Shed insulation - yet again!

Now that my shed's starting to take shape as a workshop, the next step would seem to be insulating and heating.
I've got a 2kW fan heater for when I'm in there and plan on fitting a 120W tubular to keep condensation at bay.
Having scoured the archive, I've ordered a load of 25mm kingspan from Seconds, and will board that over with ply. I plan on making a panel with window sized lumps of kingspan to bolt over the windows when I'm out, thereby getting insulation and security.
Which only leaves the floor. I'm reluctant to insulate and board over it, and going underneath seems unlikely to work. But, there's a chap on ebay selling 9mm EPDM in decent quantities.
How well do people think a rubber floor covering would serve as insulation?
TIA -- Rob
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Rob Hamadi wrote:

Nit brilliant, but not too bad.
Solid floors are not a huge heat loss..in essence the soil itself acts as a insulant to where the cold really is - the air.
In a typical shed the walls and roof are infinitely worse.
A good layer of carpet, is a pretty good starting point.
If the floor is raise wood and ventilated, you will have a real problem though. Draught proofing it with hartdboard or a vinyl or rubber sheet is the starting point, but I would be less than satisfied if that were all there was,.

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I did calculations for this. Is it a concrete floor or wood on joists?
For a concrete floor, the heat loss without insulation is the least out of the whole structure including walls and roof. For example, in my workshop it was a few hundred watts out of a total of over 12kW.
For a cabin with wooden floor, I used Celotex under the wooden floor and that was worth doing.
With floors, the effective heat loss is dependent on the perimeter dimensions as well as the area, so proportionately a larger building has a smaller heatloss per area of floor.
You would get some insulating property from EPDM, not least of which is not having feet in contact with hard and cold floors. There is the mechanical cushioning effect as well. If you plan to spend a fair bit of time out there standing up, then I would do it.
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Rob Hamadi wrote:

You might find sticking a stat on the fan heater works as well or better. I use mine on its lowest setting (800W) and leave the stat set to 5 degrees or so. With a well insulated building it only kicks in very infrequently. A burst of 800W every few hours is probably cheaper than 120W continuously, and you also get more air circulation.

It won't hurt. However you probably won't lose that much through the floor anyway. I have an uninsulated floor (3/4" ply on 2" high joists, lifted off a solid concrete base by half bricks) in my workshop and it still remains very easy to heat.
--
Cheers,

John.

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I would look to use a small compressor based dehumidifier as the background heater. They are available in the 200-400W range, and look for one which can run continuously into a drain rather than needing its tank emptied manually. In addition to heating, it will remove the moisure from the air, making it much more effective at keeping things dry, which means you probably won't need as much heating from it and it will be cheaper to run. (Also, you'll get a bit of extra heat for free, the latent heat recovered from condensing out the moisture.) Make sure you draft-proof the shed if you do this, or you'll be dehumidifying you back garden;-)
You might also need a frost stat based heater, as dehumidifiers often won't operate if their evaporator is icing up, but if you suitably insulate the shed, it might rarely/never get cold enough inside for that to be an issue.
--
Andrew Gabriel
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On 2007-12-05 13:41:53 +0000, snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) said:

I've done this in the workshop and it's surprisingly effective. I'm not sure what the equivalent heat output is, though.
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The energy output is the energy input plus the energy which would be required to boil away the same quantity of water as the quantity of condensate which is collected. So it's more than 100% efficient in terms of electricity use in exactly the same way a heat pump heater is (although probably nowhere near to the same extent).
--
Andrew Gabriel
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On 2007-12-06 00:15:31 +0000, snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) said:

Sure. I was just pondering how much. I imagine that one factor would be the amount of water extracted and hence a connection to the relative humidity?
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Andy Hall wrote:

Not the RH, only the amount of water and the temperature. About 2-2.5kJ per gram of water.
Andy (third of this thread!)
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Thanks chaps.
To fill in the part I missed out - it's a 10'x8' raised wooden floor (18mm or so T&G on 2" joists), which itself sits on top of a raised wooden deck.
Sounds like my best bet might be to go with the rubber flooring at first then, if it's still losing too much, go the kingspan & chipboard route at a later date - re-laying the rubber on top of it, of course. -- Rob
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Rob Hamadi wrote:

Shame you could not celotex under it.
My experience is that wind is the killer..with a suspended floor.
Mine here is block and beam. and it could use more insulation than it has.
Anyone know WHY a suspended concrete floor has to be ventilated?
I know its true for high radon areas, but here in Suffolk?
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Don't be too sure. What about Orford Ness?
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I can try a plausible explanation based on my personal experience.
I have a log cabin where the (suspended) floor on treated wooden joists can be added after the whole structure is erected, which to me is a bonus for various reasons. However, to keep a long story short, I have built the whole structure (with no floor) on top of a levelled crenellation made of driveway paving bricks, which in turn sit on a lightly sloping slabbed area. By using a crenellation (basically, a brick followed by an empty space of the same size) I have created a number of ventilation openings (a total of No 26 75mm x 200mm openings) for a 5 x 3 m log cabin. Quite a ventilated structure, you would say.
However, as the wooden suspended floor is not in place yet, everything still stands on the slabbed floor at the moment. After rain, particularly during damp days, the slabbed flooring itself becomes damp. Maybe a thick polythene barrier had to be put under the slabs or even under the concrete upon which the slabs themselves were laid, but this has not been done. So, soil moisture raises through concrete and slabs and remains on the slab surface despite the ventilation holes. Whatever is suspended on top of the slabs will get a high portion of that humidity on its lower surface unless moisture is prevented to raise.
Having the ventilation holes is a start but not enough (when I blocked the ventilation holes for a test, there was much more humidity on the slab surface in the same damp weather conditions). My plan is that of addressing the problem of ventilation & wind-caused heat dissipationin the following way:
- Close the ventilation holes with louvre air ventilators (e.g., see http://www.screwfix.com/prods/72707/Heating-Cooling/Ducting/Louvre-Air-Vent-Gold-152-x-229mm ;jsessionid=4XRMAPP5DSG4KCSTHZOCFGA). This would dlimit wind-caused heat dissipation, plus insects, rain, and garden rubbish from entering the cavity under the still-to-be-fit suspended floor.
- Lay a sheet of thick polythene on the slabs directly to block moisture to the slab level
- Fit joists, using a number 75 x 75 short pieces of pressure-treated fence posts (between 100mm and 150 mm long) to hold them at the right height (because of the crenellation that raises the shed floor level w.r.t. the slabs)
- fit 50mm thick Kingspan polyurethane rigid foam slabs between the joists, kept in place by recycled treated battens underneath
- Put 18 mm cheap (chinese) ply, suitably treated with deep- penetrating thin impregnating agent to prevent rot
- Put 18 mm T&G (crappy) floorbords, provided with the log cabin.
I imagine someone will be a bit shocked, but I believe that would definitely stop both moisture from raising to the suspended floor level and heat from being dissipated through the floor.
Any comments?
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I can try a plausible explanation based on my personal experience.
I have a log cabin where the (suspended) floor on treated wooden joists can be added after the whole structure is erected, which to me is a bonus for various reasons. However, to keep a long story short, I have built the whole structure (with no floor) on top of a levelled crenellation made of driveway paving bricks, which in turn sit on a lightly sloping slabbed area. By using a crenellation (basically, a brick followed by an empty space of the same size) I have created a number of ventilation openings (a total of No 26 75mm x 200mm openings) for a 5 x 3 m log cabin. Quite a ventilated structure, you would say.
However, as the wooden suspended floor is not in place yet, everything still stands on the slabbed floor at the moment. After rain, particularly during damp days, the slabbed flooring itself becomes damp. Maybe a thick polythene barrier had to be put under the slabs or even under the concrete upon which the slabs themselves were laid, but this has not been done. So, soil moisture raises through concrete and slabs and remains on the slab surface despite the ventilation holes. Whatever is suspended on top of the slabs will get a high portion of that humidity on its lower surface unless moisture is prevented to raise.
Having the ventilation holes is a start but not enough (when I blocked the ventilation holes for a test, there was much more humidity on the slab surface in the same damp weather conditions). My plan is that of addressing the problem of ventilation & wind-caused heat dissipationin the following way:
- Close the ventilation holes with louvre air ventilators (e.g., see http://www.screwfix.com/prods/72707/Heating-Cooling/Ducting/Louvre-Ai ...). This would dlimit wind-caused heat dissipation, plus insects, rain, and garden rubbish from entering the cavity under the still-to-be-fit suspended floor.
- Lay a sheet of thick polythene on the slabs directly to block moisture to the slab level
- Fit joists, using a number 75 x 75 short pieces of pressure-treated fence posts (between 100mm and 150 mm long) to hold them at the right height (because of the crenellation that raises the shed floor level w.r.t. the slabs)
- fit 50mm thick Kingspan polyurethane rigid foam slabs between the joists, kept in place by recycled treated battens underneath
- Put 18 mm cheap (chinese) ply, suitably treated with deep- penetrating thin impregnating agent to prevent rot
- Put 18 mm T&G (crappy) floorbords, provided with the log cabin.
I imagine someone will be a bit shocked, but I believe that would definitely stop both moisture from raising to the suspended floor level and heat from being dissipated through the floor.
Any comments?
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hi i have an 8 by 10 shed which i use to watch the football in whats the best way to insulate it the gap i have is 1" which needs to be insulated ? ?
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In message
snipped-for-privacy@aol.com writes

bovine excrement would prolly do the job well
--
geoff

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