I am considering building a home office in the garden (kind of elaborate
shed). Size would need to be around 6ft x 10ft.
I am thinking of starting with a regular commercial shed, and doing a DIY
Has anyone done this? I need to add the maximum insulation to help keep it
warm/reduce heating costs/keep cooler in summer, and add a double glazed
window, and extenal door.
What is the best way to add insulation, and what thickness is required to
meet the highest insulation standards. I want to end up with a
white/magnolia flat finish on the walls, and a laminate floor.
What would be cheapest way to heat the "office". Some heat will be gained by
the computer/lighting etc. Would it be better to use underfloor heating
under the laminate, or a aircon unit (as a heat pump), or something else?
I haven't done it myself, but have sen it done several times.
Your approach is corect in teh essentials. Don't forget floor insulation.
Mmm. You should be able to wedge about 50mm of celotex between the
structural bits, and plate over with foil backed plasterboard. Paper or
skim or both and paint.
Floor is a bot more of an issue. Ether replace it completely with an
insulated tupe or put studowrk across it,celotex insulate, chip out and
To be honest, the computer/lighting stuff should be enough. Backed up
with an electric heater for really cold days.
UFH means really designing a custom floor from scratch and unless wet is
no saving at all. Aircon isn't bad..but its an expensive install.
You have to balance installation costs (a couple of quid for an electric
heater versus thousands for aircon or UFH) - against running costs over
the units lifetime. A couple of grand buys a lot of electricity.
A small shed well insulated should only need 200-500W to be cosy. The
lower end of that is about what all the installed gear+ human will
generate like as not. That leaves 300W to find.
IIRC providing that it's more than a specified distance from a neighbours
boundary and below a certain size, then no planning permission or building
control is applicable as it's "Deemed To Satisfy" BUT - as it's intended to
be wired for electricity, then Part P of the building regs will apply.
It's a long time since I delved deeply into planning and building regulation
matters, so this info may well be long past its 'sell by' date.
Yes, I looked at that. If you want to avoid having to deal with the
bureaucrats, you have to look at both building regulations and planning
legislation. For the purposes of these, you can find enough
information on the web site of either your local authority's web site
or that of another.
I won't reproduce all of the factors here, but you have to look at:
- Permitted development rights for the property. Get the original
planning consent and see whether any specific limits have been set, or
defacto allowances removed. This will tell you whether or not you can
use the generic allowances which determine what proportion of the plot
can be built upon and the proportions in relation to the main house.
- Take a look at the Land Registry records and other documentation for
the property (colloquially known as the "deeds") and see whether there
are any specific covenants limiting what you can do
Assuming that those tests pass and you can use the generic rules, the
aspects to look at (again involving planning and building control) are:
- Volume of the building
- Floor area
- Distance from any highway
- Distance from boundary. This one is supposed to be 1m, but in the
context of sheds is widely ignored.
- Height of the building. There is a 4m limit here to the apex of the
roof. This can be a determinant of floor area as well, although the
design of the building can help here. For example, one can have a
sloping roof with a low slope or a cabin with low pitch to the roof.
Unless he wants to build something massive, it should be possible to
stay inside the rules and not involve the jobsworths.
I understood this did not apply to a building such as a small shed if the
floor area was less than 15 square metres - and only applied to a buildings
between 15 and 30 square metres if it was not constructed of "substantially
incombustible material". Hence the typical wooden garden shed is exempt.
Thanks Andy. Duly e-mailed to said offspring. The idea is to move to a
house where this would be most feasible, so there aren't any specific
details as yet. However, I believe it involves a grand piano so I'm
staying out of it if I can.
I have just built one..
13mm ply on the inside.. 65 mm cavity wall bats.. 6 mm ply outside for the
walls and roof ( 12 mm ply outside on roof).
The floor is 18 mm ply on top of polystyrene on top of ply on top of timber
bearers on top of concrete fence posts.
Cheaper than a commercial shed before the conversion.
Yes although it was a cabin (thicker timber rather than cladding).
Normal house standard would be 70-80mm of Celotex/Kingspan. I used
50mm to avoid reducing the internal dimensions too much.
You can put as much as you want but it becomes a trade off. I added
internal studding to create a depth of 60mm, then an air gap which was
ventilated to the outside was left behind the Celotex and the front
face taped with foil adhesive tape. I used T&G cladding over that,
but plasterboard would be OK too. If you think you will want to fit
a lot of heavy things to the walls, then ply would be a better choice.
You can joint and paint either.
For the floor, I had a concrete plinth laid. I then laid treated
floor bearers and built a frame for the floor with a perimeter and
joists of 150mm depth, 500mm apart, isolated from the bearers with
DPC. I added small blocks about 60mm down from the top on sides of
the joists and then cut and fitted Celotex in there. Flooring was done
in ply and I used an industrial rubber flooring on top of that
(slightly different application to a home office. Laminate could have
been used on the ply.
The roof is done similarly to the walls, so all 6 surfaces are insulated.
I added secondary glass as opposed to DG units for door and windows.
If you are going to do this type of thing with a commercial shed, I
would look at replacing the supplied windows which are normally not
I haven't needed to bother because there is enough heat from equipment
inside. A building of this size only needs a few hundred watts.
If I were going to use the building as a habitable office, I would fit
an aircon unit with heat pump capability.
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