Frost Inside The Attic?

SOSSW

First, let me apologize for the long post but I want to explain the situation the best I can and include all the details...Here is goes.

Monday we received a call from the owner of house we roofed late last summer here in central Iowa. He said he has a lot of water on his attic ceiling and we need to take a look at it. He is so concerned he thinks he will have to put a tarp on his attic floor to catch the water.

I went to look at the house yesterday and here is are the known details:

1. The house in question is a two story farmhouse with a full and open walkup attic with two dormers. It is the hip roof style. These type houses are everywhere.

2. When the homeowner called, the outside air temp was in the low 30's.

3. When I went to look at the house yesterday, the outside temp was 4 degrees.

4. When we roofed the house, we tore off 3 layers of grey 3 tabs and replaced them with 30lb paper and onyx 30 year Owens-Corning laminates.

5. The original brick chimney was no longer being used and so the homeowner requested it be torn down below the roof. We checked to make sure nothing was being vented through the chimney and it wasn't so we tore it down as per his request.

6. Upon talking with the homeowner yesterday, he said in 2005 the whole house had insulation blown in including the attic floor. He used to be able to go into the attic with a t-shirt on and now there is such a temperature change between the 2nd floor and the attic, you need a coat.

7. The homeowner has had every window in the house (except the attic windows) replaced in the last 5 or 6 years.

8. The roof has never leaked since we replaced the shingles, even through hard rains and strong winds.

Upon inspection of the attic, the entire north face of the attic had frost on the nails poking through and most of the decking boards. There was also frost on the west wall on the north side of the dormer where the sun doesn't get to it this time of year. There is no snow on the roof. The homeowner said last week there were icicles hanging off the nails inside the attic. The last two weeks it has been below zero degrees at night and not more than 5 degrees during the day on most days here. The homeowner said even after the attic was insulated in 2005, this problem was not there last winter.

Here is my thinking...
The first thing I did was re-check the chimney to make sure it was not venting into the attic. There was not heat or vapor coming from it. I went to the basement to verify where the furnace and hot water heater were venting and they are not going to the chimney.

There are no signs of leaks. The only stained boards are where the chimney used to go through the roof and the homeowner confirmed previous water problems around the chimney which is why he wanted it taken down. I should note that the attic is open with not much stored there so you can see everywhere very easily.

I asked if they were using a humidifier and they are. It is cold enough outside that humidity is not a problem...it is very dry which leads me to believe that any moisture is being created from inside the house.

My theory is this: There is moisture coming from the rest of the house from the humidifier and everything else in the house (shower, dishwasher, oven, etc.) and rising to the attic. The sun heats the shingles on the south side and most of the east and west side where the sun hits. Any moisture on these surfaces evaporates and then condensates on the northern surfaces where there is no sun shining and creates frost. This keeps happening and the frost just keeps accumulating until the temp rises and it all melts and creates the runoff he alerted us to. When we re-roofed the house we replaced the vents with the same number and like kind. The ventilation should be the same as it was. Since this problem was not there last year, could the 3 layers of shingles have been acting as insulation to buffer the temperature difference? Is it possible that removing the layers of grey combined with adding 1 layer of black have compounded the problem by allowing the roof temperatures to escalate where the sun is hitting the black shingles?

Possible solutions: dehumidifier, more ventilation, insulate attic ceiling and add vapor barrier???

Have any of you seen this problem before? Maybe it is a common occurance that I am just unaware of. Even though the roof is not leaking and our work does not seem to be a direct cause of the problem, I would like to get to the bottom of this and help find a solution.

Any input and discussion is greatly appreciated.

Bob

K2

I've seen this problem and I live in a semi arid climate. That humidifier is the culprit but I have seen people's living styles, cookin styles, large families, cause the same problem in my climate.

roofwiz74

I've ran into this problem on a few old homes here with finished attics.it was venting.
and of course alot of it was all the newer appliances,second bathroom,just some bad choices in materials and improvements on a hundred year old home.

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Ed the Roofer

Yes, I have seen this before, many times. The internal humidity conditions contribute to the internal moisture/frost conditions.

The insulation added should have, like the homeowner stated, created the significant variance in heated living quarter temperatures to the unheated attic temperatures.

Seal the access way from the staircase to the attic and any other sources which allow the humidity/moisture content to permeate the attic environment.

Is their a continuous non-punctured vabor barrier on the under side of the insulation to diminish the moisture permeability?

Did you address the INTAKE Ventilation?

Does the intake ventilation and exhaust ventilation NFVA balance each other out, or even provide slightly more intake than exhaust? A continuous BALANCED ventilation scenario would provide the proper air flowage to eliminate or minimize the moisture build up in the attic.

If there is a powered exhaust fan, does it have a humidistat as wel as a thermostat? Is the RH setting adjusted properly?

Are there any bathroom exhaust vents expeling the humidity directly into the attic?

The lack of proper INTAKE ventilation and the typical IMPROPERLY BALANCED intake to exhaust flowage are usualy the reasons for this condition becoming so exasperated and magnify the problems.

Obviously, more information is required for a precise analysis.

Ed

dougchips

I've seen bathroom fans vented into attics before, are all of the vents going somewhere?

dougchips

Ed types quicker!

Ed the Roofer

Man, there were no answers when I stardted typing. Did everybody just wake up?

Ed

roofwiz74

where is the dryer vented?the bathroom exhaust vent?what about heat up there,forced air,radiant?
I've noticed that when doing work on these old homes sometimes fixing one thing uncovers other things wrong.or make them worse.kinda like a used car,fix the radio fuse and the trans goes out.lol

__________________
You have ONE advantage over me.....you can kiss my butt and I can't!!

roofwiz74

you guys are quick.lol sounds like it's unanimous.check the venting,close the attic.lol

__________________
You have ONE advantage over me.....you can kiss my butt and I can't!!

dougchips

I love how me find a post at the same time but you always type quicker. I use to type at 30 wpm but now my keyboards are each different and it slows me down.

Ed the Roofer

Ah, DougChips, old school phraseology.

We learned to "type", and nowadays, they learn to "key".

Ed

dougchips

Waiting for my daughter to ask me what a typewritter is. My wireless key board at my office has a funny shape and it takes a while to get use to it. Whereas my laptop keyboard is a standard shape, when I switch computers my typing is off for a while. Sometimes the signal in the wireless one is screwy and it misses some letters.

Grumpy

Attic problems are always about one or the other... ventilation and insulation.

Proper insulation would keep over humidified air int he living space. However it's better that the living space be properly humidified anyways. The average family puts 2-4 gallons of moisture into the air just through daily living, cooking bathing, perspiration etc...

Ventilation will remvoe what ever hot air enters intot he attic. Make sure no bath fans vent into the attic. Also check load bearing walls which might be used for pipes that run from the basement/crawlspace all the way to the attic. These can sometimes become windo tunnels ans if the basement has a furnace will carry hot air into the attic and we all know how air holds moisture.

He had insulation blown in? Chances are any intake that existed, doesn't sound like there was any anyways, has now been blocked. I know in my area the insulation guys just don't care and block all overhangs.

This happens every winter. we do a fair bit of ventilation upgrades to correct problems like these but no guarantee.

joasis

The bottom line is something from the heated area is venting into the attic, which is not properly vented....only time I saw something like this was in a small home where someone decided the gable vents caused their heating bills to be high, and sealed them...bathroom vent fan and stove exhaust hood both vented in attic...wonderful.

__________________

AaronB.

Im tyoing as I read, s if any of this was already ststed, please forgive me...

Last winter was really mild in the Midwest, so you may not have had the deep freeze effect that we have this year.


Was a new vapor barrier installed? Blown in cellulose will not stop air infiltration, so insulation alone cannot solve the humididty problem without an intact continuous vapor barrier. It is generally hard to do this with cellulose or fiberglass.

If the humidifier was the culprit, and the water is only on the north (cold) side of the roof, wouldnt we still see some eveidence of the same on the south side, say early in the a.m.?

Spray foam insulation creates its own air seal, as well as double the r value per inch of cellulose or fiberglass, even around junction boxes and can lights. You would probably need a dehumidifier for the living space, but it is way better than destroying the roof deck.

What type of ventilation system is in place up there?

And now that I peruse the rest of the posts, I see everyone has already said it.

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tinner666

One thing was missed on all the posts. Look for a LEAKY Dryer Vent Hose. One of these puzzled me for 2 winters.

Ed the Roofer

Thank you Tinner.

I had not contemplated the potential for a "leaky" hose connection in my previous post, just one that would have been absent.

Ed

Grumpy

Airvent recommends that all vent hoses be insulated to prevent "leaky" hoses and just general heat loss.

RED HORSE 554

I agree with Joasis this is warm air getting into the attic and causing the moisture filled air to condensate getting this result. (Find the path of air) and (create more air movement in the attic) space.The hood duct could have a hole in it or a break in the pipeing as well all the vent fans from the baths.Or an open from the crawl space by way of vent pipes for the drains and or supply lines. As many here stated. Or not enough venting due to iso blocking the eve holes and or covered the vent screens with dust closing them off to dissallow the needed amount of air movement.

CO2Solutions

That's about it, I do a lot of attics! what I mean by this is I complete a lot of Dry Ice Blasting projects for mould in attics AND every single one has related to poor ventilation. Most of the time it is something as simple as the soffits being blocked with insulation - either the home owner has added more insulation or hired a contractor to blow in insulation and they go in and spray everywhere including blocking the soffits. Other times, there's also not enough roof vents for the square footage of the home...

I'm sure this may not be the case for every climate, for mine it is...4 seasons...