COMMENTS PLEASE, before I smash things up!

[sleepybubble]

Gus,

When you have reduced the hearth to nothingness ;-) and your back to the building it back up stage, and presuming your going to be using some floor tiles to make it back up again. You might want to invest in a bag of Self levelling compound, and some timber to make shuttering. Also when you tile the hearth use flexible floor tile adhesive.
Dont go putting celotex in anywhere, you need to take the weight of the stove. Have you tried to dry fit the stove to the opening yet?

Your doing well as the hard part is cracked all the mess and dust should be finished with soon.

[SteveH]

 You can make insulating concrete with "Mica fill"... Expanded Mica flakes... Will be fine with the heat, but I'm not sure on the loading... 

[KenB]

Gus,

Before you start, look at the building regs part J, I think.

This gives the minimum dimensions of the hearth projected forward from the existing chimney breast brickwork.  I think the measurement is 500mm - so you will have to do this if you want to meet building regs.

I laid 600mm x 600mm slabs outwards from the original chimney line. 

Don't make the hole for the stove too small or it will be a pain to sweep the flue or clean.  There are minimum clearance measurements between the stove and any brickwork.  Give yourself plenty room - working in tight spaces is a PITA.

If you follow part J, you will will at least have a "legal" installation and your house and contents insurance won't be null and void   



Ken

[MR GUS]

 All read & partially absorbed, will re-read & act upon..

 As per Austroflamm G3 paperwork, with my stainless steel clad sides minimum spacing from...

 NON FLAMMABLE OBJECTS

 300 mm from rear

 200 mm from sides

 400 mm from front

Though here is where it confuses me slightly, ..safety requirements to flammable objects & to supporting walls of reinforced concrete construction with convection shell are..

300 mm from rear (same)

200 mm from sides (same)

800 mm from front  (doubled)

I AM probably being a moron, but regardless could someone please explain (I'm a tad mystified as to legal, v, recommended, v the doubling up of the front size , but not only that but the fact that concrete / walls flammability et al is pretty blooming low!

Also adding into the mix is the question of the hearth material (will have to ring stovax / Austroflamm as to whether the hearth reaches 100 degrees c from heat of this burner or not in which case materials & depth of projected hearth can be re-thought.

The thought of sticking some 70 mm xtratherm foam down was based on what they do for new builds prior to pouring concrete ..so in theory it is surely wight bearing & some,..though would need a good deep dig!?

Additional info, it's a 1970's house so old style poured concrete foundations, & floors which by my understanding would negate the need for a built up hearth (like it is now) still complying with part J of the regs ..as I (a numb-nuts) understand & reassurance sought via 
www.stovesonline.co.uk/stove_building_regulations.html

 which is nice plain speak, though feel free to shoot me down in flames, lest I burn via my own ill fitted flames!
I would like to make it lower than the 4.5 inches  height it is now preferably using a complimenting natural stone which may then be used on the wall (totally) so large tiles or a slab of stone
..good stone cutters in peterborough incidentally

[MR GUS]

the other interpretational juxtaposition is with regards to burners that aren't designed to run with the door open, reducing the 1 foot " fuel fall-out" scenario, though I imagine that (like a lot of things) would be on the whim of any council official as to gospel or not!
dodgey territory

[ajstoneservices]

Gus

Not too far from the pond. SDHW and Pool.

Tony

[sleepybubble]

re: minimum vs. reccomended.... and flamibility of concrete...

With regards, the hearth and based upon a solid concrete floor and the whole 100 deg C thing....Does the stove have a manual (read it! ;-0 )... and does the stove have a heat shield plate on the bottom of it. This will be a thin sheet of metal that is not part of the body of the stove. Usually making it bloody impossible to sack truck the damn things around without damaging it. If it has then its there for a reason and you've probably answered your own question and are good to go at 12.5mm, which funnily enough is the standard thickness of PEI5 floor tiles. i.e. frost resistant. (also read thermal shock resistant)

With regards natural stone for a hearth, you need to be careful of what stone, its not for no reason that hearths and fire sorrounds are made usually out of marble and granite and not standard porous limestone or sandstone ...
Plus some stones actually stain quite badly, you can get sealers for stone HG do a good range, but then again your introducing chemicals to a heat source which is not funny. Unless your into that sort of thing, in which case just go straight for the solvents

Convection shell - what you would like to create by insetting the stove. The air inside the inset is going to be hotter than the air in the room. Considerably. That air is going to come out like an upside down waterfall running up the wall the stove is set on. This is the purpose of a mantel to break up this air hot air flow and stop it scorching the portait of the queen hanging above every victorian fireplace.
Cast concrete doesn't burn but it does crack under thermal stress, there is a lot of water involved in the concrete manking process. I guess building control need to cover their arses.  Bricks are fired in ovens which removes the water content and should be less susceptable to thermal stress.

I almost sound like I know what I'm talking about, phew!

Do you intend to get the installation inspected when you have finished? Because if you do then you might want to get the inspectors involved now... It is a notifiable modification after all.  If on the other hand your not so fussy about getting the buildings fuzz inside your house then proceed with common sense... I don't expect you to answer that question!

[MR GUS]

GOOD CALL!
Rang stovax just after 9 am monday, waiting for a callback from alex in customer service.
Mentioned that information was scant on the tested burners on the government backed site (the breakdown of the tested to ES (or whatever) are simply not clear to the layman.

 though I can confirm the G3 IS a complete devil to move via a sack barrow, having had to tie it down &  lift it over the threshold, definitely a two man job to move it into the next room as & when!
 Instruction manual I had to download, but doesn't have the required info, nor does it mention overall efficiency or any of that guff!

from how things are progressing the overall size of the fireplace hole is going to have to be increased (width) in order to gain the distances required (as per your enlightening explanation) though now the lintel height is the can we-can't we issue?  ...basically I reckon having done a few measurements the burner standing 300 from the back of the fireplace back wall will only in theory be 1.5 inches within the recess.
with that in mind  is it a safe bet that the flue can now pop out of the back without too much worry & "ba-da-bing"
Stovax called back hearth temp is only 80 degrees c ..which is nice! so possibilities afoot!
..If I take the height of the floor up again  then estimate there'll only be a matter of 2-3cm from the top of the stove to the lintel bottom, do you see any probs there?

 other possible double negative being again the lintel, it's obvious we need to widen the width of the cavity, however based on previous pictures how far can I remove without the lintels integrity being disrupted? (typically)
lintel measurments..
front facing to inside fire 9.5cm
length (left to right) 108 cm
height 7.5 cm

 Do you reckon I ought to get a quote from "the super smash brothers" / local builders at this point or carry on a little.
 I'm keen to fire up my Stihl TS400 disc cutter ,..but also keen to do it right as thats some weight in the fireplace!

[dhaslam]

That distance of 300mm being the same from combustible and non combustible surfaces doesn't make much sense.   The stove (Mulberry)  I have just bought says 50mm for the latter. 

[MR GUS]

..yes does seem a bit odd! but thats the way it always seems to go unless you really are au fait with product / material.

 My biggest worry now is what hearth material (the wife took 2 years to finally decide on the exact tiles I'd originally mentioned for the bathroom)  ..will have to get her out to the stone place fast!
Incidentally, here at bodge central (due to previous owners,..man of the cloth too) whilst excavating the hearth came across WOOD, charred & in amongst the cement amongst the hearth (will try & get a pic) ..anyone know why that would be, sort of flies in the face of non combustables in the area

[MR GUS]

Based on the 80c hearth temps typically attained does this mean i'll still have to go for a split 3 piece hearth of stone or will it now weather thestorm as a singular piece?
lots of cutters out there seem to do this for expansion joint purposes but is 80c going to require it?

[MR GUS]

the initial bend into the chimney seems to be cement / terracotta piping (need to scrape it & see what happens) definitely not angular like a regular schematic of fireplace construction

..should I start worrying now!?

[MR GUS]

Had a builder in this morning as I want to get an end to this & a fire lit! (& no nagging wife)

 He implied that the bend could go (ie lintel where you like, as high as I like) ,,and has gone off to do a quote.

 Why when I look at my old houses (victorian for example) are these straight up no elbow necessarily? ..will a rain cowl on top do the trick.

 the original fire was an open lobby (just to refresh memories)

[Richard Owen]

..will a rain cowl on top do the trick.

 

Are you putting in a flue liner? If so, you can proper terminators for the liner that sit on top of the pot and keep rain etc. out.

[MR GUS]

Financial constraints this year, will look at it as & when we get hold of some good stuff cheap(er) & retro-fit it.
In the meantime it's a clock ticking thing (wife & heat requirements) ..complete with the need to get the living room complete & start on the home office proper!

We have LOTS of wind here so I'm looking to A, not Heinz the metal via lots of rain.

 B, draw versus wind around the house, so need to look at fitting something to achieve both.