I had a masonary chimney removed to just below the roof line. In the attic I have about 4' of brick that transitions to cinder block at the attic floor.

My idea was to try to remove the rest of the red brick and clay liner up to the cinder blocks and then seal somehow.

What would be the best way to seal the cinderblock opening?

Or if I am unable to get the rest of the red brick off and I still have about 3' stacked from attic floor... how would I seal at that point?

 

I'm not sure I totally understand the question Wouldn't plywood seal it up good enough?

 

That's one idea I had... if I can remove brick all the way to the blocks and the top is flush I was going to glue plywood to the top and just cover with insulation.

However, if Icant easily remove the bricks, I might end up with a jagged top.

 

It shouldn't be a big deal to remove brick and mortar with a hammer and chisel. The opening shouldn't need to be sealed air tight but if it does - stuff some insulation in it.

 

I removed it to floor.... flush with cinderblock.

I could do the following:

Plug the flue with some insulation as a backer and use it as a backer to cover top with concrete.

Cover it with plywood using construction adhesive.

Cover it with SHEET METAL using constructive adhesive or screws?

I mention sheet metal in case would is not acceptable from a fire block perspective?

Or something else? Would love your suggestions as I am taking a break from removing the bricks and will resume later this afternoon.

 

I assume the chimney is no longer being used so you are abandoning it in place and that you've removed the above the roof portion to avoid water problems?

Depending on where the chimney leads I do different things. If it went to a furnace or water heater that had a smaller side inlet to the flue I break up the bricks and toss the rubble down the flue. It soon plugs the hole at the bottom and builds up filling the chimney. It's an easy way to dispose of the debris and the rubble provides a good plug. It can be capped with a layer of mortar or fiberglass stuffed in to make it air tight. Still, I just take it down enough to be able to repair the roof. There is no reason to take it down to the floor level of the attic. Except that I see you are in California. If in earthquake country I'd take it down somewhat to minimize the chance of debris crashing through the ceiling.

 

Yes, It was leaking real bad and need of attention. I have condensing furnace and water heater now so it was more cost effective to just knock it down. SoI had a contractor remove the outside portion to just under the roof deck and then they repaired the deck and reshingled.

I was going to leave it at that until after they were done, I went into the attic and the chimney (which was built on a slant to begin with) was teetering back and forth with a little tug.

I carefully removed all the brick with just a little tap of a hammer and chisel. The clay liner I just shattered. It was a real mess!!! Not to mention 110 degrees in the attic. That I reluctantly had to work thru since leaving it there able to move it back and forth didn't sit well with me.

As for plugging it I wished I would have thought of just filling the thing with the rubble. Alas all the debris is sitting in the town dump now.

However, I just glued a piece of 16x16 sheet metal over the top and rolled out a batt of insulation over the top. I hope that is sufficient.

 

That should be fine. In a perfect world we schedule all our attic work for the winter time

 

As I mention, I glued a 16x16 piece of sheet metal to the top/opening of the cinderblock using PL8 Loctite. Checked this morning and there is no budging it.

Is it a bad thing that I permanently sealed it with glue like this?

Theres an empty 8x8 liner now spanning 2 floors of house, does that act like a vacuum or something now? Will it condense?