Expand opening in chimney

[PawsOfEvil]

Im trying to install a new 'Hole in the wall' type fireplace into my old chimney. The new fire requires an opening in my chimney like this (Studio 1 dimensions in left column)

Untitled

• PawsOfEvil
• 25 Nov 2011
• 1

The current chimney is quite narrow 1025mm wide, the opening is currently 560mm wide by 590mm high. Having exposed the blockwork I expected to find a lintel but instead found this arch/throat piece that has bricks above it. The rest of the chimney appears to be made from concrete blocks.

Untitled

• PawsOfEvil
• 25 Nov 2011
• 1

The new fire will need to sit higher than the old one with the top of the frame ending up about 1 meter off the ground, this takes it to within the arch.

Here is a picture of the problems I have at the minuite.

Untitled

• PawsOfEvil
• 25 Nov 2011
• 1

The red box is a rough approximation of the size and location of the new fire. I will have to take out a large portion of the current blockwork to fit it in, to ensure the chimney is well supported I was thinking about building a new supports to take a new lintel. A bit like this

Untitled

• PawsOfEvil
• 25 Nov 2011
• 1

The whole chimney will then be framed to make it about 1400mm wide by 350mm deep on completion.

Do you think this will work? Would I need 2 lintels one at front one at back? Can I replace the arch higher up with a 100x65x1200mm concrete lintel using acro props? Do I still need a throat piece if I am fitting a gas fire?

Thanks guys.

 

[hotrod]

It's a nice fire the studio 1 (so is the studio 2). I very nearly fitted one at my own house but opted for a DRU instead.

Are you lining the flue? You need to leave working clearance to make the flue connection so this will be a consideration for your proposed lintel height.

You can't take that much masonry out of the breast without doing something to support it. In a bit of a rush but I'll have a ponder and pop back later.

 

[PawsOfEvil]

The flue is a proper class 1 and if you lie on the left hand side of the fire you can see all the way through. It has passed smoke test last few years so I'm not going to use a liner as it will save a few quid. The fire states it must be converted to rear vented by sealing off the flue liner connection on top if it is fitted into a brick chimney, I was going to go with that option.

I need to cut into the masonry by about 100 mm either side to a depth of 330 mm which is about half block width so yeah I reckon that extra support will definitely be required.

What is really bothering me though is the arch. Im not sure how to remove it as it is full depth and forms part of the flue so I think it will need to be replaced higher up.

 

[hotrod]

What is really bothering me though is the arch. Im not sure how to remove it as it is full depth and forms part of the flue so I think it will need to be replaced higher up.

Yes you would need to replace it higher up. You have said that the flue is a proper class 1 so I am assuming the concrete/clay liners are either seated directly off that throat lintel or off a gatherer unit.

Either way if you take that support out it will need putting back, or a suitable replacement, at the desired height.

 

[PawsOfEvil]

I have found a very helpful pdf from Wavin UK who make chimney components if anyone else is ever interested the link is

https://environment7.uwe.ac.uk/resources/constructionsample/Conweb/heating/hepworth chimneys.pdf

Taken from that pdf here is what I currently have fitted in my home.

Untitled

• PawsOfEvil
• 27 Nov 2011
• 1

I am curerntly considering buying a new corbel piece, fireplace lintel and flue adaptor. Using acro props ad strongboys supporting the blockwork above my current lintel and removing/replacing 2 brick courses higher with the new wider items.

Alternatively I was wondering if a simple gallows bracket and lintel would do? The fireplace is not on a shared wall but is a cavity wall.

 

[TheJay]

How did this turn out for you and what did you do?

Thanks for the image, I think this is the fireplace type that we have. Shame the link doesn't work any more.