DIY Doctor UK DIY Forums

i need to take down my cimney stack and rebuild it.
rebuilding it is not a problem, i would like to know what
the mix is for rendering the flues and do i need building reg/planning permission?

Since 2002 work on chimneys needs consent from the local council.
Parging of chimneys stopped in 1965.
Now chimneys must be lined with proper clay liners or
made of concrete or lined with double skinned stainless steel.
The internal size of a chimney must relate to the size and type of fire
to be used usually 225 x 225 mm.
The flue must be able to cope with a temperature of 1000 degrees C.
If the flue is too small for the size of fire, or too big the fire will not burn
correctly.
Bends must be no more than 45 degrees.
There must be a plate informing the owner what the chimney is
designed to burn.

From a practical view, a chimney that is inside the main fabric of the
building and is protected from the cold and wind will work better.
When lighting a fire, the chimney that is insulated will start quicker.

When lighting the fire, the initial heat has to lift a plug of cold air
up and out of the chimney, some 16 feet of cold air will be pushed
upwards and out an easy air supply and a quick to warm chimney
will make life a lot more pleasant.

A fire that has a direct supply of outside air is cheaper to run,
in as much as it is not burning air youv'e paid to heat, and it will
stop any drafts in the room.

On the other hand, a fire that burns too quickly, will burn cold.
So, a fire needs a controlled air supply to burn at its hottest.
On tick over, a fire that has a cold flue, or that struggles to find
air to burn will go out sooner.

thanx for the advise, will let you know how i get on.
thanx again

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