Can I DIY cinderblock fireplace for wood burning insert

[avionator]

I scored a 1/2 price VC Montpellier II wood insert off FB Marketplace some time ago and it's rapidly approaching install time. I have another thread on here where I discussed the viability of installing it within our existing ZC fireplace (spoiler: it's not viable). So now I'm left with a few options: build a masonry fireplace, buy a precast kit (think Mason Lite) or ditch the project and buy a woodstove. For various reasons I don't think a woodstove is going to work in our specific situation (mostly my other half doesn't love them).

Some quick info: current ZC is about 20 years old but has almost never been used. Has Selkirk Metalbestos pipe that extends roughly 24 feet up a chase. All i really need is a way to mason a firebox to place the Montpellier II into and then connect to existing chimney pipe.

Given the high cost of a precast system and the very high cost of a mason building a fireplace I am considering taking on this job myself. I'm very "handy" and have done a lot of work around our house.

From what I can find code requires 10" thickness walls or 8" thickness if firebrick is used for a fireplace. Is there any reason I couldn't mason a simple cement-block box to put the Montpellier II into? It doesn't have to function like a proper fireplace as the insert would handle all of that. I would check with a local engineer (my neighbor is a structural engineer) about the framing below the fireplace (it's already doubled in some areas and span is pretty short).

 

[EbS-P]

The fireplace must be code compliant masonry from bottom to top of chimney. If question is how will you support all the weight?

To answer your question cinder block alone is not code compliant.

Edit.. I would put the VC back on the market. Look at the alcove free standing stove builds here if you want the most affordable and probably the least time solution

 

[gthomas785]

Let's ask @bholler

 

[EbS-P]

Some quick info: current ZC is about 20 years old but has almost never been used. Has Selkirk Metalbestos pipe that extends roughly 24 feet up a chase. All i really need is a way to mason a firebox to place the Montpellier II into and then connect to existing chimney pipe.

I read a little closer….
No you absolutely cannot do this!

Read the insert manual. It’s says it can only be installed in a code compliant full masonry fireplace.

 

[Ctwoodtick]

My non- professional thought would be to just get a free standing woodstove and install it to code. Inserts are for folks with existing masonry chimneys that are safe to use that they want better heat from. It reminds of an old Kohler commercial where some lady walks into an architect office and ask the person to build a house around a specific faucet she really likes.

You’d be spending a lot of time money and effort to accommodate the insert you scored.

 

[EatenByLimestone]

This is probably the perfect time of year to offload a VC insert.

 

[bholler]

I scored a 1/2 price VC Montpellier II wood insert off FB Marketplace some time ago and it's rapidly approaching install time. I have another thread on here where I discussed the viability of installing it within our existing ZC fireplace (spoiler: it's not viable). So now I'm left with a few options: build a masonry fireplace, buy a precast kit (think Mason Lite) or ditch the project and buy a woodstove. For various reasons I don't think a woodstove is going to work in our specific situation (mostly my other half doesn't love them).

Some quick info: current ZC is about 20 years old but has almost never been used. Has Selkirk Metalbestos pipe that extends roughly 24 feet up a chase. All i really need is a way to mason a firebox to place the Montpellier II into and then connect to existing chimney pipe.

Given the high cost of a precast system and the very high cost of a mason building a fireplace I am considering taking on this job myself. I'm very "handy" and have done a lot of work around our house.

From what I can find code requires 10" thickness walls or 8" thickness if firebrick is used for a fireplace. Is there any reason I couldn't mason a simple cement-block box to put the Montpellier II into? It doesn't have to function like a proper fireplace as the insert would handle all of that. I would check with a local engineer (my neighbor is a structural engineer) about the framing below the fireplace (it's already doubled in some areas and span is pretty short).

There can be no framing under it. You would need to start building it from the footer up then pour a hearth slab. Then your firebox. And no you can't use your existing chimney either.

 

[stoveliker]

It doesn't have to function like a proper fireplace as the insert would handle all of that.

This is where your thinking goes wrong.

An insert is only good *because* of what the fireplace around it handles and can handle.

That is why one has to have a working fireplace for an insert.

Zero clearance fireplaces might be a best solution for you if a stove is out of the question. They don't need a working fireplace.

 

[avionator]

Soooo..... anybody interested in a VC Montpelier II?

I really hoped the firebox could be masonry and connected to the existing selkirk chimney, but I will trust that there is some reason why that isn't sufficient. All your advice is appreciated.

Time to shop for a new ZC insert I guess.

 

[avionator]

Anybody know of any zc units that meet the 25c rebate requirements?

 

[bholler]

Soooo..... anybody interested in a VC Montpelier II?

I really hoped the firebox could be masonry and connected to the existing selkirk chimney, but I will trust that there is some reason why that isn't sufficient. All your advice is appreciated.

Time to shop for a new ZC insert I guess.

It's just the fact that the chimney is not listed for that use and therefore could never meet code. It may actually be safe but there is no way for us to know

 

[avionator]

That's what I figure. Honestly I don't see why I couldn't wrap the unit in ceramic fiber matte and that would be safe. Certainly not code, but that stuff stands up to forge temps..and talk about lightweight!

 

[avionator]

Any reason I couldn't get a larger zc fireplace to insert the montpelier into? Wouldn't have to be pretty as the faceplate would cover it, just big enough to fit. Any low-cost mfgrs out there?

 

[Rickb]

Most ZC fireplaces dont allow for modification. Which inserting a stove into would be.

 

[avionator]

Even if no sheet metal is removed? The VC specifies that it is allowed into a zc unit. I would have to very careful about finding a suitable ZC... am I wrong?

 

[bholler]

Any reason I couldn't get a larger zc fireplace to insert the montpelier into? Wouldn't have to be pretty as the faceplate would cover it, just big enough to fit. Any low-cost mfgrs out there?

Doesn't the manual for your insert say it can't be installed in factory built fireplaces?

 

[bholler]

Even if no sheet metal is removed? The VC specifies that it is allowed into a zc unit. I would have to very careful about finding a suitable ZC... am I wrong?

If the insert manufacturer fireplace manufacturer chimney manufacturer and liner manufacturer all say it's ok then it is. But you are looking at a new fireplace new chimney new finish on the face and then you will still have a drafty air cooled fireplace and chimney with a nice insert stuffed in it

 

[avionator]

Doesn't the manual for your insert say it can't be installed in factory built fireplaces?

page 17 of https://woodstoves.net/documents/Ve...pelier-II-Wood-Insert-Installation-Manual.pdf seems to indicate it should be ok and lists allowable modifications.

 

[avionator]

If the insert manufacturer fireplace manufacturer chimney manufacturer and liner manufacturer all say it's ok then it is. But you are looking at a new fireplace new chimney new finish on the face and then you will still have a drafty air cooled fireplace and chimney with a nice insert stuffed in it

yeah, this is all a pain in the butt. I really don't want to change out our existing chimney. Have double wall chimneys changed that much in the last 20 years that i should expect a new ZC would need a new chimney?

 

[bholler]

yeah, this is all a pain in the butt. I really don't want to change out our existing chimney. Have double wall chimneys changed that much in the last 20 years that i should expect a new ZC would need a new chimney?

The chimney would need to be one that is specified for the new fireplace

 

[bholler]

yeah, this is all a pain in the butt. I really don't want to change out our existing chimney. Have double wall chimneys changed that much in the last 20 years that i should expect a new ZC would need a new chimney?

Ok I was looking at an older vc manual so as long as the fireplace manufacturer is ok with this insert being installed in their fireplace you could install a new zc fireplace and install the insert in it.

 

[avionator]

bholler, you seem to be a knowledgeable sweep, I really appreciate your time helping me out with this. Happen to know of any budget-option ZC fireplace mfgrs?

 

[bholler]

bholler, you seem to be a knowledgeable sweep, I really appreciate your time helping me out with this. Happen to know of any budget-option ZC fireplace mfgrs?

Nope I won't install them sorry. And you need to find one's that allow vc inserts that probably isn't going to be the cheapest ones

 

[EbS-P]

bholler, you seem to be a knowledgeable sweep, I really appreciate your time helping me out with this. Happen to know of any budget-option ZC fireplace mfgrs?

The industry is moving in the direction of complete prohibition of inserts in ZCs. It has not happened but it’s being discussed. I highly doubt you would find any new ZC that in the manual allows for an insert. Any new ZC will require a new chimney.

What is your budget?