Chimney and roof advice

Straight answers to the questions homeowners actually ask us, without trying to talk you into work you do not need.

Is chimney repair covered by home insurance?

This is the single most common question we get, and the answer turns on one distinction: insurers cover sudden, accidental damage; they do not cover deterioration.

Usually covered: a stack blown down or damaged in a storm, impact damage from a falling tree, damage caused by a vehicle or fire. These are events.

Usually not covered: failed pointing, eroded flaunching, spalled brickwork, a stack that has leaned progressively over years, or general wear. These are maintenance, and virtually every buildings policy excludes them.

The grey area is where a storm finishes off a stack that was already in poor condition. Insurers frequently take the view that the underlying cause was wear rather than weather, and decline. That is a common outcome, so it is worth knowing before you rely on a claim to fund the work.

Two practical points. First, most policies require you to prevent further damage — so reasonable emergency costs are often recoverable, and you should keep receipts. Second, photograph everything before anything is moved or repaired.

Can a cracked chimney be repaired, and how?

It depends what has cracked, because "a crack in the chimney" covers several different problems:

• Cracked flaunching — the mortar cap around the pots. Very common, and straightforwardly repaired by cutting out and recasting it. Worth doing promptly, because water running down inside the stack causes much more expensive damage.
• Cracked or open mortar joints — addressed by repointing, provided the bricks themselves are still sound.
• Cracked brick faces (spalling) — where frost has blown the outer face off saturated brick. This is not repairable by pointing; affected brickwork needs replacing, which usually means a partial rebuild.
• Horizontal cracking through the joints on one face — often a sign of sulphate attack, which causes expansion and leaning. This is structural and does not stop on its own.
• Cracked render on a rendered stack — water gets behind the render and is then trapped there, so cracked render on a chimney tends to accelerate damage rather than protect against it.
• Cracked flaunching — the mortar cap the pots sit in, and the most common failure of the lot. See flaunching repair.

If the crack has produced damp indoors rather than just looking wrong outside, work out which of the three causes of chimney damp you are dealing with before spending anything: see damp on a chimney breast.

What you should not do is fill chimney cracks with sealant or a hard cement patch. It looks like a fix, traps moisture behind it, and usually moves the damage into the brickwork.

Can a chimney flue or liner be repaired?

Yes, though it is a different discipline from the masonry work we do. Flues can be relined — commonly with a flexible stainless steel liner, or by cast-in-situ methods — where the original flue has deteriorated, is leaking fumes between flues, or needs to suit a new appliance.

If the flue has had a fire in it, the masonry needs checking as well as the lining — see chimney fire damage.

The important safety point: if you are getting smoke or fumes coming back into the room, smell combustion gases, or have a carbon monoxide alarm sounding, treat it as urgent. Stop using the appliance, ventilate, and get a suitably qualified engineer to inspect it. For a solid fuel appliance a sweep or HETAS-registered installer is the right person; for gas it must be a Gas Safe registered engineer. That is a legal requirement, not a preference.

We work on the structure of chimneys — brickwork, pointing, flaunching, pots and flashing. We will tell you plainly if what you actually need is a flue or appliance specialist.

How do I know if my chimney needs attention?

You do not need to go on the roof. Most of the useful evidence is visible from the ground, from an upstairs window, or from inside:

• Damp or staining on a chimney breast, particularly upstairs and particularly after driving rain
• Mortar debris, sand or brick fragments in the gutter or on the ground
• Joints visibly recessed, or daylight showing through them
• The mortar cap around the pots cracked, crumbling or missing
• Pots visibly tilted or loose
• Brick faces flaked or crumbling, usually worst on the weather side
• Plants or moss growing out of the stack
• The stack out of vertical compared with a downpipe or the corner of the house
• A cracked mortar band where the stack meets the roof, instead of lead flashing

A useful trick: find an old photograph of the front of your house — an estate agent listing, a street-view image from a few years ago, a family photo. Comparing then and now is the most reliable way to tell whether a stack has actually moved.

Choosing a roofer without getting caught out

We have set out plainly on our about page what we will and will not claim on this website, and why. Apply the same test to anyone else you are considering.

Roofing and chimney work attracts doorstep callers, particularly after storms, because the customer usually cannot see the defect or the finished work. Some straightforward protections:

• Do not agree to work on the doorstep. A genuine defect will still be there tomorrow. Urgency is the primary tool used to prevent you getting a second opinion.
• Get it in writing — scope, materials, access, price, and what is excluded.
• Ask for photographs of the defect before and the work after. On a chimney you cannot inspect it yourself, so this matters.
• Ask what mortar is being used and why. A specific answer about the brick type is a good sign; "cement" without qualification, on a soft Victorian stock stack, is not.
• Be wary of a price that only makes sense without scaffolding for work that needs it.
• Never pay a large sum up front for materials on a job of this size.
• Check the scope covers the actual cause. Repointing a stack when the leak is at the flashing is a common and expensive mismatch.

When is the best time of year for chimney work?

Spring to autumn is easiest, because mortar needs reasonable conditions to cure and cannot be laid in hard frost or when frost is forecast before it sets. That said, the work is weather-dependent rather than season-dependent — a dry, mild spell in January is more workable than a wet week in June.

The practical advice is not to wait for a leak to prove the point. Problems found in late summer can be dealt with before winter; the same problem found in December has to survive the worst of the weather before it can be fixed properly.