Block off plate vs insulation

[SterlingSL]

I would stick with the truth if it's you that's demanding it. Or seek to get a letter like Hogwildz mentioned.

But I didn't see any info really on your chimney? Is it possible to confirm its integrity and clearances or not?

No one I suspect is going to be very happy once you tell them you want work redone, espescially if insulation or clearances were never even discussed and when you brought it up already was just brushed off. It could really change the scope of the work.

Wouldn't the fact that the chimney goes through the center of my roof mean that clearances are not sufficient? Also, I have a wood fireplace mantel which is technically touching the brick on the front side of the chimney.

Seems like a company that installs this stuff should know better than this. It's a huge liability should someone's home burn down and insurance balked and a lawsuit is filed...


Really, the only reason I know about an insulated liner is because I chose to do a little research. It's not common knowledge for a new buyer like myself.

 

[SterlingSL]

So is insulation on the liner something they come pre-installed with or is this something that the installers will do on-site? I'm considering pulling the liner myself and wrapping if there are some instructions how to secure it properly and what type of insulation to use. That job is bound to be easier than the BOP which I still have to do (got bad sick this weekend and could barely move around).

 

[Coyoterun]

This is probably the type of insulation kit you want. http://chimneylinerdepot.com/product/chimney-liner-insulation-kit-6in-x-25ft-5in-thickness/

That link is for a 25' kit, you need to get one that matches your liner length.


Instructions: https://chimneysweeponline.com/ffwrap.htm

 

[kennyp2339]

Here I got this from Bhollar, it explains the clearance thing pretty well http://www.rumford.com/code/clearances.html

 

[armanidog]

There is a pour down chimney insulation mix. It is made to insulate already installed steel liners.
https://www.rockfordchimneysupply.com/chimney-insulation-mix-everguard.php

Everguard insulation mix is a ready mix, vermiculite based insulation material. Simply prepare by gradually adding 4-7 gallons of water. When the insulation is properly mixed, it will hold together when squeezed in your hand, and no water should come out. Pour the mix around the chimney liner, while shaking the liner slightly to let the mixture settle, then let it solidify.

This pour-down insulator is an alternative insulating method to using Super Wrap. Great for tight fitted lining jobs or insulating after a liner has been installed.It's easy to work with. It will fill dangerous voids and cracks in the masonry work while strengthening the chimney walls.

It cures into a lightweight, semi hard mass that supports a liner in the chimney and forms a thermal barrier that keeps the flue gases warm.

This product adds performance to your liner and is very durable. It is UL listed for zero clearance to combustibles. The mix eliminates moisture buildup between the liner and the chimney structure. It is accepted by building code officials, and what's better is that it can also be removed.

 

[Squisher]

While pour in insulation is a option, if it's being poured to insulate for clearance issues than the liner needs to be spaced (with spacers) so that the insulation gets around the whole liner to the proper thickness and that the liner is not touching the masonry clay liner at all. I'd avoid pour in insulation myself.

Yes just like the links show, you can pull the liner and a 1/2" insulation wrap can be put around the liner, secured and then dropped back down. You should match the insulation kit to the liner as in use the liner manufacturers recommended and listed insulation kit.

And the other link provided gives the relevant information on clearances for a masonry chimney. It's not impossible to build with proper clearances, but it's unlikely. And further it can be impossible without being highly invasive to confirm proper clearances.

 

[yooper08]

I have to agree with Squisher here, avoid the pour in and get the 1/2" wrap. To be technically correct, get the one listed in the liner mfg's manual or ask them about another one and keep the email/get it in writing (mine mentioned theirs or an approved wrap with certain specs, which typically is an 8# density ceramic wrap).

 

[Ashful]

So is insulation on the liner something they come pre-installed with or is this something that the installers will do on-site? .

Most come as a kit with a 20" wide foil-backed blanket, foil tape, and binding wire or a wire sock to hold it to the liner.

 

[SterlingSL]

Liner pulled and insulation installed. Thanks @Coyoterun for the links and info. That's where I got it from.

Phase 2 tomorrow: fabricate and install a BOP. Found some 14x10' roll flashing at home depot. Got a HYUGGE block of Roxul to go with it!

 

[black smoke signals]

Does the chicken wire cage surrounding the liner make this install snag proof from bricks or mortar joints?

 

[SterlingSL]

I would say it is definitely not snag proof. It took for-damned-ever just to get it over the insulation. My chimney is very cavernous though and I highly doubt I'll have any trouble getting it back down.

 

[Coyoterun]

In that picture it looks as if the "chicken wire" is pretty loose on there. I thought it's supposed to be pulled tight to snug it up a bit.

 

[black smoke signals]

Tearing the insulation on its way to the stove thus exposing the liner my only concern here.

 

[Xtrl9]

In my experience yes to both. The mesh covering does protect the liner overall and when its on there snug stops the insulation from detatching while you are feeding it down the chimney. I had a hell of a work out feeding 23' of it down 18' at a 45 for 5' and making the turn 45 back into the fireplace. It got seperated from the liner during this process and when i asked the inspector he told me that's his experience with the wrap insulation and why they make the nice preinsulated stuff. It also tears off the foil covering the insulation pretty well and is a real pain to get over the whole length of the liner.

 

[Hogwildz]

Roll metal ain't going to be thick or rigid enough. They do sell sheets of 26g sheetmetal in the duct dept at most box stores.

 

[SterlingSL]

In that picture it looks as if the "chicken wire" is pretty loose on there. I thought it's supposed to be pulled tight to snug it up a bit.

Tearing the insulation on its way to the stove thus exposing the liner my only concern here.

It is somewhat loose. I pulled it tight end-to-end to the point where I felt I may tear it if I pull it any more. The only way to snug it around the circumference of the liner would be to run the hose clamps every few inches and then I don't see the point of the mesh.

I put the liner back in the chimney this morning and it went down without a hitch. I have a large chimney though and the installer cut out a massive hole in the previous damper. It went around the bend with a little help from my daughter guiding it while I lowered it in. No sangging, no tearing. I went cray-cray with the spray on adhesive as well and double taped the seam. I was pretty happy with it. I'm glad I didn't read how difficult it might be getting it back in, I probably would have bailed. I don't want to buy another $300 insulation kit.

Roll metal ain't going to be thick or rigid enough. They do sell sheets of 26g sheetmetal in the duct dept at most box stores.

Thanks @Hogwildz - back to the hardware store. Our Lowes carries some 25g 'Steelworks 24-in x 3-ft Aluminum Sheet Metal'. Is Aluminum an issue? The only steel sheet I can find is 30g. Too thin? A question: why do I need thicker material? Isn't the point of the BOP to block air flow? I don't see it supporting anything other than the Roxul above it. Even thicker sheet metal won't block heat or does it?


Edit: I ended up finding some weldable steel sheet in 22g.

 

[Hogwildz]

It is somewhat loose. I pulled it tight end-to-end to the point where I felt I may tear it if I pull it any more. The only way to snug it around the circumference of the liner would be to run the hose clamps every few inches and then I don't see the point of the mesh.

I put the liner back in the chimney this morning and it went down without a hitch. I have a large chimney though and the installer cut out a massive hole in the previous damper. It went around the bend with a little help from my daughter guiding it while I lowered it in. No sangging, no tearing. I went cray-cray with the spray on adhesive as well and double taped the seam. I was pretty happy with it. I'm glad I didn't read how difficult it might be getting it back in, I probably would have bailed. I don't want to buy another $300 insulation kit.



Thanks @Hogwildz - back to the hardware store. Our Lowes carries some 25g 'Steelworks 24-in x 3-ft Aluminum Sheet Metal'. Is Aluminum an issue? The only steel sheet I can find is 30g. Too thin? A question: why do I need thicker material? Isn't the point of the BOP to block air flow? I don't see it supporting anything other than the Roxul above it. Even thicker sheet metal won't block heat or does it?


Edit: I ended up finding some weldable steel sheet in 22g.

Either will work. Lows & HD usually both carry sheets of 26 g galv in the duct dept, but either of those will work. If the 30 is stiff enough for the span, that would be fine also. For the gap around where the liner goes through the plate, you can stuff some door rope gasket in the gap.

 

[Hogwildz]

Here is a couple links:
26 g & 16 g
https://www.lowes.com/pd/The-Hillma...old-Rolled-Weldable-Steel-Sheet-Metal/3054561
https://www.lowes.com/pd/The-Hillman-Group-24-in-x-4-ft-Plated-Steel-Sheet-Metal/3054567

Oops, missed your edit. That will work. Bend slightly less than 90 degree 1" bends around the perimeter, which ads strength & give you a tab to secure with.

 

[SterlingSL]

Took all day with caveman tools to manufacture three plates. The longest process was creating cardboard templates and transferring the cuts and the bends into the metal. That stuff doesn't bend easy. Pictures later as I haven't bolted them up yet.

I don't think my 3/4" self-tapping screws are going to be long enough. Not sure they're beefy enough either to go through the heatform metal, it's pretty thick. Not sure what gauge of steel the heatform is but my screws are rated up to 12g. I don't want to secure my BOP yet as I don't know how much movement they'll need when installing the insert. So I'm hoping I can secure it when they are here without much trouble. Might have a carbide tipped bit on standby I suppose

I have this monster sized bag of Roxul. How much of that should I shove up in the existing damper/smoke shelf area? If you suggest the whole bag I suppose I could find a way to lower some down from the top when the installer gets back here to finish with the insert.

Also going to use the rope gasket as I have about a very rough 1/2" gap between the plate and liner.

 

[yooper08]

Definitely don't need the whole bag, 1 layer is fine. If you can stack a couple pieces together, perhaps better, but the plate has to be able to support that weight regardless of how much you put in there.

 

[Hogwildz]

That.s the reason to put the bends on the perimeter, it helps wedge the plate in place. Then a few screws in each run will be plenty. Its been a while, but I'm thinking the heatform is about a 10g or so. I used self tappers from HD, and while they do work, count on a few to shear off before they fully seat. No bigger, move over a couple inches and try again. You can seal the perimeter tabs & any other ooops holes with silicone. DO NOT silicone the gap around the liner.

 

[Xtrl9]

If you get some self tapping screws like these https://m.lowes.com/pd/The-Hillman-...-Interior-Exterior-Sheet-Metal-Screws/3811413

Just a reference for the tip shape and ss would probably be my choice for material. You could do it with a #8 but i would probably try for a #10 or #12

You can predrill the metal and then the screw is going to have a much easier time tapping itself. The drill screw/self reaming tapping screw/teks drill a rough hole which then gets formed around the threads and it works fine if you're just attatching sheet to sheet*; once your base material thickness and hardness approach 3/16 ~7 gauge i find teks to be a bad choice of fastner. Ymmv

* if you really want the material to hold better the threads of your screw should only engage the base material. If you had predrilled clearance holes in your block off plate then you would have a good template for where to either mark or drill into your base material. Final rambling i swear, if you arent marking all places to drill into your base then work one on each side so you dont end up tilting it much.

 

[Hogwildz]

If you get some self tapping screws like these https://m.lowes.com/pd/The-Hillman-...-Interior-Exterior-Sheet-Metal-Screws/3811413

Just a reference for the tip shape and ss would probably be my choice for material. You could do it with a #8 but i would probably try for a #10 or #12

You can predrill the metal and then the screw is going to have a much easier time tapping itself. The drill screw/self reaming tapping screw/teks drill a rough hole which then gets formed around the threads and it works fine if you're just attatching sheet to sheet*; once your base material thickness and hardness approach 3/16 ~7 gauge i find teks to be a bad choice of fastner. Ymmv

* if you really want the material to hold better the threads of your screw should only engage the base material. If you had predrilled clearance holes in your block off plate then you would have a good template for where to either mark or drill into your base material. Final rambling i swear, if you arent marking all places to drill into your base then work one on each side so you dont end up tilting it much.

Just be careful, s.s. screws shear & strip more easily.

 

[Ashful]

Just be careful, s.s. screws shear & strip more easily.

Exactly. Even 18-8 is soft. If 316, just forget it.

No need for stainless here. Black oxide won't take much abuse, and you'll shear off a lot less of 'em in the process.

 

[Xtrl9]

Just be careful, s.s. screws shear & strip more easily.

Exactly. Even 18-8 is soft. If 316, just forget it.

No need for stainless here. Black oxide won't take much abuse, and you'll shear off a lot less of 'em in the process.

If the hole is predrilled to a reasonable size i doubt there would be any shearing. I would take a ta in stainless over a low carbon plain finish teks. The grey galvanized teks would work fine.

I have never seen black oxide teks and most big box hardware stores don't carry them in a ta that I've seen.

I'm not arguing ss is weaker than alloy or zinc finished steel but ive had teks drill too large a hole for the threads and not be able to cut threads enough times that I was suggesting he not use them in plain finish if his base is 10 gauge.