Foamboard Over Wood Siding-tyvek Too?

72chevy4x4

the title sums it up. It sounds like the pro's don't rip the wood siding off but recommend going over it w/ 1/2" foamboard. I'm new to this-I thought it was preferred to rip the wood siding off to get a smoother surface to nail to. Now that I'll go over the wood w/ foamboard I have a question or two: start off w/ the thickness. would it be better to use the reflective 4x8 sheet stuff over the fan fold? Would the fan fold be more appropriate with smaller discrepancies in the subtrate? The siding is a lap siding, maybe 1/2" lap. If using the 1/2" stuff is ok-can you tape the seams w/ tyvek tape and not have to wrap with tyvek? I would wonder about the nail holes going through the foam-if they would allow water to seep back. The wood is in good condition-not rotted, so nailing to it is not a concern.
thanks guys,

theroofinggod

1st off 3/4" foam for rigidity,2nd nail the high points of the clapboard siding,3rd 3/4" foam is t+g/shiplap so keep it tight and forget about the tape,keep it tight to the frames of windows and doors(you can basically set it where it`s going ,tap w/the heel of your hand against the window or door frames,and it will leave a cutting guide line),put your "j" next to the insulation ,put firring strips to meet this on the sides and top,and about an inch longer on the sill area-If we meet,you have to buy breakfast

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vinylguy

chevy man,
go to your supplier and do some research hell you can install with out backer board if you wanted to why i have no idea but you could your over thinking this process but my big ? is you have never done this before? and your doing someones home yourself? good luck but i would suggest getting training first. go to your supplier and ask they will set it up for you

72chevy4x4

I've only installed on fresh osb and on jobs where the existing wood siding was removed, not 'covering' up the wood siding. I've always thought it was the cheap and easy way-with the cost of materials, the savings isn't as great as I would have thought. I'll stop in and talk with my supplier-they've been very helpful with Q's in the past.
thanks.

Patrick

Of course the savings is great, Your charging just as much and doing less work

Grumpy

Pros recommend going over it or salesmen who don't know any better?

I tell my customers if they wantt he best job to tear it off.

Tyvek on every job no ifs ands or butts, if they want warranty.

Patrick

Grumpy I used to believe that tearing off was the best, but... as long as there is no significant water damage and through the use of backboards which will ensure a smooth surface, and you have a siding system/technique that ensures the job doesn't look like you just sided over, whats the harm? If nothing else you have an added insulation value. To give an example the current house I am doing had 3" cedar clap, which the customer wanted us to strip and replace with the same thing real wood cedar clap so not being a vinyl job we had to strip the wall, let me tell you the 1/2" plywood underneath is so bouncy, and curled I feel that the old clapboard would have served as a much better base for new vinyl than the crappy 1/2" plywood had the customer opted for vinyl instead of real wood.

I do have to agree with you about the Tyvek standard practice around here is to simply use a backer with no paper, granted the foam is butted tight, just how good of a seal is it? No one that I know tapes it either