Building technology - Refurbishment Programme of Multi-Occupational Offices.
BUILDING TECHNOLOGY
00. Refurbishment Programme of Multi-Occupational Offices
01. The refurbishment programme will cater for multi-occupational offices leased to a number of small businesses. Extensive refitting will include improvement of the lightening protection, lift system and general electrical and ancillary services and toilet accommodation.
.0 Summary
.1 CDM regulations will apply because the works will extend for more than a 30 day period and at any one time, it is possible that more than 4 people will be on site.
.2 A Health and safety plan will be required, in particular detailing the positioning and swing of the crane delivering the lift car
.3 All contractors to be in possession of public liability insurance, be a member of Constructionline. Lift installer to be EN ISO 9001 company.
.4 Because building might be in use 24 hours a day, service agreement with suppliers important to ensure round-the-clock call-out and maintenance facilities in place with lift installer, plumbers and electricians.
.5 As well any statutory regulatory requirements, Listed Building Consent will also be required. It is possible that because of its listed status, lottery and Historic Building grants can be applied for which will reduce the financial burden of any alterations.
2.0 Introduction
2.1 The report refers to an existing 5-storey office building constructed in the 1920's in the 'Art Deco' style
2.2 The building is Grade 2 listed
2.3 Original drawings are available and will be referred to. They show the elevations, sections and plans and are true to scale 1:200 reductions (1/8 inch to 1foot/ 1:100). The drawings are over 70 years old and not very clear to read.
2.4 The building is currently disused and empty
2.5 It is of steel-framed construction with beams and columns encased in concrete with reinforced floors and roof decks. The framing is encased in 300mm external brick cavity walls with 100mm stone facing to the principal elevation.
2.6 Interior original features of the entrance lobby, hall and stair well are to be retained.
2.7 Proposed internal layout is to be flexible on all floors to allow occupation by a number of small businesses. Each floor is of approximately 265 m2, which is sufficient space for a maximum number of 90 personnel per floor (on the assumption that 1 person occupies 3m2).
2.8 All work to comply with approved drawings and specifications and statutory regulations.
2.9 The report will consider 3 particular requirements of the refurbishment programme.
3.0 Information and Analysis
3.1 Performance Specification for a replacement Lift System including refurbishment of typical builder's work details
3.1.1 The existing lift does not comply with current Health and safety regulations. The lift car, lifting gear and motor room equipment is antiquated and has not been maintained regularly. It is recommended that the existing lift car and all associated equipment be removed and carted off site.
3.1.2 Motor Room building projecting externally to be retained due to protected status of building. Lift shaft and its location to be also retained to reduce to a minimum any alterations to entrance lobby and stairwell area.
3.1.3 Builder to remove roof deck to motor room and construct new steel reinforced concrete roof deck cast on site in-situ. Deck to be suitable to carry lifting beam to size provided by lift car installer. Deck to be left wind and water tight. Deck design to be provided by lift car installer.
3.1.4 Machine access door and frame to be replaced with new steel door and frame with 5-lever lock and latch and 3no. keys; ensure existing ventilation and daylighting provisions satisfactory and replace as necessary; provide heating facilities to maintain 100C temperature all year round.. ...
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3.1.3 Builder to remove roof deck to motor room and construct new steel reinforced concrete roof deck cast on site in-situ. Deck to be suitable to carry lifting beam to size provided by lift car installer. Deck to be left wind and water tight. Deck design to be provided by lift car installer.
3.1.4 Machine access door and frame to be replaced with new steel door and frame with 5-lever lock and latch and 3no. keys; ensure existing ventilation and daylighting provisions satisfactory and replace as necessary; provide heating facilities to maintain 100C temperature all year round.. Provide Ensure vent to
3.1.5 All builders work to be completed prior to arrival of lift car installer. Lift shaft to be constructed on site in poured concrete or common brickwork with flush pointing internally. Sides to be plumb, smooth and vertical. Provide ventilation void for emission of smoke, provide permanent inspection lights. Shaft to have no other services except those necessary for the operation of the lift.
3.1.6 Guides for new car to be fixed in shaft by builder to lift car installers details and specifications
3.1.7 Builder to provide 3-phase DC wiring loop
3.1.8 Provide new single electric lift. All design, manufacture and installation to be in accordance with BS 5655 (EN 81-2).
3.1.9 Lift car dimensions to be at least 2m wide x 1.5m deep and to suit dimensions of the existing lift shaft. Internal dimensions to be adequate for ingress and egress of a wheelchair and attendant.
3.1.10 Mode of operation to be Simplex Collective. On the assumption that 1 person occupies at least 0.2m2, lift car should be capable of carrying at least 10 people per journey, at a speed of at least 2.0m/s, and in any case not less than 0.8m/s and not more than 7m/s. Round trip time from ground floor, to top floor and back to ground floor to take no more than 60 seconds. Maximum waiting time for car to be not in excess of 30 seconds.
3.1.11 All call buttons to be located within landing entrance at all levels. Allow for externally located digital lift car position and lift call button and direction of travel indicators.
3.1.12 All buttons within car to be clearly visible and illuminated at all times. Should be easy to use with capability for induction loops and speech synthesis. Use by the blind and frail should be respected. Access by wheel chair bound should be possible.
3.1.13 Door opening width to be not less than 1.1m wide. Door to be pre-finished stainless steel. Fire resistance of doors to conform with statutory requirements. Where tools are necessary for manual opening they should be readily available. If the power supply is lost and then restored while the door is opened manually, the person opening it should not be put at risk.
3.1.14 Interior of car to be pre-finished with mirror walls, carpet floor, suspended ceiling with fluorescent lighting and luminaires.
3.1.15 All equipment essential for operation and maintenance of lift car to be installed in motor room by lift car installer, including winding gear, traction sheave, control panel, overspeed governor.
3.1.16 Note: lift motor to be placed on anti-vibration mountings of sufficient capacity to reduce noise.
3.1.17 Lift car installer to design and erect lifting steel beam fixed to underside of maintenance room roof.
3.1.18 Lift car installer to provide oil-loaded buffers in maintenance pit in basement with easy access for maintenance purposes.
3.2.0 Specification for the reinstatement of the existing Lightening Protection System [LPS].
3.2.1 The components of the LPS comprises the following networks: air termination network, down conductors network (including joints and bonds), earth electrodes network (including test joints), earth termination network.
3.2.2 Before commencement of any work, the existing system should be tested to evaluate its efficiency before replacement; any replacement should then be tested on completion to determine a safe working system. The LPS in all cases should be mechanically robust, free of corrosion and compliant with the recommendations made in BS 6651.
3.2.3 The resistance values should be tested in accordance with BS 7430 and in any case, neither the combined resistance of the earth electrode or the resistance of the LPS measured at any point should exceed 10 ohms.
3.2.4 All new work to comply with BS 6651 which provides a procedure for calculating the overall lightening risk factor for a building and which takes into account a 450 degree zone of protection around the lightening protector (see appendix 1).
3.2.5 The air terminations network is provided primarily to intercept a lightening strike. No part of the roof should be more than 5m from an air termination network and this will be achieved by a conductor mesh 10m x 20m for the flat roof area (appendix 2).
3.2.6 Particularly vulnerable areas are all the structures projecting more than 5m above the roof (this includes the flagpole, the clock tower, the lift maintenance room, the ventilation shaft, any aerials); and the edges and parapets of the roof. All the projections should be connected to the air termination network
3.2.7 The edges and parapet of the roof should be connected to the down conductors network which will provide a low impedance path from the air termination network to the earth termination network (appendix 3).
3.2.8 Down conductors to take the shortest route to the earth termination network to minimise the probability of sideflashing, with no bends and re-entrant loops designed as shown in appendices 3 and 4.
3.2.9 Joints and bonds between dissimilar metals to be avoided.
3.2.10 Bond the LPS to the main earthing system and to any metal in the building or in contact with the earth.
3.2.11 Down conductors to be symmetrically placed around the periphery of the building, no more than 20m apart, starting from the corners.
3.2.12 The choice of the earth electrodes network to be dictated by ground conditions. In soft ground, to consist of rod electrodes spaced apart at distances greater than their depth or else several shorter rods to be installed each connected to its adjacent rod by horizontal conductors. In difficult ground conditions, horizontal strip electrodes, plates or mats will be permissible.
3.2.13 Where the installation of the earth electrodes does not achieve a low ohmic value, the electrodes should be interconnected by a conductor installed at least 0.5m beneath ground level. Protect any conductors with a PVC sleeve for a distance of 0.3m above and below ground.
3.2.14 On completion of all works, the LPS to be connected to the earth and tested as per section 3.2.3.
3.2.15 Provide record on completion of works detailing all LPS drawings, details of any soil tests carried out, all test results and details of any maintenance undertaken.
3.3.0 Problems and options in providing a complete toilet redesign for each floor as a separate let, with reference to current and imminent legislation.
3.3.1 As already discussed previously, the building can hold upto 90 people per floor. According to the Workplace (Health, Safety and Welfare) Regulations, 1992, such occupancy will require a minimum 5no. WCs and WHBs to be provided per floor. No guidance is available on the number of appliances to be provided by sex, but provision should be made for at least 2no. urinals, WCs and WHBs for men and at least 3no WCs and WHBs for women, per floor.
3.3.2 The provision of sanitary appliances will also need to comply with the design and installation of sanitation and drainage as found in BS 5572 and as enforced by the Building Regulations, parts H. Ventilation to WC areas to be by an opening light not less than 1/20th of the floor area or by an extractor fan operating at not less than 6l/s air speed and providing at least 3no. air changes per hour.
3.3.3 Further compliance will also be needed with part M of the Building Regulations for disability provision whereby 1no. toilet will be required per floor that is suitable for use by a disabled person. This toilet can be uni-sex and can be set against the need for a total 5 WC closets; i.e. provide 4no. WCs and WHBs per floor and 1no. disabled WC and WHB.
3.3.4 The existing WC area on each floor can be retained with provision of 2no. WCs and WHBs each and can be used for the male staff. Female WCs will need to be created in another room that can be accessed off the service area and be located at the rear of the male toilet area.
3.3.5 The existing gullies and ICs can be used located in the basement but all the above ground pipework will need to be renewed. Normally, in buildings between 5 and 20 stories, separate discharge pipes (SVPs) will be required for ground floor WCs to prevent back syphonage when upper floor WCs are flushed. However, although the building is 5 stories, there will be no WC provision on the roof and basement levels, restricting WCs to 4 stories. Hence, it is satisfactory to have the WCs on the ground floor and upper floor discharging in the same SVP.
3.3.6 The simultaneous demand factor and the volume floe rate in litres per second should be calculated to determine the nominal SVP bore size; in this instance it will be at least 150mm. The calculation can also be done using the principles and tables in BS 5572 to determine the stack diameter for approximate totals of discharge units.
3.3.7 Basins should be connected to a 32mm pipe if the SVP is less than 1.7m away, or 40mm if it is upto 4m away. WCs should be connected to a 100mm pipe and can be upto 6m distance from the SVP. Branch slopes should conform to minimum standards; the longer the distance to the SVP, the steeper the slope. Where waste pipes exceed the minimum and longer distances become necessary, then the other alternatives are the use of resealing/anti-vacuum traps and the ventilation of SVPs with a separate vent pipe.
3.3.8 Resealing and anti-vacuum traps are designed to maintain a water seal but they can be noisy and require periodic maintenance. Vent pipes should be at least half the diameter of the main SVP and the branch vents should be at least 2/3rds the diameter of the waster pipes served.
3.3.9 In all instances, the branch pipes must connect to the main stack in such a way that the discharge from one appliance cannot back up the waster pipe of another. This will necessitate a stagger or offset of branch pipes sufficient to avoid a cross flow.
3.3.10 Access for maintenance should be provided by the provision of rodding eyes at the head of each main connection with the male and female rooms. These should be easily reached.
3.3.11 The new SVPs will need to be located inside the building. All pipes passing through floors will need to be protected with intumescent collars to prevent fire spreading between floors.
3.3.12 The airtightness of the existing underground drains should be carried out in accordance with the Building Regulations requirements. It is quite possible that the existing underground drains are clayware with inflexible tarred joints. Any movement will have led to the joints opening up. In this instance, it may be necessary to replace the underground drains within the curtilage of the building or at least upto the connection with the main sewer. The opportunity should also be taken to ensure the integrity of manholes which should be reconstructed in class B engineering brickwork if necessary, and to ensure that all pipes running below the basement floor and between walls are adequately protected.
4.0 Conclusions
4.1 The building is almost 100 years old and is a listed building as well. It will therefore need careful and sensitive alterations. However, any internal work followed up the external cleaning of the stonework on the front elevation will add to its rental value. Before proceeding too far with any plans, it would be advisable to speak the Planning department to ensure the occupancy rates and parking provision are satisfactory ; Building Regulations requirements for fire protection should be considered carefully; Listed Building consent is critical before any major alterations and demolition of walls and partitions commences.
5.0 Recommendations
5.1 Before purchasing the building, it would be advisable to pay very close attention to the points in 4.1 above to ensure the viability of the project. With regard to the age of the building, it is possible that a great deal of unforeseen work may occur as work progresses, as has already been pointed out with regard to possible renewal of the underground g drains. But the building appears to be sound and barring any structural problems, the project should go ahead.
