defects prevention pre-course learning 20… · sound insulation fire stopping common defects in...

Defects prevention

TRAINING COURSE

Pre-course learning pack

Name:

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© Copyright NHBC 2018

Pre-course learning

Introduction

Welcome to this pre-course learning pack for the re-designed Defects Prevention

training course. We have been running this course for 22 years – in fact it was the first

formal training course we offered to the industry when we launched the training service.

Of course it has been up-dated continually over that time.

Contents of this pack page

Objectives for the Defects Prevention course 3

Outline of the course 3

How to use the learning pack 4

Section 1 - Rules for Registered Builders 5

Section 2 - NHBC Technical Standards 13

Section 3 - Claims against the warranty 18

Section 4 - The most common causes of resolutions 19

Section 5 - Common defects during construction 20

Section 6 – Other reading 22

NHBC publications (included at the end of this pack)

Why Buy This Home – HB 1022 05/16

Information about the warranty

Damage Potential Rating – Explained – HB 2557 03/10

A guide to the risk assessment rating of all Reportable Items

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Objectives for the Defects Prevention course

At the end of the course site managers will:

Be able to identify the major areas of construction which generate the most costly claims and complaints.

Be able to understand the detailed technical requirements and guidance for those areas.

Be able to identify quality construction and describe their contribution to its achievement on site.

Have considered how the most common defects occur and how to prevent them in the future.

Have undertaken a more general examination of construction best practice and content, operation and significance of each of the NHBC Standards.

Outline of the course

Pre-course pack Day 1

Introduction, Objectives and outline of

the course

Rules for Registered Builders

NHBC Technical Standards

Claims against the warranty

The most common causes of

resolutions

Common defects during construction

Review of pre-course pack

Site investigations

Engineering conditions

Site clearance

Foundations

Substructure

Drainage

Ground floors

Day 21 Day 3

Superstructure walls with a focus on

either masonry construction or

Timberframe

Chimneys and flues

Intermediate floors

Air-tightness

Sound insulation

Fire stopping

Common defects in timber frame

Roof structures and coverings

Render

First fix

Plastering and dry-lining

Second fix

External works

Post construction testing

End-of-course assessment

1 This day may be replaced by a day covering timber frame or light steel frame construction. Alternately those additional days may be included in the course to supplement the standard day two shown with a further additional day covering modular/framed construction and external cladding also available.

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How to use the Learning Pack

Please make sure you have worked your way through the contents of this

pack before attending the course. You will use some of the information

during the course and the trainer may even question you on it. There will be

reference to the pre-course information in the course assessment on the

last day.

ACTION

As you read through the pack you will see this image and

instructions in red about the actions that are required at

that point.

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Section 1 - Rules for Registered builders (hb1 12/10)

The following extracts from the rules for builders and developers registered with NHBC

are the ones that are most relevant to site managers. Where the word ‘You’ is used this

refers to the registered builder.

Registration

10 Building Standards

a You must ensure that every Home for which you submit a Site Notification or an

Application for NHBC Cover is designed and built in accordance with the

applicable NHBC Requirements.

b If NHBC Building Control Services Limited is appointed by you to act as the

Approved Inspector (in England and Wales) for any Home, you must comply with

the applicable terms and conditions as notified to you by NHBC Building Control

Services Limited.

11 Specialist professional information

a In Scotland, NHBC may require you to provide specialist information from

consultants of a particular profession. If so, you must advise them of NHBC’s

involvement and if requested by NHBC ensure that they are bound to NHBC in

respect of their duty of care as if they had been instructed by NHBC in the first

instance.

b NHBC may require you to have the Structure of a Home designed and inspected

during construction by an independent professional acceptable to NHBC, in which

case you must follow any instructions given by that professional.

ACTION

Read through the rules and make notes in the box at the end of the table summarising what you believe are the rules that affect your work the most.

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Requirement to submit Site Notifications and Applications for NHBC Cover

12 Stage One: Site Notification

a You must submit to NHBC a Site Notification for each home built or to be built by

you, or on your behalf, to be sold by you to the first owner.

d If you submit a Site Notification under Rules 12) a) you must:

i) Include in the Site Notification particulars of all of the homes built or to be built or

sold by you or on your behalf at the relevant Site; and

ii) If after submission of the Site Notification any of the notified particulars change,

you must promptly notify NHBC of the changes.

e Rule 12) a) applies if you acquire a home or Site which is partially built and in such

cases you must submit to NHBC a Site Notification together with a location plan for

all of the planned homes on the Site before any further substantial building work is

carried out to the home and/or Site.

f Each Site Notification that you are required to submit must be received by NHBC

fully completed at least:

i) 8 weeks before work starts on a Hazardous Site or where non-conventional or

complex construction methods are to be used;

ii) 28 days before work starts in any other case.

g Following receipt of a Site Notification, NHBC will send you a Product Plot

Schedule which must be used under Stage Two (Rule 13) below.

i NHBC may accept a Site Notification subject to Conditions or NHBC may reject it.

NHBC will give you reasons in writing if a Site Notification is accepted subject to

Conditions or is rejected. NHBC may in its absolute discretion give or withhold its

authorisation to a third party referred to in a Site Notification made under Rule 12)

c).

13 Stage Two: Application for NHBC Cover

a You must:

i) At least 21 days before work starts on a Home; or

ii) Before you enter into a Contract for a Home

whichever is the earlier, make an Application for NHBC Cover accompanied by

payment to NHBC of the charges for NHBC Cover and any other services

(including, if you appoint NHBC Building Control Services Limited as the Approved

Inspector (in England and Wales) or an NHBC Company as Certifier (in Scotland)

the charges for those services) as advised to you by NHBC for each Home for

which you have submitted a Site Notification.

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15 Testing and inspection

a NHBC may inspect and carry out technical investigations of any Home in a manner

and at a frequency to be determined by NHBC. For the purposes of such

inspections and investigations, you must carry out any work or tests that NHBC

may require you to carry out and provide any facilities, documents or information

that NHBC may require you to provide. NHBC’s inspections and technical

investigations are for the purpose of enabling NHBC to decide whether to provide

NHBC Cover for a Home. Any information shared with you arising from NHBC’s

Inspections and technical investigations in no way relieves you of your obligations

under Rule 10) a) to design and build each Home in accordance with the

applicable NHBC Requirements.

16 Hazardous Sites and Non-Conventional Methods of Construction

a If a Home is to be built on a Hazardous Site or where non-conventional and/or

complex construction methods are

to be used:

i) You must (8 weeks before work starts) submit with the Site Notification the

design details showing how the hazards, non-conventional construction methods

and/or complex construction methods are to be dealt with and in particular you

must show to NHBC in detail (by submission of drawings, calculations, soil

investigations, environmental reports and any other relevant information) how

hazards, non-conventional construction methods and/or complex construction

methods are to be dealt with so as to enable the building of the Home to be

completed in accordance with NHBC Requirements;

ii) You must provide NHBC with any information pertaining to the Home and the

relevant Site that NHBC may reasonably request from time to time.

b NHBC may cancel an Application for NHBC Cover and the NHBC Cover for any

Home on the basis of information submitted or not submitted by you or on your

behalf under Rule 16) a) if NHBC is not satisfied that building of the Home will be

completed in accordance with NHBC Requirements.

24 Notices of Cover

c NHBC may in its sole discretion agree in writing that you need not comply with all

of the applicable NHBC Requirements concerning the design and construction of a

particular Home, in which case you must obtain the first Owner’s written agreement

to accept that non-compliance. In such circumstances, NHBC may in its sole

discretion issue a Notice of Cover in respect of the Home containing an

endorsement excluding the relevant items from cover.

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Claims and Work required by NHBC

27 Tests, investigations and work required by NHBC

a i) NHBC may give you written notice of tests and/or investigations that NHBC

requires you to carry out in order to investigate any suspected non-compliance with

NHBC Requirements.

ii) NHBC may give you written notice of work that NHBC requires you to have

carried out in order to remedy any non-compliance with NHBC Requirements.

b Following receipt of a notice under Rule 27) a) you must:

i) Inform NHBC in writing within seven (7) days of any difficulties that may prevent

the completion of the tests, investigations and/or work specified in the notice by the

date required and NHBC may (in its absolute discretion) agree to vary that date;

ii) At your own expense carry out or have carried out the tests and/or investigations

specified in the notice and report the outcome or results to NHBC in writing by the

date specified in the notice or by any later date agreed under Rule 27)b)i) or, if no

date was specified or agreed, within a reasonable period of time;

iii) At your own expense carry out or have carried out any work specified in the

notice (together with any additional work necessary in connection with the work

specified in the notice) so that the Home complies with the applicable NHBC

Requirements by the date specified in the notice or by any later date agreed under

Rule 27) b) i) or, if no date was specified or agreed, within a reasonable period of

time.

c If you do not complete any tests, investigations and/or work that you are required

to carry out or have carried out under Rules 27) a) and 27) b) within the time

allowed, NHBC may (in its absolute discretion):

i) Have appropriate tests, investigations and/or work, carried out; or

ii) Assess the costs of carrying out such tests, investigations and/or work and pay

that sum to the Owner.

d If, in its absolute discretion, NHBC deems it appropriate to do so (for instance

because of (i) the history of any dealings between you and the Owner and/or

NHBC (ii) NHBC’s assessment of any work previously carried out by you (iii) your

financial position or (iv) an emergency) NHBC may, instead of or in addition to

serving a notice under Rule 27) a):

i) Arrange itself for tests, investigations and/or work to be carried out; or

ii) Assess the costs of having such tests, investigations and/or work carried out and

pay that sum to the Owner.

f If NHBC exercises its rights under Rules 27) c) or d) NHBC will notify you in writing

and following service of such a notice you must not undertake the tests,

investigations and/or work referred to in the notice yourself, nor arrange for any

other person to undertake them.

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g If NHBC exercises its rights under Rules 27) c) or d) NHBC will be entitled to

require you to stop work on the Home concerned (as specified in the notice, along

with particulars of the work that must be stopped) and following service of that

notice:

i) You must stop work on the Home as required under the notice; except that

ii) You must take all steps necessary to ensure that the Home is secure and

watertight.

h Where tests, investigations and/or work are required to be carried out to a Home

under Rule 27) you must at your expense:

i) Allow or obtain access to the premises referred to in the notice for you, NHBC

and/or any contractors for the purpose of allowing tests, investigations and/or work

to be done;

ii) Arrange for any damage to the Home resulting from the carrying out of tests,

investigations and/or work to be repaired and for the affected parts of the Home to

be re-decorated and left in a clean and tidy condition;

iii) Arrange for the removal and storage of the Owner’s possessions, and/or for the

provision of suitable alternative accommodation for the Owner and/or anyone else

who normally lives in the Home with the Owner’s permission.

Alternatively, in the case of Rules 27) h) ii) and 27) h) iii) NHBC may either make

any of the above tests, investigations, work and/or arrangements at your expense

or, in its absolute discretion, assess the cost of making any of the above tests,

investigations, work and/or arrangements and pay that sum to the Owner.

i If NHBC exercises its rights under Rule 27) you must immediately on demand (and

without deduction or set off) indemnify NHBC in respect of all costs and expenses

incurred by NHBC in connection with doing so. Such costs and expenses may

include administration costs, the cost of settlement of claims under NHBC Cover

and the costs and disbursements incurred in obtaining professional advice and

assistance.

j NHBC may apply Rule 27) at any time in connection with any Home and any

obligation or liability that you have under the relevant NHBC Cover and/or the

Rules and which you have not discharged in full and at the due time.

k If you dispute any action taken by NHBC under Rule 27) that dispute may be

referred to arbitration subject to and in accordance with Rule 55). If a dispute is

referred to arbitration:

i) NHBC shall continue to be entitled to carry out or make a payment in respect of

any tests, investigations and/or work specified in a notice served under Rule 27);

and

ii) The Arbitrator will not have the power to order you to carry out any tests,

investigations and/or work.

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Claims and Resolutions

28 Investigation of claims and complaints by NHBC

a If an Owner makes any claim or complaint to NHBC in respect of a Home, NHBC

may undertake its own tests and/or investigations and may require that you attend

and/or assist NHBC with those tests and/or investigations (whether or not you are

obliged to respond to the claim or complaint under the NHBC Cover for the Home).

b If NHBC requires you to attend and/or assist under Rule 28) a), NHBC will notify

you in writing (setting out particulars of the Home and the date and time of the

planned tests and/or investigations) and following service of that notice:

i) You must at your own expense make a representative available to attend and/or

assist NHBC with those tests and/or investigations;

ii) You must allow or procure access to the relevant premises for NHBC and its

contractors for the purpose of allowing NHBC or its contractors to carry out the

tests and/or investigations.

c Following tests and/or investigations carried out under Rule 28) a) NHBC will:

i) Notify you in writing of the outcome of the tests and/or investigations;

ii) Notify you of the costs and expenses incurred by NHBC in connection with the

tests and/or investigations. Such costs and expenses may include administration

costs and the costs and disbursements incurred in obtaining professional advice

and assistance.

d Following receipt of a notice under Rule 28) c) ii) you must immediately pay to

NHBC (without deduction or set off) an amount equal to the amount of the costs

stated in the notice, unless:

i) The outcome of all of the tests and/or investigations is that there has been no

failure by you to comply with your obligations under the relevant NHBC Cover and

Rules in connection with the matters tested and/or investigated; or

ii) With NHBC’s written agreement (in its absolute discretion) within a reasonable

time at your own expense you carry out all of the work that NHBC would otherwise

have to pay for or carry out under the relevant NHBC Cover in connection with the

claim or complaint.

e NHBC may apply Rules 28) a) to 28) d) at any time in connection with NHBC’s

response to any claim or complaint made in connection with NHBC Cover for a

Home built or sold by you or on your behalf.

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Resolution Service

f If an Owner makes a claim or complaint to NHBC under or in connection with

NHBC Cover and NHBC decides to provide the Resolution Service then:

i) Rules 27) and 28) will apply in respect of any tests, investigations and/or work

which NHBC requires you to carry out or arrange and/or which NHBC carries out

or arranges;

ii) NHBC may charge you a fee for providing the Resolution Service.

g NHBC may apply Rule 28) f) at any time in connection with NHBC’s response to

any claim or complaint made in connection with NHBC Cover for a Home built or

sold by you or on your behalf.

Common Parts

j If a claim is made under NHBC Cover by two or more Owners in connection with

any Common Parts (the use or enjoyment of which is shared by them) then in

respect of such Common Parts NHBC may proceed against you as if all of the

relevant Owners who share the use or enjoyment of those Common Parts and who

are also entitled to claim under NHBC Cover in connection with those Common

Parts, had made claims under their NHBC Cover.

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Notes

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Section 2 - NHBC Technical Standards

NHBC has always issued Standards, but they have evolved over the years as methods

of construction have changed, such as the significant growth in the use of thermal

insulation materials and greater use of factory-made components such as roof trusses.

Changes to the Standards are highly significant for NHBC's registered builders as they

potentially affect the construction of 80% of homes built every year.

For this reason all changes need to be very carefully considered and this is the job of

NHBC's Standards Committee, which includes a range of interested groups, including

consumers, the Housing Corporation, professional institutions and house builders.

Once the Standards Committee has approved a new Standard or amendment to an

existing Standard, the industry is advised of the forthcoming change and the relevant

information is mailed to every registered builder. Builders are then given a lead-in period

to adjust their working practices, before NHBC's building inspectors begin to check the

new requirements on site.

You will be required to have access to a copy of the NHBC Technical Standards in

order to help complete this section.

The online version of the NHBC Standards 2018 – Standards Plus – is freely available

to all visitors to the NHBC website.

Visit: www.nhbc.co.uk/Standardsplus2018

COMPOSITION OF THE STANDARDS

The Standards are divided into 10 Parts, each covering a particular aspect. The Parts

follow the usual construction process; from design through to construction on site.

NHBC Standards do not cover aspects of health and safety relating to building

operations and to the handling and use of certain building materials. Such matters are

covered by the statutory requirements.

TECHNICAL REQUIREMENTS (2018 Standards)

In Chapter 2.1, The Technical Requirements which MUST be met by the Builder are in

red text.

PERFORMANCE STANDARDS

Most of the Chapters consist of detailed Performance Standards in bold black text with

purple shaded background.

Alternative standards of performance will be acceptable ONLY if, in the opinion of

NHBC, the Technical Requirements are met and the standard achieved is not lower

than the stated Performance Standard.

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GUIDANCE

Guidance on how the performance standard may be met is shown in black text and is

based on normal construction procedures and recommended practices which have

been shown as satisfactory and acceptable over time. NHBC will consider alternative

methods to meet specific requirements, subject to prior consultation and evaluation.

Guidance is also contained in illustrations and 3D models.

Guidance is provided to demonstrate specific technical principles, and should not be

used as working construction details.

Standards questions

Starting on the next page are five questions relating to the NHBC Standards.

When answering them please bear in mind the information above, namely that the

Standards are mainly made up of guidance and performance standards. Builders are

NOT required to comply with the guidance but, if they choose to do things in a different

way they may need to prove to NHBC that their method will perform at least as well as

the guidance.

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Question 1

A lead lined valley has been formed using code 4 lead in 1.4m lengths.

Is this acceptable? Please explain your decision.

Answer

Question 2 According to NHBC Standards what is the maximum amount of concrete that can be cast in one action when reinforcement and unreinforced?

Answer

ACTION By referring to the NHBC Standards answer each question in the box provided. Please make a note of the

appropriate Standards clause with your answer.

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Question 3 A trussed rafter roof has been tiled but all the braces omitted. Can they be put in now? Please explain your decision.

Answer

The following questions relate to a development of a small site of three and four bedroom detached houses. You discover the problems described in the scenarios which follow. Record whether you find them acceptable or not. Give your reasons and note any other considerations you may need to take into account.

Question 4

Shrinkable soils require suspended floor construction, what is the minimum void

dimension under the ground floor when building in medium shrinkage soils?

Answer

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Question 5

On another house plot you see that the wall cavities to the whole of one gable wall are

only 35mm wide and the brickwork/blockwork has just been completed.

The wall ties are correctly spaced and staggered with the drip in the centre of the cavity and are sloping slightly to the outer leaf. The cavities appear to be reasonably clean and the face brickwork is of a good standard. Is this acceptable to NHBC?

Answer

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Section 3 – Claims against the Warranty Section 3 of the Buildmark Warranty covers major damage in years 3 To 10. The pie

chart shows the percentages for the major areas of construction that caused Section 3

claims by frequency in 2017 – but the category designations have been removed.

Category Percentage?

Foundations

Substructure and ground floors

Superstructure

Roofs including roof coverings

Services, fixtures and finishes

Ancillary buildings and external works

Others

ACTION

In the table below use your judgement to show which

category should have which percentage against it

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Section 4 – The most common causes of Resolutions Section 2 of the Buildmark Warranty covers the Builder’s Obligations after Completion

(with NHBC protecting home buyers if the builder should default). During this period

NHBC offers a Resolution Service if a builder and home owner are in dispute.

The pie chart shows the percentages for the major areas of complaint raised through

resolutions during the first two years by frequency in 2017 – but the category

designations have again been removed.

Category Percentage?

Foundations

Substructure and ground floors

Superstructure

Roofs including roof coverings

Services, fixtures and finishes

Ancillary buildings and external works

Others

ACTION In the table below again use your judgement to show which

category should have which percentage against it

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Section 5 – Common defects during construction

The course will concentrate on common defects and their prevention across all the main stages of construction. It will be really useful to have your feedback at the course on your experiences.

Construction stage Common defects

Foundations

Substructure and ground

floors

Drainage

Superstructure – brickwork

and blockwork

ACTION

In the table below, based on your experience, list four of the most common defects (or issues that could lead to defects) you have found at each of the major construction stages.

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Superstructure – timber

frame

Superstructure –

intermediate floors

Roof structure – including

GRP Chimneys and

Dormers

Roof coverings

First fix/carcassing

Plastering and dry lining

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Second fix and finishings

External Works including

retaining and free-standing

walls

Section 6 – Other reading

Included in this pack are three NHBC publications:

Why Buy This Home

Information about the warranty

Damage Potential Rating – Explained

A guide to the risk assessment rating for all Reportable Items

NHBC Technical Extra

A sample of the latest Technical Extra giving information and updates to the industry

ACTION

Before the start of the course, make sure you have read through the NHBC publications – you can be sure that information from them will be included in the course assessment

defects prevention pre-course learning 20… · sound insulation fire stopping common defects in...

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