How To Remove Ice And Water Shield?

 
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Old 05-04-2007, 06:09 PM   #1
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How To Remove Ice And Water Shield?


I am a general contractor doing work up in Alaska and have come across a problem I'm hoping somebody can help me with. Part of a job I'm working on is to remove existing Grace Ice and Water Shield from a 30,000 square foot roof. Are there any tricks of the trade to make this possible?
It is a 4 year old roof, with the Ice and Water Shield on structural insulated panels (outer layer is 3/4" OSB) so we are not able to simply replace the plywood, we need to remove the I&W and build a new roof system 8" above the existing one for circulation reasons.
Open to any and all suggestions, Thanks!
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Old 05-04-2007, 06:31 PM   #2
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Re: How To Remove Ice And Water Shield?


you cant remove old I&W you just clean it down and go over it.

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Old 05-04-2007, 06:49 PM   #3
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Re: How To Remove Ice And Water Shield?


yeah, not FEASIBLY possible. you would spend years taking it off. always figured that product would eventually cause more problems than good.
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Old 05-04-2007, 07:05 PM   #4
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Re: How To Remove Ice And Water Shield?


Maybe if you need it to "breathe" into your new roof space, you could use something along the line of a wallpaper perforator (maybe like a Garden Weasel) to poke millions of holes in it? Just an idea. Wait... that stuff is self-sealing, isn't it? Oh well... just trying to think outside of the box. Maybe the Jack-Rabbit tool that carpet guys tear up glue-down's with? http://www.thejackrabbit.net/
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Old 05-04-2007, 07:27 PM   #5
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Re: How To Remove Ice And Water Shield?


just go over it

you can scrape, pick, and even torch and it'll never come up
especially if its Grace ice n water
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Old 05-04-2007, 07:43 PM   #6
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Re: How To Remove Ice And Water Shield?


It will melt and run with a torch, but it may also wind up being a fire hazard if you were not careful. I also could not advise as to how the permeance would be affected by the liquified polymer which then would probably react as a bituthane coating over the decking.

You must be attempting to come up with a removal situation to increase the vapor transmission through the decking.

If that is your intention, then MdShunk probably was the closest to providing a solution.

What if you determined the quantity and diameter required of small little drilled vent holes to create an efficient permeance through the decking. Just have a set sequence and pattern to continually drill the appropriate diameter drill holes through the wood decking.

Time consuming? Yes. But the alternative is to create an 8 " high blocking and install fake 1 " x 8 " rafters over the existing surface to provide the clearance required and then re-sheath the entire structure.

The math is beyond me without a geometry book and the desired amount of vapor transmission required would be a calculation for an engineer.

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Old 05-04-2007, 09:13 PM   #7
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Re: How To Remove Ice And Water Shield?


I agree with ed the roofer. The old GIWS can't be removed, only abandonded. Drilling vent holes for ventillation, if needed or simply frame up your new stuff on top of the GIWS if not.
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Old 05-04-2007, 09:21 PM   #8
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Re: How To Remove Ice And Water Shield?


An insulated panel with OSB top, screwed to the structure? That aint gonna let the vapor through effectively, if at all (depending on the insulation type) anyways.

I think the best you'll get without replacing the panels would be to remove it at the panel seams, IF you have an open cellular structure in the insulation.

Lets ask this...why are they deciding to do this?
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Old 05-04-2007, 11:35 PM   #9
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Re: How To Remove Ice And Water Shield?


I think this 100 % I & W substrate coverage thing is about to explode! Especially with the use of OSB, and the "tighter" buildings being built these days.

It just may be the next construction defect bonanza for the attorneys.
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Old 05-05-2007, 09:18 AM   #10
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Re: How To Remove Ice And Water Shield?


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Old 05-05-2007, 02:25 PM   #11
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Re: How To Remove Ice And Water Shield?


Thanks for all the responses!

I believe the reason for removing the I&W is because condensation is forming underneath it. The structural insulate panels are one layer of 3/4 OSB, 12 inches of EPS, and then another layer of 3/4 OSB. Then the I&W, then asphalt shingles. This is in the middle of Alaska where winter temperatures get down around -30 all the time. So I'm guessing that now after only a few years since being built they are seeing the outer panel OSB beginning to rot. Exactly as Ed the Roofer said in his post, we are building a new roof 8" above the existing panel surface with a lot of ventilation to keep the top of the panels dry. So the reason to get the I&W off is not to allow permeance through the panel but to allow air to get at the panel from above.

Unfortunately I am not the engineer or architect, just the lowly contractor who can make suggestions, but in the end we just have to say yessir and get it done.

Here are some of the suggestions I've had from here and other sources (Grace technical engineers have not yet got back in touch with me):

1. It's not possible. Forget it. Go over it. (Not an option in our case).

2. It's not possible, try making holes in it using various methods from drilling holes to using those Jack-Rabbit carpeting tools. (Only an option for us if we can show that pulling it up really is completely impossible).

3. Try scraping it up using a flooring/carpet stripper. Something like this www dot palmerdistributing dot com slash strippers dot html (sorry it won't let my paste in URLs). (I don't know... what do you guys think?)

4. Try getting it cold since it is easier to pull up cold. Use ice or dry ice to get it very cold then pull it up. (Seems a bit outlandish and/or expensive, but what do you guys think?)

5. Set up a skillsaw so that the blade barely cuts into the OSB. (Seems like the blade would gum up right away. What do you think?)

6. Attack it with chemicals. (We can't damage the panels but do you know of anything that might help?)

7. Hire about 40 guys and give them scrapers and say goodbye to your retirement because it's going to take them weeks to get it off. (I was rather looking forward to retirement, so I'm hoping to avoid this one).

Sounds like the majority are leaning to #1 or #2. Please no votes for #7.
Looking forward to more responses. Thanks again!
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Old 05-05-2007, 02:31 PM   #12
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Re: How To Remove Ice And Water Shield?


BTW For all those who are bemoning the use of I&W over the entire deck, you will be pleased to know that the engineers/architects are asking for not one but TWO layers of new I&W over the entire new roof that we add.
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Old 05-05-2007, 02:34 PM   #13
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Re: How To Remove Ice And Water Shield?


A couple of other thoughts if the 3/4" OSB is rotted:
Replace the SIPS ?

Separating the foam from the OSB with a Hot Wire? then gluing new OSB to foam?

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Old 05-05-2007, 02:41 PM   #14
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Re: How To Remove Ice And Water Shield?


Two is no better than one, but if they are trying to accomplish a venting system, why add to the problem?

If the OSB is rotting, wouldnt it need to be repalced? I say install permanent decking and plywood facer.
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Old 05-05-2007, 03:26 PM   #15
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Re: How To Remove Ice And Water Shield?


Another option I failed to consider, is to use a commercial gravel scratching device.

I haven't used one in years, but the spinning drum had a bunch of abrasive prongs attached. The intent was to be able to spud the gravel surface off of a built up hot asphalt roof with an embeded gravel surface.

In most cases, when this machine was used, it created more damage to the underlying plies of felt paper instead of just dislodging the embedded gravel surfacing.

There probably is some other types of equipment that is used for scoring concrete or asphalt roads, which could basically scratch off the I & W shield membrane with minimal distruption of the underlying OSB board decking.

But, if the decking is already in the beginning stages of some form of disintegration or decomposition, why in the heck would the engineers/architects even consider going over the top of it with a completely new system. The degradation will surely contnue and the cost of doing future repairs will be increased exponentially.

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Old 05-05-2007, 05:51 PM   #16
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Re: How To Remove Ice And Water Shield?


Hello,

I live in Alaska and We had the same issue with the school in Scammon Bay. Call USKH in Anchorage and ask them how they solved the problem. I shingled on the school the first time but was not there when they had to build the vent space on top of the original decking.

Keith

BTW USKH is an engineering firm if you didn't know.

Last edited by Roofboy; 05-05-2007 at 05:56 PM. Reason: Adding info.
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Old 05-05-2007, 05:58 PM   #17
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Re: How To Remove Ice And Water Shield?


How would doing this even solve the problem? They need a vapor retarder or barrier on the warm side.
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Old 05-05-2007, 06:09 PM   #18
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Re: How To Remove Ice And Water Shield?


Keith (Roofboy), I would be very interested in speaking with you. I have actually spoken with USKH (they were only helpful in saying that it had been done before but couldn't tell me how). Could you give me a call? I would very much appreciate it. 907-561-1026
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Old 05-05-2007, 07:23 PM   #19
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Re: How To Remove Ice And Water Shield?


Quote:
Originally Posted by AaronB. View Post
How would doing this even solve the problem? They need a vapor retarder or barrier on the warm side.
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Old 05-06-2007, 09:35 AM   #20
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Re: How To Remove Ice And Water Shield?


3in12,
Are you in the Western US?
I am Grace Tech Rep in the West.
801-573-2789, james.p.morgan@grace.com
Jim

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