Garden Office - External stud wall on subfloor or joist ring?

[Dunksyo]

Hi all,

Long time lurker first time poster!

I’m currently in the research stage of my garden room/office. I’ll be going for a suspended floor on groundscrews, with a floor using double joists on the rim, then singles at 400 centres. All 6x2.

I’ve seen a few builds using Egger protect tongue and groove as the subfloor and then screwing/nailing the stud walls straight down on this but after reading through the Egger installation guides they recommend leaving a 10 mill expansion gap against any walls. Obviously this isn’t possible when the stud walls are fixed to the top of the Egger protect.

Should I be mounting my stud sole plates onto the joists instead? And then laying the floor leaving a gap between the floor and sole the plate.

Is laying the subfloor to the end of the joists and then the stud walls on top acceptable from an expansion point of view? I’m looking at a floor size of around 6m by 3m.

Cheers,

 

[23vc]

Can’t see any harm just stud walling over the boards. Can still have their expansion gaps at the perimeter etc and less cuts/gaps to foam. Assuming the t&g boards are fixed to the joists not floating on an insulation layer

 

[Deluks]

Stud down onto chipboard is common practice, but a shyte idea!
Plate first, floor after.

 

[Dunksyo]

Stud down onto chipboard is common practice, but a shyte idea!
Plate first, floor after.

So something like below? Yellow is the outer ring double joist, red is the stud wall sole plate. The green is the joist and 22mm Egger protect, with a gap between the wall for expansion.

Because I'm looking at using CLS 38x89mm I'm not left with any joist for the long edge of the board to line up, will I need to add noggins along the entire length in that case?

Can’t see any harm just stud walling over the boards. Can still have their expansion gaps at the perimeter etc and less cuts/gaps to foam. Assuming the t&g boards are fixed to the joists not floating on an insulation layer

Thanks for the reply. There won't really be a perimeter as such because I'll be boarding right up to the edge of the joist, like seen below. The boards will be glued to the joists, glued together and also screwed as per Egger's installation guide lines.

 

[23vc]

While I agree plonking walls on floorboards isn’t great generally, I can’t really see the downside in this context. It’s all glued down and never coming up anyway so just forms a single structure.

 

[Dunksyo]

While I agree plonking walls on floorboards isn’t great generally, I can’t really see the downside in this context. It’s all glued down and never coming up anyway so just forms a single structure.

That's my thinking. I was just thinking about the expansion gap the install guide mentioned between the boards and perimeter walls, but I guess if the boards aren't butting up against a wall that doesn't matter!

 

[^woody^]

It's a timber shed. Do whatever is easiest, don't get bogged down in theoretical detailing that will make no difference in this situation.

 

[mrrusty]

then screwing/nailing the stud walls straight down on this

Which is exactly what I did with mine, except my build was sips with the sole plate fixed directly on to the flooring. It's been fine.