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This section provides snippets and links for cost conscious and environmentally concerned builders. This includes new and upcoming Building Regulations, financial /mortgage, insurance considerations, etc. For further information please follow the link in the first instance then, when you have a specific project in mind, call us to discuss optimising your project for sustainability. Books
Materials
in Construction Timber
Materials
in Housing
The BedZED
Project Books Materials
in Construction Some 420 million tonnes of materials are used in construction in the UK each year. This equates to 7 tonnes per person. The total consumption of all materials in the UK amounts to some 678 million tonnes or 11.3 tonnes per person. So construction accounts for over half of our resource use by weight! By selecting construction materials wisely we can really reduce our environmental impact. Every
activity involved in extraction, processing and delivery of construction
materials results in energy consumption, pollution and waste.
The capacity of the earth’s natural systems to absorb these
environmental loadings has reached or is approaching it’s limit in many
areas, the most prominent and topical of these is the increasing production of
greenhouse gases and the earth’s capacity to absorb them.
Hence this report looks at the embodied CO2 associated with each construction material.
Waste to landfill in the UK has reached its limit as suitable
landfill sites are running out. Other such critical issues include toxic emissions to water
and air, acid deposition and ozone depletion.
Timber Materials
in Housing The
BedZED Project BedZED employs state of the art energy efficiency, with super-insulation, double and triple glazing and high levels of thermal mass. BedZED meets all its energy demands from renewable, carbon-neutral sources, generated on site, and so eliminates the 29% contribution to CO2 emissions and global warming. In achieving this energy efficient carbon-neutral design, BedZED invests in more construction materials than standard houses. However, as their report shows, the embodied environmental impacts of BedZED’s construction materials are within the same range as standard UK housing. The total embodied CO2 of BedZED is 675kg/m2 , whilst typical volume house builders build to 600-800kg/m2. Despite the increased quantities of construction materials, the procurement of local, low impact materials reduced the embodied impact of the scheme by 20-30%. The
BedZED project has shown that in selecting construction materials, major
environmental savings can be made without any additional cost.
In many cases, the environmental option is cheaper than the more
conventional material. For
example, highly durable timber framed windows are cheaper than uPVC and
saved some 6% of the total environmental impact of the BedZED scheme and
12.5% of the total embodied CO2
. Recycled aggregate and sand
are cheaper than virgin equivalents and are available as off-the-shelf
products. Pre-stressed
concrete floor slabs save time and costs on site and by using less
materials saved some 7% of the BedZEDS’s environmental impact compared
with concrete cast in-situ. New
FSC softwood from certified, sustainably managed woodlands is available at
no cost premium, while local FSC green oak weatherboarding is cheaper than
brick and shows a life cycle cost saving over imported preserved softwood.
Reclaimed structural steel and timber are available cheaper than
new and offer 96% and 83% savings in environmental impact. Time
for a sound check The
new Approved Document E (ADE), ‘Resistance to the Passage of
Sound’, has been launched and is downloadable from the Office of
the Deputy Prime Minister’s (ODPM) website at www.safety.odpm.gov.uk/bregs/approved.pdf/approvede.pdf
It is effectively a complete reworking of its predecessor (Part E: 1992
edition) which runs out on 1 July 2003, and at 76 pages is twice the size. ADE
deals with sound transmission generally, identifying flanking transmission
and reverberation and naturalising the information on airborne and impact
sound which comprised the limited of the previous guidance. The new
section on acoustic conditions in schools (albeit only a paragraph,
ominously cross-reference to yet another ‘to be published’ DfES
Bulletin 93 ‘The Acoustic Design of Schools’). This adds a non-domestic element to the regulations, pacing
the way for the incorporation of other specific public sector acoustic
memoranda (hospitals, health centres, laboratories, etc) into future
amendments. ADE: 2003 also
applies to flats, hostels and hotel accommodation. Sound
Standards In Clause 0.6, it is recognised that improving the sound insulation of historic buildings may result in detrimental visual intrusion, in which cast, ‘it will be reasonable to improve the sound insulation as much as is practical, and to affix a notice showing sound insulation value(s)… in a conspicuous place inside the building.’ ADE:2003 goes into more detail than its predecessor and takes account of construction leakages which had not previously been factored in. The method of determining the mass of a particular wall type has been expanded to include the effects of wall ties, mortar joints, brick frogs and voids, although fewer graphic examples are given, All examples replicate the requirements in the 1992 edition, although there appears to be a change in the density of large concrete panels, previously listed at 1,500kg/m2, documented in the new edition as a composite figure. A great deal of extra information has been added to usefully detail junctions and closers. Also, there is regular ‘dos’ and don’ts’ box containing handy titbits such as ‘Do stagger the position of sockets on opposite sides of a separating wall’; and, ‘Do not build cavity walls off continuous solid concrete slab floor’ Pre-completion testing is a new requirement (see box). To carry out pre-completion testing, residential buildings should be broken down into sub-groups, to enable a thorough evaluation of sound transfer between properties. Tests will normally include four airborne tests and two impact tests at different locations in the sub-group, and ADE:2003 sets out suggested locations. In
Section 7, detailing the permissible reverberation in common internal
rooms, once again, what might at first appear to be a straight forward
section has been complicated by overworked examples. As a rule of thumb,
soffits (of stairs and corridors) should be covered with absorptive
material Class C. However, where large areas are involved (and hence small
areas of material saved result in large savings), and alternative method
of calculation incorporates relaxations to take into account the
absorptive coefficients of floor and wall finishes and fixtures and
fittings. Robust
details ‘It’s a dilemma,’ the spokesman said , ‘In general, the needs of heat conservation necessitate low mass construction, whereas sound insulation needs high mass construction.’ Reading the two documents together could show up any number of discrepancies, although, as with ADL;s RSDs, the details are not intended to show good construction practice, but simply the specific detail compliance with the relevant sound reduction elements. However, even within the new document there are confusing details. Diagram 4.2 (Clause 4.24) is a curiously scaled comparison between in situ and purpose-built drylining on masonry. Improvements need to be made to many of the diagrams, not least the unintelligible diagrams 0-1 to 0-3 in the opening section, to make the document more readable, and discrepancies between this and the current regulations should be highlighted. For example, the independent ceiling detail – shown as Floor Treatment 1 (Diagram 4.3) – now insists on 125mm between the top of the ceiling layer and the bottom of the separate soffit above, instead of the current gap of 100mm. This tendency not to highlight changes is annoying and will inevitable lead to needless errors in the future by architects not remembering, or realising, that they need to check. DWELLINGHOUSES AND FLATS – PERFORMANCE STANDARDS FOR SEPARATING WALLS, SEPARATING FLOORS AND STAIRS THAT HAVE A SEPARATING FUNCTION
ROOMS FOR RESIDENTIAL PURPOSES – PERFORAMCE STANDARDS FOR SEPARATING WALLS, SEPARATING FLOORS AND STAIRS THAT HAVE A SEPARATING FUNCTION
Noise
from above Before completing a couple of the flats, all five of us, together with several tradesmen, walked around to identify possible areas of sound transmission between floors, walls, ducts, etc and to agree on the necessary practical detailing and workmanship standards on site to comply with regulatory guidance. On practical completion, all of the flats were let. Five months later, we were called out by a resident to investigate her complaints that she could hear people upstairs. We stood in silence as a 20 stone brickie was dispatched to march about upstairs in hob-nailed boots. When he reappeared, we all assumed that he gone to the wrong flat because we had heard nothing. It was when the complainant then said that she could hear voices in her bedroom, while we all stood in her living room, that we realised that she was potty. But after making a fuss, within 10 days, everyone in the block was complaining of noise problems, After loads of inspections, nobody knew what the problem was, or the solution, or who’s liability it was, In fact, no one could really work out if there was a problem at all. In the end, we resolved to visit each resident saying that, in order to detect the real cause of the problem, all flats would have to be stripped back to the original building shell and re-done. Given that every resident had just finished decorating, we heard no more about it. Maybe
this is what it means in ADE: 2003, Clause 1.35 where it stated that
‘once a dwelling-house, flat or room for residential purposes is
occupied, any action affecting it should be a matter for local
negotiation’. Testing
time Given that ADE:2003 includes a requirement for pre-completion testing, and that pin-pointing the exact location of sound leakage is notoriously difficult, this BRE guidance document is a handy though simplistic guide and is referred to in ADE:2003, Clause 1.37. The only discrepancy seems to be that IP14.02 quotes a sound insulation margin of failure in tests as ‘up to 5db’ whereas ADE:2003 suggests ‘no more than 6db’. In approved Document L(ADL), clients can check over the contractor’s completed work with a thermographic survey or smoke text. While the ODPM says that the need for ADE:2003 pre-completion testing may be phased out in favour of reliance on RSDs, the contractor and/or architect may decide to take on the liability and cost of ensuring that all has reasonably been done to deal with sound transfer – one of the more subjective construction complaints. However, it will always be a case of discover after the event and remedial treatment will be difficult and expensive. The other difficulty is that although ADE:2003 refers to pre-completion testing, this is meant in a contractual rather than construction sense, since elements or units cannot be acoustically tested prior to the building being completed. On the other hand, in contractual terms, the completion certificate can be withheld if non-compliance is shown. Testing must be done by a UKAS accredited body. Pre-completion testing, which comes into force in January 2004 for new houses and flats, can be avoided if the building is constructed in accordance with Robust Standard Details (RSDs). These are being drawn up by the House Builders Federation and the date of enforcement is six months later than the implementation of ADE:2003 to give them time to be completed, tested and checked. However, since pre-completion testing (and BRE IP14/02) deals with discrepancies of workmanship, compliance with RSDs will not necessarily translate into the way things are built on site precisely because of poor workman ship. It is all a bit of a catch-22. The BRE’s IP14/02 suggests some likely causes of failure – and in typical wise-after-the-event troubleshooting, suggests remedial action – some more constructive than others. One example reads: ‘Problem:Lower than expected airborne sound insulation (Through separating walls). Probable cause: Excessive sound transmission through separating walls Solution:
Rectify construction error
How to Achieve a Satisfactory Final Warranty Inspection
Objective
The
Logic Test Basic Concept THE LOGIC TEST Will the issue result in * A risk to health and safety? * A claim against the warranty? * Significant disruption to the occupier? If the answer to any of the above questions is YES then the item will be classified as CRITICAL and confirmation that a Satisfactory Final Inspection has been carried out will be withheld until the relevant issue is resolved. If the answer to the three standard questions is NO then the item will be classified as NON-CRITICAL and confirmation of this would be provided to the housebuilder. It will remain the builder’s responsibility to address any outstanding NON-CRITIAL issues. However it should be noted that, in come circumstances, a number of individual NON-CRITICAL issues affecting a property, taken together, would be regarded as a CRITICAL failure, for reasons of causing significant disruption to the occupier. In such circumstances, confirmation that a Satisfactory Final Inspection has been carried out will be withheld until the outstanding matters are resolved. It
is important to understand that in this context the pre-handover
inspection performed by the warranty organisation is concerned with the
checking of warranty items. It
is not a snagging inspection and is not part of a building regulation
service.
Examples
of the Logic Test in Operation Example 1 Inadequate means of escape window from 1st floor bedroom. A risk to health and safety. This fails the logic test and hence would be classified as CRITICAL. Example 2 Self-closing device missing from fire door A risk to health and safety – therefore fails the logic test. This would be classified as CRITICAL. Example 3 Flat development- internal layout – proposals indicate excessive travel distances to corridors and no proposals for smoke ventilation have yet been provided. Fundamental health and safety issues that are also likely to affect spatial planning therefore fails the logic test and hence would be classified as CRITICAL until such information is received and approved. Example 4 Earth bonding not secured to rising main. A risk to health and safety and therefore fails the logic test and hence would be classified as CRITICAL. Example 5 Inadequate provision for access for disabled persons (level site, no ramp) Rectification would involve considerable disruption to the homeowner and therefore fails the logic test and hence would be classified as CRITICAL. Example 6 Small area of roof insulation missing. Passes
the logic test therefore classified as NON-CRITICAL. Note that a large expanse of mission insulation might be
classified as CRITICAL, for reasons of potential disruption to the
building occupier PLANNING As with C1/97 the starting point for discussions regarding any change to this Government guidance is to enforce and clarify the existing guidance. The debate on the provision of affordable housing through the planning system will be a major issue between HBF and the ODPM over the coming year. Land
for Housing Regional
Housing Forums Barriers
to Brownfield Highway
Issues Sustainable
Drainage Building
Regulations Part C Water
and Electricity Industry Issues Energy
Labelling
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