Bending Roofing Iron

xelasnave · #1 05-12-2020, 08:54 PM

The caravan is hot even with air conditioning running and fans..it needs shade... I have gone thru every option imaginable up to building a new house...a car port over but that may be very expensive I will get a quote next week..however I just realised I could just nail up a frame and cover it with iron.. almost a normal roof...but the best way would be to bend the iron to match the curve of the roof...so the beams can run across which is easy to do...anyone bent roofing iron..would not have to be much.
Alex

RAJAH235 · #2 05-12-2020, 10:21 PM

Hi Alex,
After looking at all the 100 odd caravans in this caravan park for many, many years, all of them which have built a "fly roof" over said caravan, are all just flat.

None conform to the shape of the c'van roof.

Not necessary for shade.
They mainly build them to deaden the sound of the rain & of course, cooling.

Just keep it about 6"/150mm above the c'van roof.
Installation consists of...
Short vertical posts secured to the c'van (to your required height) with a flat bracket on the top & attach the new sheeting to it.

Stay safe.

glend (Glen) · #3 05-12-2020, 10:49 PM

Alex, I suggest you use Suntuff Polycarbonate corrugated roofing, it is vastly more flexible than metal and you can cut it easily with a jig saw. It cannot be damaged by hail and has a long guarantee against UV damage (15 years I think). I used this stuff for my observatory roof and it has been great, allows a bit of light through, depending in what colour you choose, and can follow curved shapes provided you align the ridges with the bend. Unlike metal roofing it does not transmit heat as much. And you can buy it at Bunnings.

http://polycarbonate.com.au/domestic...ntuf-domestic/

xelasnave · #4 06-12-2020, 12:30 AM

thank both of you very much. I appreciate bouncing my ideas of someone ..being a hermit has certain disadvantages.
i cant get over these little cabins and houses..one I liked small but would suit me..they present it as $16,500...but if you want the type of cladding in their photo..thats an extra $2000...and there is this and that ..it was up to $26,000 when I gave up as I could see it hitting $40,000 soon...not that the money worries me but you need an engineer to tell you the ground is flat, Council fees this and that...talk about feeding the mob...anyways got a bed for the observatory but yet to get a mattress however I could see basically living in there..its cool...but I will find out if I can get someone to build a big car port over the van and annex...
it was so hot today the desk top just shut down..the other day it went to 110 f...well on Monday I am buying a life jacket so I can float around in the dam ... anyways I am getting things done..the two microscopes are set up in the observatory and the little bits and pieces you have laid out and the new desk came today so I can set up the processing department...
anyways first step is get the solar panels off the roof..heck I can then rig a shade cloth at least ... and got to buy that fire pump if I have time on Monday and I can spray the van...that will help keep it cool...its a day by day improvement thing.
alex

sheeny (Al) · #5 06-12-2020, 05:03 AM

We had a similar idea of "flexing" corrugated iron for a job at work. We just wanted to put a 50mm crown in it over 3-4 metres. Forget it! The forces involved are too high, and if you do manage to do it, it will crease. If you really want a curved corrugated roof, get it rolled.

A tropical roof, is basically a radiation shield. If you look up the performance of a radiation shield you will see that 50% of the incident radiation re-radiated from the bottom. For it to work best though, air flow needs to be able to move through underneath it in any direction, so don't just bang up some timber across your van and expect good results. Spend a bit of time making frames to support the iron so the air can flow in any and all directions.

Do not use any sort of polycarbonate as GlenD suggests. Yes, it's easy to bend, but it only blocks IR radiation and maybe some UV if treated to do so. The amount of visible spectrum blocking is limited to the amount of tint in the polycarbonate only. This is why polycarbonate is used to make green houses instead of glass these days.

At my last house I decided to put clear polycarbonate over the pergola. I figured I wanted as much light as possible and the warming effect wouldn't hurt in a cool/cold climate like Oberon. It turned out to be a great place under the pergola in winter and cooler weather but summer was unbearable. Without the polycarbonate under the pergola would've been perfect in summer, so I guess I needed some amount of tint rather than clear. The reason polycarbonate works so well for green houses is it lets in all radiation except the IR, which is then mostly absorbed and turned into heat. The heat in turn re-radiates as IR, but it can't escape through the poly carb.

So my advice is use corrugated iron. Build frames so air can flow in any direction. And if you want the Rolls Royce version, insulate the bottom of the iron to reduce the temperature at the bottom surface - this will increase the temperature of the iron when in the sun (increasing its IR radiation back up) but the insulation will drop the temperature of the bottom surface of the insulation so the IR radiating down to the van is minimised.

Good luck.

Al.

sheeny (Al) · #6 06-12-2020, 05:16 AM

PS Another tip... use the lightest colour iron you can get (if you are buying it). I'm not sure if white colorbond would be better than fresh gal or not, but basically light colours reflect more visible light rather than absorb it and turn it into heat. The cooler you can keep the bottom surface of the tropical roof, the better it will work.

Al.

xelasnave · #7 06-12-2020, 06:49 AM

Thank you Al ..this time I have nothing laying around so to me it will be expensive..a guess would be 60 a square meter .... there was a product that was like your clip lock iron with insulation on it..that would be ideal I expect if you see to the air flow but the foam back would hold a lot of heat back for a start.. I see a structure that would be dangerous in any decent wind...now this sounds crazy but I am thinking ...and iron roof with a sprinkler system ... the water driven from the dam to the roof with a cheap 240 volt pump getting it's power from solar and the water collected by a gutter and taken back to the dam...which becomes a heated swiming pool...it's one thing stopping the heat but you really need to take it away hence the need for air flow....maybe a 12 volt pump running off solar panels and no battery...I have a couple of fans set up like that..but just water flowing over corrugated iron would carry away a lot of heat..
Again thanks your post has helped remind me of the fundamentals and most interesting your experience trying to bend iron..I suspected such as I had an 11 mt sections for the roof at the other place and although we were not trying to bend it just getting it onto the roof had us commenting that there did not seem to be any sag when one end was on the ground and the other end on the edge of the roof when getting ready to move it up.

The big car port with a proper roof, iron insulation and ceiling although expensive will probably actually be cheaper than trying to build a frame off the van..I would not like to bolt anything to the van it seems so flimsy..having a sprinkler on it would be smart for bush fire so not that crazy. Alex
Alex
Alex

julianh72 (Julian) · #8 06-12-2020, 07:54 AM

A bit of advice from someone who designs industrial steel buildings:

Consider just using flat sheets, sloped to shed rain away from the doorway of your caravan. You can manually spring steel corrogated sheeting parallel to the ribs, but forget manually rolling across the ribs (like a bullnose awning) - you need a roll-press to do that.

Make sure your roof overhangs the caravan on all sides, and creates shade over the doors and windows, as a lot of heat will come in though these when the sun hits them during the day.

Stand the sheeting off your caravan roof by at least 150 mm, and make sure the air space can ventilate freely, as this will dramatically reduce heat build-up. If it's open on all four sides, you won't need a "whirlybird", the roof will ventilate through natural circulation.

If you're buying new material, go for a light Colorbond, rather than bare zincalume, as it will reflect more incident heat and not get as hot.

Consider putting some fibreglass insulation blanket under the sheeting when you fix it - this will dramatically reduce the amount of heat radiating down from the hot undersurface.

Good luck!

Rainmaker (Matt) · #9 06-12-2020, 08:35 AM

Alex, depending on how permanent you want the setup, I suggest you source some secondhand 50mm insulated roofing panels from Gumtree..........

I just bought enough for a 3.5M x 7.5M carport for $700, then just some posts and beams as screwed the roofing to the beams, the other end to the house fascia, job done........

Stratco quoted me $11,700........... ended up costing me $1550 installed.

JA · #10 06-12-2020, 08:59 AM

Hi Alex,

What you are building is a radiant heat shield. For the best performance you need high reflectivity on the sun side. A white gloss powdercoated steel would be in that respect or at a pinch a gloss white painted roof of some sort. Aluminium also has excellent reflectivity if kept clean and protected/cleaned of oxidation. In fact any of the surfaces should be kept as clean as possible as dirt, dust ixidation, etc will reduce their reflectivity. Perhaps a good hose off in spring in readiness for summer.

In addition to all that use Sheeny, Rainmakers and Julian's(hello guys) excellent suggestions above. Additionally if your van doesnt already have a white roof (most do) then make it so.

Keep cool.

Best
JA

glend (Glen) · #11 06-12-2020, 09:21 AM

Quote:

Originally Posted by JA

Hi Alex,

What you are building is a radiant heat shield. For the best performance you need high reflectivity on the sun side. A white gloss powdercoated steel would be in that respect or at a pinch a gloss white painted roof of some sort. Aluminium also has excellent reflectivity if kept clean and protected/cleaned of oxidation. In fact any of the surfaces should be kept as clean as possible as dirt, dust ixidation, etc will reduce their reflectivity. Perhaps a good hose off in spring in readiness for summer.

In addition to all that use Sheeny, Rainmakers and Julian's(hello guys) excellent suggestions above. Additionally if your van doesnt already have a white roof (most do) then make it so.

Keep cool.

Best
JA

Alex, this reminded me of the Thermoshield Caravan Roof Paint, which many Grey Nomads apply to their caravans. I actually applied it to my hard roof camper that I built more than a decade ago. It goes on pretty thick, and has reflective ceramic beads in it and some people swear by it. Manufacturer claims it can reduce internal radiant temp load by 45%.

https://www.thermoshieldqld.com.au/b...rmoshield.html

A Qld product.

iborg (Philip) · #12 06-12-2020, 10:46 AM

Hi Alex

A slightly different possibility, a shadecloth carport.

I used one a double one of these for a number of years as a 'pergola' next to my house. Made a surprising difference to the heat inside the house as it was on the north side.

https://www.zelangashades.com.au/

I was able to put up the double on my own, but, only just.

Philip

PS if any one is interested I have a double and a single (never used) that I want to sell. I really need to get an add done.

xelasnave · #13 06-12-2020, 12:05 PM

Quote:

Originally Posted by glend

Alex, this reminded me of the Thermoshield Caravan Roof Paint, which many Grey Nomads apply to their caravans. I actually applied it to my hard roof camper that I built more than a decade ago. It goes on pretty thick, and has reflective ceramic beads in it and some people swear by it. Manufacturer claims it can reduce internal radiant temp load by 45%.

https://www.thermoshieldqld.com.au/b...rmoshield.html

A Qld product.

As well..the whole van needs it. Only 35 at the moment

Thanks.
Alex

xelasnave · #14 06-12-2020, 12:07 PM

Quote:

Originally Posted by iborg

Hi Alex

A slightly different possibility, a shadecloth carport.

I used one a double one of these for a number of years as a 'pergola' next to my house. Made a surprising difference to the heat inside the house as it was on the north side.

https://www.zelangashades.com.au/

I was able to put up the double on my own, but, only just.

Philip

PS if any one is interested I have a double and a single (never used) that I want to sell. I really need to get an add done.

Thanks Phillip..
I am going to remove the solar panels or perhaps get someone to do that and I just happen to have plenty of shade cloth and various tarps ... for temporary I plan on just throwing up some milk crates to keep the cloth up..
Alex

GrahamL · #15 06-12-2020, 06:47 PM

I know someone who made a large tin shed his home and lined it with those 50 mm panels ceiling and walls , it looked great inside and even without a small aircon running it was so cool inside on the hottest of days .

Nikolas (Nik) · #16 06-12-2020, 07:12 PM

Have you thought of shade cloth like a sail over the roof?

xelasnave · #17 06-12-2020, 09:25 PM

Quote:

Originally Posted by GrahamL

I know someone who made a large tin shed his home and lined it with those 50 mm panels ceiling and walls , it looked great inside and even without a small aircon running it was so cool inside on the hottest of days .

I have foam panels in the observatory and it is much cooler, but still too many gaps to instal an air conditioner.
Alex