my house is a 35yr old two story, roof is 7/12 pitch black shingles, it has continuous soffit vent and two whirly birds. i put a remote temp/humidity in the attic it indicated high temp and high humidity. the attic has batts and blown in fiberglass, but the installer did a very bad job, very bad workmanship, didn’t have a clue. i found that most of the batts carried beyond the walls and random into the soffit, and the blown in was blown into the soffits as well, thereby negating any ventilation. what should i do, it’s almost impossible to get to the soffit from inside the attic, the soffit is too deep and laying on your stomach on top of blown in fiberglass is not very productive. i wonder if it would be feasible to remove the soffit panels, they’re aluminum 1’x1′ squares, would i be able to get at the batts and be able to cut them off at the proper length, and of course any blown in would fall out this would open up the vetilation part. then go up in the attic and staple some form of ridgid panel, say two foot wide, along where the roof meets the walls, this would create a barriar to add more blown in? are the whirlybirds okay? thanks, douglas
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Replies
doug
The alum. soffit panels-cut the J or F or fascia at one location and bend down-you should be able to remove a staple (if that's how they held them in place (nail would be much more difficult). Once you got one out, the rest-dislodge and pull to that opening left from the first. continue.
Whirlybirds, no experience but if the air they allow out conforms to recommended sq inches/feet of soffit vent, it should work. If not, add more roof vents (if too little) .
best of luck.
There's been a couple of suggestions on placing cardboard or maybe foamboard between the rafters for an insulation dam-without crawling all the way out to the wall. Hope someone remembers or try a search here.
You could have a shot at taking corrugated cardboard (best would be corrugated plastic political signs but it's the wrong time in the election cycle for that), folding it into a sort of C shape, and pushing it up between the joists from the eave.
What I did in our house (BEFORE the cellulose was installed) was to take two 8-foot pieces of 1x2 lath, attach a piece of the afore-mentioned political sign to them, and make a sort of H shape, with 6" of lath sticking out one end and several feet the other (actually cut about a foot off the 8-foot length so they would fit in the attic). A short piece of lath ran crosswise to hold the pieces apart.
These could be taken into the attic, the 6" tails laid on the top plate, and then the long ends lifted up and screwed to the sides of the rafters, levering the unit into place. Worked a treat - better than I'd ever imagined.
cardboard as attic insulation baffles...
...not a very good idea.
you should not really be trying to invent a better method here.
dan's election signs are great, but forming bafflesfrom them with lath, etc is far too time consuming.
just use the foam baffles that are intended for this purpose.
also-your idea of accessing the eave area from the soffit is a very practical one. you should remove the insulation from the area directly above the ventilated soffit panels to allow air movement.
you should also remove the insulation from under the insulation baffles you will be installing at least to a point where the baffles will not be compressing it. compressing fiberglass insulation is always the wrong thing to do!
air space above your homemade..
..insulation baffles-what thickness was your free air space dan after you installed these baffles?
lath measures 3/8" thick, but you said you used 1 x 2 lath...???1 x
2 would be better known as furring.
lath comes in 4' lengths while furring comes in longer lenghts with 10' and 12' being readily available.
which did you use?
Either product would not give you the recommended 1" air space above the baffle.
The space was 3.5 inches, the thickness of the truss members.
ok...got it...
...wasn't clear about that when i read your last post about this.
i see how your idea worked better now...must agree it might be the best application for someone not used to working in the eave area of a lower pitched roof.
keep the good posts coming dan! i enjoy reading your good ones a lot!
Different questions, different answers
You mentioned snow melting from the roof and high humidity, but you only talked about insulation. Insulation won't do anything about the humidity, and roof venting may or may not solve the problem of humidity. Let me ask you a couple quesions.
Where do you think the humidity is coming from? Is the basement/crawlspace of the house damp? Are there pathways for air to get from the foundation to the attic? Examples include spaces between a chimney and the framing, whole house fans, attic stairs, recessed lights in the upper ceiling, or leaky ducts.
Is there a pattern to the snow melting off the roof? Or does it just melt off your roof faster than your neighbors' roofs? Ducts in the attic could be as much a problem as insulation, if you have them.
Tell us more.
insulation...
can, if installed correctly, certainly reduce the humidity level in the attic by virtue of the insulation's performance which is to slow the rate of heat transfer into the attic. A slower rate of heat transfer to the attic will produce a lower temp in that space and the lower the temp the lower the RH level.
The culprit in this attic-and pretty much any attic space with a high temp and RH level is undoubtedly the air exfiltration rate from the conditioned space below the attic.
Air sealing is most likely needed in this attic-big time!
That will be a difficult task due to the insulation present, but it will be the single most beneficial procedure to reduce the temp and RH levels.
insulation can, if installed correctly, certainly reduce the humidity level in the attic by virtue of the insulation's performance which is to slow the rate of heat transfer into the attic. A slower rate of heat transfer to the attic will produce a lower temp in that space and the lower the temp the lower the RH level.
Slowing the rate of heat transfer into the attic will have no effect on the humdity level, other than to cause the RH to rise (without affecting dewpoint). Added insulation may slow air exfiltraton slightly and thus help the humidity, but the effect is hit and miss.
(And the vent baffles I described using corrugated plastic and lath worked amazingly well -- even surprised myself. Only took about 2 minutes to install each baffle, and the fit was exceptional. Using preformed baffles would have easily taken 30 minutes per vent, with much poorer fit. Have you ever tried to install baffles in a 4/12 truss attic with 8" of cellulose already in place?)
you are dead wrong...
... when you state that slowing the rate of heat transfer into the attic will not reduce the RH level in the attic space dan.
air will hold progressively more water vapor as its temp rises and if the heated warmer air migrating into the attic space is slowed by use of correct air sealing and insulation plus proper code specified attic ventilation then the result will be lower RH due to a colder attic space.
Your baffles, as I stated in an earlier post are a great idea but are predicated upon the availability and cost of the material and of course you should consider the time it takes to fabricate that sort of baffle.
The foam baffles are the best choice all the way around. Cheaper, easier to move into the attic and easier to install.
Yes I have had the experience of installing the foam baffles in already insulated attics with 4-12 pitch. Not a lot of fun but learning to move in an attic space is half the battle when doing this type of work.
I have not had the experience of spending 30 minutes or anywhere near that amount of time installing an insulation baffle-ever!
I have been working in attic spaces for a good many years and have learned to be quite productive in attics-regardless of which task i might be performing.
While some of your ideas are quite interesting dan-as are many ideas presented by other posters, I think we posters should consider what we are attempting to do on these sites.
We are trying to give experienced advice to people with little or less experience than we have-at their request!
When trying to advise them of the best way to achieve a task-especially one as difficult as installing baffles in attics under lower pitched roof assemblies we need to be aware of the fact that they dont know how to do a lot of what we are supposed to know about completing such a task.
You have not posted anything that I have seen about what exactly your experience is although I have asked yopu about it several times. I dont know what you know or what experience you have with this kind of work but I do know about mine.
As I have said previously-I have very extensive experience in residential remodeling/renovation and repair-more than 50 years worth!
The weatherization-energy saving part of my experience is a big part of that experience. I certainly know what I am talking about.
I am able to use my experience to great advantage because I have tried several different approaches to implementing procedures. That allows me to advise people asking for advice in a manner that will be easiest for them to achieve the desired result. Unnecessarily complicating the subject with complicated procedures will confuse a lot of the people asking for advice.
Please try to be more diligent about how and what you are trying to advise in future posts dan.
So precisely how does slowing heat transfer reduce humidity? Explain the physics of it to me.
re-read my last post...
..I did address this issue...
Basically the colder the air temp the less amount of water vapor it can hold.
It's a special kind of physics called thermodynamics-and its quite a fascinating science that encompasses the effect of temperature on air pressure, water vapor, etc.
We are talking about a very small portion of the science of thermodynamics with this heat and water vapor transfer stuff in attic spaces.
The science was developed during the steam age as people tried to get more power from steam engines
It isnt necessary to understand that stuff in order to understand basic air sealing, insulation and ventilation of attic spaces but it will give you a more comprehensive understanding of what is actually happening I think.
You can do your own research easily on the web...try word search for "thermodynamics of water vapor".
Good luck!
But unless you're moving the humdity somewhere, the colder temperature just results in condensation. Cooling the air does not, by itself, make humidity go away.
(I had thermo in engineering school.)
different questions-rebuttal...
what do you mean by your statement about ducts deing as much a problem as the insulation here andy?
also-attic space ventilation, if installed correctly (which it rarely is in retrofitted attics) in attics where efficient air sealing and properly installed insulation exist will do a very good job of expelling the warmer moisture laden air from the space.
air sealing correctly is the key to having the 3 part attic system....(air seal, insulate, ventilate)...work properly.
As impossible as it may seem I'll bet you can do this from your attic and do it in just a few hours. I've done it on a lower(harder to reach) roof then yours and it went pretty quick. Do it on a cold morning so you can wear a coat and gloves and be comfortable. Cut a couple of pieces of 1/4" ply 16" X 4' or so to slide around on first. I alsol used a piece of heavy Visqueen thta I could slide and push in front of myself. We used a childs toy rake to pul th einsulation back and then pushed the foam baffles in. I was able to staple the top half of the baffle then slide on my plywood and plastic down to the next secrion. I think the whole attic took us less than 2 hours.
i tried that, the eve is too deep to reach, i'm going to have to do it from the outside. thanks, douglas
A child's toy snow shovel works better than the rake, for loose insulation.
But it's probably unwise to crawl around on the insulation unless your boards are essentially supported by the joists, meaning that the insulation can only be inches deep, not the foot or 18" that's common now.
i agree with
andy's method but the problem of learning to be comfortable and safe enough crawling around attic spaces is not easy for someone not accustomed to that hostile environment.
ideally, the snow should not melt off unless it's from the sun. for instsnce right now it's 27F/ 49% outside and in the asttic it's 32F/ 78%. i don't think anything else is going on except poor ventilation and not enough insulation. there's no ductwork. i wonder if the whirlybirds are effective? thanks, Douglas
You don't say what "high
You don't say what "high temp" is, and note that "high humidity" is depenent on temperature. Get a dewpoint chart and figure out what the humidity would be at 68 or so and likely it's not so shocking.
8:30AM outside it's 23F with 40% humidity. in the attic it's 30F with 73% humidity.
a little different than earlier today. thanks, Douglas
73% at 30F is equivalent to 26% at 68F, which is bone-dry by most standards. And as Perry says, once you get below freezing the RH numbers become pretty flaky.
Think about this.
Once the temperature reaches 32f outside all the water vapor in the air drops out as frost, and regardless of what the hygrometer indicates the air is dry. (it is very difficault to find any water vapor in a cubic metre of air at temperatures below freezing) In fact there is not much in air at temperatures below 40f.
wow! i had no idea, like they say, you learn something new every day. right now it's
8F and 24% out side and 20F 70% in the attic. But still disregarding humidity, that's
12 degrees warmer in the attic than it is outside. As a comparison, it's 15F in my unheated
stand alone garage, a difference of only 7 degrees. Garage 7 degrees, attic 12 degrees.
thanks, douglas
And, as you say, your garage is unheated. Plus, it's roof to volume ratio is a lot lower, so it takes more sunlight to raise it a degree.
does the stand alone...
...garage have a ceiling?
Even if there is the fact that the garage is not attached to the house indicates that the temp in the garage will be following the outside ambient air temp very closely.
RH values below 32 degrees...
No, Perry, all of the water vapor in the air does not drop out as frost at 32 degrees!
Like dan h posted-the RH values do get a bit weird at below freezing temps but the air retains the ability to hold some water vapor even at much lower temps.
whirlybirds...
I think you are referring to turbine attic vents.
If that is correct-get rid of them! Those things produce too much negative pressure in an attic space and that results in greater a higher level of energy loss.
Turbine vents are an absolute no-no in heating climates!
We always remove them when we find them while performing attic energy saving procedures.
snow melt...
does snow melt at same rate from both/all sides of your roof?
what is the directional orientation of the house?
what style is your roof framing?
it's a stick built gable roof, the gable ends are on the north/south ends.
the pitch is 7/12. thanks, douglas
please elaborate about the turbines, i didn't quite understand
what you meant by negative pressure. thanks, Douglas
so your roof...
...planes are exposed to east and west directions-right?
if so then they receive minimum solar gain-snow should melt from both sides at approx the same rates.
i was wondering how much the incident radiant heat from sun helped with snow melt.
those turbine vents-if that is what you have-move a lot of air via stack effect and even more air via windy conditions.
both situations make them suck a lot of air from the house.
any thermal breeches that result from a lack of air sealing will augment the loss of heated air from living space.
look here later tonight-i gotta go now but will continue explanation...
if i get what you're saying, the turbines work too good?
thanks, Douiglas
negative air pressure, cont'd...
I am back....and resuming my explanation on negative air pressure within your house.
Please check out the nicely done explanation on this site and get back to me with any questions.
http://www.pureairplus.com/nap.htm
that web site is way over my head, too technical for me,
i didn't understand it. thanks, douglas
thats ok...
...you don't have to understand it...just ditch those turbines! they are real bad news for energy savings-just like jenn air cook tops.
do you have one of those in the house?
friend kxm1, please humor me, discounting the energy savings, do the turbines do the job they are
designed to do? Do they exhaust the air at the roof drawing from the eves? Or do they do nothing?
Or do they exhaust too much air? i appreciate your saying ditch the turbines, but please explain why
you say they are bad news. thanks, Douglas
roof turbines no good...contd..
...sorry doug-thought you didn't want anymore from me.
sorry about the website i referred you too. after i read it again i decided it was not the best referral. i understand this stuff so well and have been advising and performing on the implementation of correct energy saving procedures for so long it has become second nature for me so to speak. i do realize-just from reading the huge number of distorted ideas in the posts on this forum from people who present as experts that this stuff is not easy to understand for someone with little or no prior exposure to it.
i want to refer you to another site-much less technical but i hope it will give you an idea of why turbines are not a good choice for house attic ventilation.
a basic rule of thumb i learneds many years ago during energy auditing training is that, yes, the turbines do exhaust too much air and at the wrong time
try this site and please get back to me. i will work with you as long as you show that you are genuinely interested in understanding the principles of proper and effective attic air sealing, insulation and ventilation
here is that site address:
!http://www.nachi.org/forum/f16/turbine-roof-vents-4334/
your link was inactive so i typed it in manually. i read all the posts.
Please indulge me, i will ask you to answer my questions in my previous
post. thanks, Douglas
ok doug...thanks for
...at least trying the sites...they had to give you some info, judging by the most recent questions you asked.
the turbines spin in reaction to any moving air that contacts them.
Ouitside air movement at 4mph is rated to power a 12' turbine (made by Air Vent-sold through Lowes and most roofing supply houses) to produce a 350 cfm exhaust! That is a lot of air being expelled from the attic! If you had 2 turbines that size you would be getting up to 700cfm of exhaust! Wow!
Don't have the chart from Air vent, but of course as the wind speed increases so will the turbine speed and consequently the volume of air being exhausted from an attic.
I am going to ask you at this point to just accept as fact when I tell you the volume of exhaust air from a turbine rated as those I mentioned above are...350 cfm at a 4 mph wind contact...that it is a large volume of air being moved from an attic space!
As the air from the attic is exhausted-at a faster and faster rate especially, the effect on the house is that of becoming depressurized in relation to the outside or ambient atmospheric pressure present. This means that the air pressure inside the house is lower than that of the air pressure on the outside. The lowered inside air pressure is referred to as negative air pressure.
Do you follow so far?
Let me know and then I will continue once I am sure you have grasped this concept...
yes, I'm on board so far ..............
thanks, douglas
great!
ok lets see if i can continue making sense to you doug.
are you familiar with the blower door test? ever seen one performed or had the procedure explained to you before?
sorry, no.
thanks, douglas
friend kxm1, we're not done, are we? I hope Mark and Dan
haven't run you off. thanks, Douglas