No tar paper under siding cedar shingles

[kmacht]

So I am getting around to all the maintence at the house I put off when building the garage and one of the projects for this year was to replace a 2nd story window. The windows are original to the house so the sill was rotted out and they were pretty inefficient. It was time to pull it out down to the window frame and put in a new construction window with nailing flanges. I have done this in the past on the house and never had a problem. This time I ran into one and need some advice. When I pulled the window out there was obvious signs of water damage with a bunch of rot on the frame and the wood sheathing that will need to be replaced. The problem I am running into though is that there is no tar paper over the sheathing. It is all over the rest of the house between the sheating and the wood shingle siding. For some reason there isn't any on this side. The water looks like it got behind the metal flashing on top of the window and just ran down both sides rotting out the wood sheating the whole way down. I would rather not tear all the siding off just to put tar paper up but I am confused on how to flash the window without it. Normally I would slip the top and sides of the window behind the tar paper so that any water running down behind the shingles didn't get behind the nailing flange. Has anyone run into this before? How do you seal off the nailing flange and what do you do about the metal drip edge up top. That seems ripe for letting water behind it if it isn't covered with tar paper. Looking for some advice.

Keith

 

[wnstwolf]

How old is the house? Is the sheathing behind the shake shingles "Zip-Wall?" you know the OSB covered in a green membrane? Was their tyvek type covering or anything? Not sure on older installs but after installing 52 windows in new construction I can say I love the Zip system.

If you have nothing but raw plywood or worse yet OSB behind those shingles there is an issue.. Barrier? Shingles are far from a water tight design and need something back there. For the window detail the rough opening should have a stick on type seal like ice/water shield, cut into strips and wrap the wntire opening starting from the top and covering all seams so everything is overlapped (water rolling down face of building would never hit a seam but over run it?) Tyvek or tar paper is good as a house wrap but not so good for the windows..

Cut out the sheathing issues rework it and look for water/Ice shield at local box store. you can go out as far as you want as the rolls are 24-36" wide...

 

[kmacht]

The house was originally built in the 50's as a ranch but had the roof removed and a 2nd story put on it in the 70's to make it a colonial. The bottom floor has 3/4" asphalt impregnated fiberboard as the sheating and tar paper on top of that. The second story has 1/2" plywood as sheating and tar paper on 3 sides of the house but for some reason none on this one side. On top of the plywood there is overlapping layers of homosote fiberboard (not tar impregnated) and grooved 12" cedar shakes.

How waterproof is the stick on type of flashing (like ice dam). My biggest concern is up the top of the window where I will have the metal drip edge flashing. If I run some of that stick on flashing on top of he metal drip edge and to the plywood will I have problems in a few years down the road? I would be worried how well the stuff sticks over time.

Replacing the rotten wood really isn't a problem. A few hours with a saw and some screws will take care of that. I just want to make sure the rot doesn't come back.

Keith

 

[wnstwolf]

You want the first line of defense under all flashing. This is tough to do if you dont remove windows. Sorry I thought window removal was part of your fix plan. The wrap would all but start in the interior of the house and fold over the rough opening out to the sheathing by 6-8"

 

[Falcon67]

I would at least caulk that window good and use the stick on roof membrane. Not called ice dam around here as we don't get those.

Note - first window I replaced in our old house (20's farm house) I started at the double window and before I was done removing rotted siding and wall framing there was a 8' x 15' hole in the front of the house. You could see all the way out the back. Very cool LOL.

 

[kbs2244]

Time to do some exploring.
Check all over that side of the house for tar paper, or the lack of it.
If they just ran out did they leave it off this window or how much?
You simply need it.
This will give an idea how big your next project is.

 

[Boomer343]

Over the years of repalcing window units in I have seen damage behind Tar paper and no damage without tar paper.

For a fix to your problem I would get a roll of Blue Skin and a can of the adhesive promoter. They have instructions on how to apply the product around the window frame and I would also apply some over the flanges after installation.

Flashings are another of my pet peeves as they are seldom installed properly usually too short and backsloped.

The Blue Skin is extremely sticky and will bond to itself in an instant and it doesn't come apart so work accordingly.

Have fun.