Air Sealing
Air tightness plays a crucial role in the energy efficiency of buildings by reducing carbon emissions, protecting the building fabric and improving occupier comfort. Of increasing importance is its role in reducing energy costs. This is why air tightness forms part of both the European Energy Performance of Buildings Directive (EPBD) and the Kyoto Agreement, both of which reflect the Government's commitment to reducing carbon emissions.
From pre-test air sealing to remedial air sealing, Stroma, with its extensive range of services, is unique in providing a one-stop-shop service. Since we offer packages which combine fire stopping, acoustic barrier and air sealing, we can reduce the number of sub-contractors required. Stroma can also advise on the best method of achieving improved air tightness if involved at the design stage.
Ultimately, Stroma Contracting, through collaboration with the Stroma testing and consultancy operation, can provide a pragmatic, cost effective and comprehensive package of services to meet the specific needs of all construction projects.
Room Integrity Testing and Installations
Enclosures protected by gaseous fire suppression systems should be tested for air-tightness upon commissioning of the system and annually thereafter. This is critical to ensure that the system will work effectively when activated. Too much air-leakage will result in the concentration of the fire suppressant agent falling too quickly.
In the event of a failed test result, we will locate and record the air leakage using smoke-puffers if permitted. We subsequently provide full reports, incorporating all necessary data, test information and certification, usually within a few days of the test. The report will include the leakage diagnosis information if applicable.
To compliment the room integrity testing service, Stroma also specialise in the supply and installation of gaseous extract systems along with fire, smoke and pressure relief dampers, to work in conjunction with the primary gaseous fire suppression system.
Air Barrier Design & Build
Airtight buildings have an effective ‘air barrier’. The air barrier is a collection of air-impermeable surfaces within the building fabric that are joined to form a single, continuous unbroken layer, or shell, around the ‘conditioned space’ within the building.
The basic principles governing a successful air barrier are that: -
- It should be positioned on the warm side of the insulation layer to prevent interstitial condensation
- It should be continuous, such that any penetrations through it or gaps in it are sealed
- It should comprise air-impermeable surfaces
- It should be build-able, and accessible for remedial work.
- It should be robust, i.e. it should maintain its effectiveness over the design life of the building.
Dwellings
Seal all services where they penetrate the walls, ceilings & floors: i.e. waste pipes, water pipes, soil stacks, boiler flues etc.
Windows & doors need sealing into the reveal and to have effective gaskets & trickle vents. Seal the windowsills.
Leakage into ceiling/floor voids needs to be addressed by ensuring the void is sealed internally or that the ceilings/floors enclosing them are sealed.
Skirtings should be sealed at edges
Top floor ceilings and ceiling hatches need to be airtight.
Penetrations for recessed lighting and electrical sockets need to be sealed.
External doors need weather strips & thresholds.
Hotels, Care Homes, Accommodation Blocks
Usually having cold ventilated roof spaces, these buildings must have a totally sealed solid top-floor ceiling.
To prevent leakage into voids above solid ceilings, ensure all walls separating them from suspended ceiling voids are air-sealed. The corridor walls are the main example.
Walls/floors separating plant rooms from the interior need to be sealed on the warm side, including around passing services and ductwork.
Ensure bathroom/kitchen services are sealed where they pass through the enclosure.
Check voids above suspended ceilings in stairwells are sealed.
Plus, any relevant details left and below.
Factories & Warehouses
Eaves, ridges, valleys need to be air sealed.
Seal around all structural steelwork penetrations of cladding (from inside).
Cladding/roof panels need to be correctly sealed.
Cap off and seal the tops of any low-level masonry cavity walls, and around columns.
Ensure ventilated plantrooms are sealed from the interior.
Check air-tightness performance of proprietary items, e.g. smoke vents, dock levellers, cargo doors, lift doors, revolving/sliding doors.
Acoustic roof liners – ensure vapour barrier in the roof system is correctly sealed at edges.
Plus, any relevant details above and right.
Other Public & Commercial Buildings
Seal dry lining at all edges, and ideally take to full structural height and seal to slab/liner.
Seal any gaps in ‘air-barrier’ found above suspended ceilings or below raised floors.
Seal tops of column casings and the like.
Seal interior from ‘external’ areas, plant rooms, risers, lift shafts, unsealed voids, etc.
Ensure air sealing applied to interfaces between ‘packages’ roof, curtain wall, masonry wall, cladding, etc.
Ensure that passive fire protection materials are also air-impermeable where they need to be.
Seal hollows in ends of concrete floor planks.
Seal gaps in beams supporting cavity walls.
Plus any relevant details above and left.
Finally, the air-permeability of both materials and assemblies must be considered, and if necessary, discussed with their Suppliers.
For example, fibrous fire-stopping batts, mineral wool, and course blockwork are not suitable air-barrier materials. Likewise, there can be a wide variation in the performance of lift doors, loading bay doors, trickle vents, sliding doors, and so on, with regard to their resistance to air movement.
This at-a-glance list for air-sealing different types of building provides some guidance for contractors and designers. It is by no means intended to be exhaustive.
Related Services
Stroma offer a ‘design review service’ in which we appraise drawing details with regard to the likely sound insulation performance, and highlight areas that should be considered for revisions, prior to the commencement of construction.
At various stages during the construction programme, we advocate carrying out ‘confidence testing’ as a means to ‘steer’ the works towards a first-time complaint result. This can help prevent the cost of remedial works and further testing. Where remedial work is required, we can offer advice on how this should be undertaken.
We can devise and deliver a complete package of services to meet your requirements efficiently and cost-effectively. For lead times and fee structures, please contact Stroma directly on 0845 621 1111 or email contracting@stroma.com and we will be happy to propose an approach for meeting your requirements.