Glueing polystyrene to polycarb roof

[Kevla1956]

Hi, folks,
I am considering fixing 20-25mm polystyrene sheeting to the underside of my conservatory roof and then covering that with Kingspan or similar to insulate it. The polystyrene is to remove the cold surface on which condensation builds up.
Does anyone have any advice on which adhesive to use to fix the polystyrene in place. I can find plenty of grab adhesives that will stick to the polystyrene but they all need one of the surfaces to be porous, which the polycarbonate roof isn't.
Grateful for any suggestions

 

[Burnerman]

I'd be very wary of using any solvent based adhesive....how about some silicone?
John

 

[foxhole]

If you are insulating with kingspan you wont need any polystyrene?

 

[Nozzle]

Polystyrene cement! (the stuff of airfix models). Not very handy in the stringy squeezy tube though - might be worth searching out an aerosol alternative


or this https://www.toolstation.com/spray-contact-adhesive/p47790

Nozzle

 

[Kevla1956]

I'm avoiding solvent glue, to ensure that I don't break down the polystyrene. I tried putting the Kingspan directly onto the polycarbonate roof sheets bit there must have been tiny gaps where condensation formed, which then dripped down. The idea of the polystyrene is to give a warmer surface, on which to glue the Kingspan.

 

[bernardgreen]

Have you considered the flamability of polystyrene ?

 

[JP_]

Never done anything like this myself, but I did look at a house with a large conservatory. I did consider building an internal timber frame, fixed to floor and the wall, which would support the insulation (kingspan sheets) and plasterboard, leaving just the main doors and a couple of glass panes clear. Never actually investigated if it was feasible though.

looks like a guy did it here
https://www.pistonheads.com/gassing/topic.asp?t=1435090

although there is no sign that it is supported from the ground - I would think the weight of plasterboard + skim coat is going to be an issue if you're just connecting to existing roof.

 

[sircerebus666]

Never done anything like this myself, but I did look at a house with a large conservatory. I did consider building an internal timber frame, fixed to floor and the wall, which would support the insulation (kingspan sheets) and plasterboard, leaving just the main doors and a couple of glass panes clear. Never actually investigated if it was feasible though.

looks like a guy did it here
https://www.pistonheads.com/gassing/topic.asp?t=1435090

although there is no sign that it is supported from the ground - I would think the weight of plasterboard + skim coat is going to be an issue if you're just connecting to existing roof.

Don't forget roofs are designed to be able to take the weight of snow so some plasterboard and a 2-3mm skim isn't going to be an issue

I would be more worried about the plastic expanding and contracting , cracking the plasterboard

I'm not a fan of covering the roof , I have a conservatory because of the light the roof let's in , I fitted a nice big rad in it to help with condensation and so I can use it in winter

 

[JP_]

roofs are designed to be able to take the weight of snow

but will it hold snow + plasterboard + plaster + insulation? Probably ...

 

[sircerebus666]

but will it hold snow + plasterboard + plaster + insulation? Probably ...

Given how manufacturers are always cautious in giving limits about what something they make can do.......

Plus if you're really that worried about it , a simple email to the manufacturer of the conservatory asking what loading the roof can take will yield answers

 

[foxhole]

I'm avoiding solvent glue, to ensure that I don't break down the polystyrene. I tried putting the Kingspan directly onto the polycarbonate roof sheets bit there must have been tiny gaps where condensation formed, which then dripped down. The idea of the polystyrene is to give a warmer surface, on which to glue the Kingspan.

So you have already sealed the roof with kingsman, plasterboard, skimmed and then observed condensation?