Exterior "soffit" wood nailed to old "soffit" wood than painted, will it cause problems?

[newworldactor]

I need to paint the exterior of my house, everything is easy except the "soffit" (I believe that is what it's called, it's the part under the roof on the sides of the house that over hang), My house is old so this part of the exterior is really thin plywood (without vents) and has old (lead) paint that is peeling off (it can't be painted over). I would like to try and avoid stripping it for obvious reasons....

What I would like to do is just cut and paint new plywood (on the ground) and just nail/screw it to the old soffit plywood. I would like to do this for 2 reasons: I wouldn't have to strip the lead paint and the 2 pieces of plywood would provide more noise insulation.

What worries me is that moisture might get trapped between the layers and rot out the wood. I am not against priming the old and new wood if that will help protect it from moisture. Will this work? Will priming be enough or do I have to design it so air can move between the layers?

I am willing to go one step further if it will help and is safe; I've worked with a sound barrier called Homasote 404. What I could do is cut the 404 and install it between the 2 layers of plywood, would that work? Or would it be better to cut strips of the 404 and stagger it so air can move between the plywood layers?

Thank you

[Tony Hwang]

Hi, For the effort, if I were you, I'd rip out the old part and install aluminum soffit panels. It provides venting, last LONG without painting.

[newworldactor]

That is a great idea, but do I have to do anything to my roof/attic (crawl space), like add more insulation? There isn't much up there and I would think it might make things colder in the winter.

But it sounds like a good solution, except it won't help with any noise insulation, I'll see what Home Depot has this weekend.

Thank you.

[David Martel]

If there isn't much insulation up there then adding more may be a good idea and it will help with noise. But first, go up into the attic and figure out how it is now vented. If the venting is adequate and working there may be no reason to use vented soffits. I like the aluminum or vinyl soffit idea with removal of the old soffit material.

Dave M.

[newworldactor]

In general does having vented soffits make ones house colder in winter? Maybe during the day?

I may cut a few holes in the plywood to increase the ventilation a little, I just don't want to do anything that will cause damage long term. I'm looking for roof design/upgrade information right now so I can figure out what is best for my house.

Thank you.

[Norminn]

If you want to get into more work now, as opposed to some later time, it is probably a good idea to get rid of the rotted soffits and add insulation. Might also explore ridge vents to the attic. The logic is: ridge and soffit vents allow movement of hot air in summer to help keep house cooler, and movement of cold air in winter to keep ice from thawing and freezing again (can disrupt shingles and cause leaks). Continuous ridge vents keep the temp more uniform, as air is not then trapped by some of the rafters. There is a formula for minimum roof ventilation .... 1:300, I think. One sq. ft. of roof vent for each 300 sq. ft. of attic FLOOR area. So, now that you have ripped out the rotted soffits, you will be able to insulate without covering up the new soffits and also be able to tell that you are fastening the new soffits to sound wood.