If you’re short on time or just short on money, tack rolls of polythene or bubble-wrap to the framing on the inside of the shed. It’s not that expensive, it’s quick to do and you will notice a difference in temperature inside your shed - though don’t get into your shorts just yet.
For this you’ll need either mineral wool (such as rockwool) or glass fibre wool. Normal polystyrene for the insulation is not a good idea particularly if you have any electric cabling: some sources reckon the polystyrene can perish the PVC sheath plus it can be a fire hazard if it is put too close to the wooden structure of your shed.
First, lay the mineral wool in rolls against the inside of the shed walls between the shed framing then use sheets of MDF or plywood and tack these to the shed framing to provide extra insulation and to retain the mineral wool. Plasterboard can also be used as a retainer but it’s not ideal for a shed environment where tools, lawnmowers and bikes can leave a nice dent in it.
If your budget can stretch, it is advisable to also lay a breathable membrane in-between the shed walls and the mineral wool (or other insulating material). This will help stop damp penetrating through to the wool. Tack the membrane onto battens to make sure that it isn’t touching the shed wall as you need to leave an air gap for circulation; any damp that does get through into the shed will then evaporate. Similar methods can be used for insulating the roof as those suggested for the walls.
So that’s the walls and roof sorted, but what about your shed floor?
The most obvious and cheapest insulation method is to lay an old roll of carpet, preferably over a water-resistant membrane. If you don’t have any carpet lying around, stop at the next roadside skip and ask the builder if they plan to dump any!
A more elegant, though costly approach, is to go for under-floor ventilation with a floating floor - one that is placed on pressure-treated bearers away from the damp ground, is the best option. Ideally you need to have at least 25mm of ventilation space under the shed to be effective.
If you’re not installing a new shed then this will obviously require some remedial work or you could just add a false floor if you can cope with a small reduction in height. Non-flammable, expanded polystyrene (one brand is Styrofoam) can be used to create a floatation floor. This is placed on top of your old floor (preferably with water resistant membrane underneath) and then a layer of plywood, cement board or something similar should be placed on top of the insulation and the whole lot should be screwed down. Alternatively, lay 25mm battens onto the membrane, add your chosen insulating material between them and then add the solid false-flooring on top.
Next, turn your attention to any draughts around the windows or doors frame.
A draughty door frame can be improved by tacking some rubber strips (about 3-4cm wide) on the inside of the frame to form a seal along the crack when the door is shut. If the design of your door can accommodate it, you could also try the ‘E’ profile weather strips that are always available in DIY stores. For any gaps around the window frames, just use any tube of ‘liquid’ wood or hardening-foam filler.
The single glazed windows that are standard with most garden sheds are not designed to retain heat and they are also prone to condensation. A cheap solution that offers good results in all but the coldest weather is secondary-glazing film that you stick to the inside of your windows.
For a more hardy solution to wintery chills, DIY secondary-glazing kits can be a good addition to keep out draughts and to keep in the heat. These are usually acrylic or polycarbonate panes held in place on the original windows with some form of fixing strips such as magnetic tape.
You never know, once you have insulated your shed, you might just consider spending a little more time in there keeping it tidy…
With the warmer weather not that far away, many of us will find ourselves spending a lot more time in our sheds just pottering around. Or maybe even tackling the dreaded clear-out that we’ve being promising to do for sometime now.
Well, once you’ve cleared out your shed and decided which is the “good stuff” that you’ll be neatly putting back (and made the annual promise not to let it get into that state again) why not take the opportunity to improve your shed’s insulation? Let’s face it, it’s not empty that often - carpe diem and all that.
So what can you do to make your shed so much more snugly in time for the next cold snap?
If your shed is tongue and groove then you do have a head start: it’s certainly the best external cladding for keeping out the worst of the UK wind, rain and snow (also known as summer). Irrespective of your shed’s construction however, you do have a few insulation options: