Replies

1. 
   mike_guertin | Nov 20, 2004 05:45am | #1

   If you don't have great attic ventilation and you have air leaks from inside a heated space into a cold attic in winter - you will get condensation and sheathing rot. this can happen regardless of the waterproof shingle underlayment (WSU).

   I follow a process I call 'stormproofing the roof' where I run a 3' roll along the eave edge, 18" piece along all wall/roof intersections (like the sides of a dormer), 3' down valleys and then run 4" strips along every sheathing seam. Water ain't gonna go through the sheathing so once you seal up all the edges and joints and intersecting surfaces - you've made the roof watertight. Then when you roof it you can put down regular tar paper and the shingles.

   OR if it is as small as you say - just wrap the whole thing.

   MG

1. 
   dvc61 | Nov 20, 2004 06:04am | #3

   Mike, I never thought of doing the seams as you mentioned...great idea! Thanks for the tips.   Doug

2. 
   RichBeckman | Nov 20, 2004 05:51am | #2

   The Ice and Water shield products do say on the packaging that the product is a vaper barrier when applied to the entire roof, so the roof should be properly vented in that circumstance.

   The Ice and Water shield products also say that the product is not designed for exposure to sun and that it shouldn't be applied when it is going to be exposed for more than 30 days.

   I use Ice and Water shield liberally, but I wouldn't cover the entire roof unless the slope is 3 in 12 or less.

   In your case, I would use the Ice and Water on the eaves and in the valleys and perhaps at the meeting between addition and existing. Then I would do the rest in 30# felt. If I thought it was going to be a few weeks I would also cover the Ice and Water with the felt.

   I probably would also tarp the area that is the meeting between existing and new.

   Rich Beckman

   Another day, another tool.

   
   

   ---

   Edited 11/19/2004 10:04 pm ET by Rich Beckman

1. 
   dvc61 | Nov 20, 2004 06:08am | #4

   Good point about the suns' effect on the membrane, hadn't thought of that either. Thanks,  Doug

3. 
   toolbear | Nov 20, 2004 07:47am | #5

   Watched the CA parks dept doing a new loo at Lime Kiln SP on the coast.  The entire roof was covered in peel n stick.  The flashings were copper.  The trim was redwood and they gave it two coats of oil paint before installing.  Tax dollars in action.

   My last house had skylights.  They leaked.  We had four buckets under the bloody things in a rain.  Redid the roof from wood shingles (loath) to 3 tab (more better) and found the roofers had saved on the flashings.  A few yards of PnS would have preventd the problems.  If I could afford it, I'd cover the whole roof in the stuff.

   The ToolBear

   "Never met a man who couldn't teach me something." Anon.

4. 
   seeyou | Nov 20, 2004 02:05pm | #6

   I'm gonna play devil's advocate and disagree with most of the previous posts. I only use ice & water shield where I need it to protect the inside of the house during a reroof (valleys, temp. flashings, etc.) Any other use of it seems to me to be a catch all solution to poor building practices. For example, if I can't stop ice dams with ventilation or other design changes, then I use it at the eaves. I can't imagine any earthly reason to apply I&W S to gable ends. Proper edge metal or roof overhang will stop water from getting in. If your wall abutments and penetrations are flashed correctly, then the water stays on top of the roof rather than running underneath it.

   If you think you need I&W S at the eaves, use it. But, install it so it continues 3' on the horizontal past the interior wall ( which will be more than one run on a 4/12 roof).

   I invented ice and vodka shield.

1. 
   mike_guertin | Nov 20, 2004 04:36pm | #7

   I used to think as you describe: Don't use a bandaid - flash it right from the get-go. I absolutely agree with the ice dam part. WSU doesn't prevent ice dams or shingle damage due to them, it just stops the water from getting inside.I like using WSU as insurance. Despite best efforts to flash perfectly three things can happen: Damage to flashing, unusual weather that drives rain right around flashings (I build in 110 and 120 MPH zones on the coast) and a disaster (hurricane, mild tornado, hail storm). It's nice to know that beneath my flashing and roofing I have an almost bulletproof membrane backing up the system. I've seen lots of people, as perhaps you have too, who don't even attend to flashings now. I've seen some guys using WSU AS the flashing. Yikes.MG