value Area for Floor

Typical U Value areas and psi value

length measurements.

Include all external walls, windows, doors and floors. (Rear walls and windows not shown above).
All measurements to be taken in accordance with SEAI BER Assessor Methods, using internal dimensions
to measure lengths and areas.

What is the
Energy Performance Coefficient (EPC)?
DEAP calculates the Energy Performance of a building and measures it against a notional
compliant version of the same building simultaneously. DEAP then calculates and compares the
dwelling’s Energy Performance Coefficient (EPC) and Carbon Performance Coefficient (CPC) to the
Maximum Permitted Energy Performance Coefficient (MPEPC) and Maximum Permitted Carbon
Performance Coefficient (MPCPC) for Building Regulations TGD L 2019, currently set at MPEPC of
0.3 and MPCPC of 0.35.
 8

Lambda Resistance U value

Thermal conductivity Thickness divided 1 over sum of all resistance
by lambda value

U wall

U floor

psi value U values x areas

Y value calculation

D.E.A.P.

Dwelling Energy
Assessment Procedure

Fig 9 – Flow Diagram of a BER calculation

9 How do U values & Thermal Bridging
affect the Energy Performance of a building?

As outlined earlier, DEAP uses the areas of building elements (roofs, walls, floors) and their
corresponding U values to calculate how much heat will be lost through the fabric of a building.
The lower the U value, the less heat loss through that particular element.

The building heat loss through thermal bridging is then accounted for by entering
a factor for thermal bridging (y) into DEAP. A lower (y) factor will result in a better BER result.

It is important to note that the higher the thermal performance of the building’s plane elements,
the higher the risk of condensation occurring at cold bridged junctions. As U values are lowered
(improved), correct detailing becomes extremely critical to avoid surface condensation occurring.

By using Roadstone Thermal Liteblock Standard Details*, you can claim a default (y) factor of 0.08
as described in paragraph (3) of the DEAP manual extract . (See Page 6)

Fig. 10

The psi values associated with the Roadstone Roadstone recommend that to get the
Thermal Liteblock can be used to significantly full cost benefit saving to the overall build cost of
reduce the (y) factor of a building and improve a building type, a full detailed (y)
the BER results when an overall (y) calculation is value calculation is carried out. Roadstone can
carried out. provide this service through their nominated
thermal modelling technical support teams.

The solution to comfortably complying with Part L for Architects,

Engineers, Assigned Certifiers and Building Contractors

Roadstone has thermally modelled each critical junction detail, ACD’s as listed in TGD L 2019
appendix D1, D2, D4 and D6 and has calculated the psi value for each junction. This means we
can provide a validated (y) factor calculation to our customers when using the Roadstone Thermal
Liteblock system and the improved benefits of this will be evident in the improved BER results for
your building. By using the Roadstone Thermal Liteblock System you can comfortably comply with
TGD Part L 2019 thermal bridging requirements.
The Roadstone Thermal Liteblock System provides the following benefits:
10

► Certified construction details that comply with TGD L 2019.

► Roadstone Thermal Liteblock is heather in colour for ease of identification during construction
► Fabric first approach with reduced thermal conductivity at cold bridges.
► Full certified (y) factor and thermal modelling service is available. **
► An improved BER rating for your building providing added value and additional
energy cost savings

Contact a member of our technical team for further guidance

The effects of Thermal Bridging

(y) factors on the BER of a typical semi-detached house:
We have taken a typical 126m2 semi-detached sample house used to demonstrate compliance with
Part L of the Building Regulations, with the following fabric U values:
Walls 0.18, Roof 0.13, Floor 0.16, i.e. within the range set out in Table D1 of TGD L 2019.
Other construction types can be used as per Table D2, D4 and D6 of TGD L 2019.

Fig. 11

House details
Jamb length doors - 8.2 m
Ground floor external perimeter - 23 m
Intermediate floor - 23 m
Eaves - 14 m
Gable (insulation at ceiling level)-9m
External Corners - 10.20m
Party wall corners with external - 10.20m
Party wall junction with floor- 9m
Party wall junction with ceiling -9m 5.1m
Rising walls-9m

All dimensions are internal

Exposed Area 243.3m² 9m 7m

This sample house has an Air to Water Heat pump providing hot water and space heating, no solar,
no heat recovery ventilation, with a wood burning stove as the secondary heating, with 1
flue and passive vents.

When we calculate the (y) factor for this house using the Roadstone Thermal Liteblock System’s
thermal bridging psi values, the (y) factor improves to 0.0266 W/m2K. This results in a BER of A2 @
49.99 kwh/m2/yr. This lower thermal bridging factor has a very significant effect on the BER. This (y)
factor calculation and BER result is based on traditional build cavity wall details using Roadstone
Thermal Liteblock psi values in lieu of defaults from Table D1 of TGD L 2019. Roadstone modelled
psi values are also available for twin-pot cavity blocks, solid masonry block with external insulation
and frame construction types.
See table 1 for summary specification and BER results.
11 The effects of Thermal Bridging
(y) factors on the BER of a large detached house:
To examine the effects of improved (y) factors further, we have carried out the same exercise
on a larger detached house. See table 1 for summary specification and BER results,
which demonstrates clearly the benefit of using the Roadstone Thermal Liteblock in key
locations, achieving lower (y) factors, resulting in reduced energy values, lower heating bills
and better BER results.

Fig. 12

This larger sample house also has an Air to Water Heat Pump providing all Domestic Hot Water,
passive ventilation, a wood burning stove as the secondary heating system with 1 flue and no
solar thermal panels.

By implementing the Roadstone Thermal Liteblock and using the psi values from the Roadstone
Thermal Modelling research, the (y) factor is calculated to be .05 W/m2K, and the BER result is an A2
Rating at 46.84 kWh/m2/yr.

Semi Detached House Detached House

BER Improvement BER Improvement
Table 1: Comparison of specifications and BER results 12
between Semi D and Larger Detached house

Semi Detached House Large Detached House

Area 126m2 229m2

Volume 321.3 m3 606.29 m3

Primary Heating System Air to Water Heat Pump Air to Water Heat Pump
449% Efficient 449% Efficient

Secondary Heating System Wood burning Stove with flue Wood burning Stove with flue

Solar Hot Water None None

Passive Vents Yes Yes

Air Tightness Level 0.25 ac/h 0.25 ac/h

(5m3/m2/hr @ 50 Pa) (5m3/m2/hr @ 50 Pa)

Heating Distribution Fully zoned with time and Fully zoned with time and
temperature controls temperature controls

Domestic Hot Water From Heat Pump, into 200ltr From Heat Pump, into 200ltr
insulated cylinder. insulated cylinder.

U Values

Walls 0.18 0.18

Floors 0.16 0.16

Roofs 0.13 0.13 insulated at level ceilings

0.16 insulated at pitched ceilings

BER Results

BER with Roadstone (y) = 0.0266 W/m2K (y) = 0.05 W/m2K

Thermal Liteblock details A2 @ 49.99 kWh/m2/yr A2 @ 46.84 kWh/m2/yr
applied and calculated
(y) factor
13 Reducing the risk of
Mould growth and surface condensation

The improved y values that the Roadstone Thermal Liteblock system provides, offers reduced
thermal bridging and limits the risk of surface condensation and mould growth.

Surface condensation can occur on the surfaces of walls, windows, ceilings and floors and
may result in mould and mildew. Condensation in buildings occurs whenever warm moist air
meets surfaces that are at or below the dew point of that air. The key factor used in assessing the
risk of mould growth or surface condensation in the vicinity of thermal bridges is the temperature
factor (fRsi).

The temperature factor (fRsi) is defined as follows:

fRsi = (Tsi – Te) / (Ti – Te)

where:
Tsi = minimum internal surface temperature,
Te = external temperature, and
Ti = internal temperature.

For dwellings, the value of fRsi should be greater than or equal to 0.75, so as to avoid
the risk of mould growth and surface condensation. Full checks should be performed on the
likelihood of surface and interstitial condensation of a construction detail in accordance with I.S. EN
ISO 13788 and the 2019 Building Regulations. The Roadstone Thermal Liteblock System provides
improved psi(Ψ) values equal to or better than the standards set out in TGD Part L,2019 and lower
subsequent y values that limit the risk of surface condensation. The risk of surface condensation
and subsequent mould growth is significantly reduced for junctions with lower linear thermal
transmittance (psi(Ψ) values).

Roadstone Thermal Liteblock Characteristics

Roadstone Thermal Liteblock is a durable lightweight concrete block that has been developed
for use with traditional masonry wall construction. Roadstone Thermal Liteblock is CE marked to
system 2+ in accordance with the requirements of I.S. EN771-3: Specification for masonry units-
Part 3: Aggregate concrete masonry units (dense and light-weight concrete).

Table 2: Roadstone Thermal Liteblock: Typical characteristics

Characteristic Declared Performance Technical Standard

Block Dimensions L 440mm IS EN 772-16
H 215mm
W 100mm
Weight (dry) 11.2kg IS EN 772-13
Density 1200kg/m 3
IS EN 772-13
Strength 7.5N/mm 2
IS EN 772-1
Thermal Conductivity 0.33W/mk & 13N/mm2 IS EN 1745
Fire Resistance Classification 2 hours IS EN 1996-1-2
Moisture Movement 0.6mm/m I.S. EN 772-14
Shear Bond Strength 0.15N/mm 2
IS EN 998-2
Colour Heather N/A
ROADSTONE 13N THERMAL LITEBLOCK: 14

DURABILITY & S.R. 325

The Roadstone Thermal Liteblock is now available freeze/thaw resistance EN in place. The standard also
in 13N. This increased strength Roadstone Thermal states that when relevant “the manufacturer shall
Liteblock is ideal for use in commercial and high-rise evaluate and declare the freeze/thaw resistance of
residential buildings which have greater structural the units by reference to the provisions valid in the
requirements as well as locations below or near intended place of use”. This means it is up to the
ground level requiring increased durability against manufacturer to decide on a suitable freeze/thaw
freeze/thaw attack. The Roadstone 13N Thermal resistance test procedure.
Liteblock has been rigorously tested for freeze/
thaw resistance and satisfies all the durability
requirements of S.R. 325 Table 14(A). The Roadstone S.R. 325 COMPLIANCE
13N Thermal Liteblock is a CE marked product,
manufactured in our state-of-the-art plant under a S.R. 325 Table 14 sets out the durability requirements
registered Quality Management System to I.S. EN ISO for clay and aggregate concrete masonry units for
9001 and certified by the NSAI. given exposure conditions. For work below or near
external ground level where there is a high risk of
I.S. EN COMPLIANCE saturation with freezing a 13N aggregate concrete
block is specified. A minimum block density is also
Concrete blocks in Ireland are produced to I.S. indicated. This combination of higher strength
EN 771-3 ‘Specification for masonry units – Part and density satisfies the freeze/thaw durability
3: Aggregate concrete masonry units (Dense and requirements without the need for costly freeze/
lightweight aggregates)’. The standard states that thaw resistance testing. To confirm its suitability
when a suitable layer of render is applied which for use in these severe exposure conditions the
provides a “complete protection against water Roadstone 13N Thermal Liteblock has undergone
penetration no reference to freeze/thaw resistance is freeze/thaw resistance testing as outlined below.
required”. For this reason there is no concrete block
15

FREEZE/THAW RESISTANCE

The Roadstone 13N Thermal Liteblock has been tested for freeze/thaw resistance using
an in-house method based on I.S. EN 772-22 ‘Determination of freeze/thaw resistance
of clay masonry units’. Clay masonry units are typically unrendered and exposed to the
elements and therefore require a higher level of freeze/thaw resistance. The test takes
12 days to complete and subjects a saturated masonry panel to 100 cycles of freezing to
-15°C and thawing to +10°C, while spraying with water at regular intervals throughout.
This is a severe and robust test method and far exceeds the typical freeze/thaw durability
requirements of masonry units in Ireland. The Roadstone 13N Thermal Liteblock proved
to be exceptionally durable to freeze/thaw attack. Based on the criteria outlined in I.S. EN
772-22 the Roadstone 13N Thermal Liteblock can be classified as Freeze/Thaw Resistance
Category F2 (suitable for use in severe exposure conditions) and therefore satisfies the
freeze/thaw durability requirements of S.R. 325 Table 14(A).

ADVANTAGES

• Traditional concrete block

• Light weight
• Reduced thermal bridging
• λ< 0.33W/mK
• High strength
• Freeze/thaw resistance tested
• S.R. 325 Table 14(A) durability compliant
• Retains strength when wet
• Accepts standard block fixings

For more information on the Roadstone Thermal Liteblock, including a full range of Part L
compliant thermally modelled technical drawings and AutoCAD details, see
www.roadstone.ie
 BLOCK RANGE

100mm SOAP BAR

100mm SOLID
7.5 N/mm2 and
13 N/mm2

140mm SOAP BAR

140mm SOLID

CAVITY CLOSER

CAVITY CLOSER STOCK BRICK

3D DETAILS INDICATE
WHERE THERMAL
LITEBLOCKS CAN BE USED

EAVES

JAMB

BELOW SLAB
 SEPERATING WALL A

SEPERATING WALL B

SEPERATING WALL C

GABLE
 16
19
Sample Thermal Bridging Details
Download the full range of Technical Drawings from
www.roadstone.ie/thermal-liteblock.

440 x 215 x 100 Roadstone Floor U Value varies, must be within Ranges set
Standard Blocks out in Table D1 of Appendix D of TGD part L
350
440 x 215 x 100 Roadstone 2011 for Psi values to be applicable.
Thermal Liteblock 150
DPC See configuration options A and B below,
DPM / Radon Barrier depending on y value requirements.
Roadstone Custom Psi values
Cavity Wall U-Values vary,
see appendix D of TGD part L 2011.
Floor insulation to tightly abut blockwork wall U Value Part L Roadstone TLB
Range (Ψ) Psi (Ψ) Value
Install perimeter insulation with min. R value of
2.27m2k/W or greater (W/m2K) Option Option
All Blocks (Including Thermal A B
(example 50mm of PIR λ 0.022 = R2.27)
Liteblocks) to be minimum
7.5N in accordance with
section 1.1.3.5 TGD Part A 0.18 0.080 0.036 0.042
FFL
2012)
0.15 0.042 0.033 0.040
225mm min.

Ensure wall X and Y are to

Y Engineer's as modelled by NSAI registered Thermal
insulation is installed
Specification Modellers:
at least 225mm
below top of floor X
insulation
GL

215

140 DPM / Radon Barrier

Annex E of SR 21 Material
Annex E of SR 21 Material

Note: Alternative Configuration Depending

on Y Value Requirements Use Roadstone Thermal Liteblock All options pass f Rsi assessment,
configuration A or B as advised by no surface condensation predicted
OPTION B Y-Value calculation and Roadstone
Technical Support Options A and B in the 0.15 and 0.21 W/ m² K U Value
Can be single block or ranges surpass default Psi values and therefore a default
two soapbars y-value of 0.08 can be assumed using these options
without a y-value calculation, provided all other details
in the building comply with the published ACDs / Roadstone
details.
OPTION A

440 x 215 x 100

REVISION: B DWG. NO.: DETAIL RS 1.01 b FF DATE: May 2019

TO BE READ IN CONJUNCTION
SCALE: NTS JUNCTION: FULL FILL CAVITY WALL/ INSULATION ABOVE SLAB
WITH Y-VALUE CALCULATION
Copyright © ROADSTONE This information is supplied in good faith and no liability can be accepted for any loss or damage resulting from use.
 20

440 x 215 x 100 Roadstone See TGD B for fire cavity barrier
Standard Blocks requirements. (Fire cavity barrier not
440 x 215 x 100 Roadstone included in Psi-Value Calculation)
Thermal Liteblock
DPC
Partial fill Cavity Wall Roadstone Custom Psi values
U-Values vary, see appendix D of Continue cavity wall insulation across
TGD part L 2011. U Value Roadstone TLB
wall abutment zone Part L
Range (Ψ) Psi (Ψ) Value
(W/m2K)

0.18 0.045 0.042

150 350

As modelled by NSAI registered Thermal

Modellers:

440
Partial fill insulation to be secured
firmly against the innerleaf of the
cavity wall
Roadstone Thermal Liteblock first
block in party wall, block on flat.
215

All options pass f Rsi assessment,

All Blocks (Including Thermal
no surface condensation predicted
Liteblocks) to be minimum
7.5N in accordance with TGD
Part A 2012) *Note:

In the 0.21 Uwall Range the model surpasses the default

Psi value and therefore a y-value of 0.08 can be
assumed using this option without a y-value
calculation, provided all other details in the building
comply with the published ACDs and/or Roadstone
modelled details.
215

REVISION: B DWG. NO.: DETAIL RS 1.06.1 DATE: May 2019

TO BE READ IN CONJUNCTION
SCALE: NTS JUNCTION: PARTIAL FILL CAVITY WALL/ PARTY WALL PLAN DETAIL
WITH Y-VALUE CALCULATION
Copyright © ROADSTONE This information is supplied in good faith and no liability can be accepted for any loss or damage resulting from use.

350
440 x 215 x 100 Roadstone 150 Roadstone Standard Block
Standard Blocks
Roadstone Custom Psi values
Ensure that full depth of U Value Part L
440 x 215 x 100 Roadstone Roadstone TLB
insulation between and over
Thermal Liteblock
joists extends to the inner edge Range (Ψ) Psi (Ψ) Value
Continue cavity wall insulation to of the wall (W/m2K)
top of gable
OR
270mm above bottom of ceiling
tie and insert cavity tray 0.18 0.272 0.173

Roof buildup:
0.15 0.152 0.129
Varies, to achieve U values within the
As modelled by NSAI registered Thermal
wall 0.21 or 0.15 Range (refer to
Modellers:
Appendix D of TGD part L 2011)

Roadstone Thermal Liteblock at location of

Ceiling Insulation zone only.
Pack compressible insulation
between last joist and gable
wall

Partial fill Cavity Wall

U-Values vary, see appendix D of
Partial fill insulation to be secured TGD part L 2011.
firmly against the innerleaf of the All options pass f Rsi assessment,
cavity wall no surface condensation predicted

*Note:

Both the 0.21 U Value Range and the 0.15 U Value

range models surpass the default Psi values and
therefore a y-value of 0.08 can be assumed using this
option without a y-value calculation, provided all other
details in the building comply with the published ACDs
and/or Roadstone modelled details.

REVISION: B DWG. NO.: DETAIL RS 1.15 DATE: May 2019

JUNCTION: PARTIAL FILL GABLE CAVITY WALL/ VENTILATED ROOF - INSULATED AT ATTIC TO BE READ IN CONJUNCTION
SCALE: NTS
FLOOR LEVEL WITH Y-VALUE CALCULATION
Copyright © ROADSTONE This information is supplied in good faith and no liability can be accepted for any loss or damage resulting from use.

Files are compatible with Autocad 2013 and newer.

www.roadstone.ie
Phone: 01 4041200
Email: info@roadstone.ie