Controlling water and water vapour is fundamental to the proper functioning of any building. Controlling moisture is important to protect occupants from adverse health effects and to protect the building, its mechanical systems and its contents from physical or chemical damage. Yet, moisture problems are so common in buildings and can cause problems for building owners, maintenance personnel and occupants.
To control water and water vapour for long building life and good indoor air quality, we must control liquid water, prevent excessive indoor humidity and water vapour migration by air flow and diffusion in order to limit condensation and moisture absorption, and select moisture-resistant materials for unavoidably wet locations.
The method I’ve chosen is rainscreen cladding using the Kingspan BENCHMARK KS1000QK (100mm core horizontal barrier panel) and the idea behind this method is having multiple layers in the external wall of a building, each performing specific functions instead of a single layer acting as a structure, thermal and acoustic insulation, moisture and wind barrier all at once.
The outer rain screen layer is used as only the first line of defence against wind and water coming into the building, it is not completely sealed or waterproof but acts as a screen to prevent most water and wind entering the building.
The external cladding is not waterproof but it acts as a shield for the waterproof membrane behind it as well as providing a narrow gap so that water may drain and evaporate off the inner wall. The rain screen cladding is a barrier which protects the waterproof membrane from excess from water ,wind and sunlight because it will never be 100% waterproof and the membranes will degrade in sunlight over time.
There are two different variations of rain screen cladding; drained ventilated and pressure equalised. These are both ‘open jointed rainscreens’.
The method I have chosen is a drained ventilated rain screen cladding system which have gaps at the top and bottom of the wall and a single cavity running through the full height of the wall. This variation assumed that water will get behind the outer rainscren into the cavity, and thus allow the water to drip down the waterproof face of the inner wall and drain out of vents at the bottom.
This will also create a current of air from bottom to top to help evaporate water and keep the cavity dry.
A major advantage of rain screen cladding is the flexibility of the materials that can be used because the external, visible, rainscreen layer does not have to be watertight, it can be made out of almost any material and finished with any texture or colour. They are also very adaptable to shapes such as curves. The rainscreen cladding I will use will be made out of recyclable materials to which would provide a sustainable cladding option and be more cost effective. Rainscreen facades also can come with lifetime guarantees from their manufacturer because they are modular and made up of single panels which means if there is a problem with a single panel it can be replaced with ease and at minimal cost making this material extremely efficient for my large-scale building.
This method can be used in accordance with the BRE regulations classification report reference number 299571, issue 1.
As shown on the section, I will use the Siga Majpell 5 vapour/Air control barrier in accordance to reference standard EN 13984 to reduce the condensation and provide permanently airtight building envelopes for roof, wall and ceiling structure. Performance building supply.com
All joints are to be taped with Siga Sicrall single high performance tape. The 100mm Rockwool Duo Mineral fibre insulation is protected by the EPDM membrane sealed inside of the Karrier panel. This is a breathable membrane to help reduce condensation. The Siga Majpell 5 Vapour/ Air control Barrier overlapped with Siga Dockskin high performance primer applied to the floor with concrete slab to prevent condensation in accordance with BS 5250:20111 (Code of Practice for control of condensation).
https://www.ribaproductselector.com/Docs/5/206865/external/AG080314.pdf
BS 5250: 2011 Code of Practice for Control of Condensation in Buildings
https://www.jjroofingsupplies.co.uk/permavent-black-breathable-membrane/
https://www.building.co.uk/cpd/cpd-7-2017-rainscreen-cladding/5087063.article
https://www.kingspan.com/gb/en-gb/products/architectural-facade-systems/rainscreen-facades
Controlling Air Flow and heat Flow
Controlling air flow is a crucial and intrinsic part of heat and moisture control in building envelopes. Its important for a number of reasons; controlling moisture damage, reducing energy loss, and to ensure occupants comfort and health. Airflow across the building enclosure is driven by wind pressures, stack effect and mechanical air handling equipment such as office fans. An effective air barrier system is required between the exterior and interior spaces to control airflow by these elements.
Uncontrolled air flow will cause condensation of the water vapour in the air , reducing durability and increasing health risks.
https://buildingscience.com/documents/digests/bsd-014-air-flow-control-in-buildings
The Karrier Panel System for cladding complies with BS EN 14569 and has a U-value of 0.08 W/m2k and will be used to ensure water-tightness alongside the sign Maipell moisture vapour layer whcich will provide air tightness in accordance with eN 13984 standards. https://www.ribaproductselector.com/SearchAll.aspx?s=Karrier+cladding+system#
Ventilation moves outdoor air into a building or. Room, and distributes the air within the build g or room. The general purpose of ventilation in buildings is to provide healthy air for breathing and comfort for occupants.
There are three different types of methods to ventilate a building: natural, mechanical and hybrid ventilation.
Sound
We have to be wary that the site is in close proximity to the Ormeau Road Embankment which is a hub for noise pollution from traffic and building works. And so, action must be taken to battle any unwanted noise from neighbouring cars, buildings, people, or construction. Using an effective air barrier and insulation can control the movement of sound in the building and prevent any additional unwanted noises in the office.
The Kingspan Karrier System complies with BS 8233 and is manufactured and supplied under a quality system certified to BS EN ISO 9001: 2000. The manufacturing plants are also iSO 140001 (enviornmentally) accredited.
https://www.ribaproductselector.com/Product.aspx?ci=4454&pr=KingspanInsulatedPanels-KarrierPanelSystem
The acoustic properties of this building are that all panels have a single figure weighted sounded reduction, Rw= 24dB. This will effectively soundproof the offices alongside the use of Rockwool insulation which has excellent acoustic insulation, preventing noise transmission and comply with euroclass A1 to BS EN 13501-1.https://www.ribaproductselector.com/Product.aspx?ci=6375&pr=Rockwool-ROCKWOOLInsulationSlabsRWA45RW3-RW4-RW5-RW6
The Kingspan Topdek insulated membrane roof panel has an acoustic reduction under 23dB which also complies with BS 8233.
The CasoLine MF ceiling finish is a suspended ceiling system designed for most internal dry lining applications. The grid is full concealed and the ceiling lining is joint-treated or plastered to present a seamless appearance. The ceiling comprises of a lightweight metal framework formed from Gypframe ceiling sections clip-fixed to the underside of Gypframe perimeter channels. The framework is suspended from the structural soffit using strap hangers or angle sections. The ceiling boards are screw-fixed to the framework to form the ceiling lining. The system is used in line with Gyproc plasterboards. This system has a sound reduction index of 55-66dB and so is an extremely effective method of sound insulation.
Cavity partitions in the building can help contain sound in certain parameters of the office such as meeting rooms and private offices. GypWall STAGGERED stud acoustic partition system can be used to further contain noise. This is a non-loadbearing stud partition which achieves reduced sound transmission by staggering alternate studs within a single framework, which partially decouples the plasterboard linings on each side of the partition. It provides very high levels of sound insulation with minimal footprint making it efficient. https://www.british-gypsum.com/white-book-system-selector/systems-overview/partitions/gypwall-classic?tab0=2
Light
Providing Structural Support and accommodating Movement
The Northern Ireland building control regulations state that a
“building shall be designed and constructed so that the combined dead, imposed and wind loads are sustained and transmitted to the ground, taking into account the nature of the ground-
safely; and
Without impairing the safety of another building.
The building will have to carry dead loads consisting of the weight of roofs, beams, walls and otherwise permanent parts of the building. I will also have to consider Live loads in the design of the structure. These include rain, wind and snow and keep changing from time to time. Environmental loads also must be taken into account such as the minimum snow load on a roof or any other area above ground which is subject to snow accumulation and earthquake loads which constitute to both vertical and horizontal forces on the building. Foundation movement, fatigue, vibration and impact are amongst other loads which effect structures.
Types of Loads on Structures – Buildings and Other Structures