Installing wood burner

[Jen729]

Hi

We're in the process of preparing our chimney to install a wood burning stove.

We've chipped the plaster back to try and find the lintel. We've discover a very thin metal bar on the opening and a brick arch around 4 1/2 ft up.

Do we need to remove the metal bar and do we need to instal a lintel if we already have a brick arch?

We would like the opening to be 4ft x 4ft.

Thanks
Jen

 

[Robbie uk]

Looking at the condition of the arch it would be better to have a new concrete lintel put in. The metal bar can come out at the same time.

 

[u587162]

Do you know what tolerance a metal RSJ beam can take when positioned some half a meter above a inset / cassette type fireplace? As it is not an open fireplace I'm assuming they reach about 200 degrees?

We have this issue at the moment and though we will probably use cement plaster board to clad it, I'm a little concerned about thermal expansion etc and what damage this might do to the wall.

 

[Saycheese5]

Under the stress of heat, metal will expand at a different rate and could create visible cracks in the masonery. Looking at the pic, the brick arch does not look very strong.

I've enlarged my fireplace opening using a concrete lintel, no metal beads for external corners, Natural Hydraulic lime render, lime putty plaster then clay paint. I'm about to install the woodburner but had to notify Building Control because I'm doing it myself (insurance, etc).

I would think a metal beam is likely to get very hot in the section directly within the chimney flue and transfer some of the heat around it and within the masonery.

Having said that a metal lintel has steel rods in it but that's not enought to create visible cracks.

 

[u587162]

We will line the grey thermalite blocks with plasterboard so that will cover any cracks but it's more the structural integrity I am worried about.

What temperature is needed to melt or do damage to a RSJ beam and if it expands can it sufficiently push bricks what with all the expansion and contraction?

 

[ree]

You will need to install a lintel - that arch wont fly.

Your opening must be according to the stove Mfr's required dimensions - until you have them its useless to open up the fireplace.

You could meanwhile have the flue swept and the stack and terminal examined?