Ventilation System Design Criteria CONSTRUCTION GUIDELINES Review acoustic, air quality and Risks overheating analysis and Part associated L/sustainability requirements Low risks associated Passive System Mechanical System Continuous Mechanical Extract Ventilation Continuous Mechanical supply and extract (MEV) with trickle vents for background with Heat Recovery (MVHR) for background ventilation ventilation (with carbon/NOx filtration) Purge ventilation through openable windows (1/10th to 1/20th of floor area of room) Purge ventilation through MVHR and openable windows. Summer overheating control through openable windows Summer overheating control through MVHR (+ extra fans if needed) Note: a hybrid system may be applicable where there is a risk associated only with the overheating criteria. In this case, a passive system with additional MEV or larger opening vents could be implemented to deal with summer/ overheating ventilation. Living/Dining Living/Dining Bedroom Bedroom Bathroom UC Kitchen Bathroom MVHR Kitchen UC Extracted air Trickle vents Extracted air Fresh air supply Continuous Mechanical Extract Ventilation (MEV) Continuous Mechanical Supply and Extract with + trickle vents to habitable room windows Heat Recovery (MVHR) - Carbon/NOx filtration 49
CONSTRUCTION PARAMETERS 2.3 Living/Dining FIRE Bedroom STANDARD APPROACH Bath UC Kitchen Apartment Blocks 30 mins fire resistance B1 - Means of warning and escape FD30 fire door ·· All Be First residential apartments 60 mins fire resistance between flats are to be provided with a residential sprinkler system designed and installed 60 mins fire resistance between flats and in accordance with BS 9251:2014. common corridors/ 30mins fire resistance up to 1.1m height between flats and ·· A stay-put evacuation strategy should gallery access deck be adopted. apartments and either a single natural ·· It is Be First’s preference to have open- or mechanical smoke shaft. plan living, kitchen and dining spaces ·· A single stair is acceptable, subject to within flats, therefore examples layouts travel distances. show protected entrance halls with 30 minutes fire resistance. All doors within Periods of fire resistance for elements the protect entrance hall (except the of structure: bathroom) must be FD30 fire doors. Conditions Minimum periods of fire ·· For protected entrance hall designs, resistance (min) an LD2 detection and alarm system Height of ≤5m ≤18m ≤30m ≥30m should be provided. This generally top occupied consist of a smoke detector in the storey above 301 60 60 120 protected entrance hall and a heat access level 301 60 90 N/A detector in the kitchen (subject to the Sprinklered fire alarm installer’s detailed design Unsprinklered and risk perception). Note 1: 30 minutes fire resistance to elements of ·· If open plan apartments are structure only applicable to individual dwellinghouses considered, they should achieve the recommendations of BS 9991 or be subject to a fire engineered solution. ·· Single direction travel distance in common corridors is limited to 15m with sprinkler protection to 50
CONSTRUCTION GUIDELINES ·· The stair must discharge directly to each compartment floor level or via outside or via a protected route to vertical compartmentation (refer to outside. No accommodation to open figures overleaf) into this protected route without a ·· Cavity barriers should be provided in ventilated lobby separating them. accordance with applicable guidance recommendations (i.e. ADB or BS 9991) ·· A fire alarm override switch should be provided in a secure location accessible B4 - External fire spread for the fire service to initiate a building wide simultaneous evacuation alarm, if ·· Facades will be designed in accordance deemed necessary. with space separation analysis undertaken by the fire engineer. ·· In view of upcoming regulations and legislation changes, current ·· The external fabric will achieve recommendations are to be reviewed European Class A2-s1, d0 or Class A1, on a project by project basis. regardless of building height. B2 - Internal fire spread (linings) B5 - Access and facilities for the fire service ·· All internal linings will be provided ·· Any building above 18m in height will in accordance with the applicable be provided with a firefighting shaft guidance recommendations i.e. including: Approved Document B or BS 9991. ·· Firefighting stair B3 - Internal fire spread (structure) ·· Firefighting lift ·· Smoke ventilated firefighting lobby ·· All elements of structure to be ·· Dry riser if building height <50m designed in accordance with relevant ·· Wet riser if building height >50m guidance. Refer to table below. ·· The distance between the firefighting ·· All apartments are to be provided stair door and the firefighting lift will with 60 minutes fire resistance not exceed 7.5m between each other and between ·· Riser inlets will be provided within common corridors. 18m of fire service vehicle access and outlets will be provided within the ·· Where apartments are accessed via stair enclosure at every floor level an external gallery and escape is including Ground Floor. only possible in a single direction, 30 ·· All points of every apartment will be minutes fire resistance up to a height within 45m of the outlet (or fire of 1.1m is to be provided between the service vehicle for buildings <18m) on apartment and the gallery. a route suitable for laying hose. ·· Compartment floors are to provide Dwellinghouses the same level of fire resistance as elements of structure. ·· For houses up to 3 storeys high, sprinklers will not be utilised. Therefore, ·· Potential firefighting shafts will be houses should be designed in provided with 120 minutes fire resistance accordance with Approved Document Part B to ensure compliance with ·· Any service risers will be provided with Building Regulations. the same level of fire resistance as the elements of structure. This can be achieved either via fire stopping at 51
CONSTRUCTION PARAMETERS 1 Shaft/riser access door(s): 60 minutes fire 1 4 resistance if they are accessed or located 2 4 in the protected common corridor 2 2 Shaft/riser wall: 60 minutes fire resistance 3 if they are accessed or located in the protected common corridor 4 3 Fire stopping and passive fire protection at compartment floor level. Fire resistance period at least equal to that of a compartment floor. 4 Fire Resisting compartment floor Risers provided with horizontal fire stopping at each compartment floor level (equivalent to elements of structure) 1 1 Shaft/Riser access door(s): Fire resistance 3 period at least half that of the 2 compartment floor 3 2 Shaft/Riser wall: Fire resistance period 2 equal to that of the compartment floor Risers open throughout the building but 3 Fire Resisting compartment floor enclosed in fire resisting construction equivalent to elements of structure 52
CONSTRUCTION GUIDELINES Ventilated FIRE ENGINEERED SOLUTIONS common corridor Although Be First’s preferred starting point for design development is the max. 7.5m Ventilated standard approach outline above, there firefighting may be justification for a fire engineered solution to overcome specific design stairs challenges, on a project by project basis. Firefighting For example: lift ·· Single direction travel distances in Components of a firefighting shaft for residential common corridors could be extended buildings - residential buildings only to 30m if a Double Reversible Mechanical Extract (DRME) system Min. fire resistance 60 mins is implemented. This approach would Min. fire resistance 120 mins need to be supported by Computational Fire main outlet Fluid Dynamics (CFD) modelling as part of the fire engineering justification. 0.6m2 mechanical smoke extract shaft ·· Open-plan apartments greater than the maximum dimensions recommended in guidance, with unenclosed kitchens, are possible with a fire engineered justification. Residential sprinkler protection and Category LD1 detection and alarm system is required as a minimum and CFD modelling will be required as part of the fire engineering justification. Both approaches would need to be discussed and agreed with Approving Authorities. 25m-30m with sprinklers Protected means of escape corridor Smoke detection required in corridor to operate smoke control system. 53
CONSTRUCTION PARAMETERS 2.4 ACOUSTICS INTERNAL SOUND LEVELS to establish the existing levels of environmental sound at the site and Be First homes should provide a quiet, surrounding buildings. The survey shall comfortable space that enable suitable be undertaken in accordance with the conditions for relaxing, resting and sleeping. principles set out within the latest version of BS 7445. Site layout ·· Parts of the Borough are located close to several railway lines (including both ·· At feasibility stage, consideration London Underground lines, and National should be given to reducing noise Rail services). Where necessary, a throughout the development by baseline vibration survey shall also be optimising the site layout. This can undertaken to determine whether any help to minimise the requirements for specialist design measures are required enhanced façade sound insulation to control vibration or any associated measures later in the design process. re-radiated structure-borne noise. ·· Early thought should be given to Internal sound levels building orientation. For example, setting the building further back from ·· The building envelope shall be a road or railway, or locating more designed to achieve appropriate sensitive spaces (such as bedrooms) internal sound levels within dwellings in on a quieter façade. line with the latest version of BS 8233. ·· Landscaping can also be used to ·· In developing the façade introduce acoustic screening between specifications, consideration will also major noise sources and external need to be given to the maximum amenity areas. This will help with sound levels due to individual noise providing a calming, restorative events (LAmax). soundscape for residents, and an increased sense of enjoyment. ·· Internal sound level criteria within dwellings are set out within the Environmental surveys Employer’s Requirements (ERs) document. ·· An environmental survey shall be undertaken at an early design stage 54
CONSTRUCTION GUIDELINES Noise, ventilation and overheating Standard specification apartments ·· Background ventilation strategies (in Living/Dining line with Approved Document F, ADF) for the development shall be designed Bedroom with due consideration of external noise. Bath UC Kitchen ·· Any trickle ventilators provided as part of the ventilation system will need to Designed to achieve a 5dB improvement be acoustically rated to achieve the on ADE required internal sound levels. Designed in line with ADE requirements ·· Consideration will also need to be given Enhanced specification apartments to the internal sound levels that would be achieved if relying upon openable Living/Dining windows as part of the strategy to control overheating. Reference should Bedroom be made to the Acoustics & Noise Consultants “Acoustics, Ventilation and Bath UC Kitchen Overheating Residential Design Guide”. ·· Where internal sound levels with an open window are likely to exceed 45 dB LAeq,T during the day, or 40 dB LAeq,T at night, the design team shall develop alternative strategies to mitigate overheating and present these to Be First for approval. INTERNAL WALLS AND FLOORS The standards set out below are to ensure Be First residents feel a sense of privacy within their homes. In certain situations the Be First requirements exceed the statutory minimums set out in Approved Document E (ADE). Party walls, doors and floors ·· Be First require that party walls and floors between dwellings, and between a dwelling and corridor / stairwell achieve a 5 dB improvement on the minimum numeric standards within ADE. Designed to achieve a 5dB improvement on ADE 55
·· Doors entering apartments off breakout from ventilation equipment corridors shall be designed in line with within the cupboard to indiscernible the requirements of ADE. sound levels in the surrounding spaces. ·· This is of particular importance should ·· It may be beneficial to consider utility cupboards back on to bedrooms localised acoustic enhancement of (which should be avoided through doors in certain areas, such as where layout planning where possible). apartment entrance doors are ‘back to back’, or are in proximity of lifts. Separations between dwellings and areas Partitions within apartments of different use ·· Internal partitions within Standard ·· Noise from non-residential areas will specification apartments shall be need to be controlled to minimise specified to achieve the minimum disturbance of neighbouring residents. performance standards set out Noise intrusion criteria are set out the within ADE. ERs document. ·· For Enhanced specification ·· Where apartments back on to lift or apartments, internal walls shall stair cores, an independent wall lining be specified to achieve a 5 dB should be provide to reduce the risk improvement upon ADE standards. of noise from lifts being transferred to apartments. This can typically be ·· Utility cupboard partitions and doors accommodated within a 100 mm zone. shall be designed to reduce noise Living/Dining Bedroom Stair Lift Bath UC Kitchen Independent wall linings between apartments and stairs/lifts 56
CONSTRUCTION GUIDELINES ·· Where apartments are adjacent ·· Ventilation equipment will normally to non-residential areas such as require in-duct attenuators to meet commercial units or plant rooms, the internal noise levels. consideration should be given at an early stage to the need for enhanced ·· Fans/MVHR units, and rainwater/ separating constructions between soil pipework, should not be installed these spaces. Specialist acoustic floor directly onto lightweight walls as this or ceiling details may be required. can result in unwanted structure- borne noise. ACOUSTIC FINISHES ·· Sockets will need to be acoustically Acoustic finishes shall be provided treated to maintain the acoustic within corridors to comply with the integrity of partitions. Back to back requirements of ADE. sockets should be avoided. Should a more industrial look (e.g. exposed ·· Building services distribution routes will services, hard floors, exposed soffits) be need to be designed to avoid crosstalk preferred, it will be necessary to agree the between different areas. approach with Building Control. ·· Penetrations through party walls must As part of this approach, thought be avoided. Penetrations through should be given to enhancing the sound corridor walls are acceptable. reduction performance of the apartment entrance doors to offset noise build-up within the corridor. BUILDING SERVICES NOISE AND VIBRATION Building services within apartments will need to be designed to minimise both noise and vibration, in order to limit disturbance of residents. Building services plant shall be designed to achieve the internal and external noise and vibration criteria set out within the ERs, and local policy. The following should be considered in developing the building services design: ·· Locating fans and MVHR units away from noise sensitive spaces such as bedrooms. 57
CONSTRUCTION PARAMETERS 2.5 OFF-SITE PREFABRICATION Be First encourage innovation and are keen be explored at the earliest possible to explore Design for Manufacture opportunity, due to the space planning and Assembly approaches. Off-site considerations and layout implications standardised construction of that entail. components can offer increased cost- certainty, speed, minimisation of waste All townhouses should utilise modular and improved quality and consistency of or pre-fabricated methods. Schemes the Be First brand. should seek to utilise the GLA PRISM application, which aims to help Design teams should review the potential the design process for precision for off-site standardised construction manufactured housing (PMH). Spatial at Stage 1/2. In some cases, the planning rules are combined with arrangement of particular rooms can be precision manufacturer expertise in order standardised as ‘pods’ (e.g. bathrooms, to establish viability of PMH. utility cupboards etc). This should 58
CONSTRUCTION GUIDELINES Positives for implementing bathroom ·· Layout implications with regard to pods include: delivery and installation are critical (setting a clear path for movement ·· Programme benefits of pods, and avoidance of structural ·· Singular trade involvement and downstands etc.) limitation of snagging issues due to ·· Allowance for increased wall build-up factory quality control along party wall locations (50mm either ·· Reduced maintenance requirements due side) and floor build-up, dependent to use of robust materials such as GRP upon pod type and application ·· For this to be a suitably viable option, the following points need to be ·· Tolerance needed above pod - service considered: ceiling void min. 250mm ·· Need to be on procurement path early ·· Variation needs to be limited, ·· if used, +130 - 150mm FFL for level rationalising the number of access adaptability / trap in shower bathroom types +50mm either side of party wall to be added 59
CONSTRUCTION PARAMETERS 2.6 TARGET EFFICIENCIES WALL TO FLOOR RATIO NET TO GROSS Efficient building forms reduce heat loss Design teams should target a net to through the building envelope and help gross efficiency of 75-80%. to control facade costs. ‘Net’ is the Net Internal Area (NIA) of Design teams should target a wall to the building - generally the total area floor ratio within the range of 0.7-1. of all dwellings. This means that the total external wall ‘Gross’ is the Gross Internal Area (GIA) area should be less than or equal to the of the building - generally the total internal floor area. area within the thermal envelope of the building, including communal areas. 60
CONSTRUCTION GUIDELINES 2.7 STRUCTURE AND BUILD-UPS The following guidance should be adopted across schemes, to help optimise Be First housing developments, deliver efficiencies and maximise value: 01. STRUCTURE 3.65 Cantilevers Alignment Stack 3.65 Align structural elements, avoid cantilevers, stack services/similar Spans to be max. 7.5m (e.g. 3.65x3.65m unit types grid) to prevent transfer structures, allow for construction type flexibility and to allow for alignment with parking bays 61
3150CONSTRUCTION PARAMETERS 2400 02. FLOOR TO FLOOR HEIGHTS 2500 min. Floor to floor heights of 3150mm, allowing minimum 2500mm floor to ceiling heights to principal rooms and 2400mm to bathrooms and kitchens * UC Bathroom *(London Plan - private internal space minimum floor to ceiling height must be 2.5m for at least 75% of dwelling) 62
CONSTRUCTION GUIDELINES 03. BUILD-UPS 135mm floor buildup 250mm structural zone 90-160mm services void Suggested floor build-up to allow for pod installation, level-access shower and underfloor heating. Principal room condition shown above with reduced service zone of 90-160mm depending on MVHR requirement. To be developed in relation to MEP strategy. Wall build-ups - allow 550mm for external walls, 300mm for party walls and 100mm for internal partitions (all patressing inbetween studs) 250-300mmServices Zone Lowered ceilings to immediate entrance lobby, bathrooms and utility cupboard, with clear service zone of 250-300mm to allow for crossover of services. Maintain 2500mm in hallways where clerestory windows are provided about doors. 63
CONSTRUCTION PARAMETERS 2.8 WINDOWS AND DOORS 01. WINDOWS Reversible tilt and turn or inward opening sash preferred, maximum Windows are to be composite/aluminium dimension of 1200mm: not uPVC. Aluminium windows perform better thermally and allow for slimmer Full-brick profiles and larger areas of glazing. Polyester Powder Coating (PPC) allows max. 1200m flexibility over colour and is a low maintenance finish. Full-height windows to living spaces only, with no horizontal members that obstruct Window frames are to be set back the view from a seated position (below one full brick (or equivalent) from the 800mm) external face of the building. Openable window heights are to be a minimum of 1100mm Windows should be designed to be able Allow minimum 150mm upstand from to be cleaned from the inside of the counter top building wherever possible. Align windows to top of shower screen, if bathroom is to have window Room specific conditions outlining key dimensions: Living Kitchen Bathroom 64
CONSTRUCTION GUIDELINES 02. DOORS 1. w 826 x h 2040 x d 44 mm metric door leaf (internal use, to comply with Door-set systems are to be standardised Category M4(2) with minimum corridor as far as possible. Primary entrance width of 1050mm) doors to buildings & apartments will be specific to each project. 2. w 926 x h 2040 x 44 mm metric door leaf (internal use, to comply with Standard door types throughout to give Category M4(3)) clear openings & comply with regulations will include: 12 min. 300mm min. 300mm e.g. clear opening width of 775mm, e.g. clear opening width of 850mm, dependent on supplier chosen dependent on supplier chosen 65
CONSTRUCTION PARAMETERS 2.9 STAIRS AND LIFTS 01. STAIRS - COMMUNAL ·· Stairs offset by one tread at landings to allow smooth handrail transitions ·· Typical standardised stair-core and going/rise dimensions are shown above ·· Hand-railing to extend 300mm as a guide, based on a 3150mm floor beyond the top and bottom step to floor height and be fixed at a height of 900mm from each nosing, please refer to ·· Handrails are to be set at 1100mm at Approved Document Part K for further landings and 900mm to risers above information on regulations finished floor ·· No stairs should extend to roof level. ·· Add 50mm tolerance to either side Access hatches to be provided for of the overall stair dimenions shown access, maintenance and replacement below for early stage space planning of equipment installed at roof level. 5200 2650 1200 1500 1200 min. 400 min. 250mm max. 170mm 66
CONSTRUCTION GUIDELINES 02. LIFTS Capacity Car Width Car Depth 13 pers./1000kg (mm) (mm) ·· As a minimum all lifts are to be at 1300 least 13 person/1000kg capacity and 1100 the car shape should be suitable for 2100 transport of stretchers. 17 pers./1275kg 1200 ·· Lifts are to serve all occupied floors ·· For both types, car height is 2200mm, and to provide resilience all cores are door width is 900mm and door height to have at least two lifts. is 2100mm. Doors should be 2 panel centre opening configuration. ·· An assessment should be carried out on a project by project basis to ·· Landings must have 1500mm clear establish the adequate number and turning circle in front of lift doors. size of lifts. ·· Be First and LBBD have a detailed lifts ·· Shaft sizes should be agreed early specification as part of the ERs that in the project should be followed throughout the project stages. The following table details car dimensions that are acceptable to Be ·· Open protocol, vandal resistance lifts First. Any deviation from the standard are required. dimensions will require written approval. 1300 1100 13 pers. 1500 67
HOW TO USE THIS SECTION This section summarises Be First’s Standard and an Enhanced specification for dwellings. Each specification will be set according to individual project briefs and in relation to tenure and management requirements specific to each project. 68
3.0 SPECIFICATION REQUIREMENTS 69
S PEC I F I CAT ION R EQUIR EMEN TS Living Standard Specification Enhanced Specification Item Engineered wood or laminate wood Engineered wood or laminate wood Flooring LED downlighters LED downlighters Lighting Bathroom Standard Specification Enhanced Specification Item Studded rubber/ Marmoleum Flooring Acrylic 300 x 300 grey tiles Bath panel Mirrored wall cabinet - moisture Satin white 150 x 150 tiles with mid- Storage resistant plywood dark grey grout or acrylic Floor standing toilet Fixture and Mirrored wall cabinet - moisture fittings resistant plywood Walls Wall mounted toilet Lighting Splashback Satin white 150 x 150 tiles with mid- Fully tiled with satin white 150 x 150 Ensuite dark grey grout to shower/bath area tiles with mid-dark grey grout Recessed downlights Recessed downlights Frosted glass Frosted glass N/A Ensuites in 2b4p and larger 70
CONSTRUCTION GUIDELINES Kitchen Standard Specification Enhanced Specification Item Not supplied Fridge/Freezer Mid range fan oven Built in Oven Induction hob Oven hob Supply and install recirculation Mid range fan oven Extractor hood Not supplied Dishwasher Induction hob Worktop Grey high spec laminate Supply and install recirculation Kitchen units Howdens Clerkenwell range - white Integrated dishwasher (slimline for Sink matt finish 1b) Flooring Countertop sink (1.5 for 2b+) Grey silestone Lighting Feature lighting Engineered wood or laminate wood Howdens Clerkenwell range - white (to match living if open plan) gloss finish Walls Splashback Recessed downlights Countertop sink (1.5 for 2b+) Shelving LED task lighting fitted to the Engineered wood or laminate wood underside of the wall mounted (to match living if open plan) kitchen units Recessed downlights Painted plasterboard LED task lighting fitted to the Satin white 150 x 150 tiles with underside of the wall mounted white/light grey grout or glass kitchen units Moisture resistant plywood Painted plasterboard Satin white 150 x 150 tiles with white/light grey grout or glass Moisture resistant plywood Bedroom Standard Specification Enhanced Specification Item Not supplied - space allowed Built in wardrobe in master bedroom Storage Natural carpet Natural carpet Flooring LED downlighters LED downlighters Lighting 71
S PEC I F I CAT ION R EQUIR EMEN TS Utility Cupboard Item Standard Specification Enhanced Specification Not supplied - space allowed Mid-range washer/dryer Washing machine/ dryer Individual Apartment Entrances Item Standard Specification Enhanced Specification Doorset Timber with fanlight above Timber with fanlight above Entrance ‘mat’ 150 x 150 terracotta coloured quarry tiles (or similar) 150 x 150 terracotta coloured quarry tiles (or similar) Door surround Satin white 150 x 150 tiles with white/light grey grout Satin white 150 x 150 tiles with white/light grey grout Communal Cores Item Standard Specification Enhanced Specification Post boxes Ground floor lobby boxes - Ground floor lobby boxes - SBD rated SBD rated Flooring (ground) Polished concrete or large format tiles Polished concrete or large format tiles with durable internal mat at entrances with durable internal mat at entrances Flooring (upper) Vinyl/ Marmoleum Vinyl/ Marmoleum Walls Feature walls: satin white 300 X 300 Feature walls: satin white 300 X 300 tiled datum, hardwood accents, tiled datum, hardwood accents, painted plasterboard or Forbo painted plasterboard or Forbo bulletin board lining bulletin board lining Everywhere else: exposed concrete Everywhere else: exposed concrete blockwork blockwork Concrete Stairmaster Stairs Concrete Stairmaster PPC steel top/ hardwood balustrade Stair Balustrade PPC steel top/ hardwood balustrade Notes: PRS schemes will require concierge and lockers 72
This document has been prepared by Mæ Architects Ltd with technical input from Hoare Lea and graphic design by Atwork. Version 01 published 03/2020. All images copyright Mæ.
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