Cedar siding with no sheathing...

[ryanjg117]

Discovered this as I am completing the installation of a new 72x80" sliding patio door in the basement of our tri-level home. On the exterior, I've cut the siding around the door jam to accommodate the new door's nail fin, and it's now caulked and secured in place. However, the next step is to apply 4" wide flashing tape around the door's nail fin and sheathing/house wrap. Which requires me to cut back the cedar siding even further.

So, I got some siding nails and began driving them into the siding (since I'd be cutting away sections that were nailed and the siding would have little to no support) when I discovered my nails weren't actually biting into anything. I pulled more of the cedar siding off and discovered just a house wrap, and then something very padded underneath (I'm thinking insulation baffles).

I was surprised to see no sheathing but after some Google searches I discovered it's not all that uncommon... However, this is on the corner of the house and my understanding is that home corners should have sheathing per the code? Not that I have any recourse as this house was built in the late 70s.

The problem is the siding was secured in place to the studs adjacent to the door, which is right where the flashing needs to be applied.

I think what I'm going to have to do is pull down the cedar siding around the door, apply the flashing over the nail fin and house wrap, and then re-install the siding, nailing them back into the studs and right through the flashing tape I just applied. Seems like a lot of work not to mention I'm putting holes in the flashing tape which is probably not recommended.

Only other thing I could think of is adding an additional stud to provide support for the siding, but I think I'd have to approach that from the interior of the home, or else cut back the house wrap? If I cut into the house wrap, can I repair the holes with the same flashing tape I'm using around the perimeter of the door (3M All Weather Flashing Tape)?

It's never as easy as the instruction manual states...

 

[Bob D.]

might have diagonal bracing let in to the framing, this was common before plywood sheathing.

 

[Rob-GB]

I don't think that nailing through the flashing is a big no no. Most houses wrapped with the likes of Tyvek have facings that are nailed through it not to mention a bucket load of staples.
As per Bob D older timber frame houses had diagonal bracing to prevent racking before the advent of ply or OSB.

Rob.

 

[Holzhacker]

Have to agree that lack of substrate on a 70's house is very common. I run into it from time to time on 70's and older houses post WWII.
I wouldn't worry about nailing through the flashing tape around the doorway. However, if it were me I would assess whether I could get the Cedar off easy enough to be able to re-use it. I can't help myself. If it were my house I would have to pull the Cedar, check or install insulation, put up 3/4 cdx, house wrap and then the Cedar. Obviously how feasible depends on the size of the wall and your available time.
It's 9 below zero here now and not supposed get above the teens until at least next week so I guess I'd tape the crap out of the doorway and wait until spring.

 

[deepcreek]

Sounds like you are trying to apply "new construction" best practices to a "replacement" situation.

In the case of replacement doors and windows, many of them are ordered without nailing fins when the openings in the house are bricked or sided in.  These units are installed with screws through jambs instead.

When it comes to flashing in a replacement situation, you literally do the best you can with peel-n-stick tape, low expanding foam, and elastomeric caulk.

It's not ideal, but it is standard industry practice.

Otherwise, you're going to be literally rebuilding your house as you have discovered.