Right lime mix for internal rendering of open fireplace?

[mardinor]

We've just opened out a fireplace back to its original size and intend to use it as an open fire with fire basket etc. The walls forming the fireback are brick and we'd like to render them with lime rather than the concrete recommended by the fireplace supplier. We also need to level off a damaged hearth in the opening (the bit inside the opening, not jutting out into the room).

What lime mix would you recommend? Hydraulic or fat putty? Hairy?

Common sense tells me that was probably what was there originally so will work fine...but anyone have any cautionary tips or alternatives?

Finally, can I render straight onto the brick or should I give it a helping hand by raking the joints or (sacrilege) using expanded galv lath?

Thanks
Phil

 

[Nimster]

Just to jump on the band-wagon - we're doing something very similar. Is lime plaster the best thing to use? We're getting a plasterer in (my skills aren't up to it) and I want to know what to ask for.

Thanks
Nim

 

[Nemesis]

Personally I'd leave the brick exposed - far more durable for a fireplace than mortar in the long run.

Is there a fireback?

 

[Nimster]

Normally I would have left the brick exposed, but the room is so small and the ceilings so low that it's really dark with the exposed brick. It's also in dire need of repointing and isn't particularly pretty. If it was stone (same as the rest of the walls) I would leave it, but it looks to be a ?Victorian addition/rebuild and isn't fit to be left as is.

 

[Nemesis]

Hmmm. Well I would avoid the cement route, but if it's going to get very hot it may cause probs of course.

We have only plastered behind a solid fuel boiler which isn't giving out the heat a fire will. But we used plain ol' lime readymixed in tubs from Ryedale (go on - have a go...) and so far it's proving OK. But I would certainly recommend a fireback is installed.

http://www.bygones.net/thumbs.asp?strCategory=Firebacks

 

[Nimster]

Sorry, should have said, we're fitting a log burning stove so won't need a fire back. We'll put a back of some kind in the other fireplace as that is just having a fire basket. The chimney with the log burner will be lined (as it's currently filling the upstairs room with smoke) but the other will be left as it's fine.

 

[Nemesis]

Well lime should be OK - it is where out boiler is installed, and the lime mortar in the stone behind our stove is fine, but it MUST be left to cure without the stove being on or you may have probs!

 

[NT]

Most houses have lime plastered brivck chimney breasts so it should be fine, as long as it dries fully before use.

NT

 

[Nemesis]

There's less heat there though!

 

[NT]

ohh I am slow.

NT

 

[Craig]

Searching through the archive (3 months ago!) I found this pertinent thread.

We are about to put a hob grate (not a register) into an opening. The brick throat is a real mess, so there will be quite a bit of making good - bricks and lime to go in.

The original creation is a joy to behold, clearly minutes of effort by an untrained loon back in the 18C. Recreating something so "skilled" should be OK...

Can I just use normal bricks? Thats what the "original" ones look like?

Mardinor - did you use Lime render rather than the dreaded fire cement? How did it go?

Here is piccy: http://www.putfile.com/pic.php?img=4176126

 

[Moo]

How on earth does the horizontal brickwork in pic 8 stay up?

 

[Mark]

It looks slightly arched?

I wouldnt linger underneath it though.

 

[Gervase]

It's a nice bit of barrel vaulting - commonly found under hearth slabs and above cellars. Properly made it'll stand up to an enormous amount of weight on top.
It does depend on the integrity of the joist to keep it 'sprung' however - so I wouldn't fancy having to replace that particular piece of timber!

 

[Craig]

How weird - I just posted this but it appears mid thread and is listed as being posted in May???

___________________


Searching through the archive (3 months ago!) I found this pertinent thread.

We are about to put a hob grate (not a register) into an opening. The brick throat is a real mess, so there will be quite a bit of making good - bricks and lime to go in.

The original creation is a joy to behold, clearly minutes of effort by an untrained loon back in the 18C. Recreating something so "skilled" should be OK...

Can I just use normal bricks? Thats what the "original" ones look like?

Mardinor - did you use Lime render rather than the dreaded fire cement? How did it go?

Here is piccy: http://www.putfile.com/pic.php?img=4176126

 

[andrew gayton]

check that the smoking room is not caused by equal sized pots on the same stack - this can allow smoke to come down the flue..... cure this with pots of differing heights. mix vermiculite in with the render to provide some insulation ..... this will help protect the brick substrate. you will probably find that haired mortar will work best..... the reinforcement will help stop cracking.... as whatever you use may well crack........

 

[NT]

What ever's going on with pic 1, youve got a woman sitting in the fireplace and a dog in the plaster??

Any sideways movement on that joist in pic 8...


NT

 

[andrew gayton]

nice double v v on the joist. nice morini also.

 

[Gervase]

I'm sure I'm not alone in thinking "What in the blazes is a morini? Some fancy piece of joist-work or brick bonding?"
Doh!

 

[andrew gayton]

G - it is a motorcycle of italian origin (heathen..... : - )........) - A