Maintenance Care · 7 min read
Preparing Garden Buildings for Winter: One Afternoon, Done Properly
One thorough autumn afternoon — roof, water, doors, contents — buys a garden building an easy winter and an uneventful spring. The deep dive behind the autumn visit in our seasonal rhythm.
One good afternoon in autumn
Preparing Garden Buildings for Winter
Winter doesn't wreck sheds — it finds what autumn left undone. Here's the one thorough afternoon we'd give any garden building before the weather turns.
We've hand-built garden buildings in our West Midlands workshop since 1995, and here's the pattern behind almost every "winter damage" story we hear in March: it was preventable in October. Not with heroics — with one unhurried afternoon. Our annual maintenance checklist sets out the year-round rhythm of four seasonal visits; this is the deep dive into the autumn one. Pick a dry Saturday before the clocks change and work in order: roof, water, moving parts, contents.
First, the roof — while the weather still lets you
Every winter leak starts small, and it starts now. Get the covering right before the November rain — nobody fixes a roof well in December.
- 1
Walk the felt laps
Sight along each lap — where one sheet of felt overlaps the next — for edges starting to lift, especially at the ridge and the lower edge, where wind gets a fingerhold. A lifting lap is five minutes with adhesive today; after the first gale it's a torn sheet and a wet ceiling.
Tip: Tap home any nail head standing proud — a raised fixing is a wick for water.
- 2
Check the EPDM perimeter, not the middle
An EPDM rubber roof barely notices winter — the membrane has a life expectancy of around 50 years — so look at the edges instead: the trims, the corners, the line where the rubber turns down over the fascia. Anywhere lifted or wrinkled gets fixed now; the field can look after itself.
- 3
Find where the drips would start
Go inside on a bright day, pull the door to, and let your eyes adjust. Pinholes of daylight in the roof are next month's drips. Check the ceiling corners for tide marks too — a stain always sits downhill of the entry point, so trace it back up the slope.
Careful: Daylight through the covering itself, not at a lap or trim, is urgent.
If the covering is at the end of its life, autumn is the time to know it — not February, under a flapping tarpaulin. Our felt vs EPDM guide will help you judge repair versus re-cover, our rubber roofing page explains what a long-life membrane involves, and the kits live in our aftercare shop.
Managing the water
Up top
- Sweep leaves off the roof — a sodden mat along the lower edge dams water exactly where the covering is weakest
- Clear gutters and downpipes, then tip a bucket of water through and watch it leave
- Check the drip edge throws water clear of the fascia instead of curling it back underneath
- Prune overhanging branches where you can — they restock the roof all season
At ground level
- Walk the base in heavy rain: water should move away from the building, never stand against it
- Pull back soil, gravel and compost bags creeping up the bottom rails
- Cut vegetation back so air moves round every wall — cladding that can dry after rain is fine; cladding held wet is not
- Keep the airflow under the floor open — moving air keeps the bearers sweet
The door and window pass
Timber takes on a little moisture as autumn deepens. Ten minutes now saves a binding door in January.
- 1
Check the swing before the moisture arrives
Open each door slowly and watch the gap around the frame — you want it even all round. A door that kisses the frame in October binds by December, so adjust the hinges now, while the timber is dry. Opening windows should latch without persuasion.
- 2
Oil everything with a pin in it
A drop of light oil on every hinge, lock, catch and hasp, then work each a dozen times. A stiff lock on a freezing morning invites force, and force pulls fixings out of frames.
- 3
Do the draught check — then resist over-fixing it
On a breezy day, close up and run the back of your hand around the door and window edges. Slight, even air movement is healthy ventilation; a channel of wind at one corner is a misaligned door or a perished seal. Fix the alignment, don't stuff the gap — a shed sealed airtight is a condensation box.
What's inside matters as much as the shell
Lift it off the floor
The floor is the coldest surface in the building and the first place damp air condenses. Power tools, fabric, cardboard, seed and feed go up onto shelves or battens — even two inches of air changes everything.
Put petrol tools to bed properly
Winterise mowers and trimmers the way their manuals say — usually running the tank dry or treating the fuel with stabiliser before the last cut. Stale petrol is the commonest reason a mower won't start in spring.
Never store a cover wet
Furniture covers and groundsheets come in bone dry, every time. A wet cover folded into a corner is a season-long damp source that spoils itself and everything near it.
Give metal a wipe
Hand tools winter best clean, lightly oiled and hung up — a blade resting against a cold wall picks up condensation with every mild spell, and by spring that's rust.
A word on materials
Our timber buildings are framed in tanalised timber carrying a 15-year anti-rot guarantee, so winter is no mortal threat to the structure — but the guarantee protects the timber, not your contents, and it assumes water is managed rather than ignored. A composite building asks even less: the cladding, with its 30-year manufacturer warranty, wants only a wipe-down. Gutters still block and hinges still want oil, though — the composite owner gets the same afternoon, just a shorter one.
Through the winter: the five-minute habits
Preparation done, winter asks only for glances.
- Air the building for half an hour on crisp, dry days — moving air is the cheapest dehumidifier there is
- Ease snow off flat and pent roofs with a soft broom, gently, from the edges — never a shovel or blade
- Don't let ivy or climbers take hold — they clamp moisture against the cladding and lever into gaps
- After any storm, a slow walk round: covering flat, trims in place, door swinging true
- Move anything slumped against the walls — leaves, a leaning fence panel, the hurriedly parked wheelbarrow
If you open up in January to streaming windows or a musty edge, don't wait for spring. Our guides to stopping damp and mould and ventilation and condensation trace the causes — nearly always airflow, a drip, or something that went in wet.
The spring handshake
When the first decent dry spell arrives, winter hands back its report card — and because you did the autumn afternoon, it should be a short read. You'll walk the roof line to see how the covering rode the storms, clear whatever silt the gutters gathered, probe the bottom rails and the floor by the door for softness, and read the south and west faces to judge whether a re-coat is due. That inspection, and the four-season rhythm this afternoon belongs to, is laid out in our annual maintenance checklist. The checklist owns the year; this afternoon is the year's most valuable entry.
Winter questions we're asked every year
Should I heat my garden building over winter?
For ordinary storage, no — dry and aired beats warm. Heating an unventilated building loads the air with moisture, which condenses on the cold glass the moment the heater goes off. If you work out there, heat while you're in and ventilate afterwards.
Do composite buildings need any winter preparation?
Less, but not none. The cladding only ever wants a wipe-down — that's the point of it — but gutters still block, drainage still matters, locks like their drop of oil, and contents still belong on shelves.
Can I leave petrol in the mower over winter?
Follow your machine's manual — it outranks any general advice, ours included. The usual options are running the tank dry or treating the fuel with stabiliser before the last cut. Untreated petrol left standing until March degrades, and it causes most spring non-starters.
Is a musty smell in winter something to worry about?
A faint earthiness after weeks shut up is normal; airing on dry days sees it off. A persistent musty smell is damp announcing itself — find the roof drip, wet corner or wet-stored kit, and treat the source, not the smell.
Ready for the autumn afternoon?
Timber treatment, EPDM roof kits and the rest of the aftercare range, from the workshop that built your shed — delivered free across the UK mainland.
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