Having a hell of time trying to work out how to design a tiny house with a rainscreen and PBR metal siding.
Tried AI failed.
Tried ASC, not their wheel house. All manuals are without rainscreen.
Tried YT almost all videos have no rain screen and just slap the metal straight onto plywood or onto WRB.
No bueno.

I have sorted out most of it around window trims etc.
Elevated the planes on furring strips except for the window header flashing and the Top Plate metal terminations.
C6 trim and corners are good.

But I can’t figure out the details of the Z drip under the window.
Here’s a diagram of one option but I a concerned about water going down the sill tape and behind the vertical metal leg of the Z drip.
The other option is putting the vertical Z drip leg on top of the furring strips.
But that creates two channels and blocks the furring strips channel exhaust at the top.

Only Reddit can save me now.
Someone take pity and help me out.
Before I lose my mind.
Diagram enclosed.

PS: The PBR isn’t installed horizontally, it’s vertical. Artistic license displaying it in undulating waves.
Thanks to anyone willing to help. I am in a time crunch.

Edit: I could cut off the vertical leg against the WRB and that would stop the potential of getting water behind it and mist terminate the PBR with a single metal layer.

Thanks to whoever asked IF I still need a rainscreen if the PBR ribs allow enough airflow. It’s an interesting question. I thought I did for more airflow and to keep the metal off the WRB.
BUT now I doubt it. I rarely see it and that might be the reason?

My rough draft lol

Mud bricks... Self building plan now ...slow and steady. Need ideas from civil engineering brains and more worldly enlightened minds.

🏡 I’ve been living in my tiny home for about two years, and it’s been such a wonderful experience to downsize.

🌼 My interior design style is Tiny Maximalism. 🩷💛🩵🧡

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Any ideas on what to do with this storage space? I didn't want to make holes in the wall.

While browsing tiny-house groups, I occasionally come across DIY builders who are framing doors and windows without fully understanding what is happening structurally above the opening.

At first glance, a lintel (also called a header) may look like just another piece of lumber.

It's not.

The lintel is responsible for transferring the weight from above the opening to the studs on each side. Without a properly sized lintel, part of the roof load can end up being transferred directly onto your window or door frame.

That's when problems start.

Ever Seen a Window That Won't Open Anymore?

Or a door that suddenly starts sticking?

In many cases, excessive structural load can be one of the causes. (Foundation movement can also create similar problems, especially in cold climates where frost protection wasn't properly considered. That's a topic I'll cover in a future article about tiny houses on permanent foundations.)

If the wall above an opening isn't properly designed, the weight of the roof can create deflection over time.

That movement can:

• Put pressure on windows
• Distort door frames
• Create cracks in drywall or finishes
• Affect long-term structural performance

The larger the opening, the more important the lintel becomes.

Not Every Wall Carries the Same Load

One mistake I often see is assuming all openings require the same lintel.

They don't.

The required lintel depends on:

• The width of the opening
• The snow load in your region
• Whether the wall is load-bearing
• The amount of roof supported by that wall

For example, a small gable-end wall supporting only a narrow strip of roof typically requires a much smaller lintel than a long exterior wall supporting roof rafters or trusses.

That's why span tables exist.

Snow Load Matters

This is where location becomes important.

Someone building in Arizona doesn't face the same design conditions as someone building in Quebec, Alberta, British Columbia, or Newfoundland.

The National Building Code of Canada provides snow-load values for cities across the country.

In the example shown in my book, the Montreal region uses a ground snow load of approximately 2.5 kPa.

That value directly affects the size of the lintel required above openings.

The more snow your roof can accumulate, the more load the structure must carry.

Understanding Tributary Width

One concept that often confuses people is something called tributary width.

Simply put, it's the portion of the roof load that is transferred to a specific beam, wall, or lintel.

A lintel supporting only a small strip of roof might carry very little weight.

A lintel located under roof rafters or trusses could be supporting a much larger portion of the roof.

That's why two windows with identical widths can require completely different lintels depending on their location within the structure.

Tiny Houses Are Not Exempt From Structural Rules

Because a tiny house is small, some people assume structural loads don't matter as much.

That's not really true.

Even though the building is smaller:

• The roof still carries snow
• Wind still creates loads
• Openings still interrupt the wall structure
• Loads still need a proper path to the foundation or trailer

In many cases, tiny houses actually concentrate loads over shorter spans, making proper framing even more important.

An Example

Using the example shown in the table in the image linked:

• Ground snow load: 2.5 kPa
• Exterior load-bearing wall
• Roof and ceiling load only
• Tributary width up to 4.9 m

For an opening of approximately 1.64 m (5'-4"), the table indicates a lintel equivalent to approximately:

(2) 2x8 SPF members

This is only an example and should never replace the span tables applicable to your own project and location.

Supporting the Lintel Properly

The lintel doesn't work alone.

The load carried by the lintel must be transferred into the jack studs and king studs located on each side of the opening. Those studs must then continue down to a structural element below, such as:

• The floor system
• A load-bearing wall below
• The trailer structure (for a THOW)
• A foundation

A properly sized lintel is only part of the equation. If the load doesn't have a continuous path to the structure underneath, the framing won't perform as intended.

My Recommendation

Before framing doors and windows:

1. Determine the snow load for your area.
2. Identify which walls are load-bearing.
3. Determine the tributary width supported by the wall.
4. Use the appropriate span table.
5. Verify local code requirements.

A properly sized lintel is inexpensive compared to replacing damaged windows, correcting structural sag, or trying to fix a door that no longer closes.

The goal isn't simply to create an opening.

The goal is to ensure the structure continues carrying its loads around that opening for decades.

For those who built their own tiny house, did you size your lintels using span tables, an engineer, or did you simply follow common framing practices?