Terrace Home Guide - GIB® · Terrace homes have at least one vertical intertenancy separation and the performance requirements of ... Maximising the usable and saleable floor space

Terrace Home GuideAn overview of intertenancy options

CBI 5113

NOVEMBER 2016

Our cities are becoming denser, urban populations are growing, land prices are rising, and this is impacting the types of homes we are building. BRANZ is forecasting that by 2017, multi-unit dwellings (apartments/townhouses/units) will make up a third of all new consented dwellings, and in Auckland this will be close to 50 per cent*.

Attached dwellings present design challenges that don’t appear when designing detached houses. New Zealand Building Code (NZBC) provisions that typically do not apply to detached dwellings need to be considered in the design and construction of terrace homes. These provisions include protection from fire and airborne sound.

*National Construction Pipeline Report 3, July 2015.

NATIONAL SUPPORT

VISIT: Winstone Wallboards Limited

37 Felix Street, Penrose 1061 ,

Auckland, New Zealand

POST: PO Box 12 256, Penrose 1642,

Auckland, New Zealand

PHONE: +64 9 633 0100

FAX: +64 9 633 0101

Free Fax: 0800 229 222

EMAIL: [email protected]

WEB: gib.co.nz

GIB® HELPLINE

0800 100 442

front cover: Interior of a Warren and Mahoney terrace home in Christchurch. left: Terrace homes are growing in popularity, particularly in Auckland and Christchurch.

GIB® TERRACE HOME GUIDE GIB® TERRACE HOME GUIDE2 3NOVEMBER 2016 NOVEMBER 2016GIB® HELPLINE 0800 100 442 OR GIB.CO.NZ FOR MORE INFO GIB® HELPLINE 0800 100 442 OR GIB.CO.NZ FOR MORE INFO

Helping you find the right intertenancy system for your project

This visual guide was developed to help navigate

through the design and construction challenges of

terrace homes and to provide a summary of some

of the different intertenancy systems and solutions

available, as well as clarify their performance

requirements.

Throughout, this document will direct you to specific

support and systems literature for technical assistance

and details. The GIB® Helpline is always available

where our technical team of builders and engineers

can provide GIB® specification assistance.

CONTENTS

Helping you find the right 5

system for your project

Performance 6

NZBC requirements relating 6

to sound transmission

Best practice — sound 6

Environmental and services noise 6

Gaps, flanking and insulation 7

NZBC requirements relating 7

to protection from fire

Penetrations through fire 8

and noise separations

Plumbing and ducting 8

Electrical 8

Other design considerations 9

Security 10

Unit value and sale price 10

Raise the ceiling 10

Fussy details, site tolerances and 10

additional trades add complexity

Intertenancy system weight 10

The right intertenancy system for the situation 10

GIB® warranty 10

The cost of the intertenancy specification 11

Comparing intertenancy systems 12

GIB® Systems 15

Double timber frame systems 15

GIB Intertenancy Barrierline® Systems 17

Beware of substitution 18

Copyright 18

A precast concrete intertenancy wall erected on an Auckland terrace home site.


Performance

The physical arrangement of a terrace home can

present challenges when trying to comply with the

performance requirements of the New Zealand

Building Code (NZBC).

Meeting NZBC requirements is of the highest priority,

but cost and ease of construction also impact on the

choice of intertenancy system. From different levels of

noise control or fire protection to considerations like

accessibility, understanding the impacts of different

characteristics is essential when choosing the most

appropriate solution for your site and customers.

NZBC requirements relating to sound transmission

Research has found that owners and occupiers are

increasingly unsatisfied with noise transmission levels

at the minimum Building Code level and we strongly

advise that these requirements are exceeded for

most intertenancy situations. Aim for higher levels

of noise control.

NZBC Clause G6 — Airborne and Impact Sound aims

to protect people from the effects of undue noise

transmitted between abutting occupancies.

Terrace homes have at least one vertical intertenancy

separation and the performance requirements of

NZBC Clause G6 state that intertenancy walls shall

have a laboratory tested Sound Transmission

Class (STC) of no less than 55. Verification Method

G6/VM1 states that field results shall be within 5dB

of these performance requirements and common

interpretation is that a Field STC (FSTC) 50 complies

with the minimum NZBC requirements.

NZBC Clause G6 Acceptable Solution G6/AS1

suggests the following construction techniques to

minimise the level of sound transmission through

building elements:

— Physical separation of each face of any wall which

is common to two or more occupied spaces.

— Use noise control building elements.

— Avoid rigid service connections, such as plumbing

services, where reticulation passes through an

intertenancy wall.

— Make the installation airtight by sealing all joints

and around penetrations and service fittings.

NZBC Clause G6/AS1 comments that intertenancy

walls should not be used for mounting fixtures and

appliances which are likely to be a source of noise

e.g. telephones, TV sets, stereos, cupboards with

doors and service switches. Where the location of

services in intertenancy walls is unavoidable, they

may require additional treatment to ensure that noise

control performance is not degraded.

To limit transmission of impact noise on walls, soft

close drawers and cupboard doors are simple and

effective solutions for cabinetry.

Locate driers and the like on external walls or other

non-critical walls. When positioned on the floor, place

them on resilient mountings.

Impact Insulation Class (IIC) and Field IIC (FIIC) only

apply to floor/ceiling elements that form an intertenancy

separation. Full details for ceiling/floor systems are

found in the GIB® Noise Control Systems literature.

Best practice — sound

ENVIRONMENTAL AND SERVICES NOISE

Environmental noise from traffic, street noise or cafes,

is currently not specifically covered by the NZBC,

but under the Resource Management Act (RMA) some

sites, such as those near motorways and airfields, have

requirements to reduce the noise impact on occupants.

Homeowners also often expect this.

Noise from plumbing, wastewater and sewage can

also generate unwanted noise and while not specifically

accounted for in the NZBC, consideration of this

is important.

GAPS, FLANKING AND INSULATION

Noise can seep out of any gap, adding to reliance

on good design and workmanship when constructing

intertenancy walls. Although acoustic seals and

sealants can be useful, best practice is to avoid gaps

in intertenancy walls.

Sound can also travel along structural elements

like steel beams. If structural elements run through

intertenancy walls, seek specialist acoustic

engineering advice.

Correct fibrous insulation is important to mitigate

the transmission of sound. Closely follow GIB® Noise

Control System specifications. What makes good

thermal insulation is not always an ideal acoustic

absorber. Rigid insulation like polystyrene has great

thermal properties but can reduce STC ratings rather

than improving them.

A puncture in a bag filled with water — no matter how small — will cause water to leak out. Noise is the same — any gap will allow sound to pass through, degrading noise control performance.

NZBC requirements relating to protection from fire

Compared with detached houses, attached houses

require fire walls between tenancies. Passive fire

systems protect adjacent property and create safe

environments for homeowners. However, they are

frequently incorrectly designed and installed, or later

compromised. NZBC Acceptable Solution C/AS1

requires common walls between terrace homes to

have a minimum 30 minute Fire Resistance Rating

(FRR). All the systems listed in this guide meet or

exceed this requirement.

An FRR is determined by standard furnace testing and

represents three outcomes in minutes:

— Structural adequacy — the time a prototype

specimen continues to carry its applied load.

— Integrity — the time for which a prototype

specimen prevents the passage of flames and

hot gases.

— Insulation — the time for which a prototype

specimen limits the transmission of heat.

Care must be taken to ensure accurate design and

construction of elements required to have an FRR.

Aspects such as junctions and penetrations are

best accommodated with forethought and early

communication between all parties involved in

design and construction.


Penetrations through fire and noise separations

Penetrations in fire and noise walls are a significant

area of vulnerability and where most problems

occur. However, penetrations are easily dealt with

through upfront planning and good communication.

Designers, installers, electricians, plumbers and

sprinkler installers should contact specialist passive

fire protection suppliers and refer to their technical

literature for fire collars, insulation and sealants when

considering any work that would breach a fire wall.

Some intertenancy systems, like GIB® Intertenancy

Barrier Systems for Terrace Homes, are designed

to allow wall linings to be penetrated by plumbing

services up to 65mm in diameter and electrical

services penetrations not exceeding 90mm x 50mm.

Chase wall detail to avoid penetrations in intertenancy wall linings.

PLUMBING AND DUCTING

Where possible, avoid running plumbing services in

intertenancy walls. If running plumbing services in

intertenancy walls is unavoidable, it is best to select

an intertenancy specification with a central barrier.

Check carefully whether plumbing penetrations need

to be fire and acoustically sealed.

Another option is to create a false wall to hold

pipework off the intertenancy wall and maintain acoustic

separation between units. See detail below left.

ELECTRICAL

Aim to locate electrical outlets within internal partition

walls where possible. Mounting electrical outlets back

to back should be avoided, unless an intertenancy

separation with a central barrier has been selected.

Where no central barrier exists, detail electrical outlets

in intertenancy walls to have baffles or proprietary

acoustic and fire rated flush boxes.

Unit 1

Unit 2

Chase walls

Intertenancy Wall

Bathroom

Bathroom

right: A Speedwall® intertenancy system installed on site.

GIB® TERRACE HOME GUIDE 9NOVEMBER 2016 GIB® HELPLINE 0800 100 442 OR GIB.CO.NZ FOR MORE INFOGIB® TERRACE HOME GUIDE8 NOVEMBER 2016GIB® HELPLINE 0800 100 442 OR GIB.CO.NZ FOR MORE INFO

Other design considerations

SECURITY

Customer perception of security can be a consideration

when selecting an intertenancy system as some

prefer a secure separation in the centre of the

intertenancy wall. For example, the GIB® Intertenancy

Barrier System has 25mm thick GIB Barrierline®

contained within galvanised steel GIB® H-Studs as

the central core.

UNIT VALUE AND SALE PRICE

Maximising the usable and saleable floor space within

each tenancy is a priority for developers and as the

footprint of the chosen intertenancy system will have

an impact on the unit space; performance needs to

be balanced against system cost.

RAISE THE CEILING

Particularly in dense residential living, using architectural

features such as higher ceilings is a cost effective

way to make smaller floor plates feel larger and

create a better sense of value and quality of living for

occupants. A minimum floor-to-ceiling height of 2.7m

is suggested to gain more space as well as improve

access to natural light and ventilation.*

FUSSY DETAILS, SITE TOLERANCES AND

ADDITIONAL TRADES ADD COMPLEXITY

Tight sites often determine how the build programme

is staged. For instance, tilt slab intertenancy walls

require specialised lifting equipment and long lead

times. Early discussions between the contractor and

neighbours can be advantageous to ensure access.

Complicated or fussy detailing can impact the project

time frame and workmanship, and requires careful

coordination and supervision of sub trades.

NSW Department of Planning and Environment

Discussion Paper, Options for Low Rise Medium

Density Housing as Complying Development,

November 2015.

INTERTENANCY SYSTEM WEIGHT

The mass of intertenancy walls is an important

consideration for designers and structural engineers.

Weight can impact on safety requirements and

foundation design, particularly in seismic areas.

GIB® WARRANTY

The builder is under a Building Act obligation to pass

the warranty information on to the client at the end of

the job. The easiest way to do this for GIB® systems

is to email the client a copy of the GIB® warranty and

our Care and Maintenance document, both available

on the GIB® website.

THE RIGHT INTERTENANCY SYSTEM FOR

THE SITUATION

One intertenancy system may not be right for every

terrace home. From low cost social housing to luxury

terrace homes, there are variances in the level of

performance and cost expectations. The following

pages set out a range of intertenancy systems

available, all of which can utilise GIB® plasterboard

as the interior lining.

THE COST OF THE INTERTENANCY SPECIFICATION

The breakdown of costs for each intertenancy system has been independently assessed by a third party Quantity Surveyor and aims to reflect the price tag of each intertenancy system, including all material components, labour, additional foundation design, equipment hire, sub trades and penetration design.

Costing has been based on a typical multi-unit terraced house construction containing five, two story units with four intertenancy walls. Each wall was assumed to be 10m long x 5.70m high to the eaves with a 30 degree pitch forming a raking wall, and constructed with standard timber framing. Each Intertenancy wall area is approximately 71.00m2 with three electrical outlets each side of the intertenancy walls, i.e. 12 per wall.

The ground floor is a typical 100mm reinforced slab utilising a Rib raft™ system with specific design for heavier foundations required by concrete systems. There are no cantilevered soffits. The site is assumed to be within a 20km radius of the Auckland, constructed on a flat site, with soils of good load bearing capacity and excellent access. All rates include subcontractor margins. Compiled June 2016.

*

right: Terrace home under construction.

SYSTEM TOTAL COST ($)

Precast Concrete

Masonry

Autoclaved Aerated Concrete

Speedwall

GIB® Barrier System (average)

GIB® Double Frame (average)

MaterialsLabour Foundation Electrical

0 2000 4000 10,0006000 12,0008000 14,000 16,000


Comparing intertenancy systems

Figures are a guide and for specific performance or technical information, contact the supplier.

Higher performance can be achieved through specified design.

Load bearing

Double frame Barrier systems Concrete systems

System GIB® double frame systems GIB Barrierline® Speedwall® Typical autoclaved

aerated concrete

Typical concrete block Typical precast

concrete

Description 2 disconnected timber frames,

with a minimum of 2 layers 10mm

GIB® Standard plasterboard

Central 25mm plasterboard

barrier within a double frame timber

wall, 1–2 layers GIB® plasterboard

either side.

Galvanised steel-sheathed

panels filled with lightweight

concrete form a barrier

between double timber

frame walls, 1 layer GIB®

plasterboard either side.

Lightweight

concrete block central

barrier within double

timber frame walls,

1 layer GIB® plasterboard

either side.

Filled concrete block

work, strapped and

lined with 1 layer GIB®

plasterboard either side.

Concrete tilt slab,

strapped and lined with

1 layer GIB® plasterboard

either side.

Minimum footprint

Noise performance

STC rating 1 55–59, 2 60–64, 3 65+ — — — — — —

Fire performance Meets and exceeds

30/30/30

Meets and exceeds

30/30/30

Meets and exceeds

30/30/30

Meets and exceeds

30/30/30

Meets and exceeds

30/30/30

Meets and exceeds

30/30/30

Buildability considerations Installed as described in the GIB®

Noise Control Systems literature to

ensure performance.

Installed as described in the GIB®

Intertenancy Barrier Systems for

Terrace Homes literature to ensure

performance.

Installed as described in

the Speedwall® literature

to ensure performance.

Additional subtrade

required.

Heavier foundations

required, additional

subtrade required.

Heavier foundations

required, additional

subtrade required,

crane/lifting equipment

required, long lead

times possible.

Services Easy to design through

good planning. Plumbing

services should be avoided

in intertenancy walls.

Allows for penetrations up to 65mm

diameter and 90mm x 50mm

rectangular through the wall linings

without hampering acoustic or fire

performance.

Allows for penetrations up

to 65mm diameter through

the wall linings without

hampering acoustic or fire

performance.

Allows small penetrations

through wall linings.

The framed cavity can

be used to accommodate

services.

Allows penetrations


The cavity of a strapped

wall can be used to

accommodate services.

Allows penetrations


The cavity of a strapped

wall can be used to

accommodate services.

Indicative weight Approx 45–65kg/m2 54–65kg/m2 70–90kgm2 70–90kg/m2 350–380kg/m2 350–380kg/m2

Source information gib.co.nz gib.co.nz Speedwall® Intertenancy Systems 2016 for Terraced Housing and Apartments.speedwall.co.nz

Supercrete™AWS type 1 wall superbuild.co.nz

RapidStak™ Mortarless Masonry for Intertenancy Walls firth.co.nz

Various

GIB AC

C

GIB M

asonry

GIB Precast

GIB Speedw

all

GIB D

ouble Frame

235–257mm

GIB Barrier Line

280–300mm 188–321mm

260–310mm

300–306mm

305–331mm


GIB® Systems

Winstone Wallboards Ltd offers a wide range of cost effective intertenancy GIB® wall and floor/ceiling noise

control systems. An overview of the most frequently used double timber frame and barrier systems has been

included in this document. Each of these systems requires no specialist labour or equipment and they are

compatible with GIB Aqualine® Wet Area Systems and GIB EzyBrace® Systems. A full list of intertenancy systems

as well as associated detailing is provided in the GIB® Noise Control Systems literature, the GIB® Intertenancy

Barrier Systems literature and on the GIB® website.

GIB® Noise Control Systems have been extensively tested and independently evaluated and can be depended on

to perform. However, specifications can be sensitive to component substitution.

DOUBLE TIMBER FRAME SYSTEMS

For technical guidance and construction details, see GIB® Noise Control Systems technical literature.

GBT(L)A 30a

Double timber frame structure with studs at a maximum of 600mm centres and nogs at a maximum of

1350mm centres with 75mm insulation and two sheets each side of 10mm GIB® Standard plasterboard.

Noise / STC 58

Fire / FRR 30/30/30

Indicative weight 45kg/m2

System Footprint 245mm

GBT(L)A 30b


1350mm centres with 75mm insulation and two sheets of 10mm GIB Noiseline® one side and one sheet of

10mm GIB Noiseline® on the other.

Noise / STC 58

Fire / FRR 30/30/30



right: A GIB® Intertenancy Barrier System under construction.


GIB® INTERTENANCY BARRIER SYSTEMS*

For technical guidance and construction details, see GIB® Intertenancy Barrier Systems, 2016.

GBT(L)AB 60a

Double timber frame with GIB Barrierline® central barrier. Studs at a maximum of 600mm centres and nogs at

a maximum of 1350mm centres with 90mm insulation and two 10mm GIB® Standard plasterboard each side.

Noise / STC 68

Fire / FRR 60/60/60


System Footprint 300–330mm

GBT(L)AB 60b

Double timber frame structure with GIB Barrierline® central barrier. Studs at a maximum of 600mm centres and

nogs at a maximum of 1350mm centres with 90mm insulation and one sheet of 10mm GIB Noiseline® each side.

Noise / STC 64

Fire / FRR 60/60/60



GBT(L)AB 60c

Double timber frame structure with GIB Barrierline® central barrier. Studs at a maximum of 600mm centres and

nogs at a maximum of 1350mm centres with 90mm insulation and one sheet of 13mm GIB Noiseline® each side.

Noise / STC 67

Fire / FRR 60/60/60



GBT(L)A 60


1350mm centres with 75mm insulation and two sheets each side of 10mm GIB Fyreline® plasterboard.

Noise / STC 60

Fire / FRR 60/60/60



GBT(L)A 90c


1350mm centres with 75mm insulation and two sheets each side of 13mm GIB Fyreline® plasterboard.

Noise / STC 63

Fire / FRR 90/90/90



GBT(L)A 90d

Double timber frame structure with studs at a maximum of 600mm centres and nogs at a maximum of 1350mm

centres with 75mm insulation and two sheets each side of 13mm GIB Noiseline® plasterboard.

Noise / STC 68

Fire / FRR 90/90/90




Interior of the Zavos Corner project in Wellington, designed by Parsonson Architects.

Beware of substitutionThe performance of GIB® Systems are very sensitive

to design detailing and construction practices. All

GIB® Systems have been developed specifically for

New Zealand conditions and independently tested or

assessed to ensure the required level of performance.

It is important to use only GIB® branded components

where specified and to closely follow the specified

design details and construction practices to be confident

that the required level of performance and quality is

achieved on site.

For further information call our GIB® Helpline on

0800 100 442.

CopyrightCopyright © Winstone Wallboards Ltd 2016. All of the

material contained in this brochure, including all text,

tables, charts, graphs, drawings, images, diagrams

are protected by copyright. These materials may not

be reproduced, adapted or transmitted in any form

by any process, without the permission of Winstone

Wallboards Ltd. Winstone Wallboards asserts its moral

rights and reserves all other intellectual property rights

in the materials contained in this brochure.

GBT(L)AB 60d

Double timber frame structure with GIB Barrierline® central barrier. Studs at a maximum of 600mm

centres and nogs at a maximum of 1350mm centres with 90mm insulation and one sheet of 13mm

GIB® Standard plasterboard each side.

Noise / STC 61

Fire / FRR 60/60/60



GIB Barrierline® plasterboard is manufactured to Winstone Wallboards specific specification from a reputable overseas manufacturer.*


FOR MORE INFORMATION VISIT

gib.co.nzOR CALL THE GIB® HELPLINE

0800 100 442

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Terrace Home Guide - GIB® · Terrace homes have at least one vertical intertenancy separation and the performance requirements of ... Maximising the usable and saleable floor space