I have a workshop floor that is 4" concrete on a DPM on hardcore/soil.
The plan is to put a wooden floor in to make it more comfortable to stand on
for long periods.
I don't want to lose too much ceiling height so i was planning to put tiling
batten (25mm) down as mini joists with mortar under to adjust the levels and
18mm ply as the floor surface.

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

The area is 30 sq metres so I don't want to waste money on polystyrene
unless it is going to make a useful difference.

The walls and roof will be insulated for comfort in both Summer and Winter.
Depending on how cold it gets and how much I use it in Winter there will be
some form of space heating at least to the level to prevent icicles forming
on my nose!!

TIA

Bob

Bob Minchin wrote:
I have a workshop floor that is 4" concrete on a DPM on hardcore/soil.
The plan is to put a wooden floor in to make it more comfortable to stand on
for long periods.
I don't want to lose too much ceiling height so i was planning to put tiling
batten (25mm) down as mini joists with mortar under to adjust the levels and
18mm ply as the floor surface.

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

The area is 30 sq metres so I don't want to waste money on polystyrene
unless it is going to make a useful difference.

It probably will.
Polystyrene conducts at a rate of .04W for a meter cube, with 1C
difference on the sides.
Divide by .025m, and that's 1.6W/m^2/K.
Multiply by 30, and that's 48W/K.
For 10K over ambient, that's 480W.
ISTR that a gap and a floor is about 4 times that - from some sums I did
a while ago.
The end result - when the shed is hot for a long time may be different,
as the ground underneath will heat up, and then insulate somewhat.
But this takes a long time, comparatively.

Do the sums.
How long do you use the shed?
How hot do you want it.

If you're going to be heating it 8 hours a day, 365 days a year, using
electricity, then you probably want to insulate the walls too.
If you're going to be using it for an hour every few weeks, it may well
be cheaper to simply put in a few heaters.

http://www.bre.co.uk/filelibrary/BR_443_(2006_Edition).pdf
contains all the information you need to work it out - there is probably
much easier ways.

Bob Minchin wrote:

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

I didn't bother with mine (3/4" ply over 2" high bearers supported on
half bricks), and it seems to still be very efficent from a temperature
control and heat loss point of view. The air gap under my one is open to
the outside as well. The walls and roof are well insulated.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Ian Stirling wrote in message
...
Bob Minchin wrote:
I have a workshop floor that is 4" concrete on a DPM on hardcore/soil.
The plan is to put a wooden floor in to make it more comfortable to stand
on
for long periods.
I don't want to lose too much ceiling height so i was planning to put
tiling
batten (25mm) down as mini joists with mortar under to adjust the levels
and
18mm ply as the floor surface.

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

The area is 30 sq metres so I don't want to waste money on polystyrene
unless it is going to make a useful difference.

It probably will.
Polystyrene conducts at a rate of .04W for a meter cube, with 1C
difference on the sides.
Divide by .025m, and that's 1.6W/m^2/K.
Multiply by 30, and that's 48W/K.
For 10K over ambient, that's 480W.
ISTR that a gap and a floor is about 4 times that - from some sums I did
a while ago.
The end result - when the shed is hot for a long time may be different,
as the ground underneath will heat up, and then insulate somewhat.
But this takes a long time, comparatively.

Do the sums.
How long do you use the shed?
How hot do you want it.

If you're going to be heating it 8 hours a day, 365 days a year, using
electricity, then you probably want to insulate the walls too.
If you're going to be using it for an hour every few weeks, it may well
be cheaper to simply put in a few heaters.

http://www.bre.co.uk/filelibrary/BR_443_(2006_Edition).pdf
contains all the information you need to work it out - there is probably
much easier ways.

Thanks Ian,

I'll get my calculator out.
I'm not sure how much I will be using the building which will be a hobby
woodworking shop for when I retire. I anticipate projects running for some
days whilst making the item but then brief daily forrays to apply finish and
then to let it dry.
I plan two heat sources.
1 a balanced flue domestic gas fire re-jetted to run on propane.
2 a sawdust burner fuelled from the shavings and sawdust from the dust
extraction system on the machines.

The latter will be free fuel but I'm not sure how much sawdust it will
consume or I will produce and I expect propane will workout dear to run for
long periods but convenient for short stays
To an extent, I can be flexible when I use the workshop and avoid it in the
depths of winter if heating costs are too high.

Bob

John Rumm wrote in message
...
Bob Minchin wrote:

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

I didn't bother with mine (3/4" ply over 2" high bearers supported on
half bricks), and it seems to still be very efficent from a temperature
control and heat loss point of view. The air gap under my one is open to
the outside as well. The walls and roof are well insulated.

Thanks John,
Helpful experience.

Bob

Bob Minchin wrote:

I plan two heat sources.
1 a balanced flue domestic gas fire re-jetted to run on propane.

One downside of this is the amount of water vapour it will create in the
room. Not so good for rust free tool storage.

It might also be worth thinking about some form of frost protection
heating to keep it above the dew point in there for the same reason.

I found in my workshop a small wall mounted fan heater on a thermostat
set to about 5 degrees does the job nicely. With the amount of
insulation in place it does not kick into action often - and when it
does only runs for five mins or so.

2 a sawdust burner fuelled from the shavings and sawdust from the dust
extraction system on the machines.

Nice idea...

Do you have to manually load it with shavings?

(otherwise you may find the place melts when you run a thicknesser for a
couple of hours!) ;-)

The latter will be free fuel but I'm not sure how much sawdust it will
consume or I will produce and I expect propane will workout dear to run for
long periods but convenient for short stays
To an extent, I can be flexible when I use the workshop and avoid it in the
depths of winter if heating costs are too high.

My one is ok all year round, and will get to comfortable in about 10
mins from its coldest. Note however it is only 1/3rd the floor area of
yours.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sun, 16 Apr 2006 13:36:27 GMT, "Bob Minchin"
wrote:

I have a workshop floor that is 4" concrete on a DPM on hardcore/soil.
The plan is to put a wooden floor in to make it more comfortable to stand on
for long periods.
I don't want to lose too much ceiling height so i was planning to put tiling
batten (25mm) down as mini joists with mortar under to adjust the levels and
18mm ply as the floor surface.

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

The area is 30 sq metres so I don't want to waste money on polystyrene
unless it is going to make a useful difference.

The walls and roof will be insulated for comfort in both Summer and Winter.
Depending on how cold it gets and how much I use it in Winter there will be
some form of space heating at least to the level to prevent icicles forming
on my nose!!

TIA

Bob




From having done an exercise of insulating a garage for use as a
workshop, the floor is the least worthwhile area to insulate in
comparison with the walls, roof and of course the doors.

To give you a rough idea, pre-insulation it would require about
12-15Kw to achieve 15 degrees or so in the winter.

Of that, something like 400-500W was through the floor.

With 50mm of Celotex on walls, roof, doors the heating requirement
comes down to about 3-4kW worst case.

I also debated whether or not to implement a wooden floor and didn't
a) because of the loss of height and b) to have made it interesting I
would have wanted to run extraction ducts under the floor implying at
least 180mm as a depth. I did the calculations for either thin
Celotex or polystyrene and worked out that there would be a saving of
about 300W. In the context of 12kW that is nothing and even
compared to 3kW is not a lot when other issues like several hundred W
of lighting, plus machinery and so on are accounted for.
For comfort I use mats instead.




--

..andy

On Mon, 17 Apr 2006 20:14:02 GMT, "Bob Minchin"
wrote:


I'm not sure how much I will be using the building which will be a hobby
woodworking shop for when I retire. I anticipate projects running for some
days whilst making the item but then brief daily forrays to apply finish and
then to let it dry.
I plan two heat sources.
1 a balanced flue domestic gas fire re-jetted to run on propane.
2 a sawdust burner fuelled from the shavings and sawdust from the dust
extraction system on the machines.

The latter will be free fuel but I'm not sure how much sawdust it will
consume or I will produce and I expect propane will workout dear to run for
long periods but convenient for short stays
To an extent, I can be flexible when I use the workshop and avoid it in the
depths of winter if heating costs are too high.

Bob


Is the building reasonably close to the house?

I set up an arrangement with a heat exchanger and secondary circuit
run from the CH system in the house. Well insulated pipework runs in
an underground duct and there are radiators in the workshop. This
is comparatively inexpensive to run.

I'm concerned about the idea of using open flame heating in a
woodworking area. While one should try to keep it as dust free as
possible, I am concerned about finishes etc.



Although a sawdust or woodburner seems like a good idea, you have to
be doing a lot of work that produces shavings and sawdust to keep it
going. Really it is only rough preparation work such as planing and
thicknessing that produces much of a volume of this.



--

..andy

John Rumm wrote:
Bob Minchin wrote:

I plan two heat sources.
1 a balanced flue domestic gas fire re-jetted to run on propane.

One downside of this is the amount of water vapour it will create in the

Balanced flue.

Andy Hall wrote:
On Sun, 16 Apr 2006 13:36:27 GMT, "Bob Minchin"
wrote:

I have a workshop floor that is 4" concrete on a DPM on hardcore/soil.
The plan is to put a wooden floor in to make it more comfortable to stand on
for long periods.
I don't want to lose too much ceiling height so i was planning to put tiling
batten (25mm) down as mini joists with mortar under to adjust the levels and
18mm ply as the floor surface.

Is it worth putting insulation underneath eg 25mm polystyrene or as the
space under is not ventilated, would the static air gap underneath be
virtually as good as the insulation?

The area is 30 sq metres so I don't want to waste money on polystyrene
unless it is going to make a useful difference.

The walls and roof will be insulated for comfort in both Summer and Winter.
Depending on how cold it gets and how much I use it in Winter there will be
some form of space heating at least to the level to prevent icicles forming
on my nose!!

TIA

Bob




From having done an exercise of insulating a garage for use as a
workshop, the floor is the least worthwhile area to insulate in
comparison with the walls, roof and of course the doors.

To give you a rough idea, pre-insulation it would require about
12-15Kw to achieve 15 degrees or so in the winter.

Of that, something like 400-500W was through the floor.

With 50mm of Celotex on walls, roof, doors the heating requirement
comes down to about 3-4kW worst case.

I also debated whether or not to implement a wooden floor and didn't
a) because of the loss of height and b) to have made it interesting I
would have wanted to run extraction ducts under the floor implying at
least 180mm as a depth. I did the calculations for either thin
Celotex or polystyrene and worked out that there would be a saving of
about 300W. In the context of 12kW that is nothing and even
compared to 3kW is not a lot when other issues like several hundred W
of lighting, plus machinery and so on are accounted for.
For comfort I use mats instead.




I think this is very true...OTOH if you ARE shoving a floor in, and the
insulation is cheap, well 300W is 300W.

As the ambient temps rise....right now I guess day/nightime averages are
around 8-10C...I have noited that the underfloor heating is simply not
coming on..the Aga, a 750W device . plus the usual electricals that run
24x7...freezers and fridges...is capable of heating, with a bit of solar
gain, the WHOLE front ground floor of the house...about 1500 sq feet.

and 300W 24x7x52 is 2621 units....a couple of hundred quid at least..

Ian Stirling wrote:

John Rumm wrote:

Bob Minchin wrote:


I plan two heat sources.
1 a balanced flue domestic gas fire re-jetted to run on propane.

One downside of this is the amount of water vapour it will create in the


Balanced flue.

Yes - sorry read straight past that without actually seeing it!


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tue, 18 Apr 2006 11:32:46 +0100, The Natural Philosopher
wrote:



I think this is very true...OTOH if you ARE shoving a floor in, and the
insulation is cheap, well 300W is 300W.

As the ambient temps rise....right now I guess day/nightime averages are
around 8-10C...I have noited that the underfloor heating is simply not
coming on..the Aga, a 750W device . plus the usual electricals that run
24x7...freezers and fridges...is capable of heating, with a bit of solar
gain, the WHOLE front ground floor of the house...about 1500 sq feet.

and 300W 24x7x52 is 2621 units....a couple of hundred quid at least..


That was worst case though -3 outside.

My pattern of use tends to be evenings and weekends, although
obviously a retired person or someone using it occupationally might
use it all day. I then heat the place to 18 degrees. I have over
provisioned the radiators to 6kW output so that it heats quickly. At
other times there is a night setback temperature of 10 degrees.

I reckon that the averaged outside temperature over the year is
probably closer to 10 degrees. Given that and partial use, I reckon
that the averaged heat loss is probably equivalent to 100W or so
equivalent. At that point, I don't think it's worth the insulation
cost for this depth of floor.
If I were going for a deep floor and at least 50mm Celotex, I might
consider it, but I rejected that on loss of height grounds, plus the
amount of floor support to cope with several tons of machinery.




--

..andy

John Rumm wrote in message
...
Bob Minchin wrote:

I plan two heat sources.
1 a balanced flue domestic gas fire re-jetted to run on propane.

One downside of this is the amount of water vapour it will create in the
room. Not so good for rust free tool storage.

It might also be worth thinking about some form of frost protection
heating to keep it above the dew point in there for the same reason.

I found in my workshop a small wall mounted fan heater on a thermostat
set to about 5 degrees does the job nicely. With the amount of
insulation in place it does not kick into action often - and when it
does only runs for five mins or so.

2 a sawdust burner fuelled from the shavings and sawdust from the dust
extraction system on the machines.

Nice idea...

Do you have to manually load it with shavings?

(otherwise you may find the place melts when you run a thicknesser for a
couple of hours!) ;-)

The latter will be free fuel but I'm not sure how much sawdust it will
consume or I will produce and I expect propane will workout dear to run
for
long periods but convenient for short stays
To an extent, I can be flexible when I use the workshop and avoid it in
the
depths of winter if heating costs are too high.

My one is ok all year round, and will get to comfortable in about 10
mins from its coldest. Note however it is only 1/3rd the floor area of
yours.


--
Cheers,

John.

Hi John, Andy & others

My experience is that prevention of condensation damage in workshops is best
achieved by heating the machines. they only have to be a little warmer than
the surrounding air for nothing to condense.
In my metalworking shop, I heat the lathe bed, the milling machine, a custom
cabinet with a warmed metal sheet in the back and a cast iron surface plate.
Each has a number of aluminium clad wirewound resistors powered from 24
volts. Between 3-4 amps total has kept each item completely rust free in an
otherwise unheated workshop (apart from when I go in and use a fan heater if
needed)
The lathe was bought in 1979 and the mill in 1987 and neither have a single
rustmark.
In the garage, ( my current woodworking shop, a tambour fronted cupboard
with two mains lightbulbs in series (for long life & much reduced fire
risk) in a metal mesh housing keeps chisels, saw blades, spindle moulder
cutters, planes etc rustfree.


The woodburners I've been looking at -
http://www.thehotspot.co.uk/products...bcat=2&range=5 are manual
loading.

I may need to supplement the wood supply with a trailer load of broken
pallets every now and then and it will possibly burn woody garden waste. I
currently save the latter for an annual donation to my employers bonfire
party each November but when I'm retired I may burn it myself.


The gas fire as well as being balanced flue has completly enclosed flames
behind a glass door with a convector heat exchanger. It is a valor Homeflame
I've been offered free originally for spares for the one we have in the
lounge.

The workshop is about 100 feet from the house so connecting to the house
cental heating is possibly not on.

Bob

On Tue, 18 Apr 2006 21:07:25 GMT, "Bob Minchin"
wrote:



Hi John, Andy & others

My experience is that prevention of condensation damage in workshops is best
achieved by heating the machines. they only have to be a little warmer than
the surrounding air for nothing to condense.
In my metalworking shop, I heat the lathe bed, the milling machine, a custom
cabinet with a warmed metal sheet in the back and a cast iron surface plate.
Each has a number of aluminium clad wirewound resistors powered from 24
volts. Between 3-4 amps total has kept each item completely rust free in an
otherwise unheated workshop (apart from when I go in and use a fan heater if
needed)
The lathe was bought in 1979 and the mill in 1987 and neither have a single
rustmark.

Not a bad idea at all. I suspect that metal working equipment is a
little easier to keep rust free because generally it doesn't matter if
it's oily.

With woodworking equipment, one has to be a bit more careful to avoid
contaminants getting onto surfaces to be in contact with wood since
some will spoil the surface for certain types of finish.

In the garage, ( my current woodworking shop, a tambour fronted cupboard
with two mains lightbulbs in series (for long life & much reduced fire
risk) in a metal mesh housing keeps chisels, saw blades, spindle moulder
cutters, planes etc rustfree.

I haven't had an issue at all since I was able to economically heat
the workshop to at least a background 10 degrees. I occasionally run
a dehumidifier as well but only on higher humidity days.


For some reason I seem to have quite corrosive finger oils so in any
case, I use various preparations according to tool and surface. So
for example, planes, chisels and cutting tools get a wipe with
camellia oil periodically.

Machinery such as combination machine, bandsaw, wood turning lathe
gets a wipe with either Boeshield T9 or Felder Metallglanz for
surfaces.




The woodburners I've been looking at -
http://www.thehotspot.co.uk/products...bcat=2&range=5 are manual
loading.

I may need to supplement the wood supply with a trailer load of broken
pallets every now and then and it will possibly burn woody garden waste. I
currently save the latter for an annual donation to my employers bonfire
party each November but when I'm retired I may burn it myself.


The gas fire as well as being balanced flue has completly enclosed flames
behind a glass door with a convector heat exchanger. It is a valor Homeflame
I've been offered free originally for spares for the one we have in the
lounge.

The workshop is about 100 feet from the house so connecting to the house
cental heating is possibly not on.

Actually you could if the pipes were well insulated. I covered mine
with a substantial foam sleeve and ran them in 160mm soil pipe.

However, if you have a good supply of scrap wood, it could well be a
good option.





Bob


--

..andy