Case studies matching "green roof"

Cambridge University, Department of Civil EngineeringBauderBLUE STORMcell with BauderSOLAR G LightSynopsisThis new build project in the centre of Cambridge combines a Sustainable urban Drainage Solution (SuDS) with vegetation and renewable energy in a warm roof construction.The client for the Department of Civil Engineering at Cambridge University, R H Partnership, identified sustainability as being a key driver in the design of the roof, but also sought a single source supplier that could provide a guarantee for both workmanship and products. Bauder’s systems range encompasses products to meet all the sustainability objectives, and with our network of approved contractors carrying out the installation, we could offer the comprehensive guarantee that was required.Bauder Building BoardProject:Cambridge University Department of EngineeringLocation:CambridgeRoof Area:1610m²Client:University of CambridgeSpecifier:RH Partnership ArchitectsMain Contractor:SDC LimitedApproved Contractor:Voland LimitedThe specificationTo meet the sustainability criteria set out by the client, the Bauder technical team designed a roof system combining an extensive blue roof, a green roof and a solar PV array. The first and most fundamental element of the roof system though is the waterproofing. Bauder Total Green Roof System (BTGRS) was selected as it provides robust and durable waterproofing with a life span in excess of 35 years, as validated by BBA Certificate 10/4744. The Plant E cap sheet has also been tested by the FLL to ensure long term root-resistance, making it ideal for use in conjunction with the BauderSOLAR G LIGHT system. The BauderSOLAR G LIGHT system is a unique way to combine rooftop vegetation with renewable solar energy. The PV panel mounting boards are held in position using the growing medium as ballast, meaning the waterproofing is not penetrated and therefore compromised. The mounting boards incorporate a water retention feature which allows a small amount of excess rainwater to be stored for short periods of time for the various plant species to feed from. The BauderSOLAR G LIGHT system’s unique mounting system lifts the panels above the vegetation allowing the plant life to grow freely and therefore qualify a greater area of the roof as biodiverse.In addition to the BauderSOLAR G LIGHT system, a blue roof was added to the build-up. Blue roofs are sustainable drainage solutions designed to manage stormwater on a flat roof to reduce water runoff rates and ease flash flooding and standing water in built up areas. The BauderBLUE Roof System attenuates water from a flat roof over a 24-hour period via a restrictive flow outlet. Calculations are carried out to determine the rate at which the water should egress the rooftop. This is determined by the local planning authority and is often set as low as 5-8 litres per second per hectare. With these calculations, Bauder can design each flow restrictorto meet the necessary runoff rate. For the Department of Civil Engineering, the main roof area of 1455.5m² required two flow restrictors, each with flow control holes to ensure the specified discharge rate of 0.77 litres per second was achieved. The maximum depth of water the roof is designed for is the H-max. When the water level reaches H-max, it will drain via the emergency overflow pipe. These overflow pipes are set at the same height as the H-max level. On this project the H-max was calculated to be 99mm. Although an unlikely scenario, this provision for a ‘once-in-a-hundred-years’ storm event will ensure that the structural integrity of the building is always preserved.Project challengesThe roof deck was constructed using a pretensioned concrete plank roof structure. Due to the large span of these planks, the dead load weight to the roof would be restricted. This being a blue roof with green landscaping and PV (a reasonably heavy build up), presented the issue of balancing the need of the roof design and the weight restriction of the supporting structure. To add to this challenging scenario, the pretensioned deck did not provide a completely flat finish. When installing a blue roof, a flat deck with no positive or negative falls is essential, as detailed in the 2018 update of BS 6229 – Flat roofs with continuously supported flexible waterproof coverings. To overcome this onsite challenge,the final deflection of the fully loaded roof was calculated and the concrete deck was screeded to give a flat finish.The resultBauder believes this project to be one of the first of its type in the UK to bring together so many rooftop systems in one space. Project management and clear communication was paramount in order to ensure a smooth installation. The Bauder project team consisted of green roof and solar PV product managers, area technical manager, technical design team, site technicians and approved installers for the waterproofing.With all the different elements being installed, green roof and solar PV product managers worked with our technical team to design the best possible PV array configuration for optimum energy generation whilst also qualifying for the maximum biodiverse area.Bauder site technicians worked closely with Bauder approved contractors, Voland Asphalte Ltd, to ensure works were kept to schedule and that a high quality of workmanship was maintained throughout.To ensure the landscaping is maintained, irrigation was installed by Access Irrigation Ltd. The system, Permadrip Pro, is a drip line irrigation system with anti-syphon design to resist clogging and pressure regulation. Due to the specialist nature of the irrigation system, Access Irrigation Ltd provided a bespoke design service.The result of this network of expertise was a multi-faceted support service for the client, specifier, main contractor and roofing and PV installers. System installedBauder Total Green Roof System (BTGRS)1 BauderPLANT E 42Green, 5mm torch-on root-resistant capping sheet.2 BauderTEC KSA DUOA self-adhesive, elastomeric, bitumen underlayer. This underlayer was used to ensure thorough sealing of lap joints in low temperatures when the roof was installed.3 BauderPIR FA-TETissue-faced flatboard insulation faced on both sides with aluminium foil to provide efficient thermal output.4 Bauder Super AL-ETorch-on air & vapour control layer. Once installed on the concrete pretensioned plank deck, it can act as a temporary waterproofing layer, allowing internal works to be carried out immediately which was a huge advantage on this new build project.BauderSOLAR G LIGHTThis BauderSOLAR G LIGHT system was a key factor in the specification of the project to meet the sustainability criteria specified by the client. 40 PV units were installed on the main roof area on the Departmentof Engineering. The forecasted energy generated for this arrayin its first year is 9.91MWh with a CO2 saving of 5.242 tonnes/a. BauderBLUE SR-B flow restrictorThe BauderBLUE SR-B flow restrictor is designed to be used in conjunction with a standard Bauder bitumen blue roof vertical outlet DN70. The flow restrictor is comprised of four parts; baseplate, overflow pipe, baseplate inner and baseplate outer seal. The polyamide baseplate fits within the 70mm vertical outlet, with the EPDM outer seal creating a watertight fit. The HDPE Overflow slots into the central hole of the baseplate with an inner EPDM seal preventing any leaks. The baseplate has a number (1-12) of 10mm restrictive flow holes bespoke to the project. The flow restrictor has no moving parts, hugely reducing the need for maintenance or risk of failure.

After a particularly contentious and protracted planning process, this semi-detached, red-bricked house, part of a group of five properties that form Regent’s Mews in affluent London NW8, finally boasts an impressive third storey extension as a result of the erection of a mansard roof.The new dormer windows to its front aspect lend this 1980’s property a delightfully modern aesthetic, whilst the provision of a green roof to the rear aspect underlines its eco-credentials. The installation of Glazing Vision’s elegant sliding-over fixed rooflight above the stairwell, together with 4 additional fixed rooflights, has maximised the light streaming into this new living space, and also provided an all-important source of ventilation.Initial proposals to convert this house from two to three floors were rejected way back in 2001 by the local Planning Department on the grounds of it being “visually intrusive, overbearing massing not part of the existing architectural language and overlooking neighbours”. These same considerations faced Robinson Leigh Architects, whose track record of successful planning application had led to their appointment in 2013 by a client keen to find a solution to the planning impasse.There were a number of challenges for the architects, as they sought to design a scheme that would prove more successful through planning. The house is situated in St John’s Wood Conservation area, where restrictions on the character and appearance of all buildings are strictly applied. Normally any roof extension in this area would not be permitted and the house, indeed the entire mews, had been identified as an “unlisted building of merit”. Consequently the planners insisted that all new work to the house “must match existing original work in terms of choice of materials, method of construction and finished appearance in order to maintain the cohesion of the mews.The variety of roof forms in the mews, however, presented an opportunity for the architects to put forward their proposal of a flat-topped mansard roof as “a modern interpretation of the surrounding architectural precedent” said Leigh. Critically, the new mansard roof would also not add height above the general roof level of the neighbouring properties in Regent’s Mews, and thus would not be visually intrusive. The design of the three new dormer windows at the front of the house did depart from that of the dormer windows on the other mews houses though – they were square in contrast to the prevalent curved headed windows. However, given that they were really only visible from within the actual mews, the planners considered this alteration in form to be acceptable. Furthermore, the recessed glazing of the dormer windows ensured that the privacy of the occupants using the living spaces would not be compromised.The choice of materials also had to conform to the surrounding properties: the dormer windows were lead-clad, and the roof was tiled in Welsh slate, which softens its appearance and reduces the “apparent bulk of the structure.Another complication for Robinson Leigh related to the impact upon the large villas of Langford Place to the rear of the property. Vehement objections from these residents, who were concerned that the roof extension would shatter the illusion that they are set in extensive grounds led the architects to revise their proposal: the pitch of the northwest slope of the mansard roof was adjusted to a 70 degree angle in order to reduce its prominence in the views from these villas, particularly from 5 Langford Place. A second flat roof, which adjoined the house was removed, and Robinson Leigh extended the mansard roof to the parapet. This then gave the client more internal space, eliminated any overlooking issues, and created a more homogenous and symmetrical design.The architects cleverly designed both the main roof level of the mansard to be landscaped with indigenous flora in order to respect the planners’ preference for ecological biodiversity in the area as well as to attenuate water run-off.In conjunction with these structural requirements imposed on Robinson Leigh’s design of the mansard roof, unlocking natural daylight in the “dark zones” in the interior of the new storey was a key priority. Mindful of the rejection of the glazed roof proposal from 2001, which the planners had deemed to be too intrusive on the neighbours and at odds with the surrounding architecture, the architects sought to reduce the amount glazed by 50%, whilst simultaneously addressing the problem of reduced levels of natural daylight resulting from the recessed dormer windows.Robinson Leigh’s solution was to propose a more sympathetic glazing arrangement to the flat-top of the mansard roof, comprising four large fixed rooflights and a sliding over fixed rooflight from Glazing Vision, that would achieve the high specification they desired. These rooflights, pointed upwards to the sky, would maximise the amount of daylight entering the extension and bouncing off the hardwood timber, which had been used extensively, as Leigh points out, to “draw together several disparate elements of the interior design, such as the sliding walls, pocket doors and floor-to-ceiling shelving and cupboards”.Glazing Vision’s sliding over fixed rooflight was to inhabit the space immediately above the stairwell, which had also been lined in timber to subtly link the top floor with the ground floor and to help draw the eye upwards. Timber frames had also been used on the windows. As with the other four rooflights, Glazing Vision’s sliding over fixed rooflight needed to be made to a bespoke size – the architects required it to be the exact size of the stairwell, or indeed over-sized, so that the frames were not visible from below. Precision-engineered at the Glazing Vision factory in Norfolk, the special sliding over fixed rooflight was supplied in two sections, with an overall span of 2400mm and a width of 2240mm. The minimalist internal framework, finished in pure white rather than the standard grey, ensured that there were unfettered, sky-only views from the inside, thereby enhancing the impression of space and loft. Through the clear glazing of the Glazing Vision rooflight natural daylight absolutely flooded the stairwell, permeating also down to the lower floors.Given the stringent planning controls on the appearance of the mansard roof and the concerns of the vociferous neighbours, Glazing Vision’s sliding over fixed rooflight offered another invaluable benefit to Robinson Leigh. The footprint of the unit on the roof remained fixed, both open and close. This meant that there was no bulky additional furniture required, whilst the minimalist exterior framework was finished in slate grey to blend harmoniously with the Welsh slate roof tiles.No less important was the need for natural ventilation in the mansard roof extension. The architects were keen to create a venturi effect in the central core of the house and stairwell by channeling the airflow through the opening of the rooflight. The Glazing Vision rooflight, specified by Robinson Leigh to slide side-to-side rather than up and down, is electronically controlled at the touch of a button from inside the house, retracting the sliding section over the fixed section of glazing. Once the sliding section is fully retracted, there is a 50% clear opening in the rooflight, out towards the sky, thus providing superior air quality within the top floor, as well as intensifying the amount of natural daylight. An essential security feature of the Glazing Vision sliding-over fixed rooflight is that it is supplied with a manual override as standard.The design, approval and erection of the mansard roof extension took three years but Robinson Leigh have succeeded in updating a tired-looking 1980’s mews house with a new, sophisticated, modern exterior, that quietly complements the surrounding properties. The new third storey has exceeded the client’s needs for additional living space, and the clever use of rooflights has ensured the interior is light, bright and inviting.