Hi there,

 

I'm erecting a SIPS extension in March, and as part of the building regs I need to install a minium (additional) 20mm of insulation to the internal walls, and 40mm to the Ceilings.

 

Looking at the details now I've noticed that the Architect has recommended this is installed as a continuous layer and battened over, rather than what I had figured I would do.

 

I thought it was, batten out the wall at 60cm centres, and cut insulation to fit in between.

 

are there some magical fixings that can penetrate through a batten and hole PIR insulation hard against a SIPS panel?

I am confused. Is this additional insulation in the existing part of the house?

 

If the sips panels themselves need additional insulation, I would instead be looking for thicker sips panels?

13 minutes ago, Tin Soldier said:

are there some magical fixings that can penetrate through a batten and hole PIR insulation hard against a SIPS panel?

 

Yep... wood screws ..!

 

I would use a light bead of spray foam on the edges to make an airtight join and then batten back at 600mm centres, 400mm is better. 

 

Batten is 25mm, insulation is 40mm at best and they will be 12.5mm OSB sheathed so a 5x80mm wood screw would be fine. Put them 150mm from each end of the batten then at 300mm centres. 

 

Walls could have slightly shorter screws due to thinner insulation but TBH I would go 40mm everywhere as the cost difference is negligible and it saves you buying two thicknesses 

Yes it is lined internally. 

I probably should have said why

 

The planning for our house extension has taken a rather long time, during which a couple of things have happened.

 

1. The insulation requirements have gone up between planning, and building regs sign off

 

2. Kingspantek SIP system prices have increased significantly

 

for various reasons Kingspan Tek (and their partner) are willing to honour a quote we got from them over two years ago, but any change will bring us into a requote and the new prices.

The new prices add on circa 8k to the cost, as such I opted to internally insulate myself as it will be significantly cheaper - though more hassle

 

Edited November 27, 20178 yr by Tin Soldier

woodscrews  woodscrews you say.. well that is pleasant to hear

 

Would that make a robust enough makeup to hold kitchen cabinetry etc?

 

a woodscrew through 25mm batten 25mm of insulation, and then 15mm of OSB board?

Happy to change to 400 centres but I'm worried stuff will pull off the walls

 

ok I only have two upper cabinets and a mantel/extractor planned.

So work out where the cabinets will go and either put more battens or just use long screws into the OSB behind everything. 

 

With 12.5mm plasterboard you are only talking about a 120mm screw and they aren’t expensive. 

as much as I'm slightly embarrassed by the simplicity of this and just how long I looked for an answer for the weekend - I found some fancy helical fixings for stonework,

 

I like woodscrews, they're nice and cheap and quick

You need helical fixings for exterior insulation when it’s thick. Wood screws over 150mm become unwieldy and also provide cold bridges. 

Roger that Peter..

 

I should have known to ask on here first

For the bit where the kitchen cabinets are going, fit 50mm battens instead right down to the floor, glued and screwed to the OSB of the SIP panel and insulation in between.  Then continuous insulation and thin battens everywhere else.

 

The slight reduction in insulation will be small and I would (cough) not mention this to your BC inspector.