Stripping asphalt shingles from an old roof with Ice and Water Shield underlayment?
Well, that's the challenge I had recently on my old house (house is about 80 years old). I had a roof that was stripped and re-shingled 22 years ago (1989). It's a fairly low-slope roof (2 1/2 - 12 pitch) with a southern exposure, and it takes a real beating from the sun. I knew it had an Ice & Water Shield underlayment around the perimeter because I was the one that installed the roof 22 years ago. Yeah, that's right.
I&W shield membrane was rather new then, and I remember being excited about being able to buy some back then from a local roofing supplier. As a young man in my late 20's, it never occurred to me that I would ever have to strip that roof off. The norm then was to only strip a roof after it had two or more layers of shingles. I figured if I did still live there 20+ years later and needed to do the roof, I'd just put a new layer over the top since I stripped it this time.
Well, here I am 22 years later, and in the past couple of years the shingles deteriorated significantly.
It was in such bad shape, I didn't want to risk putting a new roof over it. Plus, that practice--though still used--has proven to be not as durable as a tear-off and re-roof. I wanted my new roof to last as long a possible because I'm probably going to be too old in another 15 or 20 years to do this again.
So now I'm thinking about that I&W underlayment and am wondering how difficult it will be to tear the roof off with that stuff. I like to be prepared so I wanted to know things like whether it would be better to plan the tearoff for when the temps were cool or would it be better in the hot sun. Or any other tips or techniques that would help me out. I know roofers have to be running into some of this now, so I hit the internet looking for info.
I really didn't find much. I guess since most roofs put on 25 years ago didn't use I&W shield, this is still kind of a new issue. But, since I figure there is going to be a lot of this over the next 10 or 20 years, I thought I'd document my experience to help out the next guy.
I gathered the tools I figured I might need. I even sharpened the blade on that heavy duty ice scraper hoping that could be my tool of choice.
I got started early in the morning to see how it went in the cooler temps.
Well, it sucked. Wherever the shingles had contact with the ice and water underlayment, they were completely embedded in it and were not budging. Another part of the roof was getting some direct sunlight, so I figured I'd try the "hot" method. It was a little different since the stuff was softening up a bit, but that stuff still wasn't coming up. I mean, it wasn't even close to coming up.
The above photo pretty much says it all. You can see how the portion of the shingle that directly contacts the I&W shield is now part of the roof. The most I could do was scrape off the portions of the shingles that overlapped the shingle below. So basically you're removing about 60% or so of the shingle (maybe more) and ending up with the rough equivalent of a single layer of asphalt roofing (like the old roll roofing). On the left side of the pic, you can see where the I&W shield ended below the roofing felt, and subsequently the shingles above this point come off clean. I should note that even where there was overlap of roofing felt over the I&W shield, the shingles still stuck to some extend (not as bad, but still stuck).
Here you can see what it looked like after removing the remainder of the shingles. Damn glad I only used that stuff on the perimeter.
The one positive here for me was that the shingles were so severely stuck that I knew relatively quickly there was no way in hell I was going to be able to scrape them off. Otherwise I might have spent a lot more time trying other ways to remove them.
So my choice was rather simple now. I can either tear off the roof decking and replace with new decking, or I can scrape enough to get a relatively smooth surface to shingle over. I ended up doing both.
This was essentially a three-sided hipped roof over a small addition off the back of my house. Two sides had a few areas where I needed to replace some decking, and there was also an area where I needed to fix some of the framing because they did some really hokey framing on this house. So I cut out the old decking where the I&W shield was, and replaced with plywood. I'll add here that even cutting those old boards off the roof was a lot more difficult due to the ice membrane. I ended up cross-cutting the decking about every 3 feet, and then prying up the group of boards as 3 foot by 3 foot sections, because the I&W shield just wasn't letting anything go.
On the third side, I had replaced that area of decking with plywood when I did the roof the first time, and it was still very solid. So I really didn't want to send a solid roof deck to the landfill. Plus, I kind of liked the idea of leaving part of the roof like this just to see if it holds up as well (I think it will).
A few more notes on Ice and Water Shield.
I don't know what brand of I&W shield I had originally on the roof. I still have some of it, but it doesn't have any brand information on it. It did have the granular surface that many brands still have today. It may be that some brands are easier to remove, or that depending on the climate, pitch, or other factors, some may tear off easier. With mine being a low slope roof with a southern exposure, it may be the worst-case scenario, so maybe some of you will have better luck.
The new Ice and Water shield I installed (made by Grace) is a little different in that it has a sort of film on the surface that I believe is meant to allow shingle s to come off easier. But that's not how the stuff was 20 years ago, and that's not how a lot of the stuff sold today is. In addition, it's going to be another 20 years before we know how this new stuff works.
Also, on low slope-roofs (like mine), some people recommend putting I&W shield over the entire roof. I'm damn glad I didn't do that last time, and I did not do that this time either. For the remainder of the roof I used a double layer of 30 lb felt (each layer overlapped by 18 inches). Here's a link to the write-up I did on Shingling a low-slope roof.
There's also a high-temp version of I&W shield available. I've seen it recommended for metal roofs, but I don't know much more about it than that. I was surprised to find that my local menards actually had some high-temp stuff in stock. Actually I was surprised that between Menards and Lowes, I had about 5 choices of I&W shield in stock. I got the Grace stuff primarily because of the film that is "supposed" to prevent shingles from sticking, but also because I had a rather small roof and the extra expense of the Grace (it cost more than the other brands) was not that big of a deal.