Membrane Roofing - Avoid Windy Rain and Ice Dam Leaks

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By Tim Carter
©1993-2010 Tim Carter

Summary: Installing membrane roofing on roof trouble spots can minimize or eliminate leaks due to wind blown rain and ice dams. These sheets of modified asphalt seal out water leaks and close nail holes where water can make its way into your home.

Related Articles: 
Shingle Installation, Ice Dam Barriers, Membrane Roofing Manufacturers

The past two winters and summers have made me a believer in water and ice roof membrane products. The people in our coastal areas have been pounded with hurricanes which are accompanied by vast amounts of wind driven rain. Homeowners in the snow belt of the USA were buried with record snowfalls in the winter of 1995-96. These snows create ice dams. The ice dams in turn create rivers of water in houses. Fortunately there is a group of products which can minimize or eliminate entirely leaks caused by these problems.

What are the Membranes?

The membranes which eliminate the roof leaks are simply sheets of modified asphalt. Standard asphalt is mixed with rubber and other proprietary compounds to make it sticky and flexible. This mixture is then applied to a plastic sheet. The plastic sheet allows you to work on top of the product. Without it, you would get stuck on the roof like a fly on fly paper! The membranes are usually about 3 feet wide and come in rolls that contain about 60 to 70 linear feet.

Where Do They Go?

The membranes are installed on areas of a roof that typically can be trouble spots for leaks. Leaks from wind blown rain or ice dams can develop at the lower edge of a roof near the gutters, along the side edges of a roof (rake edge), in valleys where two different roofs intersect, at skylights, other flashing areas (chimneys, plumbing vents, etc.), and at roof slope changes.

The membranes are applied directly to the wood roof deck surface before any felt paper or shingles are applied. That is one reason why they are so sticky. They stick tenaciously to dry, dust free, solid wood.

How Do They Work?

You might ask why one can't simply use heavy 30# felt paper in these same areas to prevent leaks. That would be a fair question. The reason is simple. The nails used to tack shingles penetrate the felt paper. The felt paper does not completely seal around the shaft of the nail. This is where the water starts its journey into your home.

The membranes are different. The thick layer of rubberized asphalt readily coats and seals the shaft of any nails that penetrate the membrane. This is why they stop water. The water which gets under the shingles simply flows over the top of the membrane until it gets to the bottom edge of the roof. There it exits without doing any interior damage.

Are They Worth the Expense?

If you have ever experienced a persistent leak from an ice dam or a leak from wind blown rain, you already know the answer to this question. Ice dam leaks are sinister. Once they start, there is no safe way to stop the leak. It is cold, slick, and dangerous on the roof. I know of a roofer who broke his back trying to break up an ice dam. I can tell you that I would never go up on a roof to beat the ice. Not only is it dangerous, you can cause severe damage to the shingles.

Gale force winds, thunderstorms, and hurricanes can make life interesting while up on a roof as well. I have been there. It is frightening and idiotic to try to stop a leak during a violent storm. 

Oh yes, insurance companies will take care of all your problems you say. You can't be serious! Why go through all of the hassle and problems in doing repair work? You talk about nightmares......!

If you are re-roofing or installing a new roof, give the membranes strong consideration. It is very tough to install them at a later date.





Comments:

Jim
23 Dec 2007, 16:02
Tim,
I am getting icicles on the inside of my facia board in the middle 2' section of my southern facing 12' roof edge. I cleared an ice dam during today's thaw and now I have drips where the icicles were. Here are some facts:
*Low pitch roof - 13.5% slope
*Architectural GAF shingles - mfg says OK to apply to 12% slope and higher
*Rubber membrane applied to entire roof area - 12' by 24'
*1' wide overhang
*Continuous venting from soffit to peak: soffit and ridge vent
*R38c insulation - 12' rafters
*heel height is at least 6"
*shingles do not extend beyond drip edge
*Northern roof section not a problem as area under is not insulated or heated
*I now have gutters but last year I did not and I had the same problem

I see no water problems on the inside of the heated area. I removed a soffit vent and found no sign of water anywhere.

Any ideas/suggestions?

JR


AsktheBuilder
23 Dec 2007, 16:49
JR,
The ice dam membrane needs to lap over the gutter or fascia board so that all drips happen at the back of the gutter.
rich
31 Dec 2007, 14:25
how can i stop big sheets of ice from falling off my rubber roof is there to put on the roof to break up the big sheets.
AsktheBuilder
31 Dec 2007, 16:29
Rich,
Go visit a local roofing supply company. They should have the accessory pieces you need.
Damian
07 Nov 2008, 23:02
When applying the membrane do you overlap the edges or butt end together?

Thanks

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