The Mystery of Roof Edge Assembly

Lascaux

Is there a legitimate reason why the wall inside the roof edge assembly would be left open? The section that is open is above a kitchen window. All construction appears to be original in this 1950's home.

Also, should not the sheathing on the wall assembly extend up past the top of the floor joists and onto the top plate? In this picture the top plate is hidden by the drip edge and is not visible:

shazapple

I think what you identify as "soffit hanger" is typically called a 'lookout'. What you are referring to as the "top plate" is just fascia board, the horizontal 2x4 on top of the studs and below the joists is the actual 'top plate'.

The uncovered area on the left is to let ventilation enter the soffit vent and into your attic space. This is a typical and required building practice. The uncovered area on the right is probably because the builder install the lookout and soffit before installing the wall sheathing, or it was removed during a renovation.

Lascaux

Here is the next stage of soffit removal that exposes the interior construction...





At this point, I intend to sheath up to the highest horizontal 2x4 in the picture and insulate whereever possible while using rafter vents to leave a 2" path immediately below the roof running from the continuous soffit vent up to the ridge vent.

Currently, the wall section that is covered is sheathed with a soft particle board. What is the proper sheathing to use here? Can XPS be incorporated?

Lascaux

I should have stated that this roof section has a finished attic room with side attics. Currently, insulation is minimal. Insulation will rise several inches above the floor joists that are visible at the top the images.

Lascaux

Here is a diagram that describes my situation:


How do I sheathe and insulate this wall under my eaves?

Thanks!

wkearney99

It would probably help your insulating to have the sheathing come up farther but not a tremendous amount. Particle board would seem an odd choice for that area but since it's not exposed to the elements it wouldn't much matter. Having it left open looks like someone was being lazy. That and you lose the air infiltration blocking of the board. I'd definitely cover them, barring some other unknown reason for leaving them exposed.

Meanwhile I'd wonder about the condition of the roof sheathing. What's with the discoloring? Or is that one of the reasons this has been opened up?

Lascaux

Thank you. My goal is to stop air infiltration into the subfloor between the floor on this west side where the prevailing winds hit. Although, for a while, there will still be opportunities for the wind to find a crack elsewhere.

The roof deck on this 1950's house is 1x6 plank on rafters, with 1/4-inch spacing. Before I bought it, I thoroughly inspected it. All the planking is in good condition. The roof was immediately stripped and new shingles were installed because of a leak on the east side that had been left unattended during a foreclosure.

As you noticed, there seems to have been some moisture infiltration on this west side. It's not too bad, and the rafters are all in good shape. However, I primed all the exposed rafter tails. I suspect that the combination of the house's poor envelope, the adjacent finished attic, the western exposure, nearby trees, and the kitchen below, contributed to the moisture problem. A lot can happen in 60 years.

Lascaux

Perhaps the brick cladding has something to do with the fiberboard sheathing? The fiberboard is unstained, but it's not a sturdy sheathing.

wkearney99

Subfloor? I thought this was about the roof?

Yeah, covering up those top ends would seem like a good plan, especially if this side faces into the wind. No sense leaving just the filterglass insulation exposed to it from the side. Looks like you can already see where the airflow through it has left dirt behind. It's useful to follow the dirt to see where to/from the air has been penetrating. Follow the dirt to see where and seal up accordingly.

Lascaux

The subfloor of the second story finished attic room.

wkearney99

Couldn't tell there was a room involved, from the messages nor the drawing. But still wouldn't change the suggestion to cover it. You'd still be avoiding edge-on airflow hitting the side of that insulation. Especially since you're planning on be careful to maintain good soffit and roof ventilation.