The Outbuilding Every Homeowner Forgets to Check

We spend a lot of time here on the parts of a home that get looked at. The front porch, the borders, the raised beds, the paint colour on the back door. 

The structures at the bottom of the garden get almost none of that attention. 

The old shed, the sectional garage, the lean-to store, the greenhouse frame that came with the house and has been holding tomato plants for thirty years. Nobody photographs those. 

Which is exactly why they get to sit there for decades without anyone asking what they are made of, and why specialists in asbestos removal in Hampshire and other regions get so many calls in spring and summer, when the garden makeover finally reaches the far end of the plot.

The good news is that this is easy to get right, and the material in question has usually been sitting there harmlessly the whole time.

The Part Of The Plot Nobody Ever Surveys

Asbestos was not fully banned in the UK until 1999, and around 1.5 million buildings are still thought to contain it. When people picture that, they picture lofts and ceilings. In practice the highest concentration on a domestic plot is often outside the house entirely.

The reason is economics. Outbuildings were cheap, functional structures where nobody was spending money on appearance. Asbestos cement was inexpensive, waterproof, fireproof, rot-proof and light enough to fix to a timber frame in an afternoon.

 It went onto garage roofs, shed roofs, coal store lids, greenhouse bases and every kind of lean-to across the country, and it has been quietly doing its job ever since.

Nothing about that is a problem while it is left alone. Material in sound condition, sitting undisturbed on a roof, is not releasing anything into your garden. The care is worth taking because of what happens when it is broken up. 

Around 2,500 people die from mesothelioma in the UK each year, and the HSE estimates roughly 5,000 asbestos-related deaths annually. These illnesses take twenty to fifty years to appear, which is why an afternoon of enthusiastic clearing feels like nothing at the time.

What You Are Looking For

Six things account for most of it.

Corrugated roof sheets. 

The classic grey wavy panels on garages, sheds and workshops. Still the most common find on a domestic plot by a wide margin.

Flat wall panels. 

Sectional prefabricated garages, shed walls and infill panels between timber posts.

Guttering and downpipes. 

Heavy, grey, slightly rough to the touch, and much more brittle than the plastic that replaced it.

Soffits and eaves boards. 

The boards tucked under the overhang on a garage or outbuilding roof.

Old water tanks and flue pipes. 

Found in outbuildings that once had a boiler, a heater or a working supply.

Greenhouse staging, bases and the odd plant pot. 

Asbestos cement was genuinely sold for horticultural use, so it does turn up in a potting shed.

You cannot identify any of it by eye. Not you, not a landscaper, not a roofer. 

Confirmation comes from a small sample analysed at a laboratory, and in the UK that means a UKAS-accredited one. Cement sheeting and modern fibre cement can look near identical, particularly once both have weathered.

How To Tell It Is Deteriorating

Sound sheeting has a smooth, sealed surface. What you are watching for is the point where that surface has gone.

Look for a chalky, powdery bloom that comes off on your hand. Look for heavy moss and lichen growth along the sheet laps, which holds moisture against the material and speeds up the breakdown. 

Look for hairline cracking, flaking, delamination at the edges, and any place where the surface has softened into something visibly fibrous rather than dense.

Then look at the ground. Debris sitting in the gutter, chips of sheet in the border below the drip line, or fragments in the soil where the dog digs all tell you the roof is shedding. That is worth acting on rather than watching for another season.

Four Things That Make It Considerably Worse

Pressure washing. This is the single worst thing anyone does to an asbestos cement roof, and it happens every spring. The jet strips the weathered surface layer and throws fibres across the garden and onto everything downwind. If a roof or a garage wall needs cleaning, it needs identifying first.

Drilling, cutting and grinding. Hanging a bracket, running a cable, cutting a hole for a vent or trimming a sheet with an angle grinder all release fibres directly. Power tools are the fastest route to a problem.

Breaking it up to fit the skip. Very common, entirely understandable, and the point at which a manageable job becomes a contaminated garden. Asbestos waste cannot go in a hire skip or a household bin under any circumstances.

Climbing on it. Asbestos cement roofs are treated as fragile by default, and falls through fragile roof sheets are a well-documented cause of serious injury in the construction industry. A thirty-year-old shed roof will not hold an adult.

Worth adding to that list: do not burn it, do not crush it as hardcore under a patio, and do not leave broken sheets stacked behind the shed for a future weekend.

Why The Garden Makeover Is The Moment It Matters

Nothing about an intact outbuilding demands urgent action. What changes the picture is a project.

Taking down the old shed to make room for a garden room. Re-roofing the garage. Laying decking or a patio right up to a wall panel. Removing a greenhouse. 

Getting tree work done where branches have been rubbing on a roof. Clearing up after a storm has cracked a sheet. Every one of those is a moment where undisturbed becomes disturbed, and where a small identification cost at the start saves a large clean-up cost later.

Garden rooms in particular are worth planning around. People site them where the old shed stood, which means the old shed has to come down first, and that demolition is the step that needs sorting properly before anything gets poured or built.

What Doing It Properly Actually Involves

It is less dramatic than people expect. Removal of a straightforward cement garage or shed roof is typically a day's work for a two-man crew.

The method matters more than the drama. Sheets come off whole rather than broken, kept damp to suppress fibres, unbolted rather than smashed. Everything is double-wrapped, labelled and taken by a permitted carrier to a facility licensed to receive it, and the job produces a hazardous waste consignment note. Keep that note. 

If you sell the house later, it is the document that answers the obvious question about what happened to the old garage roof.

Most outbuilding cement work falls into the non-licensed category, which means lighter controls than the higher-risk materials found indoors. Non-licensed is not the same as do it yourself. 

It still calls for trained operatives, controlled methods and legitimate waste routes.

Leave It, Or Lift It

If the outbuilding is sound, sealed and nobody is touching it, leaving it alone is a perfectly reasonable decision and often the right one.

If it is crumbling, if debris is coming off it, or if it stands where your next project is going, get it identified and get it removed by someone who does this for a living. Then go and enjoy the part you were looking forward to, which was never the shed.