Low Slope roof ventilation changed and now there's trouble

A few years ago I had my roof resingled and the roofer suggested installing a ridge vent on my home. I’ve since learned the product is not recommended for my roof pitch.

Of more concern is the roof was not intended for ventilation. Now there is obvious signs of mould showing on the cathedral ceiling. How should this be remedied?

Please help?!?!?!?

Is your roof less than 4/12 pitch?

if the measure is the same at the cathedral ceiling line as the roof pitch - I think it is - then it is a 4/12.

What type of ridge vent did he use? Is the moisture form outside or inside?

Remember…ALL homes have mold.

The product used is Roll Vent by Benjamin Obdyke in Warminster, PA.
My roof has a lower deck and an upper deck (standard sidesplit configuation). Let’s look at each part separately.

The lower deck forms the cathedral ceiling supported by a centre I-Beam. There are no soffit vents on the lower deck. Or just a couple of little heat register vents (2 at the front and two at the back).

The upper deck has attic space and soffit vents. The ridge vent on this roof is 20’ and the ridge is give or take 30’ long. There is mould/mildew showing on the sheaving inside the attic.

Sounds to me like there is a bathroom vent venting into the attic space. Or some kind of moisture venting into the attic. Find the source of the moisture and vent it outside the attic space.

It isn’t very often that a normal house can produce enough moisture in an attic to produce mold and mildew without the help of a moisture vapor source.

To vent it properly, there are many factors that have to be addressed. But for now, the best thing you could do in the cathedral area is install a continuous soffit vent to be able to get air flowing in every bay of the ceiling, if infact it is a true cathedral ceiling. AND find the source of the moisture!!!

Hi, thanks for the great into…

The bathroom vent is directly outside through the roof. The pipe went directly up through the roof. This issue seems to be that the pipe was not insulated and the vent was dry mounted. As I’ve been told, this is not appropriate for the Canadian climate and this low pitch roof. I’d like someone else’s opinion if possible.

IMHO, it is a true cathedral ceiling: by that I mean this…

the ceiling line follows the roof line. the outside roof sheeting is nailed to the top of the 2X6 roof strut (insert correct name if strut is not correct) and the gypsum is nailed to the inside of the same 2x6. There is an I-beam support running the length of the room. I calculated the slope to be 4/12. Inbetween the struts - so sandwiched inbetween each span is pink insulation and originally, it was not vented at the soffit or the peak.

The moisture came from the ridge vent and the the mould / mildew is evident at the highest point in the ceiling.

since my last posting, I have instructed the roofers to remove the ridgevent. It is now resealed to its original form.

What I still wonder about is the mould / mildew problem. Will it continue to grow now that the roof is sealed?

As for the upper deck roof, it now has 3 vents and new soffit vents. Well, sort of soffit vents. The contract cut holes in the wooden soffit with a jigsaw at intervals around the roof. These holes were recovered by the vented aluminium soffits. I’m not sure this is a good thing because the holes seem large enough to allow bug to enter the attic.

Again, if someone has another solution or can see obvious pitfalls with this solution, I certainly would appreciate your help. As a single woman fighting the roofing company, I feel a little helpless.

If you have moisture in your attic area, the vent will more
than likely reduce the moisture.

Heat rises. If the attic has poor ventilation, the moisture
gets trapped and it becomes like a rainforest in your attic.

Every year I tell people to take the bags of their vents
because it can actually create serious problems regarding

Every house will create heat. As the heat begins to rise,
depending on the humidity, your attic will trap the heat
and create moisture.

I know it may seem odd to have a vent or a hole in
your roof, but in most cases, proper ventilation will
prevent any moisture.

Granted, I don’t know what kind of job your roofers did
but I just thought I would add my two-cents.

It is not good to remove the ventilation. If the moisture was coming from the vent, then your roofer needs to repair the roof. I would NOT close off the attic vent. THis will counter-productitve in your plight.

If the ridge vent was not leaking, your moisture is most likely coming from INSIDE the house.

All homes have mold, and your attic already has bugs living in it.

For some time now people just think they know what is going on. Blocking the vents, well kiss the warranty goodbye and most of your ceiling. Is there any intake vents for this Ridge vent. If not there is the problem. 2 cathedral ceilings must have baffles installed with ridge vent to work due to insulation blockage. 3rd do you have new windows in your home? 4. what type of insulation do you have R-value? Its funny how nobody reads the little instructions on the package and in the package. Ah well thats what keeps me busy i guess. Go to www.airvent.com it will explain the whole thing in more depth. Good luck

Is your cathedral like this?


ok, here we go.
First- You say your roof is not meant to have ventilation…wrong, all roofs half to have ventilation, homes must breath or you will get condensation, mold and rot.
Second- You say the Benjamin Obdyke roll vent is not made for your roof…wrong, it is made for any pitched roof that can except shingles and is an excellent product for ventilation.
Third- You say you have 2"x6" rafters for your ceiling, being that the house has been reroofed, I am assuming the house to be 20 years old or so, thus you are probably correct in the type of framing, I doubt it has cathedral trusses like Aaron had asked about, they are probably more like this.
Scroll down to cathedral ceiling. Sorry I couldn’t find a better cut out picture but what you have would be a solid 2"x6" or 2"x8" sitting on top of the wall plate and running up to the ridge board on top. The drywall is on bottom, your pink batted insulation in the center and then the plywood for the roof, then the felt paper, then the shingles. ok
This is a very common problem for cathedral style roofs built in the 60’s-the 80’s, because there is not enough room between the 2"x6" or 2"x8"to get your required r-50 for canada they put as much insulation as they could get in the small confined space, but what a lot of builders didn’t know is they needed to leave one and a half inches of air space between the insulation and the roofs plywood, or it is usually done today with styrofoam or plastic vents you stick in between each rafter running from the wall all the way to the top of the roof.http://www.owenscorning.com/around/ventilation/raftrmate_attic.asp
This is done to allow the cold air to come in thru the soffits and exhaust the heat and moisture out the top of the NEEDED ridge vent.
It may be a building design flaw in the way the house was constructed and not entirely the roofers fault. I hate to say it, but some really good roofers know nothing about proper insulation or ventilation, but they know ya need ridge vent. :smiley:
You may want to contact a good insulation company to help you, they usually know a great deal more about these types of problems, as it sound more like you have a insulation-ventilation problem that your roofers may not understand.
I am a exterior contractor dealing with roofing, siding, soffit, fascia, windows, doors, gutters, and insulation in the residential, commercial and industrial fields in The Northern Wisconsin area and see many problems like this all the time
I’m not here to flame, only to add a little insight to the problem you may have.
I hope the information will help.

Ok first thing, Tthe building may be flawed but it is your resposiblity as a professional to correct the problem. If you knew how ridge vent worked you would know that more insulation is not the answer. All that will do with no soffit vents is cause a serious condensation problem. There are products like drip vent to provide intake. But for god sake adding insulation on a cath ceiling is stupid. go to www.airvent.com it will explain how and what and what not to do. This is a prime example anyone can shingle. Difference is using products in the correct manor and making the warranty valid. If you have not read one of them lately try it our, BTW the owens corning warranty is by far the worst out of all the major companys selling shingles. And by their warranty you just voided it. And you said the MAGIC word but I will change the wording a bit to make it true, A good shingler knows nothing about ventilation and insulation. BTW for northern area’s an R-49 value is what you should have. Like I said before anyone can shingle, A professional knows all aspects!

Pride, you might want to read with your eyes open next time, no one here ever posted to add more insulation, and she already stated they cut holes in the eves and installed vented soffits, also the vented drip edge you are talking about will do nothing at all unless ther is an air flow for the air to go from bottom to top like I’m sure you know, they would have needed to create an air space by way of- Example: Tear roof to roof deck, install 1" (or bigger) firring strips along all rafter areas, new plywood over firring strips, vented drip edge on bottom, felt, shingle, then the ridge vent. A job like that can add a lot of $$$$$$ to the bottom line and many home owners won’t pay it.
And yes I do read warranties all the time, I usually read them 3 times each, I do everything in triplicate, thats what big jobs dictate and general contractors require. I work on jobs for free and up to multi million dollar projects, currently working on a 6.5 million dollar project for some nunshttp://www.holycrosssisters.org/Our_News/constructionBTR.htm
I also know the insulation value for the northern states is r-49 not 50, I just said 50 cause she lives in canada (somewhere) and hers will be in the 50-70’S type of area. And I am not saying owens corning is great I just found an article to post information about insulation and baffles, nothing there about shingles at all, just trying to show a picture. I really don’t care what company it is from period. I think everyone knows her problem is with the air flow, even with open soffits and a ridge vent it wont matter if there is no air baffles in the cathedral ceiling.
Like you said before anyone can shingle, A professional knows all aspects!
Good Day!

Pride has done the same thing to me…slammed me for saying EXACTLY what he said in Roofer’s Central. What a jackass.

Maybe he has TOO much pride to believe anyone else know anything else about roofing.

And you both are nuts…not anyone can shingle, either. I have seen many people F— up many shingle roofs.

Well furing strip were not desgined for that application. And yes when I notice something that will void a warranty I WILL walk from the job, if the customer does not want it done right I dont want my name on it. Here is a question how is the warranty good if you do that? As far as the baffles i think I had stated that earlier and if not i forgot to and put in other posts. Now since drip vent is sold for 20 a foot either it is put on or I can not put a roof on the house. Now your estimator has to make the point and sell that doing it right is the only way. I wont just put shingles on either its vented right or bye bye. I am sorry I had offeneded Aaron and you.

All we are saying is read and make sure you understand what yourer reading before you try to dicredit.

Firring strips are not made for any single puprose, they are made for any purpose you find a need in which to use them, just like 2"x4"‘s or any other wood, but we would npt recommend using lumber yard firring strips, they only have a height of 3/4", we rip our own at usually 1and1/4". If the job can’t be done right you walk away from it, thats great all contractors should be that way, I wouldn’t want my name on something done wrong either. And yes you did state it needs baffles, I think we all agree to that one. But since it has none you either tear out the ceiling and do it from the bottom, or when you reroof the place you raise the height of the roof 1" or more with the firring strips and redeck over the firring strips creating a 1" air flow between the old roof deck and the new one you just created, put the vented drip edge on bottom and the air will go thru the drip edge all the way up the roof between the old deck and the new deck and out your ridge vent. And if you are paying $20 per foot for vented drip edge you are NUTS, I pay $10.47 per 8’ peice, that is $1.31 per foot. And yes this system is fully warrantied thru all manufactures. I however would like to know how you are adding ventilation to the attic by just installing vented drip edge, how is the air getting into the attic? And if you are indeed cutting out the top of the fascia board to allow the air to get into the attic, what do you do on the old homes where they blocked off the air flow at the wall plate with either lumber or insulation or a cape cod style home may even be blocked again up the roof by another wall plate and insulation? I agree in all aspect if the job can’t be done right it isn’t worth doing.
These forums and others like it are meant to be areas where peolpe can learn how better themselves and thier companies. Forums are meant to be educational and learning, and a place to keep an open mind on things we may need to change to give our customers the best product they can buy. We need to rely on each other as a group that wants to learn. Not a place to flame one another. I do give you kuddos Pride for your last post, “I am sorry I had offeneded Aaron and you.” that is a sign of a good man, and I would like to appologize also.

Good Day.

Most homes I run into have Plywood and i just simply pull the baord and install the baffle renail and thats done on each rafter. Now I charge 20 a foot to do that. You cut a 1 1/2 inch cut out of the 1 x 6 and thats how I get air in. Covering with Ice and Water no problems. Well on code style homes i have cut into the ajoing wall and added low gable vents and that has seemed to work well. All of this with the Shingle rep’s and Inspectors approval. The numbers are not perfect but what can you do about it. Still using the 1 / 150 rule. My main thing is using ridge vent on homes when soffits are not there. Thats all. Because that is wrong. Over here in michigan it happens on about 3/4 's of homes without soffit vents. Also over here in michigan so many contractors just put shingles on, could care less that a 750 vent flows 45 inches and the 960 flows 55 inches about 60% percent are under ventilated and that voids the warranty. I have to appoligize i have come from an other BBB site with complete disgust. The Drip vent flows 9 inches per foot and comes with a filter to stop dirt and water infiltration. My state is so useless with their inspectors 80% don’t even get out of the cars. with that I have a bitter attitude with alot of things. SO many people get ripped off with there 160 a square 2 layer rips on a 12/12 in dims it blows my mind. Cant win them all but when you are 1 of 17 in the same paper and 2 of 17 charge what should be charged it becomes upsetting. Good evening