Wood Roofing: Separating Cosmetic Damage From Performance-Reducing Damage

Article originally published by Property Loss Research Bureau (PLRB). Reproduced by permission from PLRB

Wood shingles and shakes comprise a small, but significant, portion of the steep-sloped roofing market. These wood roofing products seem to show up in more and more hail claims. The big question lies in what is performance-reducing damage and what is simply cosmetic damage? There is a lot of mystery behind the actual


Properties of Wood Roofing:

In general, wood roofing is very fragile as it ages due to normal seasonal weather and exposure to ultraviolet (UV) radiation. Some types of wood roofing materials are more fragile than others. Longevity and physical properties of wood roofs vary between species of wood and even within a species depending on the age of the lumber when it was harvested. Foot fall splits and broken ridge shingles are very common deficiencies found on wood roofing. It can be very difficult to differentiate between hail impact damage and foot fall splits.

This writing breaks storm damage into (2) categories:

1. Cosmetic damage comes in the form of dents in lighter gauge metal and spatter marks on the roof shingles/shakes. Although these two conditions would not be considered performance-reducing damage, the observation of this “collateral damage” indicates the roof has experienced a hail event which could have damaged the roof. This typically does not call for the replacement of the items unless the damage is to the extent that it becomes performance reducing.

2. Performance-reducing damage comes in the form of a hail strike which is directly over a fresh split or adjacent to a fresh split where the hail struck an unsupported section of the shingle/shakes. If the shake is new and still retains much of its original thickness, it would typically take hail over 2-inches in size to cause a split. Badly weathered shakes can split and crack with 0.75-inch hail. This situation may call for the replacement of the roof cover.

Inspection/Evaluation Tips.

Before determining the extent of the storm damage, observe the condition of the roof beyond any storm damage including quality of shingle, age, installation defects, etc. Wood roofs drain in a different way than do asphalt shingle roofs. While rain on an asphalt shingle roof flows off as a sheet of water, on a wood roof (particularly shakes) the water finds the path of least resistance causing some of the shakes to be exposed to more water than others. This causes premature erosion to a wood product in certain areas which can sometimes give the appearance of hail damage. Although this natural weathering is not related to a single storm event, it can make a roof more susceptible to damage by hail or wind, and could cause damage which can be misinterpreted as storm damage. Examples of this are presented below.

Identifying Damage Types:

Spatter/Splatter marks – Spatter marks are areas where the natural oxidation and dirt, which have accumulated over time, is removed by the cleaning effect of the hail impact. Spatter marks are seen by owners on fences and other surfaces which are subject to oxidation. These spatter mark observations typically make owners believe their roof was damaged during the hail event. Spatter marks are cosmetic in nature and are not performance-reducing damage. Splatter marks typically do not require roof replacement. They usually disappear in one to two years. They do not affect the water shedding ability of the roof, nor do they affect its remaining service life.

Spatter marks on wood fencing-cosmetic damage | Spatter marks on wood roofing-cosmetic damage



Spatter marks on wood roofing-cosmetic damage.

Foot fall splits can be very difficult to differentiate from hail impact splits. “Foot fall splits” are splits in the shingle or shakes that are caused by people walking on the roof. This could be the owner, contractor, or an insurance adjuster. As part of the evaluation, one must rule out splitting, which occurred naturally during the aging of the shingle/shakes. Natural splitting will be apparent by the aged look of the wood within the split. Fresh splits are recently caused and can be determined by the lack of weathering within the split and the ability to push the split together so the split seems to disappear. Following the determination of which splits are fresh, the splits which have a direct impact mark on the split line are considered performance-reducing damage caused by hail. See photos below:

Note: Impact mark directly over split. Split appears fresh with unweathered wood within the split


Some of the shakes may have a fresh split but no impact is observable on the split. There may be an impact mark which occurred over an unsupported area of the shingle causing the shingle to flex and then split. Check each shingle carefully. The reason these splits are considered performance-reducing damage is because the shingle may have a portion of itself that is no longer secured by nails therefore it could come loose and expose the underlying layers of the roof. Other clues to foot fall splits, such as footprints or other mechanical damage are also sometimes visible.


Impact on unsupported shake caused fresh split. This is performance damage.


A puncture is a hailstone impact that punctures through a shake or shingle. This takes a very large hailstone on a deteriorated roof surface. The puncture exposes the underlying layers, sometimes puncturing through several layers, reducing the remaining service life of the roof, therefore could require replacement of the roof cover.

Erosion can easily be mistaken for punctures.


Erosion of shingles may appear to be hail punctures.

Shingles are now more susceptible to hail and wind damage as well as foot traffic damage.


This shingle has completely eroded away over time

Note the weathered edge tapering to nothing. A broken edge would more likely indicate wind or foot fall damage.


Roofing contractors commonly attribute curled shingles to a wind event. Curled shingles are directly related to the type of cut which the shingle was made from or improper placement of the nails. During installation the roof installer must remove shingles or shakes that were cut as “flat grain”. Flat grain is usually identifiable when the annual growth visible ring runs roughly parallel to the face of the board and appears to curve which causes the shingle/shake to shrink and cup across the width. A “vertical grain” shake or shingle tends to stay flat during its life. Lumber with this characteristic would be called “quarter-sawn”. Improper placement of nails has also been said to lead to curling or possibly allow it to happen sooner than it should. The warping and curling of wood by nature is a long term process and is not the result of a single event involving wind or hail. Shingles may need to be replaced, but may not be covered by many insurance policies.

Rotting Wood:

The deterioration of the lower end of a wood shingle or shake is very common and sometimes referred to as “butt rot”. The end grain absorbs water at a faster rate than the rest of the shake/shingle and the longer it is wet the faster it deteriorates. Organic matter like leaves and moss can expedite this process.


Moss will eventually lead to deteriorated wood.

Once the ends of the shingles/shakes begin to deteriorate, they are more susceptible to damage from natural or man-caused means. Hail that has directly impacted the deteriorated area may cause the wood to split and break. Pie has used the criteria “A hailstone impact that results in a chipped or broken leading edge of the shake with the remaining cross section less than 25-percent of the original cross section.” is considered by Pie performance- reducing damage and required replacement. This is our criteria based on remaining service life as well as effective performance. Damage to the deteriorated butt ends of shingles is not addressed in the Cedar Shake and Shingle Bureau (CSSB) in their publication “A claims Adjusters Guide to Handling Hail Related Claims” but in the appraisal process, it is ultimately up to the Umpire to determine if the shakes/shingles are damaged.

Improper Repairs:

Improperly repairing wood shakes can lead to the repairs not lasting as long as the adjacent roofing. Ridge shingles are commonly affected by improperly placed nails and should be evaluated closely before determining the extent of storm-related damage.


Splits caused by natural weathering and improper nailing on an aged shingle.

At the time of this writing, Pie could find no court cases that indicate a jury decision on the topic of damage to wood shakes and shingles but this may vary regionally. In an appraisal, it is up to the appraisers and the umpire to decide what would constitute damage to the wood shake roof covering. When conducting an evaluation, one must ask the following: What constitutes performance-reducing damage? With wood shake roof coverings, a loss of remaining service life or functionality is considered performance-reducing damage thus necessitating replacement. The appraiser or umpire must also ask what will lead to the ultimate failure of the roof system and how has this ultimate failure been affected by the reported storm damage. From the discussion above, it is evident that differentiating between normal aging of a wood shake roof and performance-reducing damage is a complex issue that must be properly evaluated by individuals experienced with wood roofing products.


1) What are the possible causes for the curled shingles in this photo? Choose all that apply.


A. Wind uplift

B. Poor shingle selection during roof installation

C. Improper fastener placement

D. Kids

Answer= B and C

B – Proper selection of shingles when the roof is being installed is important.

C – Improper fastening can lead to curled shingles/shakes if the fasteners are located incorrectly on the shingle/shake.

Is this photo hail damage?


A. Yes

B. No

B – Foot fall damage. Shingle was more susceptible as it was 23 years old and the end grain was beginning to deteriorate.

Click here to read the entire article from PLRB regarding Roof Damage