Loft insulation question

[xyz321]

Hi, we have some fibre glass insulation on the loft however I am not sure if it can be improved
We are on a semi detached house with a standard pitched roof.

Should there be insulation "under the sloping section at the end". I don't know how to describe this properly but here are couple of pictures if it helps explain what I am trying to explain. Orange plastic on the picture shows current insulation in the floor of loft.

 

[Wayners]

Normally board on inside 500mm up to stop insulation blocking off air flow.

You need vents in soffit to get the air blowing through

 

[Munroast]

I can't make head nor tail of those pictures - but the insulation lies on top of your ceiling, the void above that should be well ventilated so no point insulating it

 

[Ivor Windybottom]

Could you add some labels to say what the surfaces are?

Is the dark grey board with a light grey top the soffit?

The loft insulation should meet the cavity wall insulation, to form a complete wrap around the house. It shouldn't overlap the outer wall, and there should be space to allow the air to circulate under the roof.

 

[robinbanks]

The insulation on the floor of your loft should be contiguous with the insulation in your cavity wall, otherwise you end up with a cold spot in the top edges of rooms where external walls meet ceiling boards, and that's where condensation and mold starts

Here is an explanation of the concept; it doesn't have to be implemented exactly like this, but this is a reasonable detail. See how the wall insulation and the ceiling insulation are continuous. You have to arrange it so that the ventilation to the loft space is not blocked by stuffing wool into the corner where it changes direction. There is no rafter drawn here because that would obscure the point being made; this is what you see if you slice your house in half between two adjacent rafters. The black thing is a device to ensure ventilation to the loft space is maintained

 

[Ivor Windybottom]

Older houses don't have that vent board under the eaves, so you need to keep insulation well away from the corner. A cold(er) spot in the corner is just reality.

 

[robinbanks]

Not saying they do. I'm saying that ventilation must be maintained i.e. create something that achieves it

 

[Ivor Windybottom]

...which means leaving your rooms less than ideally insulated in many cases.