Residential Code Requirements for Roof Repairs and Replacement

First Published in Minnesota Claims July – August 2009

300px-Failure_of_asphalt_shingles_allowing_roof_leakageWhen evaluating a roof system for storm related damages, the issue of repair versus replacement inevitably arises if storm related damage is determined to be present.  In addition to the quantity of damage and feasibility of repairs, the building codes should be analyzed and consulted prior to making a final determination.  Building code requirements for roof repairs or replacement can be misinterpreted by those seeking greater compensation for storm related damages.  It is important to be familiar with Minnesota State Residential Code requirements for roof repairs and replacement, and the common misinterpretations of these requirements.

The 2007 Minnesota State Building Code (MSBC) adopts the 2006 International Residential Code (IRC) with amendments in Chapter 1309 of the Minnesota Administrative Rules without any significant amendments to the re-roofing section of the IRC.

The IRC Section R907 Reroofing includes requirements for re-covering versus replacement in R907.3.  Specifically, R907.3 states the following:

“New roof coverings shall not be installed without first removing existing roof coverings where any of the following conditions occur:

  1. Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.
  2. Where the existing roof covering is wood shake, slate, clay, cement or asbestos-cement tile.
  3. Where the existing roof has two or more applications of any type of roof covering.
  4. For asphalt shingles, when the building is located in an area subject to moderate or severe hail exposure according to Figure 903.5.

(Three exceptions to these conditions are provided, dealing with structural metal roof systems and spray polyurethane foam roofs, which are generally straightforward and not typically questioned.)

The first aspect of the residential code requirement that is often misinterpreted is the definition of “new roof coverings.”  The intent of the code is not to classify individual shingles, shakes, tiles, etc. as new roof coverings, but rather the complete installation of those materials over the entire roof.  For example, replacing a select, damaged shingle with a new shingle does not classify as a new roof covering.  Therefore, what is reasonably considered “repairs” to the roof surface does not fall under the requirements of Section 907.3 of the IRC.  The building code defines repairs, recover, and replacement differently (2006 IBC).

Note that in prior versions of the residential code, there was a 25% quantity threshold for repairs to be brought up to the current code requirements.  This threshold was the subject of abuse as some would believe that if 26% of the roof required repair, the entire roof needed replacement.  However, the 25% requirement only pertained to the repair area, not the entire roof.  For example, if less than 25% of the roof required repairs, it was not necessary that the repair area was in accordance with the current code requirements.  Likewise, if the repair area exceeded 25%, then only the repair area was required to meet code requirements, not the entire roof; the existing (un-repaired) roof could remain in place.  Some jurisdictions may not have adopted the current versions of the IRC so be aware of this previous requirement.

Condition #4 stated above is also subject to misinterpretation because the majority of the state of Minnesota is deemed to be located in a moderate to severe hail exposure according to Figure 903.5.  The intent of condition #4 is to limit future damage to asphalt shingles if they are applied over a non-rigid substrate such as existing shingles.  Shingle application over a non-rigid substrate would cause the new asphalt shingles to be more susceptible to future storm damage.  The intent of this section is NOT, however, to require full roof replacement simply because the building is located in a moderate to sever hail exposure area.

A clearer understanding of the MSBC residential requirements for roof repairs and its common misinterpretations, whether deliberate or accidental, will enable you to better handle those who misinterpret the code for their personal benefit.


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