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Old 08-28-2019, 04:27 AM
 
Location: Ypsilanti, MI
2,542 posts, read 3,744,719 times
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Quote:
Originally Posted by Doowlle34 View Post
Interestingly enough, I did schedule a consult with Mincin insulation for this Wednesday. Our roof is probably nearing the end of its useful life, but it is very steep, so we've been told that we can likely get a bit longer out of it, if necessary. The only "issue" we've had is that, in February 2018, when we had a super cold spell, we got a few drips of water from the heating vent in our bathroom ceiling (and there is an area on the ceiling where the paper-thin, outer layer of the ceiling drywall was starting to droop -- i "smoothed" this drooping part back against the ceiling and it hasn't given me a problem since then). In any event, I thought maybe we had an ice damn form on the roof, and we had some water sitting up there for a bit and it seeped through. However, more recently, I thought maybe warm air was escaping from the second floor, which then condensed in the crawl space in the attic, and that this maybe caused the minor moisture issues.
Bingo! I am pretty sure your problem was condensation from the bathroom, very cold temps, maybe a non-insulated vent duct on the bathroom fan, and maybe not enough attic ventilation too.

Personally, I am extremely opposed to ridge vents. Particularly in cold climates where their narrow open slit just above the shingles can be blocked by a heavy snow fall. Can you double-up or triple-up the quantity of box vents on the back side of the home without it becoming too unsightly? You really need to vent at or near the highest point of the roof. I am not sure what you gain by venting the entire ridge lengths on a Hip roof. Plus, O-C made some really horrible ridge vent products in the past.
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Old 08-28-2019, 09:18 AM
 
254 posts, read 99,401 times
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Ridge vents (or vents of any kind really) only work if you can draw sufficient air into the dead space to create a flow. That means some sort of soffit vents cut into the overhang or eaves. https://www.homeadvisor.com/r/soffit-vents/


Someone suggested spray foam on the underside of the plywood sheathing. I wouldn't advise this as it could trap warm moist air in the space leading to real issues with condensation. Also, if you ever develop a leak in the roof, even a small leak, the water has nowhere to go and will just sit in the space between the roofing material and the spray foam insulation, leading to rot. Attic insulation needs to include a vapor barrier between the top heated floor and the attic space. This can be achieved with fiberglass batts with the paper facing down (in the direction of the heated area) or with sufficient loose fill material blown in (cellulose, fiberglass or mineral wool). https://www.thisoldhouse.com/ideas/r...ate-your-attic
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Old 08-28-2019, 10:29 AM
 
Location: Lebanon Heights
191 posts, read 291,380 times
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I had the meeting with the insulation contractor this morning, and it was fairly illuminating. Among other things, while I was aware that we had some "old-style," roll-type insulation in the crawl space above our third floor, the insulation contractor advised that the the floor of the crawl space really hadn't been air or heat sealed (not recalling what terminology he used exactly) and further, for example, that when they updated the wiring, they didn't really seal the holes that they used to fish the new wiring (Up?) or (down?) through the house. Consequently, at least in the insulation guy's opinion, the old-style insulation (even though it was of a reasonable R value) wasn't really as effective as it could be. I also wasn't appreciating all of the different pockets and crawl spaces of my roof, so, for example, I mistakenly thought that the crawl space above our third floor extended to above our second floor bathroom. Not so. In fact, there is a separate crawl space above the second floor bathroom, which can be access through a closet in the third floor bathroom. So, we were able to see that there was no air sealing around the flexible heating tube/vent that goes into the ceiling of the second floor bathroom. So, as I suspected, and as confirmed by MI Rodgers, it is almost certain that it was heat/condensation that caused my issue back in February 2018, and not a roof leak. Also from the crawl space, I was able to get a good look at the underside of the roof in that area (where I first feared a leak), and everything looked good.

So, on ventilation, the insulation guy did seem to say it wouldn't be a bad idea to have some ventilation over, what he called "the four knee walls" which I guess basically corresponds to the four hips.

I guess I won't get the quote from the ventilation guy for a few days, but some local Dormont families have posted similar quotes in our local Facebook page, and they've typically been in the $5,000 - $10,000 range.
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Old 08-28-2019, 11:09 AM
 
2,579 posts, read 2,076,552 times
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Quote:
Originally Posted by Charley Barker View Post
Ridge vents (or vents of any kind really) only work if you can draw sufficient air into the dead space to create a flow. That means some sort of soffit vents cut into the overhang or eaves. https://www.homeadvisor.com/r/soffit-vents/


Someone suggested spray foam on the underside of the plywood sheathing. I wouldn't advise this as it could trap warm moist air in the space leading to real issues with condensation. Also, if you ever develop a leak in the roof, even a small leak, the water has nowhere to go and will just sit in the space between the roofing material and the spray foam insulation, leading to rot. Attic insulation needs to include a vapor barrier between the top heated floor and the attic space. This can be achieved with fiberglass batts with the paper facing down (in the direction of the heated area) or with sufficient loose fill material blown in (cellulose, fiberglass or mineral wool). https://www.thisoldhouse.com/ideas/r...ate-your-attic

Creating an unvented attic is a standard building method. Air and moisture will not get trapped between the insulation an sheathing because an air tight barrier will be formed. It also eliminates any chance of ice dams. Spray foam will bleed water through it so a leak can be identified. Insulating the attic the way you have describe will not eliminate the need for the op's roof to be vented.
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Old 08-28-2019, 11:17 AM
 
254 posts, read 99,401 times
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Quote:
Originally Posted by guy2073 View Post
Creating an unvented attic is a standard building method. Air and moisture will not get trapped between the insulation an sheathing because an air tight barrier will be formed. It also eliminates any chance of ice dams. Spray foam will bleed water through it so a leak can be identified. Insulating the attic the way you have describe will not eliminate the need for the op's roof to be vented.

Right. The roof should still be vented, but the venting is more efficient with soffit vents. I'll defer to you since I am not a contractor, but it never made sense to me to spray foam the underside of sheathing since it seems it would build even more heat from the shingles during summer and make the roof even hotter than normal and quicker to degrade the shingle. But if the manufacturer will warrantee that type of installation, then I guess that's OK. Does it matter if the foam is open cell or closed cell?
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Old 08-28-2019, 11:41 AM
 
2,579 posts, read 2,076,552 times
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Quote:
Originally Posted by Charley Barker View Post
Right. The roof should still be vented, but the venting is more efficient with soffit vents. I'll defer to you since I am not a contractor, but it never made sense to me to spray foam the underside of sheathing since it seems it would build even more heat from the shingles during summer and make the roof even hotter than normal and quicker to degrade the shingle. But if the manufacturer will warrantee that type of installation, then I guess that's OK. Does it matter if the foam is open cell or closed cell?
What causes damage to a roof is different air temps above and below the shingles. Spray foam eliminates that, the temperature stays the same. This is how the formation of moisture is eliminated. Vents are not needed because you are making the attic part of the houses conditioned space. As far as open or closed cell i would not have a preference but the open cell is cheaper.
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Old 08-28-2019, 11:55 AM
 
254 posts, read 99,401 times
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Quote:
Originally Posted by guy2073 View Post
What causes damage to a roof is different air temps above and below the shingles. Spray foam eliminates that, the temperature stays the same. This is how the formation of moisture is eliminated. Vents are not needed because you are making the attic part of the houses conditioned space. As far as open or closed cell i would not have a preference but the open cell is cheaper.
Good to know. Thanks.
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Old 08-28-2019, 07:19 PM
 
Location: Pittsburgh
342 posts, read 329,260 times
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Another reason why they want more ventilation nowadays is the materials used for roofing shingles is more 'earth friendly' than the old ones, which means they are more sensitive to certain things.
Then there is the roof deck materials, & also (probably) a lot more insulation R values & vapor barriers than what the home was originally built with.


I assume you have an old house.


If you look at the underside of your roof, you probably see REAL WOOD sheathing, meaning wood planks, not plywood or OSB.


You also often see gaps btwn the boards where you can see the underside of the tar paper under the shingles.
If they redo your roof, they will probably remove the old, or sheath over it, with plywood or osb, which does not behave even close to the same way under moisture & heat as real wood. It also creates a tighter house air/vapor-wise.


This is one of the reasons OC won't extend any warranty if the ventilation is not in place.


Old houses were built with plenty of space to breathe, as they did not use much, if any, insulation.
As you fill your home with more & more insulation, moisture vapor cannot escape the same way, so you have to manage it with some type of ventilation, otherwise it condenses & you will end up with a lot of rot. The new building materials *DO* rot faster than solid wood, it's what makes them more 'earth friendly'. So in order to protect for this, you must take other measures.


So ya, put in additional vents, there's more than 1 type for each application, you have choices, but you gotta move that air.
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Old 08-29-2019, 06:33 AM
 
Location: Lebanon Heights
191 posts, read 291,380 times
Reputation: 121
Yea, we are definitely an older house -- 1925 -- seemingly a strange period for Dormont, not one of the grander homes you see on Espy or Glenmore, or scattered throughout the borough, but just a solid four square, with living space on 4 floors (including a partially finished, and after some waterproofing, mostly dry, basement). So, you're also right that the underside of the roof, which I think I basically saw for the first time yesterday (although I may have peeked in the crawl space above the third floor previously), is real wood.
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Old Today, 06:06 AM
 
Location: Lebanon Heights
191 posts, read 291,380 times
Reputation: 121
Just to update this post -- my insulation quote came back, and it was actually quite a bit lower than I anticipated -- only $3,000 to air seal and add blown-in insulation to the crawl space above the third floor and the knee wall areas above the second floor. Also, I spotted a few more roofing companies doing work in the neighborhood, so I made some additional calls to get other opinions. One larger company came out yesterday, and while I don't have their quote yet, in terms of ventilation, they want to use a GAF power fan -- which is something no other company had suggested (I'm also not sure if multiple power fans would be required, as I'm not sure if a power fan on the ridge would pull air from those knee wall areas). When I asked about hip ventilation, the sales guy wasn't necessarily sure, although he said he had been working at the company for two years and could only recall putting hip vents in a handful of roofs. [After I posted this, the quote did come in -- although this new company is basically $1,500 above Gutter Helmet, with no removal/re-hanging -- although, to their credit, they said they would do the project with either a power fan, or 5' of ventilation on each hip. Further, when asked why they typically start out with recommending a power fan rather than passive hip ventilation, the reply was basically that hip vents can be difficult to do, and that is why not many roofing companies do it --which seems to make sense based on my experience thus far.]

I also talked to a independent roofer who was doing roofing work in the neighborhood as well, and although he can't get out for a few weeks, he said that he typically didn't put hip ventilation in these Dormont style roofs either.

Another discrepancy is that both of these companies simply wanted to leave my gutter helmets in place during re-roofing, rather than remove it and rehang after the roof is complete.

I also appreciate Guy's recommendation on spray insulation, although that would sort of put me back to square one in terms of getting quotes/contractors. (That said, if I had used Guy's recommended concrete contractor last year, I would have saved $2,000 and likely came out just as well, or better than I did.) In addition to having to sort of "start over" with that strategy, another concern is whether all areas of the underside of my roof could be accessed for that sort of insulation. Also, does coating the underside of the roof help keep heat in the living areas as well -- or would I still have to insulate the crawl space floor and knee wall areas, as I assume I would still be losing heat through the second and third floor ceilings.

Last edited by Doowlle34; Today at 06:49 AM..
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