NHBC STANDARDS REGULATION AND …

1 In this issue:TechnicalExtra October 2011 | Issue 04 Sound Insulation & Airtightness Scottish building STANDARDS page 4 The Flood and Water Management Act page 7 Guidance on updates to building Regulations Parts F and J in England and Wales page 9 REGULATION AND COMPLIANCET raining courses, downloads, contact details and NHBC technical events page 17 INFORMATION AND SUPPORTS electing and placing hardcore page 12 Good construction practice versus requirements for accessible thresholds page 13 Fixing requirements for guttering and fascias page 15 Cast stone page 16 GUIDANCE AND GOOD PRACTICEC hapter Pitched roofs page 1 Tiling battens to pitched roofs page 2 Door locks on the main entrance door to homes page 3 NHBC STANDARDSPage 1 | October 2011 | Issue 04 | Technical ExtraFor technical advice and support, call 01908 747384 or visit STANDARDSC hapter Pitched roofs In Technical Extra 1, we reported on a number of quality issues relating to pitched roofs.

2 The work to review Chapter is nearing completion and this article, along with the enclosed letter, highlights the forthcoming publication and, in particular, the new requirements for mechanical fixing of all ridges and hips, and a new specification for roof should read this: Technical and construction directors and managers, architects, designers and site CHAPTERNHBC STANDARDS Chapter Pitched roofs Mechanical fixing of ridges and hipsFor many years, it has been traditional to bed ridge and hip tiles in mortar to secure them to the roof. Experience shows that pitched roofs will be subject to some movement during the early life of the property. Mortar is generally not tolerant of that movement and can easily crack or de-bond, making ridge and hip tiles vulnerable when subjected to high introduction of mechanical fixing for all ridges and hips will greatly reduce the risk of tiles coming mortar specificationOur work with the National Federation of Roofing Contractors (NFRC) has provided us with a better understanding of what is considered to be the most appropriate roof mortar mix.

3 The new specification is that:Because sands will vary, roofers can make slight adjustments to accommodate regional variations. However, the proportion of sharp sand must not be less than one-third of the total sand mix is not exclusive and appropriate bagged mixes could be accepted by NHBC if they are shown to have acceptable should no longer use adapted mixes (silo mixes with additional cement content) or factory produced retarded highlighted in previous editions, dry fixing systems appropriate for the roof may provide an alternative, acceptable Chapter will soon be sending out a revised version of Chapter Pitched roofs . It contains the changes mentioned above in addition to a number of minor changes, all of which are aimed at improving quality and reducing the high cost of claims we are experiencing at mortar should be 1:3 cement:sand with plasticiser. The mix should be based on sharp sand with soft sand added to achieve good workability.

4 The sand content should not exceed two parts soft sand to one part sharp sand. YOU NEED Speak to your roof designer/supplier to ensure they are able to provide a mechanically fixed ridge and hip Adopt the new roof mortar mix without Make sure the issues highlighted in Technical Extra 1 have been Look out for the revised Chapter Pitched roofs , which will be arriving in the next few Extra | Issue 04 | October 2011 | Page 2 For technical advice and support, call 01908 747384 or visit battens to pitched roofsIt is important that tiling battens used on pitched roofs should be of good quality to hold the tiles or slates in place satisfactorily, and also provide a secure foothold and support for operatives during the tiling. INTRODUCTIONWho should read this: Technical and construction directors and managers, architects, designers and site CHAPTERNHBC STANDARDS Chapter Pitched roofs.

5 NHBC STANDARDS clause M5(f) requires that timber used for battens and counter battens should be as listed in BS 5534 states that each batten should be indelibly marked with the following information:a) Supplierb) Origin (imported or British grown, and/or species code *) c) Graded BS 5534d) Size* Redwood = PNSY, Whitewood = WPCAA lthough these requirements for battens have been in place for many years, suppliers have, for the most part, ignored them and fully graded battens have not generally been made available. As an alternative, the NFRC issued their Technical Bulletin 33 which allows for partial grading of the tiling batten by the supplier and for final selection of the battens on site. We are finding that some battens are being supplied to sites marked to TB33 to indicate some grading has taken place by the supplier, but this marking does not indicate a fully graded batten.

6 Fully graded battens should be capable of being used without any further selection on site. Full batten grading is more involved than just checking on site for excessively large knots or too much wane. Because of this, fully graded battens can only be provided by the batten producers/suppliers. A number of these suppliers can now provide fully graded roofing suppliers identify their fully graded battens from ungraded or partially graded battens, by applying a coloured stain. Unfortunately, a coloured batten does not indicate that the batten is fully graded, so it is still necessary to check the batten for the full markings as set out previously. Manufacturers are now changing their practices and it is possible to comply fully with NHBC STANDARDS and BS 5534. Fully graded battens, which are indelibly marked with the appropriate markings, should now be used on all slated and tiled NEED Ensure that tiling battens are marked in accordance with BS batten markingsPage 3 | October 2011 | Issue 04 | Technical ExtraFor technical advice and support, call 01908 747384 or visit locks on the main entrance door to homesDoor lock(s) on the main entrance door to homes were required to provide initial security by the use of a latch.

7 This requirement was included to combat incidents, reported by the police, of intruders following people into their homes before they could latch and lock the door behind them. By pushing the door closed, the latch engages and provides the initial security against anyone following closely behind. The downside of this requirement is that, in some instances, occupiers have been leaving their home with the entrance door just held on the latch and not engaging the deadbolt to provide full security. Furthermore, it appears that, in parts of the country, self-latching locks are uncommon, resulting in some occupiers of new homes locking themselves out without a main objective, from NHBC s point of view, is that the door lock(s) should be capable of being released from the inside without the need for a key. Keyless egress can be provided with both self-latching and non self-latching locks.

8 It is considered that, in light of feedback received and from the latest views of the police, the self-latching requirement for the main entrance door to houses is not essential. Therefore, both self-latching and non self-latching locks are acceptable, provided keyless egress is NHBC STANDARDS 2010, the security require-ments for entrance doors in clause D4 were updated to take into account changes in British STANDARDS for door locks in respect of security and keyless egress in an should read this: Technical and construction directors and managers, architects, designers and site CHAPTERNHBC STANDARDS Chapter Doors, windows and glazing .REQUIREMENTSYOU NEED Ensure that the lock(s) to the main entrance door to a home provides keyless egress. The lock(s) may be self-latching or non Extra | Issue 04 | October 2011 | Page 4 For building Regulations advice and support, call 0844 633 1000 and ask for building Control or visit Insulation & Airtightness Scottish building StandardsREGULATION AND COMPLIANCEREQUIREMENTSWho should read this: Technical and construction directors and managers, architects and October 2010, amendments to the Scottish building STANDARDS introduced mandatory post-completion testing requirements for sound insulation and airtightness, as well as more stringent acoustic performance requirements.

9 Transitional arrangements have recently ended, so make sure your sites TO REGULATIONSS ound insulation performance criteria have been part of Scottish building STANDARDS for many years, as has the testing of novel constructions. New criteria from 2010 are:n increased performance levels are requiredn a mandatory post-completion testing requirement for a sample of dwellings on each siten performance criteria for internal testing was added to the Scottish building STANDARDS in 2007, but testing was only required under certain circumstances. The 2010 amendments introduce a mandatory post-completion testing requirement for a sample of new dwellings on each insulationScottish building STANDARDS Section 5 NoiseStandard details the requirements for all walls and floors performing a separating role between different dwellings and also those between dwellings and adjoining non-domestic buildings, whether they are created through new build or conversion.

10 A representative sample of these walls and floors must be tested as-built for airborne sound insulation. Floors must also be tested for impact sound building STANDARDS Section 6 EnergyStandard details requirements for all new-build dwellings. A representative sample of each type of dwelling on a site must be tested to demonstrate the as-built level of criteriaPerformance criteriaWhilst the STANDARDS do not stipulate a backstop value for uncontrolled air infiltration, it is recommended that buildings are designed to achieve an airtightness value of 10m3 @ 50Pa or better. However, it is likely that the SAP will require a more stringent target than this backstop build and conversions (exc. traditional buildings)Conversions of traditional buildingsMinimum airborne sound insulation56 dB DnT,w53 dB L n,T,wMaximum impact sound transmission56 dB DnT,w58 dB L nT,w* Note that Section 5 performance criteria doesn t include Ctr, as used in Approved Document E (England and Wales).