Roof vents

[Electech]

I am looking for some help with roof vents. I have a 2000 Clayton manufactured, and it has twenty roof vents all together. I am going to replace the roof, and I would like to get rid of at least half of these. Any suggestions? Should I use soffit vents in order to eliminate the lower roof vents? What about a ridge vent, or electric vent. I currently have 3 tab 225lbs/square, do I have to use similar shingles, or can I use the 70mph 300lbs/square? I don't want to put too much load on my roof, and I think the studs are 2x3. Any help would be great.
Thanks.

[JD]

Hi Electech,

How you could vent your roof would depend a lot on the way it is constructed. Being a 2000 model, it may already be vented or have provisions to be able to install eave/soffit vents. Does your home have an overhang and soffit?

Ridge vents are easy to understand and install. The hard part is installing the eave or soffit vents. Most of these vents need to have 2x6 rafters install as they would be in stick-built construction, where the full width of the 2x6 is installed on the top of the top plate of the stud wall, leaving room for blocking (bird blocks) as well as the eave vent. As a contractor, I have not found a cost feasible way to do this. It is very labor intensive and would require engineering reports and drawings that I would not be able to provide. The roof vents you are talking about are the easy way to get air intake into the roof/attic area.

As a DIY, you may have more options to pursue the eave vents. Below are the two best web sites I have found that address eave vents. The Cor-a-vent site shows may product options. The product I see as best suited for mobile/manufactured homes is the RS-400 eave vent, used in conjunction with the main Cor-a-vent product and a ridge vent product of your choice. Cor-a-vent ridge vents are a good choice, but ridge and eave products from GAF, Owens Corning are also good products and cheaper.

Cor-A-Vent RS-400
http://www.cor-a-vent.com/raft-a-vent-rs-400.cfm

Other Cor-A-Vent products
http://www.cor-a-vent.com/ventilation-products.cfm

Below is an excellent report on roof venting from Manufactured Housing Research Alliance. There is a lot of science put into this report, but unfortunately the end result was very vague for most climate areas. While HUD has stated all homes should have vented roofs, they have since pulled back on enforcement due to this research. They have found that different climate areas have different needs and in some cases, no venting is recommended. Anyways, read it for yourself and see how it applies to your area.

http://www.mhrahome.org/media/reports/attic_vent.pdf

Hope this helps,

JD

[JD]

Also on upgrading your shingles, I would not be afraid of installing the heavier shingle on your home. Being built from factory for shingles, I would think it would be OK. Your local building inspectors may not agree. It would be best to get that information from them.

JD