Insulation upstand when not having skirting board?

[flanagaj]

With a conventional build, the thickness of the 'dot & dab' / float and set and skirting board will hide the 25mm thickness of the PIR upstand of a screed floor.  If you are not planning on having skirting board, then a conventional build up risks the PIR showing.  In such a scenario, is the only option to use insulation backed plasterboard or bring the plasterboard off the wall using battens?

 

This obviously only applies to a polished slab finish or an insulated garage floor.

Edited Friday at 06:17 by flanagaj

[Nickfromwales]

35 minutes ago, flanagaj said:

With a conventional build, the thickness of the 'dot & dab' / float and set and skirting board will hide the 25mm thickness of the PIR upstand of a screed floor.  If you are not planning on having skirting board, then a conventional build up risks the PIR showing.  In such a scenario, is the only option to use insulation backed plasterboard or bring the plasterboard off the wall using battens?

 

This obviously only applies to a polished slab finish or an insulated garage floor.

Mildly confusing, so which one is it?

 

Are you having a floor covering?

 

More info and less ambiguity please!

[Spinny]

Dot & Dab brings the plasterboard off the blockwork anyway. 12.5mm plasterboard with 2.5mm skim = 15mm. Dabbed off the wall by 10mm and the front of your finished wall is circa 25mm off the block work.

 

Why no skirting board ?

People do use flush skirting with shadow gaps and stuff - is that what you mean ?

 

We have a 25mm upstand but levelling compound and flooring will cover it. 

 

Laying the top part of the screed to cover the top of the upstand could be one answer. Yes creates a small thermal bridge between floor and wall but does this matter much ?

[flanagaj]

7 hours ago, Nickfromwales said:

Mildly confusing, so which one is it?

 

Are you having a floor covering?

 

More info and less ambiguity please!

No floor covering

[flanagaj]

2 hours ago, Spinny said:

Dot & Dab brings the plasterboard off the blockwork anyway. 12.5mm plasterboard with 2.5mm skim = 15mm. Dabbed off the wall by 10mm and the front of your finished wall is circa 25mm off the block work.

 

Why no skirting board ?

People do use flush skirting with shadow gaps and stuff - is that what you mean ?

 

We have a 25mm upstand but levelling compound and flooring will cover it. 

 

Laying the top part of the screed to cover the top of the upstand could be one answer. Yes creates a small thermal bridge between floor and wall but does this matter much ?

My post was confusing.  I have an insulated garage floor slab, but I wasn’t planning on plaster-boarding or fixing skirting board.  Rather than having a 25mm slice of PIR showing, I could either omit the upstand, but that sort of defeats the point of insulating the slab.  
 

[Spinny]

Why insulate the slab, are you heating the garage ?

[Nickfromwales]

If bare walls, who gives a hoot about seeing a bit of PIR around the perimiter?

[flanagaj]

On 19/06/2026 at 20:27, Nickfromwales said:

If bare walls, who gives a hoot about seeing a bit of PIR around the perimiter?

I've subsequently discovered that you can cut a 45 degree angle on the PIR to hide the edge.

 

One final question.  How do you get a smooth enough finish on the slab for PIR.  Do you simply use a piece of timber with a side to side motion and then use a bull float at 90 degrees.  I really need to be able to do the slabs myself with my brother as I struggle to find anyone to do it without changing lots of £££

[Mr Punter]

1 hour ago, flanagaj said:

do the slabs myself with my brother

 

Well that is great news for your project.  Although you may find siblings tricky, at least they know your foibles and are not such a PITA as contractors can be.