In terms of workmanship, all bed and vertical mortar joints between blocks should be fully filled and not ‘faced up’. All block to steel junctions at columns, wind posts, floor beams, horizontal channels etc should be filled. Any expansion joints should be sealed with a sealant on a backer rod.
Some 7N blocks can leak up to 140m3/hour/m2 at 50 Pascals!!
Fair face / paint grade block work usually exhibits an air leakage rate of 5–10m3/(h.m2) at 50 Pascals.
Solid ROOF LINER SHEET AS part of a built up roof system
Liner tray – the inner liner tray will form an excellent air seal if all lap joints and penetrations through the liner tray are air sealed. The inside of the liner tray should be taken as the air seal line, with all penetrations through it being directly sealed into it, preventing air leakage into the roof void. All lap joints should be air sealed using an appropriate sealant tape and any open profiles filled with closed cell foam fillers. All junctions between wall liner trays and other wall elements / cladding can be sealed using pressed metal flashing trays, EDPMs or similar to bridge gaps.
The Metal Cladding and Roofing Manufacturers Association MCRMA have a Technical Guideline Number 14 setting out design details for profile roof cladding, which is a very useful design reference document.
Curtain walling if built to a ‘good’ CWCT standard will leak at <0.5m3/(h.m2) at 50 Pascals. Curtain walling should be air sealed to the adjacent air sealed wall element with an EPDM detail or similar. Careful on site quality control is required on site to ensure the EDPM is installed and dressed correctly to adjacent air sealed elements.
Composite profiled and trapezoidal panels should be constructed to robust air sealing details as supplied by Wards, Kingspan and the like. If so, they should leak at <5m3/(h.m2) at 50 Pascals, if built to a reasonable standard.
Plasterboard / Dry Lining
To minimise the quantity of potential air leakage paths past plasterboard on external walls, the plasterboard should ideally be as complete as possible with a minimum number of penetrations through it.
The heads and bases of all plasterboard should be sealed to the floor slab, along the full perimeter length.
Careful detailing is required for all plasterboard along the external wall including junctions with internal partitions; service penetrations; dado rails; light fittings etc.
If you have any queries regarding the specification or detailing for materials/components to be used, please contact HRS for further advice.