Plastic in patio roof?

[mattias_m]

Hello,

I am about to insulate the roof of my patio and am considering whether to put plastic above the ceiling.

Currently, there is a metal roof - batten - plastic. I am planning to fit 145mm insulation (is that too little?) and then the ceiling. Should I put plastic in between?

The space should be able to be heated in the spring and fall, and maybe even cooled a bit if the summer gets hot.

If plastic is not good, is there anything else I can use, just to help keep the insulation in place?

 

[sblixten]

Start by removing existing plastic.

 

[mattias_m]

Oh, but if the plate leaks, will the june insulation get wet then?

 

[verktygsgurun]

You must remove the sheet metal. Install an underroof and then put the sheet metal back. Then you can insulate. On the backside/underside of the sheet metal, a lot of condensation forms, not just a small drop but lots of water. Putting plastic backwards won't work.

 

[mattias_m]

You need to remove the metal sheet. Install a sub-roof and then put the metal sheet back. Then you can insulate.
On the backside/underside of the metal sheet, a lot of condensation forms, not just a small drop but lots of water. Putting plastic in reverse won't work.

Okay, does condensation form even under the plastic that's there now? I have limited space upwards, so a sub-roof will be challenging.

 

[Demmpa]

As a waterproofing layer under the roof sheet, it is possible to stretch/lay reinforced plastic sheeting, e.g. http://www.tradgardsteknik.se/katal...astduk-320g-m-sup2-3-3-x-200meter/11250-0-11/
It doesn't add any height, so it can be used if you don't use tongue & groove and tar paper under the roof tiles. Many boat owners use such plastic to build tents over the boats for storage & work.