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Author Topic: Shed Roof Insulation  (Read 1322 times)

TheLongBuild

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Shed Roof Insulation
« on: January 22, 2023, 10:32:22 pm »

So I want to insulate my Shed roof, I have read that you should leave a gap between the actual roof and the insulation, is this correct and what is the reason ?, as I have also read that as long as you put the insulation ( the polystyrene type ) right up to the wood that is fine, so which is it ?. %% %%



roycv

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Re: Shed Roof Insulation
« Reply #1 on: January 23, 2023, 01:43:30 pm »

Hi when I did my roof of the shed 12 x 8 and a peaked roof.  I fitted 2 inch thick insulation (not polystyrene) diectly in contact with the planks on the roof and this has been fine for 30 years including a move when it was all reassembled.
I have white faced hardboard as the ceiling but this is prone to warping.
Regards
Roy
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Nordlys

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Re: Shed Roof Insulation
« Reply #2 on: January 23, 2023, 02:21:15 pm »


I think technically there should be an air gap between insulation and inside of roof to prevent any condensation from damping off the roof inside.
But, in your case roycv not so!  Do you feel lucky to take a chance!
I have known garage to grow mould on inside roof just from dampness within with no air  circulation (very important).
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Colin Bishop

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Re: Shed Roof Insulation
« Reply #3 on: January 23, 2023, 03:26:43 pm »

There has been a lot about this in the press recently in connection with people wanting to improve house insulation. A 'cheap and easy' solution offered by firms with not much experience has been to apply spray on insulation to the underside of the roof. But if not done properly, as Nordlys points out, this can result in condensation or roof leaks wetting the timber and causing rot. The reason it has been particularly newsworthy is that mortgage lenders are refusing to lend on properties treated this way unless the insulation is removed!

Having said that, my workshop is the enclosed back end of a long garage and I stuffed the gaps between the rafters with rockwool type insulation and boarded over the inside. That was many years ago now and so far there have been no problems.However, the workshop is not a habitable room and for most of the year the inside temperature is the same as the outside, I only heat it intermittently in winter so there is probably  a low likelihood of condensation. If the roof actually leaks it should show through on the inside.

Colin
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Baldrick

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Re: Shed Roof Insulation
« Reply #4 on: January 23, 2023, 03:52:11 pm »

You should also consider the issue of condensation on the underside of the roof structure . In even a dry speli it would be expected that the air circulating in the building will be at 50% relative humidity and even if the roof is insulated the moist air will penetrate the insulation and condense on the boarding above. To stop this you need a vapour barrier under the insulation (polythene sheet ) to stop the circulation of air up to the cold roof surface. This applies if the shed is heated or not but worse if it is heated
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Nordlys

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Re: Shed Roof Insulation
« Reply #5 on: January 23, 2023, 03:52:57 pm »

I might have considered the insulation that you have done Colin between rafters but to be honest heating the workshop/ garage now has become much too expensive since the price hike so I'm restricted now to working out there in the warmer weather only.
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Colin Bishop

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Re: Shed Roof Insulation
« Reply #6 on: January 23, 2023, 04:05:24 pm »

We fortituously took out a two year fix on gas & electricity in 2021 so are paying around 60% of the current headline rates until September. At the time the 'experts' were advising against a fix and choosing the variable tariff but I just had a sort of feeling although never dreamed that prices would take off the way they have. Sometimes you strike lucky!

Colin
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destroyer42

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Re: Shed Roof Insulation
« Reply #7 on: January 23, 2023, 04:49:54 pm »

Hi All,
I have just installed a chinese diesal heater, in my 20 x 12 log cabin workshop which has double glazing and insulation in the roof and floor. These little heaters are fantastic and throw out a lot of heat, no fumes low noise and very economical much cheaper than gas/electricity.
See them on youtube.


Regards
Destroyer42
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TheLongBuild

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Re: Shed Roof Insulation
« Reply #8 on: January 23, 2023, 06:57:07 pm »

You should also consider the issue of condensation on the underside of the roof structure . In even a dry speli it would be expected that the air circulating in the building will be at 50% relative humidity and even if the roof is insulated the moist air will penetrate the insulation and condense on the boarding above. To stop this you need a vapour barrier under the insulation (polythene sheet ) to stop the circulation of air up to the cold roof surface. This applies if the shed is heated or not but worse if it is heated


I have some rolls of Aluminium backed insulation i was going to put over the main insulation which is then being boarded up with pallet wood. Assume this should act as the vapour barrier.

roycv

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Re: Shed Roof Insulation
« Reply #9 on: January 23, 2023, 07:55:55 pm »

Hi Nordlys, I took advice from a friend then working in Building Research and the insulation was given to me.  I do not know what it is, but it came from there.   

The workshop was put together in 1993 and dissembled for moving in 2004 and there was no indication of any problems.  All the cladding and insulation had to be removed and later put back again. 
Once the heating is established a 500 Watt oil radiator it is nice and snug in there when it is cold.  Not conquered when it is hot though!

Regards
Roy
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Nordlys

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Re: Shed Roof Insulation
« Reply #10 on: January 23, 2023, 09:14:27 pm »

I'm not an expert here at all but provided there is good air circulation across the surfaces you might be able to avoid mould growth.
You had some decent material here Roy to start with.
N.
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Rich griff

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Re: Shed Roof Insulation
« Reply #11 on: January 24, 2023, 09:41:15 am »

Hi destroyer42,
May I ask which diesel heater did you get please ?


I assume you run it on red diesel ?
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TheLongBuild

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Re: Shed Roof Insulation
« Reply #12 on: January 24, 2023, 05:01:06 pm »

Thanks for the suggestions. :-)) :-))

destroyer42

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Re: Shed Roof Insulation
« Reply #13 on: January 24, 2023, 05:04:59 pm »

Hi Rich griff,
its the Triclicks 5kw to 8kw, just click on link, My freind has the Vevor one also on Amazon, but to be honest they are all much the same depends on the style you want.


 [size=78%]Triclicks 5KW / 8KW 12V Air Diesel Heater Vehicle Heater Set LCD Thermostat 4 Holes Parking Heater Fast Heating Fan Heater For Truck, Boat, Car Trailer, Motorhomes, Touring Car, Campervans, Caravans : Amazon.co.uk: Automotive[/size]


Regards
Destroyer42
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tigertiger

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Re: Shed Roof Insulation
« Reply #14 on: January 25, 2023, 03:32:12 am »

Unless you are going to be in the shed for many hours, every day, then (for me) ventilation is possibly more important than inusulation. Even insulated, once the cold has come in it will stay in, but if the inside is even a few degrees warmer than the outside you can get condensation, and this can lead to other problems; as we all know.
I actually leave the windows open, until I am in the shed, and the heating is on. Windows are left open overnight. Security is not really a problem where we live, and with our windows only a small opening is possible. However, you don't need to leave windows open if you have good ventilation. Depending on the shed, ventilation can be added.

Going off at a tangent here. The other thing that often gets forgotten is our grandparents all wore long johns in the cold weather. A lot of us grew up with central heating and thought long johns and fingerless gloves were consigned to the history books. They were re-introduced to my wardrobe a few years back, and with the growth in outdoor pursuits, long underwear has become more technical, more widely available, and cheaper.
For the workshop, if you keep your trunk and legs warm, the old feet and hands stay warmer too.
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