Is inadequate roof or attic ventilation a defect?

I’ve been running across many homes during the past several weeks that have ventilation issues. I use the 1 sq foot of free venting for every 300 sq feet of attic space. Usually the vents should be split 1/2 on the high side and 1/2 on the low side.

I was asked why inadequate venting is a “defect” and my response is

  1. Inadequate ventilation can significantly reduce the life of the roof due to the excessive heat
  2. Inadequate ventilation can lead to moisture build-up in the attic which can reduce the effectiveness of the insulation and/or lead to possible mold/mildew issues
    Also, whenever I see a bathroom fan of kitchen fan directly into the attic, I call it out as a significant problem

I’m looking for some feedback on this issue. Is it a defect the seller should take care of or is it a maintenance item the home buyer needs to deal with?

correct on 1&2 & vent fan as for me I would just write it up in the report & leave it to the buyer & seller

I guess I was a little unclear on how I would write it up. If I classify it as a “maintenance” item, the seller doesn’t have to do anything. If I classify it as a “defect”, then the buyer can ask for something to be done about it. That’s the way it works in Wisconsin.

For a typical sloped roof attic you are correct. I would call it out as you would.

I know when you see the same thing many times you may start to second guess yourself.

One of the things I see in my area is a lot of century homes where there is no sofit (or low side) venting. Originally the houses would have had shakes on 1" roof deck boards. There was enough spaces through the boards and the shakes to allow ventilation. Now they have ashphalt shingles and often with an added layer of OSB. Sure the have static or ridge vents but noe means of providing intake air.

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.

I would note the type of ventilation and recommend aditional venting if it needed it…that’s all.

The idea of grease being vented into an attic bothers me.

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

So in Wisconsin, if your house was built correctly, and then you did absolutely no maintenance for 20 years, you would not be obliged to address any of the maintenance items identified on an inspection report? It seems silly that the state should get in the middle of the negotiation between the buyer and the seller.

Are you required by your state SOP to seperate defect and maintenance? We are not, and I don’t, I just note all found items and bring major items to the summary , all noted items are up for negotiation.:smiley:

Attic ventilation requirements and good practice changed over the years, so that an attic that once represented the state of the art could be thought of as deficient by modern standards. If I were an inspector, I think I would write it up in something like that way, saying that it once might have been normal practice but that standards have changed, and thought might be given to upgrading to current standards. It’s certainly worth noting, but my own humble opinion is that it shouldn’t be noted in such a way as to force any party to take action.

Good point, Richard. It’s building science, it’s looking at the home as a system and Greg, the people who want you to make the decision on who pays don’t always get what they want. It appears that the laws of physics and the laws of Wisconsin may be in conflict here.

Our job as home inspectors is to describe the conditions as best we can. It may be handy for those who stand to benefit to have a title slapped on a certain condition, but conditions don’t always lend themselves to handy legal descriptions. What are your options?

I’m finding roof ventilation issues every day. Roofers are slapping on shingles in one day and not even bothering with vent installations whatsoever. Or they’ll even install the ridge vent, but not even bother with the lower soffit/drip edge vent. I guess they consider this to be a Carpenter’s job. I’ve even found many ridge vents that were installed at the ridgeline, but the plywood under this fake vent was not even cut back. These roofers are absolutely hilarious…

I see this defect so much, I had to design a web page for proper attic ventilation, in order to make it easier for my client’s to comprehend proper attic ventilation. I simply note the defect, and add the link to their report.

David: Is the article on attic ventilation your own? Can I get your permission to tweak it and put it on my website?

Read this one

… Cookie


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.


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.

“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:

[size=2]If you are interested in how many BTUs is being imposed on your HVAC system due to insufficient attic insulation try this link:

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! :slight_smile:

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.

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

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

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.