OT FOAK: Cast Iron fireplaces

I'm reinstating a Victorian fireplace in my front room, one with the cast
iron insert rather than firebrick. The fireplace was opened up to the
builders hearth when I moved in so I've been busy bricking this up to follow
the contours of the insert and form a nice flue etc. What I'm stuck on is
whether I should leave the half inch(ish) gap around the insert and the
brickwork, or back fill it once it's fitted?

I've been looking about for info and found two general schools of thought,
typically contradicting each other. One says leave a gap, the other says
back fill it with a cement/vermiculite mix. Anybody had any personal
experience or have a knowledge of such things?

 

It was somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Grimley_Feindish"

uk.d-i-y x-posted

--

Dave

GS 850 x2 / SE 6a
SbS#6 DIAABTCOD#16 APOSTLE#6 FUB#3
FUB KotL OSOS#12? UKRMMA#19 COSOC#10

 

Grimley_Feindish wrote:

What I'm stuck on is

Back fill, no question. It stops accumulation of (inflammable) soot.

 

I work for a small firm of builders/developers in Surrey who specialize in
very careful & sympathetic restoration/renovation of period property & over
the years we have done a lot of these.

Because you will never get the "builder's hole" to the same size & contours
as the back of the cast iron insert there usually is a gap of an inch or so
between the brickwork and the iron insert. First fix the insert flush to the
wall (screws in rawplugs in the lugs on the insert, if if no lugs use large
washers or mirror clips) make sure it is centered on the chimneybreast,
plumb & level. Using a motar mix make good the wall flush to the insert
(which will be covered by the decorative firesurround). You don't want the
insert to move about under any circumstances. When this has gone off
backfill the gap between the brickwork and cast iron with small pieces of
brick rubble, etc.up to about 1inch from the top of the insert. Then level
off the top of the rubble with a mix of 4 parts soft sand to 1 part lime.
Seal off the back of the firebrick box as it goes up the chimney (about a
45 degree angle with a stonger mix( 2part cement to 1 part lime) as the
flames will be drawn a ways up the chimney.

A couple of tips:
1. If the hearth is going to be tiled or covered with slane. granite, etc -
do that before you fit the insert - you make a better job of it. as the
finished surface goes all the way to the insert without a gap & it saves
having to fill in the cracks with fire cement. Just remember to protect the
tiles or slate with a dust sheet or whatever when doing rest of the work.
2. Unless you have very draughty sash windows or base floorboards (with
gaps) you will legally need a ventilation grill in either an outside wall or
in the floor boards if there is a ventillated space between the floor &
ground (should be something like 100sq cm/15.25sq in.). This is true for
either an "open fire" or a gas fire. I'm assuming you have had a prof.
chimney sweep do a "smoke test" to make sure there are no blockages or leaks
in the flue. If using a gas fire make sure the chimney flue is lined with a
metal liner.

Enjoy,
Rick

 

Right, that's two to one for a backfill which is good enough for me .
Thanks.

 

Grimley_Feindish says...

Just lob it full of screwed up newspaper and polyfilla, it'll be OK.

 

Your not the bloke I bought this place of are you?

 

I've been looking about for info and found two general schools of thought,

yup vermiculite is the kit, sodding gurt bag, weighs fuk all
honest,
I was once mistaken for a builder
good luck
nick