Looking for some input on a wall buildup for a shed that will be used daily for short periods of time:

Gypsum board
1x4 strapping
2x6 framing
roxul
sheathing (taped - this will be air barrier)
Tyvek
3" comfortboard
1x4 strapping
siding

Would blown cellulose with TJI wall be a better option?

Thanks

It sounds like you're running the 1x strapping behind the gypsum board is horizontal to the 2x6 framing, with the Roxul batts between the studs?

If yes, that is leaving horizontal cavites between the Roxul & gypsum board that potentally promotes infiltration. Getting rid of the 1x4s and mounting the gypsum directly to the studs would be better.

The shed has only intermittent use, but what is the use, and is it being heated, cooled, &/or ventilated (either while being used, or when not in use)?

The shed might be used daily but only for a few hours at a time, but that could change. A baseboard will be the heating source although the shed has large windows to the south and east that will provide some heat when the sun in shining. There is no plan for ventilation. other than opening two window a crack... The shed will ideally be well air sealed.

The plan was to install the strapping behind the gypsum. Interesting that you should mention this detail - we had planned to install gypsum without strapping but were advised against it.

Again, what is the intended use, and is it going to be heated when not in use?

The vast majority of framed houses in North America has the wallboard nailed directly to the studs. In Canada there is usually a sheet polyethylene between the wallboard & studs/insulation, but 1x furring would be quite rare. What was the rationale given by those advising against it?

The owner will use it for a variety of purposes (there will be plenty of light and workbenches - woodworking, staining, projects that one would rather not do in a living space) throughout the year and probably some weight lifting, and there will be plenty of room for storage.

I don't plan on putting up polyethylene unless there is a reason to.

Will they be heating the place (a presumably lower temperature) when it's not in use?

They certainly could. It will also depend on how well it retains heat from solar radiation.