Insulation dilemmas

[RedShirtGuy]

This is my bush shed in the central goldfields of Victoria. A dirty great big metal jobbie (guessing 50m sq) with a verandah on the north and east sides. It's sitting down in a cut out with the west side next to a 1m retaining wall about 1m away while the ground on the south side starts at 1m but slopes away to ground level. The roof is corrugated iron while the walls are mostly flat with an outward "spine" spaced every 200mm or so (at a guess). While most of the roof is iron, there are a few strips of alsynite that allow light in and after insulating I would like to be able to keep these clear.

As I'm sure most know, it gets obnoxious in there during summer. It's almost intolerable, yet I'm supposed to be able to live in it.

Currently I don't have enough material to do the whole shed, but I do have a enough ~25mm thick polystyrene to do the west and maybe a little of the south walls (or a side and a bit of the pitched roof) and a roll of foil insulation (82m sq coverage) with a few big scraps from another roll. I also have enough R3 batts (no foil faces) to do the roof but not enough wire to hang them (ala BobL's technique). I don't particularly want to use the batts as I've been keeping them for a house, but thought I'd mention them anyway just in case they're easily used and reused.

My dilemmas are:
- practically no immediate budget (and I apologise for asking for the world without being able to pay for it)
- where to use the poly and foil.

The recommendation for the foil is to use it vertically (so it doesn't collect dust) with a min. 25mm gap from the surface. That sounds easy enough to achieve on the walls, but not so much on the pitched roof - mainly because of the dust collecting element...but I don't really know how big a factor that is.

The recommendation for the poly is to have it stuck flat against the surface. Again, achievable on the walls with only a small gap at the "spines". But if used on the roof there would be very little surface contact and regular gaps from the corrugations in the iron.

It's a toss up between using the foil on the roof and gathering dust, or using the poly up there with lots of gaps behind it.

The last problem is that I need as much reflective surface as possible as I only use oil lamps for light in the shed at night. I figure I might be able to stick some kitchen alfoil on the back of the poly, wherever it is situated.

Any suggestions, opinions or advice on what I should use where and what to concentrate on covering completely (walls/roof)?

While I might be able to afford only a few bits of lumber for studs/purlins now, something to keep in mind is that in the future I may be able to afford more, as well as some sheets of bracing ply...which I guess is when the batts might come into play.


UPDATE: I think I'd also prefer buying more foil wall wrap than poly and also rather than using the batts.

[Timless Timber]

Polystyrene is a good insulator - no question, which is why it is used in coolers and eskys etc.

As a roof insulation I am not a fan, it burns fiercely and gives off nasty fumes. In the event of a fire it might be the difference between getting out alive or not.

Just my 2c.

[soundman]

Well yep not overkeen on the styro either but I will admit to having used it myself in parts of my shed.
When you get amplifiers packed with two pieces 500 x 400 in each box, it mounts up pretty quick..and its free.

As far as fixing the bats...use Soundman's patented method.....spray glue.

I've insulated most of the walls of my work shed and it is the way to go.

Standard spray glue.....contact cement by the 20 litre, standard spray gun.

spray the wall spray one side of the bat..want till tacky...stick er up.

stay put on corro or the fat profiles.....then you dont have to worry about holding the bats up when you sheet over.

If you dont want to sheet over, you can use the spray glue again and wrap the bat in whatever takes ya fancy...the foil perhaps and then stick em up.
The foil basically will do bugger all.....it is used in building mostly as a moisture barrier and will do bugger all for insulation unless it is backed with some form of bulk insulation

As far as interiour walls go.

have a chat to local board merchants and see if they will sell/give you packer sheets.

Most packs of board come with a packer sheets top and bottom so the good stuff does not get dinged.

My local sells em at $10 per sheet......I can tell you I have go some decent sheets as packers and built lost of stuff out of it.

18mm of MDF will give you way more insulation ( both heat and noise) than a sheet of foil

cheers

[RedShirtGuy]

Mmm...I was aware of the fire hazards of the poly but now I'm a little more cautious about using it. I certainly wasn't going to use it anywhere near the stove and flue (which is in the center of the east side). The property is basically a 5 acre matchbox. If there's ever a good fire there the whole place will be knackered and it would insane to stay and defend, so maybe a bit of poly isn't going to make much difference. The whole area was completely burned out in '87 so it's a possibility I guess.

Something I've just thought of is that it's possible to put a verandah on the west side as I have more than enough corri and probably enough rough timber and bush poles for the job. Then I could concentrate on just doing the roof. Any idea on how that would compare to the other ideas already mentioned?

The reason for the budget restraints is that every dollar I spend on the shed is one less that could be spent on a house and there probably wouldn't be much material reuse. The MDF is a nice idea that I'd considered before but just way too expensive to do in one hit. The reusability of most of the sheets might be questionable after a few years.

To get rid of the poly would cost a bit as well, so I guess if push came to shove I could poly just the west wall to use most of the material I already have. As long as the poly can't spontaneously combust from radiant heat on the wall I'd feel reasonably safe with it there.

I also love Soundman's idea of the el cheapo packing boards. With them and a few lengths of framing timber I could put a proper pitched (or flat) ceiling in and would feel reasonably sure that I could reuse the batts easily when the time comes. In fact, if I can get the boards on the cheap, that's probably my preferred option. There would be some good opportunities to reuse the cruddy boards in the building of a house and for other low visibility projects, so in some ways it would be like an investment.


The second post (and some of the follow ups) in this thread from another forum is an interesting read and probably the ultimate solution. Serious overkill for what I need but good information. My primary concern is only the heat in summer. It's impossible to keep it cool at the moment but I can easily keep the place warm in winter.

[Timless Timber]

My aversion to Polystyrene - stems from boat building experience.

I built a little alloy 16 ft punt once... and use diit for fly fishing tours so it had to go thru passenger survey with the marine safety transport authority engineers / inspectors / surveyors.

They specified a very expensive material... closed cell, fire retardant, high density, poly urethane foam from memiry - the crumbly yellow stuff you see inside commercially made aluminium dinghy's in the thwart seats. AND they specified it had to be glass encapsulated...

They had good reasons for this.

I see people who make their own boats use styrene all the time for buoyancy material, and oneof its failing sunder floor in a boat - is how it reacts to petrol if any is spilled....inside the boat. In essence it shrivels up and turns to sticky black goo - and you only need add a thimble full of petrol to a poly styrene coffee cup to see what I mean.

This is why its not actually allowed in any surveyed boat for buoyancy purposes... a half a cup full of spilled petrol when fueling up and your buoyancy foam is vanished before your eyes.

It also compresses easy (Meaning it might compress under the weight of water if a boat is say dumped by a wave and driven under a few feet or so and suddenly not displace enough water to be positively buoyant any more).

Styrene can trap moisture against the alloy sheet and start corrosion and so on it goes.

Its also highly volatile..and the fumes injurious to your health.

So my prejudice against its use in boats from experience - I guess colors my prejudice against its use in buildings, for similar reasons... which in fairness to styrene isn't probably warranted.

It's light, cheap & relatively strong and has great insulation property's - why wouldn't you use it in a shed?

As long as your aware of it's positive and negative property's and use it accordingly, it should be fine - they use heaps of it in cool rooms.

[RedShirtGuy]

Interesting stuff TT. And I don't think it isn't relevant to using poly in a shed...except maybe the compression...if my shed got hit by a wave in the middle of Victoria I think its insulating abilities will be the last thing on my mind

It's all information that one should be aware of in any situation anyway.

I also already knew about the petrol/acetone issue...how else would I know what to use for home brand napalm molotovs

[Chris Parks]

You might be able to supplement your lights with some cheap LED's. They will run happily from a 12V car battery for hours or just build a few circuits in the shed for them and power the lot from your car battery with jumper leads. Go to all your local fruit and veg guys and get the foam boxes they don't want, you are doing the world a favour by recycling them.

[RedShirtGuy]

Yeh, ideally I'd like some small solar gear to be able to have a few LEDs that I could run for 6 or so hours a night in winter (and another setup for fans on a solar wood kiln). Even if it was just enough light to not trip into the fire place I'd be happy enough. I have a couple of portable solar lights and a wind up torch that I can take out to the thunderbox, but they don't work too great as an indoor light source over a long time. I burn citronella oil in the oil lamps to keep the 'skeeters' at bay and that's a pleasant light to sit by, but a bit of a pain to read/play guitar/craft by.

It'll all get there one day...and it's been at least 5 years in the process so far . I'm heading up there tomorrow (hangover depending) to get some of the polystyrene up off the floor and onto the walls so a little progress might inspire a lot more If I remember I'll take up a camera and share a few pics just for giggles.