Dwelling-houses and flats performance standards for separating walls, separating floors and stairs that have a separating function.

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1 Part E Robust Details Underfloor Heating New Build Apartment Developments The increasing number of Robust Detail separating floor constructions means that selecting the most appropriate option is becoming ever more challenging. In this article provides some guidance on how to specify underfloor heating to comply with the Part E acoustic regulations covering England and Wales. In addition, he comments on how the latest Part L changes will affect upper floor constructions. The use of underfloor heating within apartment developments is becoming increasingly popular as developers realise that premium selling prices can be obtained for minimal additional construction cost. That said, any desire to specify underfloor heating has been affected by the Part E Building Regulations which place more demanding requirements on developers to reduce the transmission of airborne and impact sound between dwellings sharing separating walls and floors (see Table 1). To ensure these performance standards are satisfied, compliance for purpose-built properties can be demonstrated either by conducting pre-completion tests or by registering the plots with Robust Details Limited (see for further information) and then using a so-called Robust Detail construction. Essentially, a Robust D etail (RD) is a preapproved construction which requires no site testing provided the relevant requirements of the scheme are followed. Since the first Robust Details Part E Handbook was published in May 2004, over 200,000 plots have been registered. In fact, the use of a Robust Detail is the favoured compliance option since it eliminates the risk of any expensive remedial work which may be the consequence of a failed site test. The handbook listing the RD choices is regularly updated and further proposed constructions are currently progressing through the evaluation and testing process prior to the award of RD status. Of course, this expanding range of Robust Details means it is increasingly difficult to ensure the most suitable construction is specified, but is always willing to discuss options whenever underfloor heating is being considered. In general, the following guidance should prove helpful. Dwelling-houses and flats performance standards for separating walls, separating floors and stairs that have a separating function. Purpose built dwelling-houses & flats Dwelling-houses & flats formed by material change of use Robust Detail ID E-FC-3 E-FC-4 E-FC-5 E-FC-6 Walls Floors and stairs Walls Floors and stairs Table 1 Concrete Separating Floors with Finish The widest choice of RDs exists if the intent is to screed the separating floors above either precast concrete floor planks (E-FC-4, E-FC-5) or a modified beam and block structure (E-FC-6). (Illustrations from Robust Details Handbook are shown on pages 3 and 4). Please refer to Robust Details Handbook for full compliance details. In all cases, various (s) are positioned between the floor and the screed to eliminate impact sound, with airborne sound controlled by the mass of the overall floor (see Table 2). Airborne sound insulation DnTw + Ctr db (Minimum values) Table 2 Concrete Separating Floors ed Separating Floor Type Concrete Concrete Concrete Structural Floor Impact Sound Insulation LnTw db (Maximum Values) No new plot registrations to be accepted after November 1 st mm (min) concrete floor plank. 150mm (min) concrete floor plank. Modified beam and block with dense infill blocks and 50mm concrete topping. Resilient Layer 6mm IsoRubber (from Thermal Economics) 10mm Yelofon HD10+ (from Cellecta) 8mm Regupol E48 (from CMS Acoustic Solutions) 65mm(min) sand/cement continued on page Permitted s 40mm(min) proprietary screed Renovation projects please contact for specific advice regarding suitable floor constructions No 1

2 Proprietary flanking strip supplied with see note below* cliprail with self-adhesive backing 14mm Fastflo tubing tacker panel (SD grade EPS) Resilient layer to Robust Detail requirements* Pre-cast concrete plank (or beam & block floor) as per the Robust Details handbook* ASC14 Fastflo-14 with tacker panel for acoustic screed floors Suitable ceiling treatment as in the Robust Details handbook* * Supplied by others continued from page 1... It should be noted that these resilient layers do not possess significant thermal qualities. has always recommended the installation of a thermal break on upper floors in order to enhance the system performance (accelerated response times, increased control, lower running costs). For the first time, this recommendation has been enforced by the Guidance Notes (Domestic Heating Compliance Guide) recently issued with the latest Part L regulations (effective April 2006) which require thermal insulation on upper floors should underfloor heating be specified in order to minimise downward heat losses Table 27: Minimum provisions for floor insulation states, Intermediate floors with heated rooms below, complying with both Part E and Part L of the Regulations, should have a separating layer of system thermal insulation to comply with BS EN 1264, Part 4, where the minimum thermal resistance is not less than R=0.5m 2 K/W. Fortunately, this requirement has been anticipated by Robust Details Ltd., since a 'supporting layer/board' beneath the underfloor heating is permitted without compromising the floor's RD status. In most cases, 30mm of extra high density polystyrene (or the equivalent polyisocyanurate or 'PIR' board depth) will satisfy the Part L requirement. In most cases, recommends its own 30mm Tackerboard to provide the required thermal break between the resilient layer and screed. The Tackerboard features overlapping flaps which can be taped down to effectively tank the floor prior to screeding. The underfloor heating pipework is normally slotted into anchoring rails as detailed on the ASC14 schematic (above). For ease of installation, the Cliprail anchoring system is normally stuck to the underlying Tackerboard by peeling away the backing tape to reveal a heavy-duty flexible adhesive. It should be noted that more traditional methods of fixing, such as clips and staples, are not recommended since they could potentially penetrate the underlying and compromise acoustic performance. 2

3 Floor construction details taken from the Robust Details Handbook and E-FC-3 Resilient layer (1) Resilient layer (2) Precast concrete plank laid on s 65mm (min) sand cement screed, or 40mm proprietary screed, nominal 80kg/m 2 mass per unit area 5mm foamed polyethylene layer 30-36kg/m 3 25mm mineral wool batt 140kg/m 3 (min) or 25mm expanded (SD grade) or extruded polystyrene insulation board suspended for new registrations nov Structural floor 150mm (min) precast concrete floor plank 300kg/m 2 (min) mass per unit area E-FC-4 Precast concrete plank laid on Thermal Economics IsoRubber Resilient layer Structural floor 65mm (min) cement: sand screed, or 40mm (min) proprietary screed of nominal 80kg/m 2 mass per unit area 6mm IsoRubber layer with IsoEdge flanking strip - 150mm (min) precast concrete floor plank - 300kg/m 2 (min) mass per unit area Sketch shows CT0 type ceiling treatment 3

4 Floor construction details taken from the Robust Details Handbook and E-FC-5 Precast concrete plank laid on Cellecta YELOfon HD10+ system Resilient layer Structural floor 65mm (min) cement: sand screed YELOfon HD10+ with E-strip perimeter edging and J-strip tape for jointing - 150mm (min) precast concrete floor plank - 300kg/m 2 (min) mass per unit Sketch shows CT0 type ceiling treatment E-FC-6 Beam and block floor with precast or in situ edge beams laid on Regupol E48 system For use with dense aggregate block flanking walls only DPM Resilient layer Structural floor 65mm (min) cement: sand screed, or 40mm (min) proprietary screed, nominal 80kg/m 2 mass per unit area 0.2mm (min) waterproof membrane 8mm Regupol E48, dimple side down, fully lapped up walls and Regupol tape for jointing Beam and block, min 100mm thick dense aggregate infill blocks, min 50mm concrete topping, min strength class C20, to floor blocks, min 300kg/m 2 combined mass per unit area Min 300mm from top of beam to ceiling board 4

5 Floor construction details taken from the Robust Details Handbook and Concrete Separating Floors with Floating Floor Treatment Three Robust Details are available if a floating timber floor is preferred to a screeded finish. In each case, five possible floating floor treatments are permitted (see right), the differences between the RDs being the underlying floor structure and the type of construction in which the RD may be used. For reference, E-FC-1 is a precast concrete plank separating floor for use in load-bearing masonry construction; E-FC-2 is an in situ concrete separating floor for use in reinforced concrete frame construction; E-FC-7 is a modified beam and block separating floor for use in load-bearing masonry construction, and E-FS-1 is a steelconcrete composite separating floor for use in heavy duty steel frame construction. If underfloor heating is to be specified, only resilient batten systems FFT-1, 2 or 3 are suitable as services are not permitted within the floating floor systems of FFT-4 and 5. The FFT-2 resilient cradle system is typically specified because it provides an opportunity to eliminate any unevenness in the sub-floor. The ClippaPlate can be positioned above the batten as illustrated below. FFT-1 Resilient composite deep batten system 18mm (min) t&g flooring board resilient composite deep battens ensure any services do not bridge the battens may have the at the top or bottom FFT-2 Resilient cradle and batten system 18mm (min) t&g flooring board cradle and batten ensure any services do not bridge the FFT-3 Resilient composite standard batten system 18mm (min) t&g flooring board resilient composite standard battens ensure any services do not bridge the battens may have the at the top or bottom FFT-4 Resilient overlay platform floor system proprietary platform system inclusive of greater than or equal to 16kg/m 2 mass per unit area no services to be installed in floor system FFT-5 Resilient overlay shallow platform floor system 9mm (min) t&g flooring board pre-bonded to flooring board no services to be installed in floor system 70mm FFT-1 50mm 10mm FFT-2 45mm FFT-3 FFT-4 FFT-5 * Note void dimension indicated is when floor is loaded to 25kg/m 2 400mm centres 18mm chipboard deck* ClippaPlate 14mm Fastflo tubing Resilient batten or resilient saddle system conforming to Robust Details handbook* Mineral wool insulation* Concrete structural floor conforming to the Robust Details handbook* * Supplied by others ATPA14 Fastflo-14 with ClippaPlate installed in a resilient batten or resilient saddle system 5

6 UK Ltd., Heathpark House, Devonshire Road, Honiton, Devon, ex14 1sd Tel: Fax: Web: Separating Floor Timber I-Joist E-FT-1 Timber I-Joists Use with timber frame walls only Floating floor Floor decking Joists Absorbent material 15mm thick (min) 240mm (min) timber I-Joists 100mm (min) quilt insulation (10-36 kg/m 3 ) between joists 70mm * Note void dimension indicated is when floor is loaded to 25kg/m 2 FFT1 Resilient composite deep batten system for E-FT-1 18mm (min) t&g flooring board gypsum-based board nominal 13.5kg/m2 mineral wool quilt laid between battens 13mm (min) 33-36kg/m 3, or 25mm (min) 10-36kg/m 3 Floor construction details taken from the Robust Details Handbook and Timber Separating Floor The three Robust Detail timber separating floors are distinguished mainly by the joist type E-FT-1 covers TJI joists, E-FT-2 requires the use of traditional joists, and E- FT-3 requires a proprietary open metal web joist. The integration of underfloor heating into these RDs is not straightforward. The preferred location would obviously be within the floating floor but it simply wouldn't be possible to drive sufficient heat through the overlying plasterboard, chipboard and final floor finish without increasing the flow temperature to a level which would compromise the structural integrity of the plasterboard. As a result, the plasterboard layer could be replaced by a cement-based board (which would mean that the floor must be pre-completion tested). Alternatively, it would be acceptable to install a further 25mm batten above the RD floor and position the underfloor heating within this void. Obviously, adding further height to the RD floor to accommodate the underfloor heating is not ideal, so a new floor construction being pioneered by FinnForest and Lafarge may prove a suitable alternative. Adopting techniques already widely used in central Europe, the SoundBar floor features timber I-beam joists covered with a structural deck, 35mm Soundblock board (comprising 10mm foam, 25mm fibreboard) and 40mm liquid screed. In this instance, installation of the 10mm Fastflo system within the screed layer is straightforward and the small pipe diameter means that there is no need to increase the screed depth thereby minimising the structural requirements. Finnforest is confident that the SoundBar floor construction will have RD status by the end of Further information and details of this floor construction s progress towards RD status can be obtained by contacting Indeed, to obtain the very latest information which may assist your project, please feel free to visit the website at or contact