Roof nomenclature

[jgclancy]

On below a 4/12 pitch roof it is not irrelevant.Felt paper should NEVER be used. It should be all Ice Shield then shingles for 3/12 and 2/12. Personally, I think below 4/12 should have not use shingles but it is allowed.

Think of it this way. You put down felt paper and then put four nails per shingle through the paper. Holes are everywhere. If shingles fail paper is full of holes and not going to help much.Felt paper on a roof is not a moisture barrier-period.

On shallow roofs the problem becomes less of shingle failure but rather water creep up under shingles via ice and frost.Especially, near the eaves and in valleys. If Ice Shield is used on shallow roofs it will seal all nails and act as a moisture barrier. Hence, on any pitch using Ice Shield ifor the whole roof is a great idea.

I can see where my wording indicating that what to do on less than 4/12 pitch roofs wasn't clear. Sorry.

Jim C.

[hausdok]

From CertainTeed's Master Shingle Applicator Manual

WHEN UNDERLAYMENT IS REQUIRED - Page 45

The installation of standard underlayment beneath shingles is required by many shingle manufacturers. Generally, CertainTeed recommends that underlayment be installed but does not require it except as noted below.

LOW SLOPE: All roof shingles applied to a low slope deck (2" to 4" per foot) require the used of CertainTeed WinterGuard Waterproofing Shingle Underlayment, or its equivalent,* applied over the entire deck surface. Consult the WinterGuard and individual shingle application instructions for details.

*For low slopes, underlayment equivalents to WinterGuard include:

1) waterproofing shingle underlayments meeting ASTM D1970; and

2) two layers of 36" (915 mm) wide felt shingle underlayment lapped 19" (485 mm). Shingle underlayment should meet ASTM D4869 Type I or ASTM D226 Type I (except when applying Ambassador, Presidential or Presidential T/L Shake shingles.)

COLD WEATHER CLIMATES (ALL SLOPES): WinterGuard Waterproofing Shingle Underlayment, or its equivalent, ** must be used wherever there is a possibility of icing along the eaves causing a backup of water.

**For ice dam leak protection, the equivalent to WinterGuard include:

1) waterproofing shingle underlayments meeting ASTM D1970 and

2) two layers of 36" (915 mm) wide felt shingle underlayment lapped 19" (485 mm) and fully adhered to each other with asphalt roofing cement meeting ASTM D4586 Type II, Shingle underlayment should meet ASTM D4869 Type 1 or ASTM D226 Type I.

VALLEY FLASHING (CLOSED-CUT AND WOVEN VALLEYS): Line valley by centering 36 (915mm) wide CertainTeed WinterGuard, or equivalent, ***in the valley and applying directly to deck. Consult the WinterGuard and individual shingle application instructions for details.

*** For valley liner, the equivalents to WinterGuard include:

1) waterproofing shingle underlayments meeting ASTM D1970;

2) one layer of 50 lb. or heavier asphalt coated roll roofing;

3) one layer of mineral-surfaced roll roofing; and

4) two layers of 36" 9915 mm) wide felt shingle underlayment. Coated roll roofing should be ASTM D224; shingle underlayment should meet ASTM D4869 Type ! or ASTM D226 Type I.

Water resistant underlayment is a product that consists of organic felt impregnated with asphalt saturant. Some water-resistant underlayments, such as CertainTeed's Roofers' Select, also contain a fiber glass reinforcement which increases tear strength and reduces wrinkling.

Water resistant underlayment was originally invented to keep the roof decking dry until shingles could be applied. Applying this underlayment was originally called "drying in the roof." It was also useful as a separation sheet between the roof sheathing boards (before OSB and plywood sheets were used as roof decking) and the asphalt shingles. This as important because resin pockets in the pine planks caused the asphalt to degrade prematurely unless the underlayment separated the resin and asphalt from each other.

Water resistant underlayment is made to shed most of the water that falls on it unless it is torn or punctured. Its ability to be water resistant is temporary. As the sun degrades the exposed asphalt the minerals begin to dry, absorb more moisture, lose its strength and eventually begin to tear. The less asphalt used to saturate the underlayment sheet during manufacturing, the shorter it's life. Since asphalt is the most expensive component of shingle underlayment, lower priced materials will have less asphalt and a shorter life when exposed to the sun. Lower priced shingle underlayment, for the same reason, is also subject to severe wrinkling when it gets wet or even just damp.

Underlayment is used under asphalt shingles for a variety of reasons, such as providing:

• Backup for water-shedding protection of the deck if shingles fail from wind-driven rain. The lower the slope, the more important underlayment is, since water flows more easily under shingles on low slopes.
• A protective barrier to the elements between the time the old shingles have been torn off and prior to the new shingle being applied. However , the underlayment should not be relied on as a temporary roof system, especially when the drip edge flashing is not yet in place. It is unlikely to prevent leaking in the event of heavy wind and rain.
• An agent to hide minor imperfections of the decking material and reduce "picture framing" of deck panels.
• Fire ratings (Class A or C) when used in conjunction with shingles.

ONE TEAM - ONE FIGHT!!!

Mike

[maineroofer]

if you are to use full coverage i&w,make sure you use proper ventallation.