Perimeter insulation - flooring butted up to or laid over?

[Dunc]

Hopefully a quick one: When installing the PIR floor insulation a 50mm perimeter upstand is specified. In one of the architects diagrams the upstand stops level with the screed and the final floor covering oversails this to butt up aginst the wall. In another diagram the perimeter upstand extends high enough for the floor covering to be separated from the outisde wall.

 

As this is a larsen truss frame, the inner sole plate is effectively insulated from the outside as it doesn't span the full width of the wall.

The blockwork underneath the sole plate has a course of Marmox blocks below the top block and this will overlap with the 220mm PIR, so the top block is thermally broken from the ground....so I *think* it's OK to oversail the upstand?

 

Top to bottom:

Tiles

50mm screed with UFH. Top of screed is level with the bottom of the sole plate

slip membrane

220mm PIR

150mm reinforced slab.

 

 

 

 

 

 

 

 

 

Edited 5 hours ago by Dunc
adding diagrams

[Oz07]

You may as well go with bottom drawing. No need for floor finish to go any further than the line of your finished wall and looks like your wall is in from the timber frame?

[JohnMo]

Took my insulation at the wall edge out as far as the inside edge of the skirting. So bottom image but wider.

 

I would do 200mm PIR and increase screed depth.

[Gus Potter]

1 hour ago, Oz07 said:

You may as well go with bottom drawing. No need for floor finish to go any further than the line of your finished wall and looks like your wall is in from the timber frame?

Plus 1 to that. Once you take into account the build sequence then agree second option is more practicable. 

 

I know you have just asked about the inside but can you just check the weathering detail on the outside?

 

This is a critical detail for longevity. Ask your Architect if they know whether the Larsen truss has been designed so both the inside and outside flanges require structural support.

 

@Dunc Does your cladding require ventilation behind, always worth checking the fire protection detail around doors , windows and at the wall head if this is the case.