Common AC Line Mistakes

A few times a year, we will receive a phone call where occasionally an air conditioner contractor will have installed the refrigerant piping too close to the underside of a roof deck. When the roof is replaced, a nail happens to puncture the line which causes freon to leak and your air conditioner to stop blowing cool air.

Whose at fault? The roofer or the air conditioner contractor?

In order to get to the facts, we will check the International Residential codes and International Mechanical codes.

2015 International Residential Codes.

Section M1411 – Heating and Cooling Equipment

M1411.7 – Location and protection of refrigerant piping
Refrigerant piping installed within 1 1/2 inches (38 mm) of the underside of roof decks shall be protected from damage caused by nails and other fasteners.

Steel Protection Plate

Steel Protection Plate

International Mechanical Code – 2012

Chapter 11 – 1101.3 Protection
Any portion of a refrigeration system that is subject to physical damage shall be protected in an approved manner.

International Mechanical Code – 2012

Chapter 3 – 305.5 Protection Against Physical Damage
In concealed locations where piping, other than cast-iron or steel, is installed through holes or notches in studs, joists, rafters or similar members less than 1 1/2 inches (38 mm) from the nearest edge of the member, the pipe shall be protected by shield plates. Protective steel shield plates having a minimum thickness of 0.0575 inch (1.463 mm) (No. 16 gage) shall cover the area of the pipe where the member is notched or bored, and shall extend a minimum of 2 inches (51 mm) above sole plates and below top plates.

In the end, if an air conditioner contractor runs a pipe less than 1 1/2 inches from the underside of a roof deck, that AC contractor is responsible by state code for installing a steel protection plate. If the air conditioner company decides not to do this, they leave a possible trap for the roofer later when the roof is replaced. There isn’t any way for the roofing company to see this line amongst the insulation or tight spaces of attics. It is an unfortunate situation, but the builder or AC contractor did not follow proper codes or industry standards. The roofing company should not be held liable for other tradespeople’s insufficiencies.


  1. Have your existing AC company, which performs your annual maintenance, check the lines to ensure they aren’t in any damage of the possible scenario. If he/she finds a line too close to the roof deck, have them install a plate.
  2. Before replacing your roof, contact your AC company to check your lines to ensure they are clear and free from obstruction and not at risk of any punctures. See if a shield plate or plates need to be added.

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