Attic frost


#1

Not a roofer, and I’ve spent a good 10 hours researching my problem. Any advice is appreciated.

Live in Minnesota, winter has been colder than normal, and a lot more snow than normal. Box 2 story built in 1977, bump out family room on first floor with no second story.

Had roof replaced last March. At the time had insulation specialist also out. Insulation contractor said I have more than enough insulation, he installed new flutes, and replaced exterior soffit vents. Said when/if doing siding to replace soffit’s with newer better option, but not necessary.

Roofers replaced roof, replaced box or turtle vents on the one story bump out, and plugged all box vents on the second story. The new second story vent is a ridge vent.

Noticed small amount of mold on the inside of an exterior wall. Thought for days where the moisture would come from. Removed kids toy near mold and found more! Went into attic last Tuesday night to find frost everywhere! Called insulator who says ridge vents don’t work in my climate. He says typically they are only a problem in March when we get heavy snow, but he’s seen 10+ this winter already.

Shoveled and swept out ridge vent… not fun

Roofers came out, they were in shock, stayed in my attic for almost 45 minutes. Ruled out moisture barrier problem, and bath fan leak. They were suppose to call Thursday with a recommendation. Still no return call.

Roofers who were out said I can’t have both a ridge vent and box vents. They also said snow covers up all vents. I showed them my 1st floor vents and said these metal box vents on the north side seemed to melt all the now off and away.

The guys who came out aren’t the owner, but said I’d probably have to install an attic fan that closes when not in use.

Obviously it’s a huge problem. On top of the mold in one wall, my exterior siding has multiple brown tar like streaks.

The insulation rep, and the roofers are two of the bigger companies in their trade, and I’ve had positive dealings with both prior to this.

Roofer is saying I need more insulation, and I should pay them $50 a time to shovel my roof. Insulation rep is saying the ridge vents don’t work in MN.

It’s been 5 days since being shoveled. Day one attic temp was around 42 with outside being 9… Today the attic and outside are both below freezing around 5. Today some of the frost is gone, but not much.

I guess it’s starting to work, but I need an unbiased opinion, and would love a solution suggestion.

After 5 days you can see the dampness is starting to go away.


#2

"Flutes should be installed in between every truss.Is there ice and water sheild at the eaves?Block off either the ridge vent or the box vents.Having both will short circuit the ventilation.


#3

That was fast.

We have only box vents for one roof not attached to the attic.

We only have a ridge vent for the main roof, where frost is. The box vents were plugged when the new roof was installed.

There are no soffit vents between every rafter. In the 70’s here they would only space a few vents into the soffits and the flutes are over every vent.

We do have ice and water shield for the first 4 or 5 feet.


#4

you need soffit vents between every rafter on each side.And make sure main ridge vent is clear


#5

nfllifer,

If you live in an area of high snowfall, gable vents and continuous soffits would be a good idea.

No need to plug the box vents.

You can find more information here;

roofingcontractorreview.com/Soff … ation.html

roofingcontractorreview.com/Roof … ation.html


#6

How long has this been happening. Did you notice the brown stains just recently? Do you have any moisture problems in your crawl space or basement? Do you have a humidifier? If yes, what setting do you have it a at?..


#7

Hello,

I am just wondering why ridge vents don’t work in your climate. I live in Alaska and we have about the same winter weather as the northern states, our summers are not as warm though.
Ridge vents work great here. Are your vents a shingle over kind or the metal 10ft. type. If they are the metal type they could have been flattened by the snow load.
Just my opinion.

Keith


#8

If your attic temperature was 42 when the outside was 9 , you need more insulation in your attic. Too much heat is escaping the house into the attic causing the roof decking to “Sweat”. I believe a good rule of thumb is that your attic should be within roughly 10-15 degrees of the outside temperature. Also you most likely do not have enough intake ventilation through the soffits and enough exhaust through the roof.

You should look into the Owens Corning blown fiberglass insulation. I hear it is really good.

I live in Wisconsin and this problem happens all the time to people who do not have proper ventilation. Whenever we fix it by having enough insulation in the attic and the proper ventilation the problem has not come back for any of our customers. Trust me, ridge vent works in up in this weather.

Make sure to also hire a professional in mold removal. I hear it can be dangerous.

I do not understand how your roofer and the rep could not know this is the cause but then again everyone always has different opinions.


#9

It is condinsation from lack of ventilation which freezes when it is cold


#10

[quote=“nfllifer”]That was fast.

We have only box vents for one roof not attached to the attic.

We only have a ridge vent for the main roof, where frost is. The box vents were plugged when the new roof was installed.

There are no soffit vents between every rafter. In the 70’s here they would only space a few vents into the soffits and the flutes are over every vent.

We do have ice and water shield for the first 4 or 5 feet.[/quote]

So for 1 you have inadequate intake…


#11

I do have a humidifier. It’s setting changes based on the outside temp. I’ve shut it off completely since seeing this. Dry basement, no moisture at all. Brown stains appeared about 2 to 4 weeks ago, but have gotten worse the past 14 days.


#12

[quote=“roofboy”]Hello,

I am just wondering why ridge vents don’t work in your climate. I live in Alaska and we have about the same winter weather as the northern states, our summers are not as warm though.
Ridge vents work great here. Are your vents a shingle over kind or the metal 10ft. type. If they are the metal type they could have been flattened by the snow load.
Just my opinion.

Keith[/quote]

Maybe our ridge vents are different. Or I’m not using the right term. My only roof vent is on the peak of my roof. It runs the entire length. It is made of plastic, and shingle material. The vent is only about a one inch space. On from the attic the peak of the ply wood was cut away, and a black mesh is visible. When we get the heavy snow and cold air the vent is plugged. The peak of my roof has been plugged with snow since early December.

All the homes around me have snow covered roofs, but the new construction has more of a slop and cleared peaks. Also the new construction has no trees and is windy to blow snow off.

If we are talking about the same venting, how does a ridge vent work when plugged with ice and snow?

I’ll take all your advice, and replace my soffits next spring. As for insulation it’s more than enough. Between the roll, and blown in the insulation is close to 18" and my heating bills are much less than homes a lot smaller.


#13

you need to keep ridge vent clear


#14

you need to keep ridge vent clear

that’s what i was thinking.

and is the Insulation covering the inlet for the soffit vents or no?


#15

Most brands of Ridge Vents are not reliable.

From past experience, only the Shingle Vent II and the Cobra Snow Country Ridge Vents work in snowy conditions.

Heat is supposed to escape through ANY Exhaust Vent, which then melts the snow that freshly covered it.

I took photos of several roofs last winter in the Chicago area one day after up to a 14" snow fall to prove that the Shingle Vent II works properly and melted the snow so it could exhaust the air and keep air flowing.

Along with each of these home, I had also installed 100% continuous Eave Intake Ventilation, with the shingle over style Smart Vent Product, manufactured by DCI Products Inc.

You DO NOT have enough soffit intake ventilation.

The actual and precise NFVA needs to be calculated and for your extreme conditions, you should use the 1/150 formula instead of the 1/300 formula.

Find out the brand name of the ridge vent that was installed. I would bet that it is either cor-a-vent or cobra roll vent. Both are junk for proper exhaust.

If no other solution can be found, then seal off the upper roofs ridge vents and install a Powered Attic Ventilator, which MUST have a Humidistat in addition to the typical thermostat, to work even in the winter times when the interior RH factor increases, but the temperatures do not.

PAV’s need to be sized correctly for the space being vented.

Ed