22mm or 47mm thick Sole plate?

[mrmcrae]

Hi,

 

I am about to start my SIP panel garden room however, as I am building directly on top of a concrete slab i opted out having the SIP floor as I fall under the 2.5m rule.

 

The designers removed the SIP floor and replaced with a 47x100mm sole plate.  I have been looking a little bit more into it and I have seen more convincing diagrams however using 22mm thick sole plates with the 75x47mm rail.  

 

Concrete slab thick is approx 4in thick (so I have been told).

 

My question is other than gaining a little more internal height, it there any benefit using a 47mm over 22mm thick sole plate?

 

 

 

[Conor]

Better fixing for your SIPs. 22mm doesn't give much to tack in to.

[James Newport]

As above, and less chance of the 47mm thick wood splitting when you fix into it.

[mrmcrae]

Valid points thanks. 
 

Thing is I have been a little paranoid over this whole 2.5m rule and where I have decided where to measure from (lowest part of garden closest to the house and from top of patio slab) I will be approx 5-10mm from 2.5m.  Hence looking at a thinner sole plate in case I’m supposed to be measuring from the bottom of the patio slab.. 

[TonyT]

47mm for the sole plate and reduce the height of the walls by 25mm and you have the same height

[mrmcrae]

Thanks Tony but the garden room is all pre cut from factory so don’t particularly want to mess around with it. Reducing the sole plate thickness appeared to be an easy option.

 

Sounds like the 47mm is best option so It looks like I’ll have to take my chances with the overall height and hope I’m right…