Uncapped thimble on gas flue

[vt-new-fp]

I have a flue with a terracotta lining that vents a propane heat stove on the first floor of the house. On the second floor of the house theres an old thimble to this flue that had a very old pie plate cover that was cracked. I took it off and would like to cover the hole with just wood paneling so it's flush with wall. Do I need to plug and seal the opening more or is the wood enough? Vermont. Thanks!
Pictures showing thimble on wall and close up (there was a lot of wood ash in it when I took the cover up and there had been wood stoves on the flue at some point but just the propane heater now)

 

[DAKSY]

Plug & seal it. CO is deadly.

 

[bholler]

I have a flue with a terracotta lining that vents a propane heat stove on the first floor of the house. On the second floor of the house theres an old thimble to this flue that had a very old pie plate cover that was cracked. I took it off and would like to cover the hole with just wood paneling so it's flush with wall. Do I need to plug and seal the opening more or is the wood enough? Vermont. Thanks!
Pictures showing thimble on wall and close up (there was a lot of wood ash in it when I took the cover up and there had been wood stoves on the flue at some point but just the propane heater now)

View attachment 327757

View attachment 327758

Yes it needs properly sealed with firebrick and refractory mortar