Mortar fall from chimney interior to hearth

[Woodburn]

what repair is needed for mortar dropping from domestic chimney ?

[Old_Geezer]

Replacing the mortar ?

Get a builder to look at it, suck through their teeth, and tell you how much needs to be done.

[sandyRoe]

You might need to put something up to keep Santa out of it. That old fat chap could really make a mess of it if the mortar's crumbling.

[HowardKennitby]

Is the chimney in use?

[Clanad]

Here in the U.S., if it were a "laid-up" chimney (one constructed entirely, inside and out, of bricks and mortar) and the falling mortar were chunks, you'd have a major problem.
But, alternately, if it was minor or just dust, I'd suggest getting a stainless steel insert kit installed by a fireplace specialist. I've installed one by myself and it's not difficult, but my chimeny was already lined with the code perfect clay sewer tiles. Still, the stainless steel kits are the best...

[AlBags]

How much?
Any smoke expelled into rooms above through chimney?
All depends on construction of building .. but it just could be that nothing needs doing!

[jake-the-peg]

If you're using the chimney you need to take it pretty seriously. This is chimney pargeting in old houses it would likely be a mix of lime mortar and horsehair etc. and it lines and *insulates* the chimney.

Hot flue gasses going up the chimney, heat it up and the risk is hot gasses getting into the loft cavity and starting a fire - lots of lovely dry tinder-like material up thee.

I live in a 17th Century thatched cottage and had this situation. So we put a flexible flue up (solid wouldn't go through the contorted chimney) held in place with insulating pummice beads that attached to the stove/fire at the bottom

[jomifl]

A stainless steel liner is a lot cheaper than a ceramic one (made up of a stack of tubes). If you are burning wood the acids produced will eventually eat through the liner in about 10 years(depending on amount of use). The combustion products of coal/coke are dry and don't give this problem.

[AlBags]

But it's no good you lot quoting liners .. clays .. etc, etc, etc ..
Not even been stated what the construction, chimney type, fire type and age of property is yet!