which spacing distance is correct?

[camaro1969]

I plan to space the studs at approximately cc300 and want to space them based on half the width of an insulation board.

It's common to space studs at cc600 with 45 mm timber, which gives a gap for the insulation of 555 mm (600-45). Standard insulation boards are 565 mm wide, which is 10 mm wider than the distance between the studs, I assume this is good to create pressure against the studs and thus prevent drafts.

In my case, I have rough-sawn timber that is 50 mm wide.

If you split an insulation board in half, they become 282.5 mm wide.

Am I correct in wanting to space the studs at cc327.5?

With insulation at 282.5, the stud at 50, and with the relationship that the insulation should be 5 mm wider than the gap, theoretically, I would argue that splitting the board in half requires it to be 5 mm wider than the distance between the studs. Am I making a mistake in my thinking, or does my reasoning hold?

 

[andersmc]

It is very difficult to cut insulation boards with a precision of 5 mm. That would be possible if you have a machine that does it.

 

[camaro1969]

that sounds reasonable yes, but with a ruler and insulation knife it should go fairly well,
maybe count with 10 mm even when the stud distance becomes shorter
then I theoretically frame at cc322.5, maybe it will be easiest to think cc320