# Rubber Roof over Ice & Water Shield



## R&RRenovators (Dec 29, 2008)

The right way to do it is to remove everything down to the plywood. Replace any damaged plywood and install glass base sheet over the plywood ,after adding 1/2"fiberboard. If you have alot of drains on the roof consider a tapered lot roof insulation.


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## PerpetuallyRepairing (Apr 7, 2008)

I have no experience trying to remove I&W shield but it is pretty sticky stuff. YOu are talking 13 squares or 41 sheets of plywood if the plywood would have to come off. All the skylights would have to come off as well. This would more than double the price of the reroof. 

In that case I would just rather redo what is up there by tearing off the shingles and putting another layer of I&W shield & new 3 tab shingles. I could put tear out the ceilign and put in R50 if I wanted it to last longer. THis would lessen the amount of ice damming.


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## BornaRoofer (Sep 19, 2008)

Just have him slice the ice and water at the plywood joints and dont worry about it. It will be fine. And epdm is a great product on flat or sloped roofs. Id stick with the black material though it lasts a lot longer than white does. if you need white either paint it or go with a pvc or tpo membrane.


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## RooferJim (Mar 11, 2006)

Its fine to go over the I&W shield. I would however not recomend using fiberboard at all. You should use polyiso instead as it dosent absorb water like that garbage fiberboard does. although it is more money. Fiberboard is just compressed recycled sawdust laminated together, that all it is. If you ever have a leak it holds water and rots out the decking.

RooferJim
www.jbennetteroofing.com


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## PerpetuallyRepairing (Apr 7, 2008)

Okay, Isoboard. I think as long as there isn't anything that will rot above the I&W shield I should be okay with the I&W shield. I will see if I can get anyone to install TPO or PVC if durability of the white Firestone EPDM is an issue.
Thanks.


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## BornaRoofer (Sep 19, 2008)

Firestone's white epdm called ecowhite is fairly new to the market and according to them is better than the older white epdm. But they don't offer a 30 yr warranty on it but will in black. Although they don't warrant residential at all. If you cant see the roof really and are using iso then where you live white is not that important. Theres just not that many days of hot weather to need it.


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## PerpetuallyRepairing (Apr 7, 2008)

It's visible. I don't think I can get away with black in my neighborhood.


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## the roofing god (Aug 2, 2007)

Go WITH PVC,Sarnafil,or IB roofing systems offer excellent systems


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## PerpetuallyRepairing (Apr 7, 2008)

TPO is peal & stick so the roofer prefers that over PVC. Can this be stuck directly to the I&W shield? I was also told I could put Densdeck or ISO board under the TPO. Not sure why I need a board underneath it unless it is to improve impact resistance. Neither Densdeck or ISOboard is advertised for impact resistance. The roof is pretty solid 2 x 10s 16" O.C. spanning 12 feet max. with 3/4" CDX plywood


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## the roofing god (Aug 2, 2007)

PerpetuallyRepairing said:


> TPO is peal & stick so the roofer prefers that over PVC. Can this be stuck directly to the I&W shield? I was also told I could put Densdeck or ISO board under the TPO. Not sure why I need a board underneath it unless it is to improve impact resistance. Neither Densdeck or ISOboard is advertised for impact resistance. The roof is pretty solid 2 x 10s 16" O.C. spanning 12 feet max. with 3/4" CDX plywood


NO,The iso is there to "divorce" the membranes,basically prevents expansion/contraction issues from affecting the top roof---the tpo is a cheap imitation for a PVC roof


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## BornaRoofer (Sep 19, 2008)

Actually Tpo is chemicly more like epdm than pvc. And its no imitation. Its a replacement for pvc if anything. Pvc is a carcinogenic and also is made with plastisizers wich leach out over time causing the pvc to become brittle and possibly crack.


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## PerpetuallyRepairing (Apr 7, 2008)

According to Dow's TPO (Steven's EP Fully Adhered System) installation manual the membrane can be directly adhered to plywood or concrete as long as the gaps are < 1/4". Thus if my plywood & I&W shield was put down well, it looks like I don't need an intermediate layer.

Reading industry articles there is a concern over TPO systems because they are not as time tested as PVC. Perhaps some brands of TPO are better than others?


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## the roofing god (Aug 2, 2007)

not the best application unless all plywood is screwed and exposed plywood is finished grade(top side sanded),and cut edges are sanded,you should use a slip sheet,firestone makes one of the better TPO`S,but PVC is the better product ,and much easier to weld down the line---there are topics elsewhere regarding TPO failures(including stevens)-don`t think the boss here would like me accessing other forum topics for you,so I won`t


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## AaronB (Jan 29, 2005)

Well why dont we start with......

Why and where is it leaking? A 4/12 pitch shouldnt need a low slope system, especially if you have full coverage of ice and water shield. Got any pics?


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## the roofing god (Aug 2, 2007)

sounds like skylight issues,and they don`t want to flash it with shingles,they`re worried about 2 ft of snow,but it could be flashed properly to work IMO


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## AaronB (Jan 29, 2005)

Yeah, that's what Im thinking, to, TRG.


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## BornaRoofer (Sep 19, 2008)

I always flash old leaky skylights on shingle roofs with 9" or 12" epdm peel and stick. Right to the glass and 4"-6" onto the shingles then caulk. Never had a call back on one yet.


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## AaronB (Jan 29, 2005)

Is it indeed the skylight that's leaking? 

There are better ways than covering the problem with rubber.


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## PerpetuallyRepairing (Apr 7, 2008)

Picture enclosed. The area with the sliding glass doors is 4/12 pitch. There are 5 skylights on that pitch all with curbing. One skylight is on the 8/12 pitch above it and one at the pitch transition. The two lowest skylights are leaking. They do not have step flashing on them so the ice & water shield has been the only protection there. 

Yes, the skylights could be reflashed & the problem would go away but the 20 year roof has only 3 years left on it. The cathedral ceilings are 30 feet long (sophet to ridge) with R30 insulation so ventilation is poor and ice dams are a problem. We had 2 feet of snow on the roof last week. 

I am not that comfortable just putting a new 3 tab shingle over I&W shield with such big ice dams (foot thick sometimes). I could tear out the ceiling put in R50 spray foam & reinstall it & then I think I&W shield would be okay. This is costly. The roof isn't all that visible & membranes don't seem that more expensive than shingles. Yes, it is a big slope for a membrane. Any better ideas? Thanks.


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## the roofing god (Aug 2, 2007)

LOOKS STEEPER THAN A 4,PROBABLY CLOSER TO 5 OR 6 pitch,changing into a 7 or 8 pitch main roof---If the issues are mainly the skylights ,you could build temporary insulated boxes over them for winter,I would use Certainteed Flintlastic SA 3part (white mineral surfaced) system once the weather is over 50 degrees,so the materials seal properly---It`s a 15 year mfgr warranty,but 20 year is available for commercial propertie`s when they use the exact same material-They figure a residential roof is prone to more foot traffic,and hence will wear out faster as a result


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## PerpetuallyRepairing (Apr 7, 2008)

The roof is definitely 4/12 and 8/12. It appears to be steeper because the ground slopes. Yes, The Flintilastic looks like a good solution. How long do you think it will last? I would like to get a 30 yr 3 tab shingle roof for the rest of the house. 

PVC seems like a better product because the seams are welded, not glued and perhaps snow slides off easier? PVC might be overkill for 4/12 though. 

Would I tear off the layer of shingles & nail the bottom layer of Flintilastic to the I&W shield? Can the roofer use a nail gun? Thanks.


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## AaronB (Jan 29, 2005)

If the ice gets that thick in your area, you might want to raise those curbs. Even if you membrane roof the lower of the slopes, ice will still be able to back up over the top of the skylights themselves and work its way in between the layers, over the curbs, over the flashigns, etc. 

The SPF would be a bit costlier, but would save on heat loss as well as create a true vapor barrier if you used a closed cell, and could be accomplished when you tear off the roof.


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## BornaRoofer (Sep 19, 2008)

AaronB said:


> Is it indeed the skylight that's leaking?
> 
> There are better ways than covering the problem with rubber.


Not really. If you flash the skylight with epdm it wont leak anymore.
Before shingling or after either way it wont leak if its done right.


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