Need help with a flat roof component.

[ROBERT YOUNG]

1956 home.
Salt box roof.
Roof joists and lookout rafters.
Roof joists are supported by a beam.

The beam is crushing a component.
Would this be considered a kneewall?
Thanks in advance.
knee wall.jpg

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[Jerry Peck]

Depends.

Are those studs going down to a wall below, or is there a bottom plate under those studs which is buried in the insulation?

If there is a bottom plate buried in the insulation which is bearing on joists or such, then, yes, it would be a knee wall.

If it is the wall studs below sticking up into the attic to support the roof, it still might be considered a knee wall, but I'm not sure it would be as it would be balloon framing with (hopefully) fireblocking at the ceiling level.

[ROBERT YOUNG]

Depends.

Are those studs going down to a wall below, or is there a bottom plate under those studs which is buried in the insulation?

Thanks as always, Jerry.
Studded wall.

There is no plate.
There would likely be transmition cracks and a bowed wall below.

There are 2 beams supporting the roof joists.
The lookout rafters are on a plate. Good circulation with the 4 goose neck vents.
Also, there are no joist blocks/stiffeners.
The roof joist end bearing are nail laminated. Nails are extruding slightly.

Here is another image of the attic space and beam components.
My flashlight is spotting the second beam. You can see how the joists are bearing on the beam.
You can also see mechanical damage on the beam closest your screen.

kneewall.jpg
Kneewall it is.

[Jerry Peck]

You can see how the joists are bearing on the beam.
You can also see mechanical damage on the beam closest your screen.

Looks like saw cuts to me with some wood having chipped off one side at some time for some reason.

[ROBERT YOUNG]

Looks like saw cuts to me with some wood having chipped off one side at some time for some reason.

Jerry, I suspect the knee-wall top plate/s where at a position where damage appears first on the left of the beam that resembles a carpenter's saw cut and knockout to lower the beam an inch or two.
IMO, I doubt the carpenters would be cutting on a 45% angle. Instead I would cut plumb with the outside dimensions of the beam to the desired depth, then knock out the notch.
A precise opening would act two fold. 1: To lower the beam to the desired height. 2: Act as a mechanical saddle and prevent the knee-wall from lateral movement at the top seeing there is only one bearing point.


The top of the knee-wall appears to have shifted 6" to 8" to the left, bowing the wall and making it out of plumb.
mechanical damage.jpg
Just a hypothesis mind you but I can imaging the bottom plate is fastened to a bearing wall. Under the loads of the 1998 ice storm the top plate let go and moved to the left several inches while the bottom plate remained in place being fastened at several intersections on bearing walls below.
I removed ice from roofs. One slope to the drain roof had 6.5 feet of ice. It took me 2 full 12 hour days.

[Jerry Peck]

IMO, I doubt the carpenters would be cutting on a 45% angle. Instead I would cut plumb with the outside dimensions of the beam to the desired depth, then knock out the notch.

I was thinking of something like this during construction: saw and wood chisel, or just wood chisel, to notch things to they aligned with adjacent ones.

[ROBERT YOUNG]

I was thinking of something like this during construction: saw and wood chisel, or just wood chisel, to notch things to they aligned with adjacent ones.

I see your reasoning and concur, Jerry but if you had to take 2" inches off there, there was a component 2" inches too long, wide or high added somewhere else remember.

I hammered nails in planks. My friend built custom logs homes in rural Quebec. Dam rough work at times. I use to tease his combination miter cuts. It's all behind the drywall they'd say. I refused to frame with crews like that and go work another trade until I settled into tat for a while. Work was plentiful when you knew something.

[Jerry Peck]

I see your reasoning and concur, Jerry but if you had to take 2" inches off there, there was a component 2" inches too long, wide or high added somewhere else ...

Not necessarily - 'that' member could have been larger, or 'that' stud was longer, or ...

[ROBERT YOUNG]

Not necessarily - 'that' member could have been larger, or 'that' stud was longer, or ...

Jerry, you ever build a wall frame with one oversized stud? Attaching the top plate you notice plate is higher than the other studs.
You catch it as the unit is being erected or at least I would.

Maybe the kneewall might have been built too high but I would not notch the beam.
Dismantle one plate and attach more cripples and squash blocking below the plate.

[Jerry Peck]

Robert,

You are talking about a 1956 house.

We have no idea what was done or why.

I was raising some potential causes which could lead to the need to notch that member.

[ROBERT YOUNG]

Robert,

You are talking about a 1956 house.

We have no idea what was done or why.

I was raising some potential causes which could lead to the need to notch that member.

I know. Just making conversation.

[John Kogel]

1956 home.
Salt box roof.

Would this be considered a kneewall?

I'd call that a pony wall if I could only make head or tail of it.

That's a joke. I mean what I just posted, not the fine workmanship in your picture.

BTW, they are never flat roofs. Some are Low Slope, and the rest are elevated duck ponds.

[Gregory Booth]

............how does a building with a saltbox roof, have a flat roof? What am I missing here?........Greg

[ROBERT YOUNG]

............how does a building with a saltbox roof, have a flat roof? What am I missing here?........Greg

Flat Roof: 2:12 and lower slope.
Thanks, Greg. Flat roof.

[Jerry Peck]

Flat Roof: 2:12 and lower slope.
Thanks, Greg. Flat roof.

Not a flat roof.

Low slope roof would be the term .

[ROBERT YOUNG]

Not a flat roof.
Low slope roof would be the term .

Sorry for the roof shape call.
The shed was a saltbox shape.

The roof was flat.
From my understanding, <4/12 to 2/12 is low slope.
From 2/12 to 0/12 is considered flat.
A 1/4" slope is required to promote drainage and avoid ponding.