Having reached the back of the house in this reno., I have a back veranda that looks as if it was added to form an enclosed living area.. windows across the full width of the house,walls either end,and a flat,lean-to type iron roof,called Trim-deck down here,like corrugated iron sheets,but flat..These are screwed to bearers in the usual way,then the interior ‘ceiling’ nailed the the underside of the ‘rafters’.
I want to insulate this roofing,as it gets B@88$y hot in summer,and similarly cold in winter.
I would welcome your collective guidance and ideas on how to go about this.
As a starting point, I am thinking of using rigid p/styrene sheets,cut to fit ‘tween the rafters & bearers, with the p/s-wood meetings sealed with spray foam, then a fibreglass/foil ‘blanket’ nailed to the the underside of the rafters immediately before the ceiling goes back.
Is this goin’ to work,or am I playing doggie to the wrong stump?
Thanks guys & guyessess!
Robin
Replies
Sure it isn't a steel roof? i've never heard of iron roofing.
having spray foam installed in place would be the best choice, but expensive. your solid foam sheets idea is good, but use can from to seal the edges and prevent infiltration. Paint the top surface a light colour to help with heat gain
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Hi, P
Yep,sorry.. it IS steel,it's just that we yokels call anything that is flat and heavy with zinc coating 'galvanised iron'. [it's been that way since Oz was a row of tents!]
I had planned to leave it unpainted,but should I decide to cover it,it would only be with a reflective silver finish.
I appreciate your thoughts,thank you.
Robin
If you bother installing e.g. polystyrene or polyiso sheets ... seems no reason to install batts behind it ... just choose your thickness and install foam full depth or the desired R-value.
There may be better coatings than silver for the roof deck, though. Silver coatings are becoming passe' with the advent of highly reflective white coatings that result in better performance. Explore this a bit maybe before utilizing the old fashioned technology.
Hi Clewless,
I do see your point about appropriate thickness of p/s and similar,and it is well made.It is only that the fg/foil mat is already there,but I hadn't thought the exercise through to its logical conclusion.[For all the good it seems to do,I might as well bin it,anyway!.....or turn it upside down as an anti-leak barrier :-)]
Part 2 of the job,the external finish, I hadn't given any thought to at all,save what I mentioned earlier.Your suggestion that a reflective coating would be a good idea makes a lot of sense,and I will do as you suggest and look at what is available here.I hasten to add that I'm a wee bit skeptical about the ability of surface contact coatings [paints]to reflect much heat.......light,yes..hence my original feeling of just leaving the galvanised surface alone.
But this may very well be just me.
I must thank you for your comments also, and I will remove me skeptic's hat and investigate!
Robin
PS. How goes the sailing? At this time of the year down here,it's either blowing the oysters off the rocks,or you spend an afternoon going up or down on the tide,then being towed back to your mooring!