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Thread: Shed insulation

  1. #1
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    Default Shed insulation

    In Pete's recent excellent thread on putting together a CNC controlled rotary table there was some minor discussion re shed temperatures especially in summer. I have been having some thoughts about how to insulate my new shed. The two sheds I currently work in have no insulation and it is unbearable in summer. So does anyone have any experience with normal sarking ie the silver paper type or even the newer sarking that has a small layer (5-8mm) of insulation between the paper. Are venting roof fans of any use. Happy to hear peoples experiences or thoughts on the matter.
    For information I live in western NSW where 40+ in summer is pretty frequent.

    cheers

    Mark

  2. #2
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    Hi Mark,
    In our Turners shed, we have the newer sarking, and find it's bearable, mind you the sides are 3 m high, which helps a bit. My shed at home, is 2.1 high sided and with a venting roof vent, it is hot under there. I'm thinking of putting an exhaust fan under it, to help draw some of the heat out, whether it'll work or not I don't know? I'm in the process of doing an extension, and will be putting insulation under the roof as well as another roof vent. I do have some shelter from trees growing over it.
    I've found that the higher the roof with insulation, the cooler it is, to a certain extent.
    You might want to put this question in the WWF under THE SHED, as you'll probably get some more and helpful answers.
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
    BobL is offline Member: Blue and white apron brigade
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    It's definitely worth insulating even on a low shed, but as KBPM says it works better on a high shed.

    The following is common knowledge but just in case;

    You need to remember insulation won't cool the air inside a shed - all it can do is slow down how quickly it heats up so this method assumes you are starting out with air inside the shed that is cooler than outside.

    Then of course insulation will also slow down how quickly the air inside a shed cools down at night so either you have to be able to open lots of doors and windows or use forced ventilation

    Venting fans will help, provided the air outside is cooler than the air inside.
    Having these on a pair of thermostats that measure inside and outside air temperatures is the way to go.

    Where insulation really helps is if you have an AC,
    I have a 42m^2 shed that ranges from 2.4 to 2.7m high. I have walls and roof insulated and a 4kW AC that can keep it at 24ºC even when its 40º outside.

  4. #4
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    Bob is right, the only thing that works is an air con, I have an evaporative air con, it needs new pads in it now but it still keeps the temp at least 10 deg C lower that what it would be otherwise.
    It also has the added advantage of blowing smoke and paint/chemical fumes out the door.
    I got mine s/h cheeeeep.
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    There is an insulation which looks like bubble wrap , it keeps the inside about 8-10 degrees cooler than outside it comes in rolls which are placed under the roofing iron .

    Michael

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    Quote Originally Posted by Mike4 View Post
    There is an insulation which looks like bubble wrap , it keeps the inside about 8-10 degrees cooler than outside it comes in rolls which are placed under the roofing iron .

    Michael
    Hi Michael,
    Do you know the name of that insulation. I goggled this Sisalation® Bubble Cell 100 - Fletcher Insulation
    Any idea of cost?
    I should say this shed will be 12 x 24 m with 7m wall height but I do want to wall off 6 x 12 m for an office/metrology section one day so I can air condition that section.

  7. #7
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Mike4 View Post
    There is an insulation which looks like bubble wrap , it keeps the inside about 8-10 degrees cooler than outside it comes in rolls which are placed under the roofing iron
    I have that insulation in most of my shed and my observations are that under certain conditions it might hold an 8-10º temp differential for a brief period at the max daytime temp, but it just doesn't do this across the temp range.

    In a real shed, especially if there's a stiff hot wind blowing, machinery is being used and/or dust or fume extraction for welding or spray painting etc is used, there's very little apart from AC that can consistently keep the temperature 10ºC below the outside temperature.

    Unless the shed is completely airtight any sort of a breeze blowing past a shed drags some of the air out of the shed and injects some hot air from the outside into the shed.
    All the mechanical and thermal energy from machinery also adds heat to the the air so even the best insulated airtight shed will eventually heat up and equilibrate with the outside air temperature.

    Using insulation may well enable a max shed temp to be 10º cooler than not using any insulation where the temps might reach 50-55ºC but even then it cannot do this indefinitely.

    My shed is reasonably well sealed (i.e. no eave gaps and well sealed doors and windows), shaded by trees and I have internal and external thermometers so I can check what is going on.

    Before I got AC, typically in summer when the overnight minimum drops to 20º the air inside the shed was ~22/23º because the insulation holds some heat from the day before. During the day the external temp might reach 40 and provided no machinery is used, the insulation was able to hold it below 30º for about an hour but then it started to creep up and by late afternoon it reached ~35 and it stays at that temp well into the evening, even when the outside has dropped to below 30. Of course that is when I opened up and ran ventilation fans but even then it was never cooler that the outside air temperature.

    As soon as I started using machinery or my fume hood etc the temps increased accordingly.

    This is why I gave up and bought an AC.
    While this copes with machinery, I cannot use fume or dust extraction for anything more than a couple of minutes and hope to keep the temp under 30º.

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    Mark, thanks for the comments on the thread, so in return I have a solution for you. ... build a house on top

    The retirement plan is to move to the Adelaide Hills and I will bury all the buildings on the property. It's cheap, it's effective, designed well they don't have to be dark/damp/horrible. Why we almost always build above ground has always confused me.

    However, that may not be an option for you at this stage. Following the previous Government's amazing insulation scheme, you know, the one designed to stimulate the economy but instead resulted in a whole pile of cheap fibreglass insulation being imported from China, with accompanying backpackers from Ireland to install it. The backpackers returned home, well, at least the ones who weren't electrocuted, but the Cheap Chinese insulation didn't make the slow boat back home. I don't know how much of it is around now, but at one stage they couldn't give the stuff away. I mean literally, they couldn't give it away! Have a hunt around and if you're able to provide some lining on the workshops (always nice regardless) it could be your ticket to summer (and winter) bliss. the lining may be as simple as chicken wire just to hold it in place. The only caveat is the Chinese stuff is likely made from recycled dead parrots, spent nuclear fuel, and bloated foot and mouth bovine carcasses recovered from the Yangtze River ... at least the parts of the World Heritage area that haven't yet been dammed anyway. Whatever they put in it, it stank. Especially when heated. Don't ask how I know the latter. I recommend medical supervision before, during, and after installation!

    Personally I like Rockwool. It's still not expensive and comes sans dead swine. It really shouldn't matter what you use just so long as you provide a thermal barrier. The only thing when the nice Government provided us with enough free insulation I now need scuba gear to get around my attic space is that it adds to the thermal mass of the place. In other words while (in summer) it won't heat up as fast it also doesn't cool off as fast either. Indeed it doesn't do anything fast, a bit like me really! So you could find yourself sweltering in a shed that would otherwise be quite comfortable at night unless you can open the whole lot up and get some cooling air flow.

  9. #9
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Pete F View Post
    Personally I like Rockwool.
    The MW end of my shed is clad in this stuff because the plastic bubble wrap and welding/grinder sparks are not that compatible.
    It also has reasonably good acoustical properties.

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    Mark,
    I think its AirCell , not sure but when I go home tonight I will confirm it as there is a part roll there.

    Michael

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    Not knowing a single thing on the subject, I have seen sheds with just some sort of foil sandwiched between the iron and purlins.

    A bit late now but also making the shed so the afternoon sun does not blaze inside can also help, as can lots of doors that can be opened to take advantage of the prevailing wind, however this creates dust issues.

    Another thing is painting the roof white or some colour that reflects infrared light.
    Gold, the colour of choice for the discerning person.

  12. #12
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    Hi Mark,

    It's hard to keep the air temperature of a shed down to less than the outside air without resorting to A/C.

    There is a balance between the thermal mass (concrete floor and machinery), Insulation (slowing the ingress and egress of heat) and glass (windows that let in light and heat) that will help you maintain a comfortable workshop. What that balance is for your climate, I don't know though likely local builders or building designers will have a good idea. The other area to keep in mind is shading from eaves, trees etc. I have air cell in my shed roof and I have noticed that areas of aircell shaded by the PV array remain cooler to the touch than unshaded areas. The roof with the PV array faces almost due north so gets shade all day. When I have the building well sealed I'll put some extra panels into the array to increase shade. I am building a mezzanine, for office area, that is open to the the shed below and plan to install A/C for the mezzanine area. I don't expect to gain a lot of cooling from it more the cool area spilling from the mezzanine will help push humid air up to the A/C. Mostly looking to get rid of some humidity.

    Keep in mind that our machines are effectively electric heaters. A 5kW lathe will generate 5kw of heat at full load. Some attention to the time of day you run your machines may help.

    Also don't get too hung up on the external colour of the shed. As a roofer once said to me "All roofs reach the same temperature, the darker ones just get there a bit quicker"

    Cheers

    The Beryl Bloke
    Equipment er.... Projects I own

    Lathes - Sherline 4410 CNC
    Mills - Deckel FP2LB, Hardinge TM-UM, Sherline 2000 CNC.

  13. #13
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    Ueee is offline Blacksmith, Cabinetmaker, Machinist, Messmaker
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    I too have aircell in the roof and sarking with batts attached in the walls (r1.2 i think)
    I find it works really well on hot days until mid afternoon then it starts to heat up.
    I have 2 whirlybirds but these alone are useless as the times when you need them to work the most is when there is no wind. I have mounted 2 12v car fans from supercheap under these, running off a 40w solar panel on the roof and with a temp switch so they don't come on under 25 degrees. These seem to work really well, they are on the ridge so they remove the hottest of the air.
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

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    Quote Originally Posted by Theberylbloke View Post
    Also don't get too hung up on the external colour of the shed. As a roofer once said to me "All roofs reach the same temperature, the darker ones just get there a bit quicker"

    Cheers

    The Beryl Bloke
    I guess that's why he's a roofer and not a physicist

  15. #15
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    Also don't get too hung up on the external colour of the shed. As a roofer once said to me "All roofs reach the same temperature, the darker ones just get there a bit quicker"
    Remind me never to ask that guy for advice. That is complete rot. A dark roof will absorb energy while a light roof will reflect it. There is a big difference. Science 101. Ever owned a black car?

    Dean

    ps Damn. I need to type faster.

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