Find out what the old sheets are
On a barn, a machinery store or a livestock shed, the first question is whether the sheets are asbestos cement. HSE's year-2000 rule decides how the building is treated until a sample says otherwise. A shed re-sheeted in 1995 falls under it just as one put up in 1965 does, and farm buildings are often added to and patched over the decades, so the date on the oldest bay may not be the date on the roof.
The roofer cannot tell by looking, and nobody should break a corner off to check. A surveyor takes a sample and a laboratory identifies it. What comes back settles who is allowed to do the work and by what method.
HSE puts careful removal of asbestos cement sheeting in the non-licensed class provided each sheet is lifted off intact. Weathered sheet that is not otherwise badly damaged stays in that group. Sheets that shatter in the process move the work into the notifiable non-licensed group.
If the sheets turn out not to contain asbestos, the job is simpler but the access rules are not. Our page on asbestos cement roof sheets covers the identified case in more detail.
Working on a fragile roof
HSE guidance A14 is plain on the point: an asbestos cement roof is always fragile. Old fibre cement and rooflight sheets can give way under a person's weight, and moss and damp make them harder to read from above.
Regulation 6(3) of the Work at Height Regulations 2005 makes an employer responsible for guarding against falls so far as the job allows. On a farm roof that points to methods which keep people off the sheets:
- Edge protection or a scaffold along the eaves.
- Staging, crawling boards or platforms spanning the purlins.
- Netting or a safety deck beneath the sheets, where one can be fitted.
- Clear marking of every rooflight.
The farm itself matters as well. Livestock buildings may need to be emptied for the work, or the job phased so that animals are not beneath sheets as they come off. Feed stores and grain need covering, and water troughs need protecting from falling fragments. Plan this with the farmer, working around the daily routine instead of across it, and agree where vehicles and stock will move while the roof is open.
Our page on fragile roof safety covers the access side in general terms.
Steel and fibre cement sheets
Once the old sheets are off, the replacement is chosen to suit the building. Two common choices are profiled steel sheet and fibre cement sheet. The comparison below is deliberately neutral, because the right one depends on the structure and the use.
| Point to check | Steel | Fibre cement |
|---|---|---|
| Weight on purlins | Maker's data | Maker's data |
| Cut edges | Treat as advised | Treat as advised |
| Purlin spacing | Match to sheet | Match to sheet |
| Walking on it | Treat as fragile | Treat as fragile |
Whichever is chosen, the purlins, the fixings and the laps decide how it performs. Get the maker's data sheet and set its maximum purlin spacing against what is on site, since the purlins that carried the old sheet may not suit the new one.
Before re-sheeting a farm building, ask the local authority's building control team whether approval is needed. Overcladding the old sheets is another route, set out in overcladding industrial asbestos sheets, and it keeps a sound asbestos cement sheet undisturbed.
Removal, waste and the order of work
The sequence for replacing farm roof sheets runs like this, once the survey and the laboratory result are in hand.
- Set up access and edge protection, and clear the area beneath.
- Take the sheets off whole, dampened if the method calls for it, without breaking them.
- Seal any asbestos waste in two layers and label it; a skip that locks is the rule, never an open one.
- Check the purlins and replace any that are rotten or distorted.
- Fix the new sheets with correct laps and the fixings the maker specifies.
HSE's guidance on waste rules out an open skip for cement sheet. Kent County Council's household recycling centres are for residents, so a farm's roof waste counts as trade waste, which needs a consignment note and a registered carrier.
Licensed elements go to a licensed firm. If a skip or scaffold sits on the highway, the firm responsible applies to Kent County Council, giving 5 working days of notice.
Our routine is a survey first and a single written figure after it. The commercial roofing hub lists the other sheet and cladding questions.
