Frosty Attic

[zoops]

Have some frost on the north-facing side of the attic in my house. South-facing side (other picture) is fine. Normal for the temps we've had or in need of a remedy?

 

[tikkalover]

3/4" boards for the roof = older house. How many inches of insulation is there? Need proper vents (is there vents in the soffit on the overhang outside?)and vents at the peak on the roof.

 

[db-2]

Friend on new home had this issue only a lot more in time. When melt it rains in attic
i am guessing, need vents of some kind in attic. db

 

[bucksnbears]

Better get it taken care of.
More insulation and or better venting.

 

[Obi-Wan]

At this point it's hard to add eave vents you might want to install an attic fan with a humidistat. if you install a fan make sure to close off the nearby roof vents so it draws from the whole attic not just the closet possible intake.

 

[raider]

normal... with blow in insulation like you have, your attic is an unconditioned space... it has no insulation under the roof deck, like spray foam...

i'd check to make sure you have working (open) vents... either a gable vent in each side, and or chutes, unobstructed down to soffit vents, or a ridge vent the length of the peak, or the old style conventional turtle vents a bit down from the ridge cap on at least one side...

your attic, if properly vented, will be the same temp and moisture content as the outside air... if it is not, you don't have enough insulation above the top floor of your house and heat is bleeding through... a little winter sunshine on the south facing side will warm up and melt the frost on that side... not too irregular with the temps we've seen lately imo...

 

[zoops]

1940's home. No eave/soffit vents. Does have gable end vents and a ridge vent. Probably 6-8" of insulation as I added some after doing can lighting a couple years ago.

 

[raider]

i think you want at least 15" of blow to get to code (R49) in this zone...

varies by manufacturer, but is easy to add... most lumber yards will lend you a blower if you buy the insulation from them...

 

[tikkalover]

Try more insulation. My house was built in the 70s. When I bought it 28 years ago it only had 6"s of batt fiberglass insulation in the attic and the cold air returns for each room went all the into the attic. Where the ceilings dropped down into the closets, they just laid the insulation across the hole and most of that fell into the ceiling above the closet. I put plywood across the holes for the closets and sealed up the cold air returns, put proper vents into the soffit and blew in 15"s of insulation in on top of the fiberglass = no frost problems.

 

[Rut2much]

Looking like one or 2 whirly birds might be in your future..

 

[Traxion]

Agree, more insulation probably solves your issue. But venting is a year round deal and it will surely help the problem as well, albeit a bigger project to tackle. With better ventilation your attic is cooler in the summer too and it makes your shingles last longer as well. No cooking from below!

 

[eyexer]

As mentioned poor if any ventilation and low insulation value

 

[bucksnbears]

When that frost melts, where will the moisture go?

 

[db-2]

Buck:

u got that right. db

 

[JayKay]

Yes, lack of venting, along with not enough insulation, are the culprits.

Nails sticking down through your roof deck will each have a big ball of frost on them. When it warms up, the frost melts and drips down onto the insulation, packing it down, making it worse.

Loft, just like in a goose-down jacket, is key. Water will flatten the insulation, decreasing loft. The best insulator is dead air space, and the dead air space comes from loft.

When the insulation dries, it does not "fluff back up".

You will see big gains in efficiency if you add insulation. 15" would make a huge difference. To some extent, the more you put in, the better off you will be.

If you don't have vents in your soffit, then adding attic chutes will make no difference. If you have vented soffit, then adding chutes will make a huge difference, but there needs to be enough of them, on opposite sides of the house (think: upwind and downwind) to allow air to flow through.

Someone above mentioned that the air in your attic should be the same temp and humidity as outside air. That is exactly right.

 

[johnr]

attic fan would be the easiest and cheapest, more insulation will be a key, but does not help with the moisture build up, and lack of circulation occurring up there right now

 

[BrokenBackJack]

Put in 24'' of blow-in insulation and an attic fan and you will like the results.

 

[bucksnbears]

In a modern built house, an attic fan is a moot point.
Ridge vents,gable end vents and vented soffit are all that should be needed.

 

[zoops]

In a modern built house, an attic fan is a moot point.
Ridge vents,gable end vents and vented soffit are all that should be needed.

No eaves/soffits on this era of home so I'll look at the fan route.

 

[muzzyhunter]

Lack of chutes is not the end of the world,especially in low pitched roofs,gable vents will give you good ventilation.I have seen ceiling line condensation due to improper chute installation.One house shot the cieling line with thermal camera 28 degrees,2ft down the wall 68,this was a -20 day.You have to maintain a good r value between wall plate and chute,personally I would spray foam those areas.
6" insulation would give you R19 at best,We blow R 50 on combustible heat and R60 on electric,so your definetley lacking there.Did you foam over or seal your can lights,big source of heat loss to attics.Before adding any type of fan you would want to check for leaks,chaseways for warm air to escape into the attic,adding more to frosting issues,again a thermal camera works great for this.
On the job I use a blowerdoor and manometer to pressurize ,depressurize,and zone pressure diagnostis,with thermal scan to find these things.
Just saying its not always as easy as adding insulation/ventilation,and sometimes can worsen the problem.My guess wold be seal lights and chases,bring up to R50,ventilation prob.ably adequate,attics relly dont reguire lots of ventilation.I prefer blown cellulose over fiber glass,it has some air sealing ability and will wick up moisture and dry in the summer.