Let It Breathe Roof Advice


Indoor humidity may put your health at risk



Thermal comfort is suffering as modern dwellings become increasingly more insulated and airtight. It is therefore extremely important to consider the indoor climate in your house. To achieve thermal comfort, all rooms in a house need to be ventilated properly - this can be done with natural ventilation.
The thermal comfort in a building is primarily affected by the activities of the people and pets living there. It is also influenced by pollution, humidity of the building fabric and gases such as radon, which in some areas can seep up from the ground.
Insufficient ventilation resulting in high relative humidity will provide ideal conditions for mould fungus, house dust mites and other micro-organisms. Together with the moisture-laden air, fungus spores and the secretion from house dust mites can be highly allergenic and contribute to respiratory disorders such as asthma and allergies.
Air leakage v's ventilation
Put simply, ‘airtightness’ is the control of air leakage. To get the greatest benefit from higher levels of insulation, it is important that we limit the amount of warm air escaping from the living areas of our buildings. Too much air leakage will reduce the efficiency of the insulation and can, in extreme cases, actually cause rot or mould damage to the building structure if condensation is allowed to form. 
So it is important to have a controlled air exchange through efficient ventilation to achieve a comfortable and healthy environment. This way, heat loss can be kept to a minimum whilst at the same time ensuring that condensation is eliminated, particularly from kitchens, bathrooms and laundry rooms where most water vapour is produced.
Improved Thermal Comfort with Natural Ventilation
Ventilation can obviously be achieved by opening the window for a short moment, but a far better solution is to create continuous and controlled natural ventilation with air inlets placed above radiators in inhabited rooms and outlet through vents on the roof. This activates the stack effect in the pipes, and by placing the vents close to the ridge the pressure of the wind adds to the natural ventilation system.  The result is an even and constant air exchange in all weathers.
How is the Climate in Your House?
Take a look at the ventilation conditions in your house and get expert advice on what can be done to achieve a reliable natural ventilation solution to improve thermal comfort and keep house dust mites to a minimum.
How to ventilate your roof
In addition to the adverse effects in the internal climate of your home, insufficient or non-existent roof ventilation will dramatically shorten the life of your roof. It will also void your roof tile guarantee as all roof tile manufacturers have specific guidelines on the amount of ventilation needed in the roof.
steam-house.jpgVentilation is a key consideration for almost all roofs to avoid condensation and it needs to comply with a range of regulations in the British Standard Code of Practice for Control of Condensation in Buildings. The methods for avoiding condensation in your roof vary according to the type of roof on your home.
The current legislation provides regulations for each of the two types of roof (cold roofs and warm roofs) and for the type of underlay used in the roof construction (vapour permeable underlays and impermeable underlays).
A cold roof is one in which the insulation has been laid flat over the top of the horizontal ceiling, and a warm roof is one in which the insulation is laid between and/or above the sloping rafters of the roof itself. Permeable and impermeable underlays are exactly that, either capable of allowing vapour to pass through the underlay or not. It should be clear when purchasing the underlay whether a product is permeable or impermeable.
The roof space is the area above the ceiling insulation and below the roof covering. Ventilation of this space is normally achieved through gaps at the eaves (low level) and at the ridge (high level). 
Ventilation at the eaves is usually in the form of a continuous ventilator strip in the soffit or fascia, or tile vents spaced at suitable intervals. Sometimes ventilation will be provided at eaves only, in which case it relies on the wind to force fresh air in through one side of the building and out through the opposite side. Unfortunately, air passing from eaves to eaves tends to flow directly over the insulation and can be blocked by the items people store in their lofts.
A far more efficient method is to install ridge ventilation also.  This can be in the form of a continuous ventilated dry fix system, or ridge or tile vents spaced at suitable intervals.  Air passing over the ridge will then pull in air at the eaves, allowing fresh air to circulate throughout the roof space.
Ventilation is achieved through gaps at the base and, sometimes, at the top of a roof structure that allow airflow through the void between a ceiling and the roof itself.
Jargon Buster

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