Air Testing Derbyshire.
Air Testing Derbyshire.
We have been in Derbyshire this week testing a sample of apartments in Derby city centre. We have tested quite a lot of apartments over the past two or three weeks in various locations around the north of England.
Its probably worth discussing the common issues associated with air tightness in apartment blocks. Depending on which floor they are located it can make a dramatic difference to the success of an air test.
Why is this?
Lets take the example of a three story apartment block built on a solid concrete slab and first and second floor concrete flooring. The ground and first floor apartments are essentially sandwiched between concrete, so the only potential for air leakage is through the walls or if the concrete has been penetrates to accommodate any services which is unlikely. As long as the developer ensures that the walls are not penetrated then these apartments tend to perform very well with their air test.
So lets take a look at the top floor apartment. It has the concrete floor but more often than not it has a traditional lofted space above a plasterboard ceiling. We find that top floor apartments nearly always perform poorly compared to lower floor apartments.
Why is this? Most air leakage comes from the cavity behind the plasterboard where it has been penetrated and not sealed or where it falls short of the floor. So on the lower floors the concrete floor and ceiling prevent much of the cold air getting behind the plasterboard and as long as any penetrations through the walls have been sealed, there is little opportunity for cold air to enter this space. The top floor apartment, however, also has the cold roof space above it and therefore is almost entirely (except for the floor) surrounded by cold air. The cavity behind the plasterboard is essentially open at the top where it meets the roof space. Additionally there will almost certainly be a loft hatch, spot lights and ventilation system penetrating the ceiling.
It is amazing how many developers do not realise the potential weakness of top floor apartments. We have tested apartment blocks where the lower floors have been consistently getting scores below three and then tested the top floor apartments and they have struggled to get below six.
So what can you do about it?
Its really simple. Make sure you treat each room as an air tight plasterboard box and if there is a penetration in the plasterboard make sure it is sealed up. Seal the bottom of the plasterboard, especially behind kitchen units and baths. Make sure you fit a quality loft hatch and make sure the surrounding architrave is sealed as per the tops of skirting. If you have a heat recovery ventilation system installed make sure the ducting is sealed where it penetrates into the roof space (this is one of the biggest areas of air permeability. If it is a relatively small apartment try to avoid using spot lights set into the ceiling or if you do, use bathroom rated ones with the glass vapour cover as these tend to leak less.
Tips from : Air Testing Derbyshire.
Involve us at planning stage and we can advise on both air tightness and ventilation.
beware of top floor apartments as they often perform poorly, take extra care with the sealing up.
Maintain attention to detail and seal any penetration in the plasterboard.
Check out our top tips page and down load our air test check list.
Article Air Testing Derbyshire by Phil Ramshaw (Director)
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