Rochester WeatherHiring a Roofing Contractor
Expert opinions indicated the roof on my house was reaching MTBF. Being the pro-active type, I started saving up cash with intent to have it replaced before it started leaking. I knew it wasn't going to be cheap, as the house required a tear-off.
Year 2002 came, and the first contractor gave me a ring trying to drum up business. I figured that despite not having enough saved yet, I'd have them come by and give an estimate so I'd know how much to save up. If I liked them, I'd know who to call when I had the cash ready.
Contractor #1: The Cadillac of Roofs
The estimator came by and spent a fair amount of time explaining how the roof is supposed to work. He actually provided formulas and all. I grasped the ideas, but need to do some follow-up research at the GAF roofing web site. I've included a short summary of this stuff at the end of this document.
Despite their time and attention, their price was way high ($10,500). That did include a GAF materials and workmanship warranty, which was more than the later folks could provide. Still, more than I thought was reasonable, and a warranty would be void if I end up putting up solar panels some day. It also bothered me that he was trying for a hard sell, pushing me hard to sign the contract the night he came by. If I didn't have the cash, they had a financing plan to help me out. The hard sell turned me off to them, though I think they really did want to do the job to an exceptional quality.
In 2003, when I'd saved up enough dosh to pay what I expected ($6-$8K), I contacted a few other contractors.
Contractor #2: You called?
Contractor #2 took my name and address, and I never heard from them again.
Contractor #3: Thinking outside the box, or just a cheap hack?
Contractor #3 came by and expressed a different opinion. I had a roof with one layer of cedar shakes (1920s roofing) and two layers of asphalt shingles. That left the option of a third layer of asphalt shingles. His assertion - I've never determined if it's true or not, but he was certain about it - was that since they're real wood, the cedar shakes could deal with the abuse of no air gap between them and the insulation far better than the plywood used in a modern roof deck. This all seemed good, along with the $2,200 price tag, until I looked at the rafters more and realized I had 2-by-4s at 24 inch spacing, not the 2*6 or 2*8s at 16 inch spacing like I originally figured. This quickly changed my opinion away, as I think swayback looks pretty stupid on most buildings. Besides, my garage has enough swayback for the whole yard.
Contractor #4: The well-trained market droid fails when you don't ask the right questions
Contractor #4 wanted to do the more traditional tear-off plan. He seemed to understand the venting ideas, and suggested installing four 4*16" soffit vents on either side of the roof, along with a ridge vent.
I, being a geek and having researched this stuff, had questions: How does the airflow spread evenly across the 32 feet of roof if the intake vents are spaced 6 or 7 feet apart? Well, it just does. But won't the rafters hold it into their 24 inch span? Well, the old slats -- 1*6" boards running lengthwise across the rafters to which cedar shakes were nailed - have gaps between them through which air can flow. But the ventilation won't be even across the roof, so I'll end up with warm spots, resulting in ice damming, right? No, this works good.
Eventually I gave up. Quote: $6,800 with gutters.
Contractor #5: Did I see this guy working at that used-car dealership last week?
Contractor #5 wanted to meet my expectations. He laid out some numbers, gave me a price. I started to ask some questions, but just for me, just that day if I signed right then - he'd cut 10% off the price. This threw me off. I hadn't even tried to negotiate price, hadn't even wanted to, and he'd offered to cut the price. What I really wanted to know was whether or not he planned to do it right. Oh, right, that didn't matter; all roofers are the same and it's just a matter of price. Tell me what, I drive a hard bargain, he'll throw in free gutters with the roof.
I finally got off the ventilation questions, and his plan was to install 8 2" hole vents on either side of the roof. I posed the ol', "How's the air move between the rafters?", to which the response was that if I signed the contract I could have as many bleeding vents as I wanted, in any style and color. Fuck, if I wanted he'd just bulldoze my house and install 32'*28' of dirt vent for one low price of $5,250, I wasn't going to get an offer like this again. I had 3 days under New York State law to rescind my signature on this type of contract, so it would be good to sign right then. Besides, if I didn't sign, the chances of me calling him tomorrow were 0, at least based on his prior empirical evidence...
Contractor #6: Still holding my breath 'til 2005
Contractor #6 showed up. He wanted to do a tear-off, install adequate ventilation, and had a solution to the issue of the insulation blocking the air flow: Just put furring strips (1-by-2" strips of wood) over the slats to raise the plywood decking up enough to allow ventilation.
I took a bunch of references and called people up. Of 5 references I copied, I checked out 4 buildings (2 of which had significantly more complex roofs than mine) and talked with 3 residents. Two had minor leaks that the contractor had been okay about fixing. Of the two with leaks, one couple was still overall very happy with the contractor, and the other customer indicated prior good experiences and only problems with the one recent project. Further, the BBB indicated 2 complaints in the last 3 years, for which the contractor had made good faith to address all of them.
After a week of thinking about it, I decided that despite the issues with contractor #6 I would go with them since it sounds like if there's a problem they're good about fixing it.
Oddly, while negotiating the contract they wanted to shave $210 (3%) off the cost total cost ($6,600) by putting down 3/8" plywood, which is out-of-spec (GAF recommends 1/2" for 24" rafters). Thankfully, I caught it and fixed it in the contract.
So did I select a good contractor? The installation looks good, but ask me again in 2005 after the roof has had a chance to break in and weather a few heavy storms. If I don't have any leaks by then, I probably did great; if I've had minor leaks and they fix them quickly then I did alright.
So how is this roof supposed to work?
Disclaimer: This is my interpretation, I might be wrong. Read the original materials yourself. I'm not responsible if use or misuse of this information fucks up your roof, house, or something else.
On a modern roof the attic insulation isn't supposed to be jammed against the underside of the roof deck. There's supposed to be a 1" or so gap, and you should have soffit venting ("intake") and a peak vent ("outflow"), and you get convection underneath the roof deck (see the diagram at the bottom of this page). This keeps the shingles cooler in the summer, which makes them last longer; in the winter, the whole roof stays is at the same temperature, which in theory prevents ice damming. Ice damming occurs when snow over the warm living space melts, runs to an overhang, and freezes because the overhang is cooler. Multiple layers of ice form the dam, and then water backs up behind the dam and under the shingles, which gives the shingles a ruffled look (like when you pet a cat backward).
The total ventilation the roof needs is 1/300 the area of the attic. If you have 30'*20' = 600 feet2 of attic, you need 2 feet2 = 288 inches2 of ventilation. Intake should be ~55%, output ~45% of this. This should be spread evenly, so if you have a plain roof then length cancels out:
width_of_vent * length_of_vent = (width_of_attic * length_of_attic) 300
width_of_vent = width_of_attic / 300
Note this is the total vent width, and it needs to be split between intake and outflow, and intake needs to be further split between the two sides of the house. My impression is this is a minimum recommendation, but I'd suggest the reader review the docs from GAF and elsewhere to form their own opinion.
Addendum #1: Roofing status in early February, 2004
My roof has been experiencing its first winter, and it's been an unusual one. We had an early cold in late November and early December accompanied by roughly a foot of snow over that time. We then had a thaw, and the roof completely melted off.
Starting in January, we got into an unusually long, often bitterly cold snap (for Rochester, anyway) with daily snow for nearly four weeks. The roof itself, in my opinion, worked as specified. Issues, however, occurred with the venting.
The basic problem is the gutters. Gutters don't work, because gutters have about 20 potential points of failure and any one of them failing results in a breakdown of the whole system. The underground drain must not plug AND the downspout must not plug AND it must not freeze AND the eave trough must not get filled up with leaves and/or grime AND the it must have a gentle slope AND it must be properly attached so it isn't bowed downward AND it must not freeze up AND nothing else must go wrong.
On the north side of my house, the downspout froze. The underground drain seems to be okay, so I think it just froze up over time from trickles of water running down the spout on milder days. Once the downspout seized, the eave trough filled with ice. The ice gradually built up and formed a dam, which eventually got large enough that new runoff was run up the drip-edge venting and into the house's overhang, which was cool enough for the water to freeze. It remained there until a warm day, when it melted. Since my overhang is flat on the bottom, the water ran across and down the wall, matting the blown-in insulation in the wall and reducing the insulation's efficiency. It appeared as icicles coming out between the rows of mineral siding on the side of my house, and as wet plaster and peeling paint in my foyer.
My thought now is that the drip-edge vent was a bad choice. In a warmer climate, fine -- but not here. However, to get by until it's time to replace the roof again in 30 years, I'm going to install a de-icing cable in the gutter and downspout to ensure melting and prevent damming on near freezing days.
For what it's worth, the south side of my house hasn't displayed the problem despite the downspout freezing up because the underground drain is plugged. On sunny, mild days the downspout melts partially and drains onto my driveway. I think there were enough of these days that it was unable to form the same, huge ice dam necessary to cause problems. By contrast, the north side of my roof doesn't get any sun until February, and then only a little.
Again, check back in a few years for my analysis of how the de-icing cable is working.
Addendum #2: Roofing status in mid February, 2003
The continuing saga of the ice dam: as melting started up the ice melted unevenly, bending the gutter down and outward. However, it was adequately attached to the building such that instead of just falling down it ripped the fascia board and some overhang parts off. One chunk of ice fell immediately, smashing the neighbor's car window and removing their passenger-side mirror. The remainder - ice dam, gutter, fascia board - hung for about a week before the ice melted enough to fall.
This is not, however confined to my house: 5 other houses on the street have near-identical problems, and 2 others have gutters that just fell down. By memory, the yearly average is probably that 1 or 2 houses have fallen gutters each year, but I've never seen one take the fascia board with it until this year.
Addendum #3: Roofing status in mid February 2007
The ice dam has recurred, albeit less pronounced than the prior time (but nevertheless doing what will no doubt be a costly repair). Looking at houses up and down the street, gutters unavoidably fill with ice. I agree 100% with my prior conclusion the drip-edge vent is the problem, and that it needs to be removed and replaced with soffit venting which goes on the underside of the overhang. A drip edge is acceptable in warmer climates or without gutters, but invites failure in a cold climate with gutters.
