The deck is a steel subfloor, hardwood boards, LVL rafters, polycarbonate roof.
See daylighting for details of choosing the transparency.
Since the hardware is exposed, I choose to use 'nice' solid fittings for mounting the joists.
We want to use insulated panel (ie. EPS foam with a thin colourboard skin) to improve comfort to the deck. The deck is currently polycarbonate. This works well in Winter and Spring. In SUmmer, a minimal shade cloth (to 75% of area) improves comfort but it's too hot in the middle of SUmmer. Hence: add insulated panel.
The key here is reducing radiant heat by reducing the inner (i.e. bottom) surface temperature of the deck roof.
How thick a panel should I use?
Firstly we assume a few things:
Air is 28°C, humidty is 60%, upper surface is 60°C (in the sun). By working out heat transfer (convection on the inner surface and conduction through the panel), we can find the inner surface temperature and then predict the comfort levels. And the results are:
To reduce the inner surface temperature from 45°C (PMV 2.5 = hot!) with R0.5 (20mm) to, say 32°C (PMV = 1.5 = still pretty warm) we use R1.5 (50-75mm). Below R2.0 (75mm) gains are limited.
Therefore, we select 50mm (minimum) to 75mm (preferred) thickness.
It's start - with the underfloor deck
Painted rafters - this is much easier on the ground!
Ripped leftovers and sanded, painted, etc. Undercoat is v. slow to put on. Keep a 'wet line'. Not worth spraying, but could have arranged to cut some other peices for priming. Sanding between coats was worthwhile even on this 'rough' timber.
