# Permanently covering/plugging flue hole in plaster wall



## Soapyballs (Sep 11, 2018)

We're looking to add cabinets to our kitchen wall. I removed the wall paper and discovered a flue cover with stove pipe going into a chimney. The walls are plaster. I would like to cover this hole permanently. How do I go about doing this properly and not causing fire hazards. I believe the chimney is still in use, an oil boiler is connected to it. We have steam radiators in the house.


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## Soapyballs (Sep 11, 2018)

Images wouldn't attach to first post, this is what it looks like.


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## ConstructionK88 (Sep 15, 2018)

Sheet metal and mesh sheet rock patch large enough to go at least a couple inches past on all sides. They are generally used to repair where door knobs bust holes into drywall but it's metal and sheet rock drywall compound is also nonflamable. Wouldn't hurt to stuff a little firewool inside either. It's used to line wood heaters and such.


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## Nealtw (Jun 22, 2017)

What is the chimney used for now?


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## ClarenceBauer (Mar 4, 2005)

You stated that the chimney is still in use.
The correct way to fix this would be to hire a mason to cut the plaster back around the existing area & remove the metal insert than install fire brick & fire clay at the inter most side of the area than install brick in the remaining space to within 3/4 inches of the existing plaster finish. Than repair the plaster as required to blend in to the existing.
There are many ways to just plug the hole some as stated above but you requested info to permanently close it off so use the same materials that have stood all these years also you will not have to worry about moisture affecting the repair from the back side if it is not sealed correctly the first time.


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## Bud9051 (Nov 11, 2015)

Just to emphasize, do not just patch over this. I have located several old chimney holes while doing an infrared inspection and that is with just normal chimney heat from their furnace/boiler. If the chimney were to ever experience a chimney fire those patches could result is a house fire.

Do as Clarence suggested and have the chimney repaired and then patch the hole as needed, following current fire regulations. No short cut here. Should the house experience a related fire the responsibility is now on you, you opened it up so must close it per codes.

Sorry, but I like you and don't want your house to burn down.

Bud


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## de-nagorg (Feb 23, 2014)

I agree with #5 & #6.

Do it right and never have to think about it again. 

Yes more work and $$ spent, but what is the cost of peace of mind and security. 

And welcome to the group, hope to see you again. 


ED


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## Leslie1941 (Mar 25, 2018)

Soapyballs said:


> We're looking to add cabinets to our kitchen wall. I removed the wall paper and discovered a flue cover with stove pipe going into a chimney. The walls are plaster. I would like to cover this hole permanently. How do I go about doing this properly and not causing fire hazards. I believe the chimney is still in use, an oil boiler is connected to it. We have steam radiators in the house.



What I would do is get some ROCKWOOL, and lightly pack it into the hole for about 2/3 in. For the remaining third I would fill it and I would use a plaster mix or joint compound.
Rockwool supports high temperatures. 



For lightly pack, it should allow a nail to punch through the rockwool, but not a finger. Use common sense. Roofers have a compound that can support flu temperatures. If you can, put that in just before the rockwool.


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## ClarenceBauer (Mar 4, 2005)

Leslie1941 said:


> What I would do is get some ROCKWOOL, and lightly pack it into the hole for about 2/3 in. For the remaining third I would fill it and I would use a plaster mix or joint compound.
> Rockwool supports high temperatures.
> 
> 
> ...


The problem with using the Rockwool is moisture can & will enter from the back side ( flue side ) and cause the Plaster to Fail the hole should be filled with a solid material.


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## fret62 (Jun 8, 2017)

If you want to eliminate the fire hazard you could use a flue plug or some kind of fire blocking material to plug off the hole. Get the flue size then check with your local hardware store. They might have a flue plug. I know they make fire block foam spray but see what might work better that you could just stuff into that section thats not in use. 

As long as the hole is completely plugged off it shouldn't be a fire hazard because you have cut off the air source plus it wont be leaking harmful exhuast fumes into the house.


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