Roofing 15# Felt Underlayment Or Titanium UDL 30 Synthetic Underlayment?? - Roofing/Siding - DIY Home Improvement | DIYChatroom
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Old 07-08-2012, 09:24 PM   #16
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Roofing 15# felt underlayment or Titanium UDL 30 Synthetic Underlayment??


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Originally Posted by Chris Brink View Post
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.

We also see a lot more of this in Canada, whether it is a real need due to the climate, or a bent towards conservatism, I can't say, but a lot of folks like a continuous layer of SA underlyament up that way.

My position is to let folks knwo what is out there and let them decide, some folks will pay for that redundancy, many will stop when they see the cost involved.

I hear your point on re-roofing, I think it is a good one that needs to be included in the decision process, as redecking is expensive, and a Good SA underlayment is defintley NOT coming off after it has welded itslef to the roof after 20+years.
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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Old 08-25-2014, 08:19 PM   #17
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Roofing 15# felt underlayment or Titanium UDL 30 Synthetic Underlayment??


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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.
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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Old 08-25-2014, 08:35 PM   #18
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Roofing 15# felt underlayment or Titanium UDL 30 Synthetic Underlayment??


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Originally Posted by Windows on Wash View Post
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.
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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Old 08-26-2014, 07:42 AM   #19
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Roofing 15# felt underlayment or Titanium UDL 30 Synthetic Underlayment??


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Originally Posted by bobmaki025 View Post
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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