Is inadequate roof or attic ventilation a defect?

[David A. Andersen]

"The more things change, the more things stay the same"

My hat is off to all those posts that feel ventilation is a significant deficiency.
In my past life (HVAC), V stood for ventilation. It is almost nonexistent today.

I used to recommend adding forced ventilation to most of the houses I inspected ( over 3500 ft.²). The client would agree and follow my recommendations and go down to the local supply Center, only to find that they no longer stock these items which now must be special ordered. Being a long time contractor customer of Lowe's and personally knowing the local Home Depot manager I made some calls. They just don't sell enough to keep them in stock! I have attic ventilators and whole house fans installed in every house I've ever owned. I can't even get replacement parts without special ordering them any more.

For those of you who are studying or have taken building science courses, controlling ventilation is a critical area in building design. Just because "we don't do that anymore around here", does not mean you should change your way of thinking either. Being complacent because the builder doesn't want to spend a few more dollars should not be your business practice. They quit putting weep holes in brick veneer siding around here for about five years. Now they're going overboard and your house looks like Swiss cheese! So just because they don't do it anymore, doesn't mean you don't have to do it at all. Someday it's going to come back. For those of you that are seeing high-efficiency homes such as Energy Star homes being built in your area, this lack of ventilation will be catastrophic. When new technology is used in construction, the old standards of construction must be abandoned and modified to the new technology.

The following link is a calculator written by ASHRAE standards and will help you see the effects of ventilation:
http://chuck-wright.com/calculators/stack_effect.html

If you are interested in how many BTUs is being imposed on your HVAC system due to insufficient attic insulation try this link:
http://chuck-wright.com/calculators/insulate.html

The new standard of construction in this area is to put the HVAC system in the attic to save floor space. Disregarding any ventilation increase to the attic needed to maintain HVAC system efficiency is resulting in inefficient equipment, loss of capacity, increase power consumption, and
reduced life expectancy of the equipment.

If you get tired of writing this up in your report, put it in your report template see you only have to say it once. In the event someone doesn't write, just cut it out.

I did this with auxiliary drain pan float switches on HVAC equipment located in a finish space or above a finish ceiling (the attic). Builders were outraged and called the codes Department about me because I made such a big thing about putting a six dollar switch on the HVAC unit to protect thousands of dollars of ceilings below. Well, today it's the law in this community! So don't think your words are going unheeded. When people start yelling about you, it's better than you doing the yelling!

[Roy D. Cooke, Sr]

Originally Posted by dvalley

Jimmy,

Yes, I designed that page myself. You can help yourself, but please re-configure the information a bit in order to make your web page content different from mine.

Roy,

Nice article but I like to see vented roof cavities (Ridge & Soffit) on many applications. The only unvented roof cavity I'd let roofers get away with (in my area) is the blown-in foam. One excellent foam insulation is Icynene.


And keep in mind, some roofing manufacturer's will not warranty their shingles with improper ventilation. Always check with the manufacturer's installation instructions.

Here's another nice read on attic ventilation.

http://www.airvent.com/pdf/literatur...ellingTips.pdf

I do believe the future will be no ventilation .
I think it is becoming more common in Europe to not ventilate.
I to like Icynene.
I Built a shed and closed in the rafters but first I put soffit baffles and Insulation the whole way for full ventilation.
We do need to exhaust the homes better to many do not have HRV or Bath/kitchen exhaust.
Cookie

Mentioning Shingle warantee . The Manufacture does every thing in their power to never honour a warantee

[Richard A. Hetzel]

I wish people would use generic terms instead of trade names...for example, Icynene is a trade name, not a generic term, and maybe if you're sharp you can figure out from the name that it's polyisocyanurate, if in fact that's what it is, but if generic terms are used, the rest of us don't have to running for Google to find out what the heck is being talked about. That's my rant for the month.

[Roy D. Cooke, Sr]

Originally Posted by Richard A. Hetzel

I wish people would use generic terms instead of trade names...for example, Icynene is a trade name, not a generic term, and maybe if you're sharp you can figure out from the name that it's polyisocyanurate, if in fact that's what it is, but if generic terms are used, the rest of us don't have to running for Google to find out what the heck is being talked about. That's my rant for the month.

polyisocyanurate, is a new name to me I could never spell it but I new what Icynene is and its easier for me to spell .... Cookie

[Frank L. Bartlo]

Being in Michigan, I also mention that inadequate venting increases the possibility of leakage in good roofs due to ice dams.

Yes, I've seen roofs that were noticeably bowed from buckled sheathing where the rafters were insulated. Inadequate venting is definitely a defect.

Also, in many houses I inspect that have ridge vents, the channnel is not wide enough and the venting is ineffective. Also, soffit vents are often blocked by insulation in their channels, and channels between the lower and upper attic sections of bungalows are very often blocked with insulation. I wirte up these conditions.

[James H. Bushart]

Originally Posted by pdickerson

Inadequate ventilation in the attic is a defect, not a maintenance item.

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.

[Brian A. MacNeish]

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.

[Roy D. Cooke, Sr]

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

[Frank L. Bartlo]

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.

[Brian A. MacNeish]

The 4 main things that affect shingle life are:

1) 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.

2) 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.

3) 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.

4) 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.

5) 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.

[Ed Fako]

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/publicati...CR-1220-00.pdf

Here is the revised and updated 67 page version.

http://www.dca.state.fl.us/FBC/publi...eportFinal.pdf

[Gregory A. Liebig]

Originally Posted by phinsperger

AI would not write it as a maintenance item. To me maintenance means something that has to be done regularily. Once you install the proper venting that should be it.

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!

[Brian A. MacNeish]

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/publicati...sec-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 ($) Est. Savings/yr kWh ($) Payback (Years)
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) 3.5
Attic ventilation $ 410 45 ($4) 113.9

Total $8449 9375 ($800) 10.6

*includes FPL utility rebate of $484
HE = high efficiency

[Brian A. MacNeish]

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!!

[Frank L. Bartlo]

I did another inspection yesterday in which there was buckled sheathing where there was insulation right up to the sheathing.