Insulated Panels

[B R C]

Looking to insulate the roof of my workshop. It has a good big 6 roof currently so don’t not want to replace it, I do like the look of the underside of insulated box profile with the white painted tin which looks smart and makes it lighter so wondering if insulation is available with just the smooth white tin on one side so I can fix to the underside of the purlins. What other options are there?

 

[Mur Huwcun]

I got some exactly like you said but steel on both sides when they demolished a nearby frozen food retailers stores and sheds. They were 6inch sheets with white steel on both side. At the time thought nothing of it and used them in the floor slab of the house!! Should of stored them and bought some kingspan for the slab!!!

 

[Doing it for the kids]

I cheated. I got seconds kingspan boards and sat them on sheets if only screwed the steel roof supports.

They had 100mm of depth and the insulation was 75mm leaving a nice air gap.

We painted the boards white, it’s worked very well

 

[upnortheast]

Often see s/h cold room panels advertised.on ebay & elsewhere
Screw under purlins.
Not sure how that would compare with price of kingspan

 

[How much]

Be a bit cautious with these insulated sheets they are great for insulation but insurers hate them with a passion , I had an issue a few years ago with what they call PIR insulated panels just as you describe they where installed in big grid a bit like a false ceiling under a cement asbestos roof, a surveyor from the insurers got his eye on them and wanted them pulled out or they would withdraw cover they ended up doubling the fire risk cost !!! . What you are discussing here is the heavier type than I had that where worse in that if fire got into them at the sides there is no way to extinguish the fire as you cant fight it through the face the fire spreads through the middle.

In workshop with sparks and flames that could be big issue if the panels are marked with a manufacture and model type that proves the fire retardants of them that would help insurance wise ours where not , but something designed for cold store is probably not suitable for a workshop and the open edges would be the issue in a workshop

Its all pie in sky if you never have an insurance inspection or a fire when an assessor comes out but its to late then, just be cautious !

The best option is to remove the cement asbestos and put two skin roof over with rockwoll in middle second best option overlay the cement asbestos out side the same as above and then spray asbestos white to get a lighter finish

 

[harrow]

Remember Grenfell Tower.

Grenfell Tower fire - Wikipedia

en.wikipedia.org

There will be plenty of panels being stripped off tower blocks BUT its a risk.

 

[B R C]

Good info @How much there are plenty of those cold store panels on eBay!
It’s about £7k for new insulated box profile so I’m still thinking about it, at least it would a new roof to last a long time.

 

[designanddetail]

You could always use a white liner panel fixed to the underside of the purlins and lay rockwool in the void.

 

[Doing it for the kids]

You could always use a white liner panel fixed to the underside of the purlins and lay rockwool in the void.

If you do make sure the rock wool doesn’t touch the roof else it will get damp and never dry and work well again

 

[Nigel Wellings]

Be a bit cautious with these insulated sheets they are great for insulation but insurers hate them with a passion ,

You are 100% correct to highlight this point. Fires like Grenfall have made Insurers very wary of composite panel insulation and spray foam insulation. You need to declare any such insulation to your Insurers or in the event of a claim there could be a problem. Most insulation materials have a fire rating, which Insurers will want to know.

 

[sodbuster2]

The older generation cold store panels were PUR or EPS hence the choice of used on the market. This has ,in recent years, been superseded by PIR which has a much better fire resistance albeit with a slightly lower strength panel or rockwool which is even lower strength and a lower insulation value too but with high fire resistance.
Retrofitting insulation between the purlins can be done with a closed cell such as XPS to avoid moisture transfer but I would avoid fitting below the purlins as this leaves a large cavity which can cause condensation and vermin issues.
The best solution is to remove cladding and replace with insulation/cladding above purlins or use composite panels but as ever the best solution is often the expensive one.
And beware the translucent roof sheets often degrade the insulation below so best to remove where possible.