Buildings: Is your shed up to the required ventilation standards?

Over the past few years, a greater emphasis has been placed on improving the ventilation in animal housing facilities.

A shed that possesses good airflow and no draughts will decrease the chance of an animal getting pneumonia and chills, therefore improving the performance of that animal.

Furthermore, many pneumonia-causing viruses and bacteria are airborne, and ensuring that airflow through a shed is sufficient will help to move these substances – and other waste gases – away from the animals and reduce the burden on them.

However, many sheds in Ireland over the years were not designed with this in mind. Many farmers who have sheds that are not properly ventilated are taking the necessary actions to fix these problems.  

Signs of inadequate ventilation include:

  • Ammonia smell;
  • Pneumonia outbreak;
  • Nasal discharge;
  • Animals coughing;
  • Damp bedding;
  • Condensation on the walls and the roof;
  • Open-mouthed breathing by cattle.

Recommendations

The Department of Agriculture, Food and the Marine has published a number of criteria regarding ventilation that must be met when erecting animal housing facilities.

According to the department, outlet ventilation should be provided along the full length of the roof apex: 450mm wide for a house up to 15m wide; 600mm wide for a house up to 24m wide; and 750mm wide for larger houses.

A ridge cap over the outlet is not recommended, but when provided it must stand unobstructed and fully clear of the roof by: 275mm; 350mm; or 425mm respectively, for the three widths of houses noted above.

Curved or angled upstands placed on the roof on both sides of the ridge outlet will improve airflow and prevent rain access. This is a recommended alternative to ridge capping.

Spaced sheeting is mandatory for any new roof extension or conversion work where a full ventilation outlet is not available.

Under such upstands, the roof-sheet should extend 50mm on each side to prevent rainwater dripping from the upstand.

Where spaced sheeting with a gap of at least 20mm is installed over the entire roof, then a central ridge outlet – though recommended – is not mandatory.

Mono-pitch buildings, if fitted with a front canopy, should have a minimum 275mm-wide outlet along the length of the roof, positioned near the highest point.

Image source: Department of Agriculture, Food and the Marine

Inlet ventilation should be provided directly under the eaves for the full length of each side of the house, or the lower side of a mono-pitched house.

An unobstructed depth of 450mm should be provided in houses up to 15m wide; 600mm deep in houses up to 24m wide; and 750mm deep for larger houses.

A roof overhang of 400mm is recommended when unobstructed inlet ventilation is used.

To reduce wind-speed and rain, pre-painted steel sheets with ventilation slots (vented sheeting) over their surface are recommended for inlet ventilation.

How to improve ventilation

There are many ways farmers can improve the ventilation in their sheds, without having to make major adjustments.

According to the Farm Advisory Service, improving ventilation in cattle sheds can increase productivity by 3-5% in beef cattle.

Listed below are some options available to farmers to increase airflow in their shed.

Options for improving ventilation include:

  • Yorkshire boarding: staggered wood panelling;
  • Vented sheeting or spaced sheeting;
  • Open doors and block initial 1.5m to 2m with bales;
  • Remove part of or complete solid side of sheets;
  • Knock the top block of rows from the shed wall;
  • Central ridge outlet.

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