# Roofing 15# felt underlayment or Titanium UDL 30 Synthetic Underlayment??



## WRAE (Jul 5, 2012)

*Which is better 15# roofing felt or synthetic underlayment??*

I am confused about the advantages and disadvantages of the types of roofing underlayment. I need a roof and both companies giving estimates offer a high quality shingle for close to the same price. The difference is one offers the 15# felt paper underlayment and the other company offers the Synthetic underlayment. What are the pros and cons of the underlayments?


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## Windows on Wash (Aug 30, 2011)

I prefer the woven polypropylenes (i.e. synthetics like Titanium) but I would prefer to have the more skilled roofer at the end of the day.

Upgraded underlayment does not make one roof better than the other. They are great if you have blow offs or storms move in after the tear off but the better roofer will put down the better roof at the end of the day and the choice in underlayment will not make that one way or the other.


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## AGWhitehouse (Jul 1, 2011)

+1 on what WOW said...


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## Chris Brink (Jul 5, 2012)

*Underlayment Variety*

I agree that at the end of the day the better roofer will take care of all of the little details that really make a difference. Asking about why a roofer prefers the materials he does might give you some insight into how meticulous he is. I can say that quality materials defintiely help a roof last longer.

That being said, synthetic underlayments have really become popular over the past 7 or 8 years, if you go to the big roofing shows, there are about 15 different companies selling them these days. My bias is that Asphalt is proven, lasts for years, and works really well.

"Synthetic Underlayment" can mean different things - I think the synthetic underlayment you are referring to is mechanically fastened (ie they are fastened to the roof with nails), not self adhered. 

If you are looking for a real step-change in performance, the biggest performance benefit you can pay for in underlayment is by selecting a fully-adhered roof underlayment over one fastened with nails - these come with substantially higher costs, mind you, and are usually better suited to certain types of roofs and climates. There are many manufacturers you can search to understand these products, but their basic features are that they are self adhered to the roof sheathing, provide a continuous plane of water-tightness under the primary roof cladding and are typically self sealing, in other words, when roofing nails go through them, they self gasket around every penetration.

There are also some arguments floating around that "breathable" synthetic underlayments (not all of them are breathable) are better on certian types of roofs - I think that sounds right for Tile roofing, but if you are having shingles put on, there is probably no benefit there (people have studied it and proven as much).

Sorry if this is too technical....

Bottom line is that the Asphalt underlayment is probably the better value unless you upgrade to a self adhered product, or are having a tile roof put on.


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## tinner666 (Mar 14, 2005)

One's the same as the other. It's the roof that matters. If it's done incorrectly, it'll leak anyway, no matter what you put under it.


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## Chris Brink (Jul 5, 2012)

*Underlayment choices*

Asphalt is usually less expensive, though....


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## bcdemon (Jul 12, 2010)

I agree with Tinner, if the shingles are installed properly, then it won't matter if you have 15 minute building paper or peel n stick Ice and Water shield.

If you are leaving this roof open to the weather before shingling it, then you will probably want an underlay better than regular tar paper, such as a synthetic underlay like Titanium UDL.
And unless your roof is a 4/12 or less, I don't see much point in using a self adhering on the entire roof, eves and valleys sure. But not the entire roof.


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## WRAE (Jul 5, 2012)

*Thanks to all!*

I think I have a better understanding of the 2 products. I guess the difference in cost was going to be about $700 more for the synthetic and I can't see $700 worth of improvement or advantage. I really appreciate everyone's input!!!


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## dougger222 (Feb 25, 2011)

We only use 15 pound high performance fiberglass felt. It lays out flatter than standard organic felt but costs more. Standard felt is about $20 a roll while fiberglass felt is close to $50 roll. 

We would run the diamond deck (Certainteed synthetic) but you have to use button nails, no hammer tack staples allowed.

With most laminates on the market today boasting a 130 mph wind warranty it's rare for shingles to blow off which in turn you rely on your felt to keep you house dry then.

A few years ago visited Thunder Bay, Ontario and while eating breakfast couldn't help but notice the large 3 story apartment building being roofed across the street. What caught my eye right away was they were not using any felt!!! The shingle looked like a cheap 3 tab too! They were about half way up the slope that was visable so couldn't tell if they put down ice and water shield. If this roof lost one shingle it would more than likely leak.

IMO, $700 is a waste for syn felt unless you get some additional big warranty on your roof with it.


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## Windows on Wash (Aug 30, 2011)

Chris Brink said:


> If you are looking for a real step-change in performance, the biggest performance benefit you can pay for in underlayment is by selecting a fully-adhered roof underlayment over one fastened with nails - these come with substantially higher costs, mind you, and are usually better suited to certain types of roofs and climates. There are many manufacturers you can search to understand these products, but their basic features are that they are self adhered to the roof sheathing, provide a continuous plane of water-tightness under the primary roof cladding and are typically self sealing, in other words, when roofing nails go through them, they self gasket around every penetration.
> 
> There are also some arguments floating around that "breathable" synthetic underlayments (not all of them are breathable) are better on certian types of roofs - I think that sounds right for Tile roofing, but if you are having shingles put on, there is probably no benefit there (people have studied it and proven as much).


I see no benefit in the application of a fully adhered (i.e. ice and water) application of an underlayment. The roof is your primary moisture barrier and should continue to be so. Using I&W is somewhat is just as redundant as being under a membrane roof.

If the home has ice damming issues, fix the source of the ice dam. 

If you live in an area where you have high winds, use a roof that will stay down (i.e. not asphalt).

Putting ice and water over the entire roof will make for a nearly impossible removal in the future.

Roofing underlayment do not require breathability in nearly capacity except that of shakes if you are on skip ssheathing and drying to the attic.


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## Windows on Wash (Aug 30, 2011)

dougger222 said:


> With most laminates on the market today boasting a 130 mph wind warranty it's rare for shingles to blow off which in turn you rely on your felt to keep you house dry then.
> 
> IMO, $700 is a waste for syn felt unless you get some additional big warranty on your roof with it.


First off...you and I both know that you shouldn't trust that wind rating as far as you can throw it.

We just had a storm with 80 mph winds and half of the homes in my area are missing architectural shingles that are are less than 6 years old.

A wind warranty on asphalt is a joke.

I agree that a $700 premium on synthetic is a bit steep.

My guys prefer it because it rolls out in larger sections and we only charge the cost differential which is usually less than $10 per square over good felt.


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## Chris Brink (Jul 5, 2012)

*Some People Want Redundancy*



Windows on Wash said:


> I see no benefit in the application of a fully adhered (i.e. ice and water) application of an underlayment. The roof is your primary moisture barrier and should continue to be so. Using I&W is somewhat is just as redundant as being under a membrane roof."
> 
> WoW, I undertsand and appreciate your position that is the roof is "done right" then the need for a continuous self adhered underlayment is redundant. I just want to point out that some people want redundancy.
> 
> ...


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## roofnron (Dec 7, 2011)

I agree with the 2nd post by Windows. I prefer synthetics as well because of the strength and walk-ability of the product. If you are putting on and taking of in the same day you don't need it. 

I use ice and water in valleys and other places only when required to, but I don't go crazy putting it everywhere. There are millions of sqft of complex slate and metal roofs installed all over the world without 1 square inch of it installed and they don't leak because of it not being there. 

Windows, how many of those missing shingles did the roofers actually hit the nail line? Like you said, skilled labor is probably the most important aspect of the job.


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## sixeightten (Feb 10, 2009)

We started using synthetics in 2005. We almost never use felt anymore. We do not do the roofing on most of the jobs that we put paper on. We have never had a single piece of any synthetic come loose or blow off of the roof. On many of the jobs we do, the roofer may not come out for weeks, or sometimes months. On my own jobs, I only use felt if the roofer is coming out immediately.


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## Windows on Wash (Aug 30, 2011)

roofnron said:


> I agree with the 2nd post by Windows. I prefer synthetics as well because of the strength and walk-ability of the product. If you are putting on and taking of in the same day you don't need it.
> 
> I use ice and water in valleys and other places only when required to, but I don't go crazy putting it everywhere. There are millions of sqft of complex slate and metal roofs installed all over the world without 1 square inch of it installed and they don't leak because of it not being there.
> 
> Windows, how many of those missing shingles did the roofers actually hit the nail line? Like you said, skilled labor is probably the most important aspect of the job.


I agree with you on all points.

The nails looked properly placed on the couple of shingles that I help my neighbor with. 

Once the seal breaks, the shingle is not going to stay down in most cases and that is my issue with the wind warranties (their dependence on a little strip of bitumen)



sixeightten said:


> We started using synthetics in 2005. We almost never use felt anymore. We do not do the roofing on most of the jobs that we put paper on. We have never had a single piece of any synthetic come loose or blow off of the roof. On many of the jobs we do, the roofer may not come out for weeks, or sometimes months. On my own jobs, I only use felt if the roofer is coming out immediately.


+1


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## Windows on Wash (Aug 30, 2011)

Chris Brink said:


> WoW, I undertsand and appreciate your position that is the roof is "done right" then the need for a continuous self adhered underlayment is redundant. I just want to point out that some people want redundancy.
> 
> Admittedly, my experience with this is for higher end, or architecturally specified projects, but a lot of projects use a continuous layer of SA underlayment under the primary cladding. Some DIYers want to "overengineer" to compensate for their lack of experience with a project. Some folks want an asphalt (or tile) roof, but DO live in high wind areas, etc, Metal or something more substantial just isnt in the cards for them.
> 
> ...


BTW, those are some nice looking projects.

If they are architects specifying the scopes...I can completely understand the self adhered rationale. They like to build "stuff" without much concern for cost or issues down the road.


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## bobmaki025 (Aug 25, 2014)

dougger222 said:


> We only use 15 pound high performance fiberglass felt. It lays out flatter than standard organic felt but costs more. Standard felt is about $20 a roll while fiberglass felt is close to $50 roll.
> 
> We would run the diamond deck (Certainteed synthetic) but you have to use button nails, no hammer tack staples allowed.
> 
> ...


Plastic cap nails, or button nails as you call them are not required. This is if you want your 30 day weather tight warranty where the underlayment manufacturer will guarantee that your roof will be weather tight for 30 days if you place a plastic cap nail where they mark out on the underlayment as to proper placement.
A 130mph wind warranty doesn't make blow offs rare. Everything depends on the circumstances. What temp. were they installed(are they sealed down yet. They may not seal down until the temperature rises to at least 50 deg.) Was there blowing dust when they were installed(the dust will adhere to the tar line reducing its effectiveness) are you using nails or staples (nails tend to hold better) is the nail placement proper(very few people pay attention to nail placement) are you using the proper amount of nails for your roof pitch/weather conditions. Is your base sheating plywood or osb (osb doesn't hold nails as effectively) there are many factors that are called into play when dealing with blowoffs.
Underlayment (ice & watershield discluded) is a vapor barrier, not a leak barrier. While your roof may not leak after a blow off, it shouldn't be relied upon to keep your house dry.(how much water is your insulation soaking up before it soaks through the sheetrock and you see a drip? Can you say mold?)
I have roofed thousands of roofs and I can say that while synthetic underlayments are a few dollars more, it is a safer alternative to tarpaper. Not only in the personal safety aspect, but in the home protection aspect also. By this I mean protection from storms that may arise while you have it unfinished. Tar paper doesn't last long when exposed to weather.


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## bobmaki025 (Aug 25, 2014)

Windows on Wash said:


> I see no benefit in the application of a fully adhered (i.e. ice and water) application of an underlayment. The roof is your primary moisture barrier and should continue to be so. Using I&W is somewhat is just as redundant as being under a membrane roof.
> 
> If the home has ice damming issues, fix the source of the ice dam.
> 
> ...


Using ice & watershield is code (at least everywhere I've roofed) 36" past the interior wall and in some cases, around all pipe jacks, vents, skylights, valley's etc. You also must not have ever lived where there is subzero temps. Its not always possible to fix the source of an ice dam. We put synthetic underlayment over top of the ice & watershield to prevent the shingles fom adhering to the ice&water. Most ice & watershield is granulated to prevent adherence but often times the adhesive leaches through and adheres to the shingle.


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## Windows on Wash (Aug 30, 2011)

bobmaki025 said:


> Using ice & watershield is code (at least everywhere I've roofed) 36" past the interior wall and in some cases, around all pipe jacks, vents, skylights, valley's etc. You also must not have ever lived where there is subzero temps. Its not always possible to fix the source of an ice dam. We put synthetic underlayment over top of the ice & watershield to prevent the shingles fom adhering to the ice&water. Most ice & watershield is granulated to prevent adherence but often times the adhesive leaches through and adheres to the shingle.


I am aware that ice/water is code. 

24" inside the warm wall is code here with no requirements in the valleys or around penetrations. 

I live where we have a decent winter climate and the lows get into the single digits. 

While you are correct that you cannot fix all ice dams with ventilation (i.e. gutter drains, solar melting, valleys, roof layout, etc.), I would bet you that better than 90% of them are ventilation and insulation inadequacy related. 

My point was that I see zero benefit in covering the entire roof with Ice/Water as the primary underlayment. It is a waste of money even where you do have heavy snow accumulation. 

We run two exposures (6') of Ice/Water up the roof and that is more than enough to handle even the non ventilation and insulation related ice dams.


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