Building a 5x10 Square-Drop (The Bradbury)

[gearsoup]

I'm a bit uncertain how I want to attach my spars to the wall/ceiling. It's 1.5" poplar sitting on top of 6mm ply, which is sitting on the edge of my 3/4" walls. Some people screw from the outside and hold it on end, other screw from the top and drive it into the end grain of the 3/4" ply. Of course, I'll be using PL3 in conjunction with whatever method I decide, but would love some feedback from those that have built successfully. (located loosely just for example only in photo below)

Yes, there's a lot of extra "outer skin" above the spar. I built it long and figured I'd use a trim router to bring it down to the top of the roof (and roof would be sitting in between the outer skins)

 

[Tom&Shelly]

We had a problem with PL3 expanding, making our top lumpy. Would have been better if we'd used Titebond 3. We screwed from the outside and our fix was to apply a filler to the top of the roof and sanding smooth before applying the fiber glass and epoxy.

Tom

 

[gearsoup]

I suppose I could build something similar to a Kreg jig and send the screw in at an an angle slightly off 90 degrees

 

[Tom&Shelly]

Ours didn't expand at the screws, but rather at the struts away from the screws. Hence the "lumpiness". We used Titebond 3 where the roof was horizontal with no problems. We used the PL3 in front and in back where the teardrop slopes. The idea was that PL3 wouldn't run as much at TB 3, but we didn't realize how much the little expansion of the PL3 would affect the 1/8 inch Baltic birch.

Tom

 

[gearsoup]

The idea was that PL3 wouldn't run as much at TB 3, but we didn't realize how much the little expansion of the PL3 would affect the 1/8 inch Baltic birch.

Tom

Ah, gotcha

 

[Tony Latham]

I haven't had an issue with PL3 expanding, but I always double it up with 1/4" crown staples.

This is how I wrote it in my book, and it works fine:

Once you’ve marked the spar spacing on each wall, lay a bead of PL Premium on top of the headliner and where the spar mates with the wall skin. Set the spar in position. Place these with the dado for the wires on the left side.

Drive one screw horizontally through the wall exterior into the butt of each spar. To attach them to the headliner, place a trouble light next to the spar.

This will allow you to see where the spar is from inside the cabin. Drive 1/4” crown staples into the spar about 10” apart. You need to push the headliner up into the spar before pulling the trigger. Try to set these fasteners at an equal distance and oriented in the same direction.

Since you're using a much thicker headliner, you'll need to find a different way to locate the spars from below, assuming you choose to join with both a fastener and glue.

I'm curious as to what will go on top of he spars, since it looks as if you've got about 1" to meet with the top of the walls?

Tony

 

[gearsoup]

I'm curious as to what will go on top of he spars, since it looks as if you've got about 1" to meet with the top of the walls?

Tony

Close, it's a little under 3/4" there, but lower in some other areas (it was just rough cut) I could say that I left things intentionally tall, but that'd be disingenuous. I had planned on using 2" rigid insulation, but some errors done early on meant that I needed to have my roof sit inside of the outer wall skins. I made my width a quarter inch too wide and just built around it. At 60.25, that means that if my roof sat on top of everything, I needed to have a seam in my roof and I really didn't want that, favoring one full width instead. Also, dropping it to the inside of the outer walls wasn't going to work as there wasn't sufficient wall skin (all around) to seal it up. So....all that said, I just went to 1.5" insulation instead and then once the roof is on, I'll run a trim router along the edge to bring things flush.

 

[Tony Latham]

Close, it's a little under 3/4" there

Gotcha.

T