Anyone want to help with ideas for the Mighty Penobscot house insulation requirements ?
Thanks in advance.
Walter
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What exactly is it you're dealing with? Is there ice dam forming on the roof?
If so, I'm not sure how shutting off the heat to the 3 floor would have cause that to start happening. I'm assuming you're taking care of the rafter ventilation.
Maybe I should go back and read the 400+ posts in that thread so I'm a little more up to snuff =)
~ Ted W ~
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Ted,I'm guessing heating the attic in the past with no insulation just melted everything clean off the roof, thereby preventing ice dams. Probably when he closed it off, it still leaks enough heat to cause substantial melting, but not enough heat to melt off the eaves as well.Sounds like they need to define the thermal boundary, and then get it sealed and insulated.Steve
That makes sense. Because the terms "third floor" were used, I was assuming it was 3 story plus an attic. But if the 3rd floor is the attic, then that makes total sense.
What else makes sense is that simple ventilation from sofit to ridge will solve the problem.
What really surprises me is that there aren't already 20 different people already posted to this topic. Guess everyone must be out enjoying the weekend. =)
~ Ted W ~
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Edited 4/18/2009 9:19 pm by Ted W.
Ted,
The eaves are wide with decorative rafter tails and no soffits . Ventilation on this hip roof is more problematic than simply adding some rounds vents at the eaves and then ventilated ridge.
My suggestion would be to really isolate the attic on the outside of thermal boundary, or to bring the attic back into the thermal boundary and foam the underside of the roof deck. The latter is usually easier than the former.Steve
I see what you mean - the stucco(?) going all the way up between the rafter tails and the fact that its a hip roof, makes venting between the rafters impossible, at least at the hips.
Steves's suggestion seems a practical solution, but I'd take it a step farther. By leaving the foam in the rafters open just under the ridge, venting the ridge, and finding some way to let outside air in, the little bit of heat that does make it to the attic will vent out. The cheesy little disk vents won't due because A) you would need a lot of them and B) because that house is too nice for cheesy little disk vents. Maybe a few nice looking louvered vents, a couple or three on each side would allow enough air flow and would be decorative enough to compliment the house.
Am I on the right track here? =)
~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
Edited 4/18/2009 11:37 pm by Ted W.
No need to vent if you do enough foam. If you were determined to vent it, you would need to create a vent channel between the foam and the roof deck. Venting what is now the inside of the thermal envelope would defeat one of the main advantages of the foam... the perfect air sealing. Venting as you suggest is about the same thing as lining your swimming pool to keep the water in, and then drilling a few holes in the bottom for good measure...Steve
I beg to differ. It's practically impossible to prevent 100% of the heat from getting into the attic. What you suggest would certainly decrese how much escapes to up there, but some will, and without venting it will stay there long enough to eventually make it to the roof and start melting snow.
Actually, what you're suggesting inadvertantly replicates the situation causing the premature snow melt. When the living space part of the attic was heated some 40 years ago, it created enough heat to completely melt the snow. But when they stopped heating it, enough heat from the rest of the house escaped to the attic to partially melt the snow, thus allowing ice dams to form.
If the heat is turned back on in the attic living space and it is 'isolated' from the attic space above, there will still be a small amount of heat getting up there. So again, enough to partially melt the snow and allow ice dams to form. Foaming between the rafters will help prevent that, but again not 100%. In the right conditions that trapped heat will be enough to partially melt the snow to allow ice dams to form.
Stopping as much heat as possible from escaping to the attic is a good first step. But allowing what heat does get up there to escape will assure the snow stays frozen it's ready to melt on it's own. ~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
>>I beg to differ. It's practically impossible to prevent 100% of the heat from getting into the attic.<<I see that you are talking about strategy #1(thermal boundary at the attic floor) and I'm talking about strategy #2 (thermal boundary at the roof deck).I agree, if you are going to make the thermal boundary the attic floor, then venting the roof in the fashion you mentioned would be OK. I was referring to strategy #2, which is to bring the attic back into the thermal envelope, and make the roof deck the thermal boundary by foaming it. In that case if you were going to vent, it would be between the foam and the roof deck. But enough foam on the underside of the roof deck would be a pretty sure bet to cure it without venting at all.Steve
Steve and Ted ,
Thank you both for the help with so little info to go on.
I'll try and get better details this week if you guys are still willing to help find the best solution.
Thanks again , Walter
Maybe I don't understand the way you explain it, but you donm't seem to understand ice damns. I don't understand your statement about "partially melting" Either it melts or it doesn't.The thing that causes ice damns is when it melts and runs down slope to where the over hang at roof edge is colder than space over attic and the melted re-freezes again before running off the edge.Doesn't matter is some heat escapes to attic, as long as it is not enough to melt the snow on the roof.
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Partially melt = enough of the snow melts to run down to the eve and refreeze. All the snow doesn't have to melt. Most of the ice dams I've seen still have plenty of snow still on the roof.~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
Ted,
You're entirely correct . Here are some shots from Jan . 23rd when we were experiencing our worst Winter backup issues.
Same house while I was trying to alleviate water issues.
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Wow, that's not just ice dam.. that's a damn glacier!~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
Ted, that isn't bad. You ought to see the ice I get, and my roof is insulated.
You got a major heat leak, too. I've seen R-38+ roofs w/ 16" ice damns ... primarily from e.g. skylight and recessed can lights open to the attic.
I am not saying that I don't. I know where the loss is, but can't do anymore than has already been done.
Took some pictures of both the second and third floor ceilings today -- that can be accessed from small hatchways .
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So I'm guessing that's the attic floor and rafters we are looking at. Are there sloped ceilings in the area below, or is that the rafter plate of the exterior walls that we see the rafters resting on?
The first couple shots show the 2nd floor ceiling / 3rd floor floor
The last 3 show the 3rd floor ceiling area.
There are sloped ceilings going up to the flat area on the second floor as well.
Thanks for looking.
Walter
So the second floor is that last space where the walls are and the roof starts in part way up the second floor walls, and the third floor isn't really a floor at all, just an attic? YEt that attic, with no insulation in the rafters, has a flat ceiling section? Plastered or what forms the 3rd floor ceiling surface?What's the access to the attic space? Hatch? Pulldown ladder? Is that some kind of rockwool or cellulose insulation that is down in the sloped ceiling bays and loose on the attic floor?Have you got a shot of the exterior where we can see where the second and third floors are in relation to the roofline?
Edited 4/20/2009 6:53 pm by mmoogie
Steve,
I'll take more pictures tomorrow of the exterior.
There are sloped ceilings for a ways on the second floor , with a wide flat floor area and ceiling above -- first two pictures earlier . Then another ceiling on the 3rd floor -- last 3 pictures from before .
So there are sloped areas on both the second and third floor areas that aren't easily accessed.
Thanks again , Walter
Are there any plumb walls on the third floor or is it all sloped? I guess what I'm asking is if there are kneewalls on the third floor. On the second floor are the plumb walls kneewalls or are they the exterior wall of the house?Sorry to be so obtuse...Steve
Steve ,
I'll draw a section in the morning and input it here.
Not sure my skill level on these devices will be enough to do that well.
Thanks for hanging in here.
Walter
That would really help clarify. Thanks.
I want to see a shot of what's going on in that junction box.
I don't think I'll be taking the cover off of it .
Walter, this is what I see:
Not enough insulation to keep the roof surface cool, and no propa-vents to make up for lack of insulation. And probably leaks air like crazy too, carrying heat with it.
Hard to say what to do without being there, but if your section looks like I think it will, it's a good candidate for getting rid of all that insulation, air sealing anything that connects to living space or the basement, including around any chimneys, and pumping just as much dense-packed cellulose in there as you can. There isn't enough space in the rafters to run vents unless you have access to the slopes below, so just fill it up tight, and add extra in the attic to make up for the difference.
We're doing a very similar one now, 1860's Italianate in Yarmouth. Massive ice dams last winter, due largely to snow melting around the chimney that vents the boiler that ran 24 hrs/day, due to lack of insulation and air sealing in the attic!
How is the attic hatch detailed on your project? It should be every bit as tight as a new exterior door, with as much insulative value as the rest of the attic floor.
The roof's looking good at least!
I tend to agree with your thoughts here after looking at the pics. Kind of what I figured. Lack of insulation. Possible hidden 'leaks'. Minimal ventilation.
I'll bet the J-box has nothing but electrons running through it. Looks like it was added just to splice in new stuff and add on. i.e. it doesn't penetrate the ceiling.
Yeah, that junction box doesn't look all that horrible to me. At least they used a J-box! The romex was most likely added to replace knob and tube, and there's probably some BX armored cable up there too.
That's fine, but it means that there are lots of holes for wires between the attic and the living space, and almost definitely no insulation in the interior walls. I bet on a cold day you can feel some serious drafts through the outlets on the 2nd and especially the 3rd floors.
Sealing up those holes, and any other cavities or gaps that lead down, is just as important as adding insulation. Dense-pack will double as air sealing to some degree, but it's not the same as sealing things up with foam.
You are absolutely right. Looks like small details to most people, but as we guys in the trades know (listen to me ... eye roll) ... the best work is all about the small details ... and holes really ain't no small detail ... just one most people don't like to deal with or hunt down.
Mike,
Thats about the same as I was suggesting to the owner , but it sounds better the way you've just described it.
Thanks for the help.
Walter
You're welcome. Bet you aren't getting much roofing done today! I have to go troubleshoot some leaky windows, I'm procrastinating. Nasty out there.
I'm home and going to get myself worked up to pay bills sometime today, but procrastination is fun.You are right - the cellulose is barely a hint of being enough insulation, but in places just enough to stop venting airflow.I'm curious about the 2" galv pipe. guessing it is waste vents to roof, but never seen that material used for it.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
>>never seen that material used for it.<<I've come across that a few times around here. Came across an interesting kitchen sink drain line on a job I'm on now...starts out as an s-trap into 1 1/2" copper, then reduces to 1" copper which is saddle-tapped into the cast-iron main drain. No vent of course.Steve
it looks like a galvanized vent pipe terminating in a cast-iron thru the roof
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some of the existing insualtion looks like cellulose, some looks like rock-wool
Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Maybe even a little FG batt too.Time for Corbond sprayed to the back of roof sheathing IMO.Just got a roof leak call. not surprising. Raining so hard a minute ago that I had no sat reception on the TV.
Time to find my shoes and socks...
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
mike,
You're totally correct on all your assumptions .
Posting from the cab waiting for a bunch of Grace Ultra from my downstate supplier.
Best , Walter
I think you're right:
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Edited 4/21/2009 2:55 pm ET by Mike_Maines
Edited 4/21/2009 2:57 pm ET by Mike_Maines
I'm holding out for a section sketch and a picture where I can see the whole house before I weigh in on an approach. In theory I agree with foaming the entire underside of the roof deck, but if you've got large areas of slope behind plaster that doesn't want to be disturbed, that may change the approach.Steve
Steve ,
I can't get my multi function machine to scan my drawing properly .
The basic configuration is 1.5 story walls with angled ceiling at the second floor and again on the third floor where the two hipped roof dormers are.
Foam would be tough on those angled pieces where there is plaster. Fiberglass or cellulose could be blown down those rafter bays , but no way to see whats gunnable with foam.
I'll try again later to get my scanner functioning.
I don't do sketch up yet - just cave drawings !!
Edited 4/22/2009 5:12 am ET by theslateman
Cave drawings are good...it's the !@#$ gizmo that gets the nice drawing into the ether that's not so great...
Walter, is this something like what you have there:
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Mike ,
Thank you very much for that highly accurate drawing !
You nailed it perfectly !
Lets get a dialogue going on blown cellulose vs. blown fiberglass . Saw a fellow today who blows just FG and told me lots of horror stories on dens pak .
Thanks for all your help.
Walter
>>Lets get a dialogue going on blown cellulose vs. blown fiberglass<<That could take years!Is opening the sloped areas an option? Those rafters look like they are maybe 5" deep. I doubt that any blown-in material is going to have high enough R-value to completely stop melting at that depth...
Steve,
It wouldn't be possible to open up those angled walls to enable foam to be sprayed , but small holes for cells could be repaired.
Whew, got lucky!
The slopes are the only reason my first choice wouldn't be closed cell foam all the way to the peak. That, and foam costs more. Do you have access, or can you make access, to the sloped areas? That would give you the absolute best assurance of no ice dams in the future.
It's a historic-looking house though, so I'm guessing that aside from the occasional slate roof re-do the owners (FlyfishMD?) would prefer to leave interior finishes intact.
If that's the case, at 5" dense-pack would give you about an R-19. Not nearly enough, but with 24" in the attic and kneewall spaces settling out to an R-60, the average of the two would be close to code.
If the rafters are a full 2x8, which it looks to me like the main rafters are, you get a minimum of R-30 which isn't bad at all for your location, though R38 to R49 would be better. The only way to get those numbers throughout is with spray foam.
I'm curious what the horror stories of dense pack are? I don't have extensive experience with it, but of the several jobs we've used it on the only problems I've seen are wet-sprayed 8" walls that took forever to dry, and frequent issues with sheetrock installation.
Mike,
I agree , if it were all easily accessible then foam would do the job perfectly .
Theres very little area that can be easily insulated with any material !
It will be a bit of a challenge to get a good R value thru out.
Thanks again for the accurate drawing.
Best , Walter
I am predisposed to chopped FG instead of cells. Not here to argue with anyone, but I'll explain why since you asked.Part is personal pref since I've had to remove a lot of it when opening walls in remo jobs. I hate that dust. Chopped FG is clean and more like cotton balls to handle.Another is that I have seen it burn or support fire three times in my life so I have less confidence in that fire resistant labeling than the average guy.I think most of the horror stories tho come from something that is not necessarily due to the cells. That is that it holds water a Loooooooonnngg time once it gets wet and that leads to rotten wood. Of course, the primary problem there is that there is another problem that needs to be dealt with other than the cells themselves. water should not get in.But when these hundred year old homes that have always been self ventilating with balloon framing suddenly get stuff full of cells and the airflow stops, the modest little bits of moisture wicking in here and there suddenly have no where to go so the cells slowly get wetter and wetter.
FWIW, my predisposition is to think that FG can have the same problem but to a lesser degree in that it is not as hospitable to growth of micro-organisms and that it does not absorb and wick moisture as readily.With either, the presence of moisture reduces the R-value, which will take you right back to where you are now regarding ice damning.So you really need it to be part of an overall whole house weatherization, ventilation and insulation plan.
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Thank you Paul,
My client will be following along too and try to decide the best plan of attack here.
Walter
Of course BEST is to open those sloped ceilings and spray full of Corbond.I know, I know....There is some discussion of a pour in expanding foam for closed cavities like this, but I have zero experience with that, and one concern being that too much expansion can push the plaster off, while too little will leave barren pockets where you can still have some infiltration and condensation.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
On one of my first contracting jobs we had foam poured into the studs in a kitchen we had just sheetrocked. Blew every sheet off the wall and we had to re-do. I won't make that mistake again! Otherwise I'm a big fan....
Walter,Piffin raises reasonable doubts about cellulose. I can't say I have any personal experience with the fiberglass. I've done a fair amount of cellulose, and have personally not seen anything bad come of it, but I've only been using it regularly for about yen years. I've also opened up a few walls in older houses in spots where I know it has leaked repeatedly over the years and there was no sign of any moisture problems as a result of the cellulose being there.The cells camp posits that it is precisely the behavior of cells w/regard to water that makes it better. It is hydroscopic whereas FG is hydrophobic, allowing cellulose to act as a buffer to swings in moisture, diffusing it when moisture is high, and releasing it when moisture is low. Whereas water will wick away from FG to framing, concentrating it where you don't want it. I have opened quite a few FG batt wall bays over the years where the bottoms of the bays have clearly been repeatedly wetted, to ill effect.My concerns about cells have mostly to do with when you have a real leak that goes undetected for a prolonged period. Cellulose may create real problems with mold and such if it stays very wet for a very long time. But would that scenario be any less of a problem with FG? I don't know.How deep are those rafters? Did I see in one of the pictures that you are Grace-ing the whole roof? That might be a good idea because I don't think you are going to be able to eliminate the ice dams completely with a low r-value in the sloped sections. Though I have a whole other set of worries about covering the whole roof in an impermeable membrane. Darn moisture. It'll keep ya up at night...Steve
fg is a condensing surface
cells are notMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
That's a lot more succinct that what I just said...
I have no data to back this up, but I also think that cells, blown tightly are probably going to be a better air barrier than FG.
Come on Mike , lets hear your side of this please !!
Mike can probably make a good case for cells on this.I promise not to argue with you Mike. Getting soft in my old age.
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Malo isn't the only mellow old dawg you say !!
i guess these are dog-house dormers ?
i'd do the open studs with 1" eps and horizontal strapping , the blow dens-pak cells behind the foam
if you open the rafters....i'd do the same there... if you leave the plaster on, i'd blow dens-pak behind it
in the open attic areas i'd blow 24" of cells
your fg insulator is just mouthing the gospel according to Owens -Corning
none of the building science guys will ever put fg over cellsMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Thank you Mike ,
I'm not as well versed in some of this as you guys here.
Best , Walter
I would clean whatever insulation there is in the sloped areas out, if possible. From there I think I would do things a little differently than Mike suggests. I would spray foam on the underside of the roof deck wherever possible, and run it into the sloped areas a bit, plugging up the exits from the sloped area into the open rafter areas. This would create well-sealed closed cavities in the sloped areas. Then I would dense-pack cells in the sloped areas. If you've not slated the roof yet, you could drill 4" holes in the roof deck and blow from there, if that wouldn't mess up laying the slate. Or if that is problematic, hole-saw 4" holes through the plaster ceilings and blow from the inside and patch the plaster.The reason I would go this way is because I think you have a hard time getting a good air-seal in the transitions from sloped ceiling to flat ceiling in the attic.Steve
we'd be doing a lot of sealing with gun foam too....but only what we could do with our in-house equip.
i wouldn't be bringing in a separate foam insulation company
my strategy would depend on the on-site conditions, and how much tear-out we were going to doMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
>>my strategy would depend on the on-site conditions, and how much tear-out we were going to do<<Yes. It's all armchair quarterbacking from here. Kind of hard to say what I would really wind up doing unless I was there.Steve
Thanks again Steve ,
He said while shaking his head <G>
Steve,
Grace going up about 60% of the way -- 30 lb. felt above it .
Man it just gets more complicated as we go here !!
Thanks for the help.
Walter
Mike,What about foaming the underside of the roof deck instead? Wouldn't it be easier to go that route and seal up any leaking areas there, instead of the ones in the floor/ceiling assembly?That would allow the attic to be used for storage (not sure if that's a consideration in the house in question).Just curious.Thanks,Steve'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
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You have a serious heat leak, dude. But it's strange ... if you had a REAL serious heat leak, it would seem that the water wouldn't freeze until the eave ... so it ain't so simple, maybe. You get a lot of winter wet snow or rain?
I've seen 16" ice dams ... but usually only at the eaves where the roofing is coldest.
I'd still check for some serious leaks into the attic. Fireplace chimney/flue; mech chases. You have a flue downdrafting onto the roof causing thawing?
Maybe 'closing' off the 3rd floor ... was it just shutting the heat vents there? Maybe now you are leaking lots of heat in your ducts leading to the 3rd floor into the attic and now you've created a problem that was minimal before? Just food for thought.
Thanks for the response . We'll be analyzing the floors and attic space this week.