ScaFixGuide
Chimney scaffolding: the options and the rules
Repointing a stack, replacing pots or renewing lead flashing all happen at the most exposed point of a house. HSE's roof work guidance is specific about what to use there; this guide sets the options side by side and explains the edge protection each one still needs.
By Ole Emil Frikstad Urstad · How the numbers are computed ·
Do you need scaffolding to work on a chimney?
Usually yes. HSE's guidance HSG33 says a chimney stack scaffold should be used for work on chimneys, unless the job is minor or very short, such as pointing or a lead flashing inspection, and can be done safely from a correctly installed roof ladder. The eaves below still need edge protection while anyone is on the roof.
What does HSE's HSG33 say about chimney scaffolds?
The rule sits in one sentence. Paragraph 163 of HSG33 Health and safety in roof work says that for work on chimneys a chimney scaffold should be used, unless the work is minor or very short-duration, such as pointing or a lead flashing inspection, and can be carried out safely from a correctly installed roof ladder. The guidance illustrates two forms: a traditional chimney scaffold built around the stack, and a proprietary system that combines access across the roof with a platform at the chimney.
The exception is narrower than it sounds. Paragraph 115 describes short-duration work as low-risk tasks measured in minutes rather than hours, such as inspection, replacing a few tiles or adjusting a television aerial, and paragraph 116 sets the minimum for it: a safe means of access to roof level and, on a sloping roof, a properly constructed and supported roof ladder. Rebuilding a chimney head means lifting bricks and mortar and working at the stack for a day or more. That is not short-duration work, so the roof ladder alone is off the table.
Which set-up suits which chimney job?
Once a scaffold is needed, the position of the stack decides its form.
| Job and stack position | Usual set-up | What it still needs |
|---|---|---|
| Rebuild, repoint or new flashing, stack mid-roof | Chimney scaffold on the roof, traditional or proprietary | Safe access up to the roof and a guarded route across it; edge protection at the eaves |
| Stack on a gable or front wall, or the roof is being re-covered too | Full scaffold from the ground | A lift at eaves level with guardrails, plus a chimney platform if needed |
| A few minutes of work near the eaves | Mobile tower as access to a roof ladder | A roof ladder to BS 8634 with a proper ridge hook; the tower's own manual |
| Inspection without stepping onto the roof | MEWP (cherry picker) | Firm ground for the outriggers, a trained operator, wind within the maker's limit |
HSE's roof work page lists the same families of access equipment: general access scaffolds, stair towers, fixed or mobile scaffold towers, mobile access equipment, ladders and roof access hatches.
How must a roof ladder be fixed?
HSG33 paragraphs 164 to 167 set out what a roof ladder or crawling board has to do. It must be designed and made for the purpose, strong enough to span the roof supports, long enough to span at least three rafters, and secured or placed so it cannot move. The top anchorage should bear on the opposite slope with a properly designed ridge hook, not on the ridge capping, which can break away. Eaves gutters are not a footing: the guidance says house gutters are normally not strong enough to support a roof ladder.
Two of HSE's case summaries in the same guidance involve chimneys. A self-employed roofer was killed repointing a chimney stack after reaching it with an extending ladder and roof ladder, with no roof ladder on the rear slope, from which he fell. Another fell to his death while replacing chimney pots: an access scaffold was in place, but it had only a single guard rail, and he slid beneath it when his home-made roof ladder slid down the roof.
Where does edge protection go on a pitched roof?
At the eaves, on every side someone could slide towards. HSE's roof work page says edge protection must be fitted to the eaves of any roof, and on terraced properties to the rear as well as the front. HSG33 paragraph 131 lists where most falls from pitched roofs happen: from the eaves, from slipping down the roof and then over the eaves, from falling inside the roof during work on the trusses, and from gable ends.
The minimum guardrail, from HSG33 paragraph 126 and the Work at Height Regulations, is:
- a main guard rail at least 950 mm above the edge;
- a toe board at least 150 mm high;
- an intermediate rail or barrier so that no gap is larger than 470 mm.
On a pitched roof the second case above shows why the intermediate rail matters: a person sliding down a slope arrives low, under a single top rail. Where a scaffold already stands at the eaves for other work, the eaves lift can carry this protection; our page on scaffolding for roof work shows that set-up, and gable-end scaffolding covers chimneys on the end wall.
When is a cherry picker the better choice?
When nobody needs to stand on the roof. HSG33 paragraphs 39 to 41 say a MEWP can give safe access for short-duration work such as inspection and minor maintenance without leaving the basket, and that it can avoid the risks of erecting a scaffold. Leaving the basket at height is allowed only where a rigorous risk assessment shows it is the safest way to reach a location. The ground must suit the machine, and the manufacturer's maximum wind speed applies, which matters on a chimney that sits at the highest and windiest point of the house.
A mobile tower beside the eaves can serve as the access to a roof ladder for short work. It does not replace edge protection along the rest of the eaves.
What about the gas flue in the chimney?
The stack may still be in use. HSG33 paragraph 86 says anyone doing roof work around a flue must make sure the work does not affect the flue or gas appliance, and records the case of a roofing contractor who removed a chimney stack and left a gas appliance in a dangerous state; he received a suspended prison sentence. Find out what the flue serves before the first brick comes off, and agree with the occupier when the appliance is off.
What applies in the United States?
Under 29 CFR 1926.501(b)(11), each employee on a steep roof with unprotected sides and edges 6 ft (1.8 m) or more above a lower level must be protected by guardrails with toeboards, safety nets or personal fall arrest systems. 1926.500 defines a steep roof as one with a slope greater than 4 in 12, which covers most chimneyed houses. A scaffold built to reach the stack is then a scaffold under 1926.451, with its own rules on platforms, guardrails and inspection; the OSHA scaffolding guide summarises them. UK readers will find the wider set of rules in our UK scaffolding regulations article.
When the chimney sits on a gable or close to an outside wall, ScaFix can plan the facade scaffold up to the eaves lift in 3D with its parts list; the platform around the stack itself comes from the chimney scaffold maker's instructions.
This is planning information, not structural approval. A chimney scaffold, tower or MEWP is set up to its manufacturer's instructions, and the roof edge protection and access follow HSE's HSG33 and the Work at Height Regulations 2005 in Great Britain, or OSHA 29 CFR 1926 Subparts L and M in the US. A competent person must inspect the scaffold before use.
Frequently asked questions
Do you need a scaffold to repoint a chimney?
In most cases, yes. HSG33 allows a correctly installed roof ladder only for minor or very short work such as pointing or a flashing inspection; anything longer calls for a chimney scaffold, plus edge protection at the eaves.
What is a chimney scaffold?
A working platform around a chimney stack, either built from tube and fittings around the stack or supplied as a proprietary system that also gives access across the roof. It is set up to its maker's instructions.
Can I use a cherry picker to work on a chimney?
For inspection and minor maintenance from the basket, often yes. HSE says leaving the basket at height needs a rigorous risk assessment, and the machine must stay within its maximum wind speed.
Can a roof ladder rest on the gutter?
No. HSE says eaves gutters on houses are normally not strong enough; the ladder should hang from a ridge hook bearing on the opposite slope.
What fall protection does OSHA require on a steep roof?
Guardrails with toeboards, safety nets or personal fall arrest for any employee on a roof steeper than 4 in 12 with edges 6 ft or more above a lower level.
Sources
Primary sources used for this article, with the date each was read.
- HSE: HSG33 Health and safety in roof work, fifth edition (2020) (read 23 October 2026)
- HSE: Roof work (construction safety topics) (read 23 October 2026)
- 29 CFR 1926.501 Duty to have fall protection (Cornell LII) (read 23 October 2026)
- 29 CFR 1926.500 Scope, application and definitions (Cornell LII) (read 23 October 2026)