[cmugler]

When a did my previous conversion I attached birch paneling directly to the ceiling ribs after insulating and noticed on cold mornings a strip of moisture appeared on the paneling directly below the ribs. If I put a double sided exterior foam tape on the ribs before installing paneling will this prevent the condensation and do I need to put rubber washers on the sheet metal screws also, any ideas? Thanks

 

[keeponvaning]

I wouldn’t recommend 1’8" or even ¼" I used ¼" and even that had a slight sag between the last 2 ribs on my 159. ⅜" would be a better choice and basically the same price. If you have a 138 it may work ok tho.

 

[MsNomer]

I have not had a problem (yet) with my 3/16" cheap Luan. I used nominally 1" thick "joists" below the ribs with the curve of the ribs on the upper and lower surfaces. You could make a flat ceiling by not curving the lower surface, though I suspect the curve, though slight, added strength.

For now, see my build thread with photos in my signature.

 

[keeponvaning]

The 136 has a much shorter distance between the last two roof ribs I believe. Probably ok as I suggested but no way on a 159 without adding another rib in between somehow.

 

[cmugler]

I have the 136", my main concern is the moisture showing up below the ribs and if the foam tape will remedy this

 

[pbanbury]

I installed ⅛ luan on the ceiling of our 159. I ran 1x lengthwise of the van. I attached the four lengths of 1x to the cross ribs with ¼-20 nutserts. Used various widths to accommodate mounting various things to it. This added depth between the roof metal and my ceiling allowed extra insulation.

I screwed the ⅛ luan (covered with boat hull liner) directly into these “joists”. The thin, flexible plywood shaped nicely and so far I am satisfied with it.


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[JohnnyRambles]

Glue 1/2" foam (Or even that 1/4" folding stuff) to the back of your paneling, then screw the whole thing up in place. That will thwart the conduction of heat through the ribs, eliminate the condensation issue and give you a little more insulation overall.

 

[cmugler]

can you be more specific, brand name, source? of that 1/4" folding insulation

 

[urbsk8er]

can you be more specific, brand name, source? of that 1/4" folding insulation

It's called dow board or fan fold. Any home improvement store will have it.

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[KeepMeMoving]

I put reflectics in the ribs and 1/8 insulating tape over the ribs then screwed on 1/4" plywood.

From my build...
"As for the ribs at the top? I filled them a layer of reflectix and covered then with a kflex insulating tape.

Tape
Reflectics
"
I have not had any condensation inside with temps down to about 30F outside