Worn shingles question

Yesterdays inspection…

Home had an addition built on in 2000, verification of permits and CO provided to me by seller. The addition is an extension of the garage, changing it from a single attached, to a tandem 2 car attached. The interior was drywalled/finished, and a propane ceiling mount heater was installed. Attic insulation was minimal.

The shingles on the existing home were replaced at the same time the addition was added. First pic is of addition roof, the others are of the main home. My main concern is of the addition shingles. If I didn’t know otherwise, I would say they were 20-25 years old, and maybe two layers. Any thoughts on why the shingles have a ‘dip’ in the center of all the tabs, to the extent that the edges actually cast a shadow?

Your thoughts are appreciated,

OK, all the shingles are 10 years old. They all look like they are wearing rapidly, with the garage going faster than the house. What is the orientation of these two? Garage get more exposure to the sun? You said the insulation in the garage was minimal, was there any ventilation here? Some garages get very hot when closed up all day long and the sun pounding on it all day. Looks to me like this area is just building up more heat and causing these shingles to start breaking down sooner. Just one thought on it.:smiley:

Main home and original garage roof slopes are south/north facing, addition east/west facing. Insulation was a couple of inches of loose fill, with foam board over.

1st pic main home, south facing
2nd pic addition, east side, which had the most wear
3rd pic, addition interior, heater in back rear corner


If the shingles are aging and deteriorating that quickly I would have to think there is a ventilation issue.

There is only 1 layer of shingle correct as it is an addition.

The cupping with the shadows looks like a defect due to improper ventilation.

they are all in such bad shape for their age Jeff I’d have to wonder if they weren’t defective shingles from the get go…

The possibility of defective shingles so far is my best guess. The damage to the main home shingles I am attributing to ice dams (most of that damage is at the eaves). There are also spots probably from hail damage. The addition & garage attics are open to the main home attic, which has more than sufficent ventilation. There is a small amount of edge curling on the main home, but nothing like what is on the addition.

Note: main home insulation approx 3 inches wool batt, and 2 inches Vermiculite over the batt. (yes, I am addressing the Vermiculite issue).


They look ready for a new roof Jeff.
Call out lack of ventilation too.

I agree with you Bob, ready for a new roof.

I would agree seems like a ventilation problem in attic. what type of soffit and roof vent are there?

Looks like turbines on main part of house but I don’t see anything on addition

Turbin, gable ends, and full soffitt on main home. Full soffitt on garage only, with garage attic open to main home attic.

I called for full tear-off and replacement, as well as evaluation and repair of the entire ventilation system.

Thanks to everyone!!! :D:D:D

PS… also provided links to Certainteed and suggestion to get info from seller on Brand installed, or installer information.


Good call!

Ventilation is rarely the cause of premature deterioration of shingles. Look at the class action suits against shingle manufacturers; shingle quality seems to be deteriorating…possibly due to high oil costs…asphalt being replaced with fillers??? Certainteed Shangle and Horizon brands barely lasted 10-12 years even with the light coloured granules which are known to extend shingle life due to reflection of sunlight!!

Building scientists Dr. Joe Lstiburek and Dr. Bill Rose who have studied roofing systems, venting and insulation systems rate ventilation about FIFTH on the list of causes of shingle failure/aging.

(1) shingle quality
(2) shingle colour
(3) shingle orientation (facing south, etc.)
(4) geographic location
(5) attic venting

Myth Two is that attics need to have lots of ventilation. Again, venting requirements are not based on rigorous scientific research.
TenWolde explains that attic venting originally arose as a moisture-control strategy for cold climates. Other purported benefits, such as longevity of the shingles, arose later. It is widely believed that increased attic venting will prolong the life of roofing shingles by cooling them. But research shows that venting has very little, if any, effect on shingle temperature. The most important issue in shingle temperature appears to be the color of the shingles. Light-colored shingles reflect sunlight and don’t get as hot as dark shingles.
One possible real benefit of attic venting in climates with large snowfalls is to reduce snow melt on the roof to avoid the formation of ice dams. But according to TenWolde, a more effective——and energy-efficient——way to control snow melt in almost all climates in the United States would be to use air barriers and insulation to prevent heat from entering the attic.”
**[FONT=Times New Roman] **
From the Canadian Roofing Contractors Association (CRCA) with my bold and some comments in blue (more may follow later):

"Heat build-up

The Canadian Asphalt Shingle Manufacturers Association has issued a bulletin titled “Proper Ventilation for Asphalt Shingle Covered Roofs”. In it they state that both heat and moisture build-up in attics is the primary cause of many roof problems including blistering, distortion and curling of the shingles. It has been theorized that poor ventilation of attics can cause excessive heat build-up and high deck temperatures. Since heat is the major contributor to the aging of materials, this heat build-up is said to contribute to the deterioration of many roof-covering materials. **Although a recent study **(and studies by others) by Simpson, Gumpertz & Heger Inc., demonstrated that geographical location, building orientation, and roof colour have far greater influence on roof surface temperatures than the ventilation below, inadequate ventilation is often(still)cited as the reason for roof performance problems. (people don’t seem to learn!) Material manufacturers may not honour warranties where it can be shown that there is insufficient ventilation of the space below the roof."

Bill Rose, ASHRAE, Illinois Building Research Council:
"Airtight ceilings are a more reliable way to ensure a dry attic than venting, but in practice most houses fall into a middle ground where venting balances moisture input.

Joe Lstiburek, Building Science Corporation:
“Vented attic/roof designs have the advantage of a long, proven historical track-record. However, they work best with airtight ceiling/attic interfaces and where ductwork and air handlers are not located within attic spaces. The increase in the use of complex roof shapes and cathedral ceilings has resulted in problems with vented roofs.”

Anton TenWolde & William B. Rose, members, ASHRAE:
We recommend venting of attics in cold and mixed climates. However, if there are strong reasons why effective attic vents are undesirable, unvented attics can perform well in cold and mixed climates if measures are taken to control indoor humidity, to minimize heat sources in the attic, and to minimize air leakage into the attic from below, or vice versa. The necessity and effectiveness of vents in cathedral ceilings in cold and mixed climates is still a contested issue. Unvented cathedral ceilings can perform satisfactorily in cold and mixed climates if the cavity is properly insulated, measures are taken to control indoor humidity and minimize air leakage into the roof cavity, and a vapor retarder is installed in the ceiling.

Today I finished the last 2 houses of a 21 house QC inspection contract for a low income energy retrofit project funded by both federal and provincial governments. It was originally intended to be 20 houses only but last Thursday, they threw in another house that developed attic moisture problems with water dripping down through the upper ceiling on occasions after the insulation was installed.

Small 1+1/2 story, 100+ year old house with a single older retired woman living in it
The basement sills and top 2’ of the old foundation were airsealed and insulated. Uninsulated exterior walls were blown with cellulose; outer attic floors were blown with cellulose; kneewalls were insulated with fiberglass batts; sloping ceilings and small flat attic ceiling were blown with cellulose; vented bathroom fan controlled by electronic timer installed. Work done fall 2008

-Last winter (2008-9) she had some dripping but saved immensely on fuel bills.

-Consulted local HI last summer who said there was not enough attic venting; 6 gable end vents were added (2 for each outer attic) and 2 for the small flat upper ceiling

-This past winter condensation was worse, house was colder and her fuel bills were up even though it was a much milder winter in our area!!!

What happened??

The basement housing the forced air oil furnace is very damp and acting as a huge humidifier, especially since its warmer down there due to the airsealing + insulation. Water from the damp floor (a high water table also) is evaporating at a faster rate due to the warmer ambient air. This warm MOIST air is then rising up through the house due to stack effect or wind pressure + some is being sucked into loose areas of return ducts to be delivered upstairs through heating registers.

The upper areas of the house including 3 access hatches cut to gain entry to the outer attics for insulation work were not airsealed!!! This allowed moist air into the now colder outer and upper attics where it condensed during the first winter.

Last summer when they cut into the upper gable ends to install the 6 vents to solve the former winter’s moisture problems, they actually made the upper part of the house looser, allowing more air to flow into the now colder attics this past winter with even more moisture!!! (my analogy is from boats…you have a bit of water in the bilge from minor leaks so you drill a hole in the boat bottom to let the water out!!!)

This is the fourth or fifth house I have consulted on in my career where adding venting in the attics increased the moisture problem!! I had read about this phenomenon in a 1975 book (Conservation of Energy in Housing) from our national housing agency, Canada Mortgage and Housing Corporation (CMHC). Saw my first case, in 1982-3.

BTW, our national housing agency, CMHC, is a co-sponsor of the big residential energy auditing, retrofit and conservation conference being held in Austin,TX in April, I believe…Nick posted it yesterday. Wonder how that happened??..Oh, right we have loads of $$$$$$$$ up here!!!

The clawing visible in the first picture (addition roof) is typical of organic shingles losing volatiles and becoming more absorbent. The distortion is due to differential rates of moisture absorbtion and drying/shrinking over different parts of each tab, but relatively uniform across the slope.

10 years indicates premature failure and a common cause for accelerated volatile loss would be exccessive exposure to heat, typically caused by poor roof structure ventilation but maybe made worse by the propane heater.

Main home roof seems to be deteriorating quickly too, although the pattern of distortion indicates that it’s detriorating more slowly than the addition roof. The areas of delamination along the lower edges of the tabs indicate a weakness in the asphalt design mix. The surface layer of asphalt is separating from the less viscous layer that saturates the mat. The distortion is stressing the plane along which the two layers are bonded resulting in failure at the weaker spots.

It looks like a combination of poor asphalt quality and poor roof structure ventilation to me.

Thanks guys!

I appreciate everyones info and opinions!!!


CBC TV Had a program on Market place it a bad manfacture ,.see it here



Client just called. He sounded a bit ‘stressed’, and frustrated. He “needed” me to go back to the house on Monday, and show the homeowner, contractor (roofer), roofer’s inspector, and homeowner’s insurance rep. where some things (defects) are.

He told me the seller had the roofing contractor with his “inspector” out there yesterday. Other than a few ‘broken off’ corners, they could not find anything wrong. (I almost burst out laughing at this point, but contained myself to a soft chuckle).

Also, I called out a missing coverplate and lack of an anti-tip bracket behind the range. They could not find that either. (Now I did burst out laughing). My client laughed also, as I had shown these issues to him personally.

I told him no problem, I would be more than happy to “educate” the others I would be meeting with. And, I would do it at no charge. (Home is literally 1 mile away, and he is a repeat client). This will also give me the oppourtunity to meet the homeowner, as he is looking for a new home. He had a stack of home listings on the desk, with a bunch of realtors cards (not local) from approx 60 miles away (still my service area). Me’thinks he will be needing a good home inspector!!!

This should be good for a few laughs. Will update Monday evening.

Edit: Added pic of missing coverplate behind range…

I’d hate to see what these guys call a failing roof in your area.