I agree.
Soffit vents blocked by insulation are not being utilized in the manner in which they were intended by the engineer that designed the house anymore than a permanently installed extension cord.
Maintenance would be the act of continuing to ensure adequate ventilation, not creating it., IMO.
Don’t count on ventilation for solutions to roof problems. Here’s an excerpt from a venting paper in a series called About Your House from Canada’s national housing agency:
**What To Do About a Wet Attic
**"There are many signs that an attic is wet…
The usual response is to increase attic ventilation. This is the wrong approach. In some cases, adding ventilation will actually pull more moist house air up into the attic and make the problem worse. The best way to fix a wet attic is to stop air movement, or leaks, from the house. Once this is done, the existing ventilation is usually more than enough to keep the attic dry."
“If you have properly sealed the attic, you should not need more attic ventilation. Attic ventilation is overrated. In winter, the cold outside air cannot hold much humidity or carry moisture away from the attic. In summer, attic temperatures are more affected by the sun and shingle colour than by the amount of ventilation.”
Here’s the web address for the full paper:
http://www.cmhc_schl.gc.ca/en/co/maho/gemare/gemare_001.cfm
From a 2003 technical paper from the Canadian Roofing Contractors’ Association:
“Although the primary contributor to snow melting is heat loss from the building interior, solar radiation can also provide sufficient heat to melt snow on a roof. For example, at Ottawa, enough sunlight can be transmitted through 150 mm of snow cover on a clear and sunny day to cause melting at the roof surface when the outside temperature is -10°C with an attic temperature of -5°C.”
This info may be shocking to many but I have had architects who had buildings with code venting call to enquire why they had ice dams and large icicles after they did everything “right”! There is no right in venting. If the attic is showing no signs of problems with the non-code vents you find, why fix what’s not broken??
The shingle pre-mature failure argument holds much, much less water than the attic moisture problems, etc.
May be back on after dinner with more.
Good post Brian .
I see so many with a poor fitting piece of dry wall for the attic entrance or in many cases nothing .
This is a cheap fix cost about $30:00 and saves so much heat and moisture in the winter .
Kitchen and Bath fans another fix that is required so often.
I believe Europe is far ahead of us in non vented attics.
… Cookie
It depends upon degree. I recently inspected a house that had insulation on the rafters and 6 year-old shingles that looked like typical 15 year-old shingles in some spots.
While one can’t very well achieve perfection, the idea is to make the best of a situation. And as the saying goes, the proof of the pudding is in the eating (and I’ll add digestion) thereof.
The 4 main things that affect shingle life are:
Shingle quality- When I was roofing in the 1980’s, standard 3 tab shingles with 10 year warranties lasted 19-20+ years (black was replaced at 19-20 years; my present black roof is 20 yrs old and will be replaced this year or next, depending on my time constraints / some lighter colours {light gray & frost white} lasted 24-27 years) In the last 4 years, I have seen similar shingles on starter to $500,000 homes where the shingles are failing at 12-15 years (all colours). I was extremely surprised to see the lighter colours fail so early. Obviously the quality has declined with some products or the UV component of sunlight is getter much stronger.
Shingle colour- As mentioned above lighter coloured shingles last longer (if quality isn’t a problem). Lighter shingles reflect sunlight which raises the surface temperature and begins to drive off the volatile components from the asphalts and leads to drying, brittleness, granule loss and curling. As the shingle dries, more protective granules are lost. The granules protect the felts and asphalt from the UV rays which are much more aggressive at deteriorating the felts. Once they are missing, decomposition speeds up.
Orientation- North facing shingles last longer than those on the south slopes all other things being equal. In our area, the south slopes on houses with black shingles generally fail 3-6 years before the north slopes. On some houses, I have inspected there have been as many as 4 different ages of shingles on roofs as people replace slopes only as necessary.
Latitude- The farther south you go, the stronger and hotter the sun shines so it stands to reason that the same shingle will not last as long in Florida as in Maine.
ATTIC VENTING:
This has also been a misunderstood item in relation to shingle deterioration. It is generally believed by a small but growing faction of those that read the more progressive literature/periodicals that venting may have a very small role, if any, in shingle deterioration.
A) A 2002 study by Building Science Corporation in Jacksonville, FL showed that in unvented roofs, the average temp rise at the surface (the hottest part of the shingle) of black/dark gray shingles was an average of 0.2 deg F over vented roofs during August. Others have found up 7-10 deg temp rise but this is still not a truly significant rise as the difference in temps between light and dark shingles has been measured in the 20-30+ deg F range. This is why they spray roofs white to save on cooling costs.
B) Studies have shown vented cathedral ceiling air temps to be higher than unvented standard attic air temps in the same locale. The lower sections of the vented roof were cooler but the upper parts of the vented cathedrals temps were similar to unvented cathedrals. The hotter parts of the vented cathredrals should have failed according to theory.
C) If venting is the saviour of shingles then we have a major class action law suit coming forward any day- The foamed roof/conditioned attic that is becoming more popular does not allow for any significant cooling of the sheathing and shingles inward since the R values are in the R25+ range or higher applied directly to the sheathing. Going by the theory that venting cools and saves shingles, then these roofs should fail even faster since the foam is a much better and airtight insulator than is fiberglass which has been traditionally used in unvented cathredrals.
D) In the south to reduce attic heat gain and lower cooling bills, shiny foil barriers reflect radiant heat (the larger movement of heat from sheathing to the lower attic floor) right back at the sheathing which causes it to be hotter. If the theories I hear are correct, this also should lead to faster deterioration of the roofing materials. But we hear nothing negative (shingle failure) about this practice (other than it might not be cost effective as a retrofit with a 30 year payback- Florida Solar Energy Research
Center)
E) It has been reported that two roofing manufacturers have changed their warranty conditions so as to not void their warranty because of unvented roofs/attics. Ed Fako, the Chicago roofer who’s on here occasionally, verified this a couple of months ago, I believe.
There’s much more out there about this topic if you dig deep enough and don’t depend on roof/attic ventilator and shingle manufacturer’s for the information…they have too much vested interest in keeping the “street talk” going…mmmmm!!! more $$$$$ for the vent guys; less money paid out in product warranty claims for the roof guys.
I heard my name mentioned, so I decided to pop in with some additional research which backs up Brians supposition.
I still do not totally agree with the conclusions, which is based on 1st hand experience from the past 29 years of roofing.
Ed
This report is about 40 pages long I believe.
http://www.fsec.ucf.edu/en/publications/pdf/FSEC-CR-1220-00.pdf
Here is the revised and updated 67 page version.
http://www.dca.state.fl.us/FBC/publications/AtticVentReportFinal.pdf
Our State’s SOP is to point out significant issues that could affect the value of the property now or if not addressed could affect the value of the property in the future. Also, safety items can be considered defects if they can harm the occupants of the property now or in the future. That’s part of the dilemma.
So if an attic isn’t properly vented, a significant future (or current) issue could be premature roof failure. I’m sure all of us have seen southern exposed roofs that are significantly in poorer condition than other exposed surfaces. That’s at least one of my thoughts of calling inadequate ventilation a “defect”
Thanks for all of the comments. A good discussion!
Here’s another from FSEC dealing with a total energy retrofit including additional attic ventilation to reduce cooling loads.
http://www.fsec.ucf.edu/en/publications/html/fsec-cr-978-97/
Near the end is a table camparing savings. The installed attic ventilation obviously isn’t doing much to cool the attic as its payback period is 114 years!!! OUCH!!! So if it isn’t reducing attic temps much for cooling purposes, isn’t isn’t cooling attics much for shingle life either!
**Table 7 **
*Economics of Installed Measures **
Retrofit Measure Cost () Est. Savings/yr kWh () [FONT=Verdana, Arial, Helvetica, sans-serif][size=2]Payback (Years[/size][/FONT])
Radiant barrier $1084 430 ($37) 29.3
HE air conditioner $3587 3260 ($277) 12.9
Solar water heater $1649 950 (81) 20.3
Efficient pool pump 320 1210 (103) 3.1
HE refrigerator 999 2190 (186) 5.4
HE lighting 400 1340 (115) [FONT=Verdana, Arial, Helvetica, sans-serif][size=2]3.5
[/size][/FONT]Attic ventilation 410 45 ($4) 113.9
Total $8449 9375 ($800) 10.6
*includes FPL utility rebate of $484
HE = high efficiency
Here are a couple of pics taken a 2-3 years ago in my attic. The vent faces dead north. I have seen snow in attics that was 10 inches deep and have seen it blow in through metal soffits with small holes, then up through 10-12 feet of vented cathedral to end up in the main attic of a saltbox style house.
Back in the 1980’s when our company was doing energy retrofits, there was a government grant (CHIP- Canadian Home Insulation Program) available to customers. We were scrutinized every 6 months or so as to work quality and quantity of insulation and airsealing installed to ensure the gov’s money was being spent well. Each time this occurred, we were called on the amount (not meeting codes) of attic venting in our serviced homes.
At our fourth inspection, I wanted to meet with the inspector (a certified mechanical engineering technician) to discuss attic venting issues and show him some of the research I had accumulated then about moisture/air leakage and house interior ventilation versus attic ventilation. He said he had to do his work and could only meet me at the house to be inspected. I chuckled to myself as I knew that the attic hatch entry in this house was directly under a northeast facing hip roof vent. It had just snowed with fairly high winds a couple days previous. When the inspector lifted the hatch, snow fell on him…so I said to him " Oh yeah…that’s another reason, I don’t like too much attic venting!" He actually took the rest of the afternoon off to look at the research I had. It changed his way of looking at attic venting… that was about 1984-5.
Later on in March, 1990, this fellow was now the senior draftsman/minor partner in a mechanical engineering firm. The firm wanted to get into Indoor Air Quality/air balancing by creating a subsidiary company. He had heard I was selling and installing heat recovery ventilators / residential HEPA filtration systems and was working with people with allergies and environmental/chemical sensitivies. He decided to give me a call and the rest was history. By Dec/90, I was setting up and managing a company called Maritech Environmental Services.
Life’s got a lot of twists and turns in it!!
I did another inspection yesterday in which there was buckled sheathing where there was insulation right up to the sheathing.
By buckled, do you mean delaminated veneer layers (or is it chipboard)?
Could be caused by moisture or poor quality material. Is there any water staining or mould on the innermost layer of veneer?
In 1992, I saw delaminated plywood in the attic of a $500,000 (probably $1,000,000 now) home in its first winter. I was hired by the owner’s lawyer to check the attic framing and sheathing for the “moisture” that the supplier was asserting caused the failure. All attic wood was under 19% humodity. On further inspection of the plywood stamps, it was discovered that the plywood was from the deep south and made from yellow pine, if I remember correctly. It was not even supposed to be in Canada as it did not meet the requirements of the plywood standard recognized by our code.
This roof had a double failure as the trusses were also underdesigned. I had noticed some rippling in the shingles that may or may not have been caused by the plywood. A civil engineer was hired and called the trusses. In the summer ,the whole roof was replaced at a cost of $80,000!
I tried to upload some photos of several jobs we havwe done, but I can not get the hang of how to do it.
On one forum I created for my family to communicate, I only get these monstrosity sized photos which need to be scrolled up and down and also left and right.
I am not too techie on thjis stuff. Any help? I would like to share the photo views with you guys.
The plywood I wanted to show photos of was so severely buckled, from a total lack of ventilation, both intake and exhaust. There were none of either.
The insulation was not packed solidly to the top of the rafter bays. (Vaulted/cathedral style ceilings throughout)
There was no roof leakage in the home but the 12 or so year old shingle were completely delapitated and the decking all needed to be replaced. There was black mold growing on the under side of the decking when we removed it.
A lack of ventilation was the only causation of this premature degradation, IMO.
Ed
Sorry It sounds like moisture getting into attic to me ,
Ventilation can make up for some excess moisture but no moisture and ventilation not needed .
This has been the way in Europe for a while and its comming to North America.
… Cookie
If there is black MOLD. There is moisture.
No ventilation is a defect due to manuf. requirements. If home owner wants to use the warranty on materials the OEM can claim improper installation of roofing without ventilation.
Go here
anyways- my thoughts, Ed
David,
Thank you for the tutorial, but is there one on how to resize an image that the manage attachments pop up tells me is too large to be uploaded?
On another board with the same size restrictions, (ContractorTalk dot com in the roofing section), I was able to upload the exact same images I tried over here. Go over to that site to check out the images I am referring to. Even on that site, the better photos that I wanted to upload would not go through due to being too large.
Wuz Up w/dat?
Ed
Ed,
Go to: http://www.irfanview.com/ it’s free and will let you do damn near anything to photo’s 
Jeff
Ed,
There are many FREE image re-sizers on the market today.
Here’s a few to get ytou started.
http://www.faststone.org/
http://whispersolutions.com/ImageEditLite.htm
http://www.freeserifsoftware.com/software/PhotoPlus/inAction.asp
http://www.graphic-converter.net/
http://bluefive.pair.com/pixresizer.htm
http://www.irfanview.com/
No, Brian, by “buckled” I meant very noticeably warped, so there were obvious hills and valleys on the roof. Bent, put (probably) not broken, if you will. But I couldn’t see it in the attic. It obviously had expanded due to heat or moisture, and there was nothing to indicate leakage (relatively new roof with shingles that appeared good), and insulation was crammed right in from the drywall to the sheathing.