Venting garage roof

I have a question about venting a garage roof. I am turning my detached garage into a woodworking shop. I am adding heat and ac and will thus insulate. I know that a building with an attic space needs to be vented. However, can I insulate right onto the roof, in other words, put the insulation right between the joists and right up against the roof sheeting? Or do I need to make an attic space and vent the roof? Thanks Rob Through the golden door our children can walk into tomorrow with the knowledge that no one can be denied the promise that is America. ~Ronald W. Reagan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

insulating right onto the roof is known as a "hot roof", which might be against building code in your area, can negatively effect heating/cooling bills, and possibly void your roofing shingle warranty and effect your roof in other ways
most seem to recommend ventilation
here's plenty of information on the topic from google archives of this group: http://groups-beta.google.com/groups?as_q=%22hot%20roof%22&safe=images&as_ugroup=alt.home.repair&lr=&num 0&hl=en

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You need to keep an airgap. Typical job would require a ridgevent and eave vents with special cardboard or foam inserts above the insulation so the air can flow and keep the shingles a bit cooler and moisture a place to go.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
which vent to use on a grage flat roof covered with tar paper?
Mike

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Rob Hall wrote:

Assuming it is not a flat roof, your roof will last longer and you will have less likely hood of leaks if you do the attic and vent it. Your garage - workshop may also be cooler in the summer that way.
--
Joseph Meehan

26 + 6 = 1 It's Irish Math
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
During a reroof I had a turbine unstalled in the garage roof along the southern California coast. It had been about 10 warmer than the patio slab prior to the turbine and after installation it has been about 10 cooler. It was surprising to me to find that much difference. Ensure that the outlets for tools are wired separate from the lights in the woodshop.
On Sun, 06 Feb 2005 23:50:29 GMT, "Rob Hall"

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.