We are planning on using a standing seam metal roof on our 4-12 pitch sips roof. We are considering using a self adhesive   (ice & water barrier) for underlayment, over felt paper.  The reason being less threat of being blown off,  less penetrations in osb, and ease of installation. might justify the cost increase.   Any thoughts or recommendations?

Stonelake;

thats the wrong installation the IWB is meant to take the place of felt , it is meant to stick to the deck, sticking it to felt is a waste of money and the product

IWB over felt would also be a real mess and a nightmare to install!

sorry.............what I was saying  was to use the IWB in place of felt.........................

Ice and water and ease of installation doesnt go together, unless it's cold enough so it doesn't bond. Use a synthetic underlayment with cap nails, it's light, easy to roll on, lays flat and doesn't wrinkle or tear. The cap nails will seal your staple penetrations.

My carpenter indicated that the IWB goes on easy, and will stay put despite wind.  He says he has seen it stay on a long time if the roofing installation is delayed for months with no bad effects.   What is the name of the product that you are referring to?

Posted By Stonelake on 20 Sep 2010 11:26 PM
My carpenter indicated that the IWB goes on easy, and will stay put despite wind.  He says he has seen it stay on a long time if the roofing installation is delayed for months with no bad effects.   What is the name of the product that you are referring to?

there are many on the market, some for shingles , some hi-temp for metal, why don't you ask you carpenter which one he like to use?

My peel and stick underlayment has been on for months exposed to the weather, and not one bit of it has moved, curled, or anything. The only problem so far is the "walkable" surface, which is like a thin white felt mat, is starting to degrade and is not so walkable anymore on the steep parts.

Posted By Stonelake on 20 Sep 2010 11:26 PM
My carpenter indicated that the IWB goes on easy, and will stay put despite wind.  He says he has seen it stay on a long time if the roofing installation is delayed for months with no bad effects.   What is the name of the product that you are referring to?

I guess it would go on easy on a 4/12. Steeper pitches and hot weather and it's a pain to roll out fast, flat with no bubbles and overlapped properly efficiently. Really cold and it won't bond well and wont roll out flat unless always stored upright.  Stuff is a pain. Most cases you need to snap lines. 

Synthetic underlay resembles housewrap and comes in 10 sq rolls (4'x250') Preprinted fastening locations and easy to walk on. There are many manufacturers and I've tried several, I like PermaFelt and Rex and hate Typar's. Thing is, it's less than $12 a square versus $60+ a square for IWB.