Insulating shed against heat from sun

[Becky2181]

Hi guys,

This is my first post and I am looking for advice on insulation. We have put up a shed to use as a home office and want to insulate the roof to keep it cool (we live in Spain).

We have got the this silver insulation to put up, our plan it to leave an air gap top and bottom, so it would go shed roof, 1/2 inch air gap, silver insulation, 1/2 inch air gap, plaster board.

My questions, does this sound right?, should we use thicker insulation?

Our plan is to also insulate the walls in the same way. We are also thinking about painting the outside of the roof with solar reflective paint.

Any advice welcome

Many thanks

 

[Doggit]

If you paint it with the solar reflective paint, then you'll have done the biggest part of the job. Do I assume the silver insulation is the thin multi layered stuff, in which case it would be a waste of time; you've be better off with 30mm of celotex, but as the main heat will come from the air itself, so I don;t know if an air gap will improve things, as that's where the heat will sit. But as with any spanish property, you really want tiles on the floor to soak up the heat.

 

[footprints]

As you can imagine it's not a common problem in the UK! It did cross my mind that a second "dummy" roof over the first with an air gap and open at the sides for air circulation might be a solution just like a heat shield on an exhaust or any component you wish to shield from direct heat.
But then perhaps it's just the heat getting to my brain as we have got our day of summer today!

 

[Doggit]

Ahh, venting the air either side is a sensible idea, but you'd want at least an inch or two to get a good airflow, but you can't really do that on the sides though. But you still didn't mention the type of insulation you are using.

 

[tomfe]

If you can, and it makes financial sense, convert it to a warm roof. I have 2 workshops one with coroline roofing and the other with 130mm of pir both are black. You can cook a chicken in the one without insulation.

 

[Alec_t]

I would have thought you need the silvering as the outermost layer to reflect the sunlight/heat. Then a support layer as necessary, then an air gap then the roof itself. Mind you, your silvered roof would probably dazzle the neighbours and be highly visible from the International Space station .

 

[endecotp]

shed roof, 1/2 inch air gap, silver insulation, 1/2 inch air gap, plaster board.
My questions, does this sound right?

No.

Paint the roof white.

Add vents so that the hot air can escape.