Enclosing a Class A chimney and some additional stuff

[Badfish740]

Here's a picture of the side of my house (I've since removed one three foot section of Class A because it was really not necessary and gave the appearance of a rocket ready for launch ) which, in the words of my wife, looks kind of "industrial."

Starting from the left we have the telephone box, electric meter, wood furnace chimney, AC unit, radon vent, and oil furnace chimney. The utilities I really can't do anything about. I had considered putting a fence up to hide the electric meter, etc...but the power company won't have it. I am going to create a little "lean-to" in order to hide the AC unit that will blend in with the house more but will still provide adequate airflow-it should also help performance since the unit sees a lot of direct sun during the day. What I'd like to eventually do is enclose both chimneys in separate chases in such a way that they will be equally spaced/sized and of equal height. The chases would then be faced with a cultured stone product to create the illusion of two old stone chimneys. This will all be done when we re-side the house with Hardi-plank since we're going for a less contemporary and more Colonial look overall.

I'm not really sure where to start. Obviously both chases will need some sort of footing since between the framing, sheathing, and cultured stone/mortar there will be a considerable amount of weight to support. I'm assuming that these would need to be set below the frost line (about 46" here)? After that I would bring the walls up to the level of the foundation walls with concrete block and then transition to steel studs so as to give a little wiggle room with clearance to combustibles. Would exterior OSB be fine for sheathing? Basically I have an idea of how to go about all of this in terms of clearances, bracing, an access door at the bottom for the cleanout, etc...but the big mystery to me is how to cap it all off. I would like to finish the chase in such a way that a minimum of the Class A sticks out of the top, but I'll retain the current cap. Basically I'd like to be able to go up on the roof and clean by simply popping cleanout plug at the bottom and the cap at the top and brushing from the top down as I usually do. I suppose I could find a large piece of slate (I think they even make cultured "slate" like materials now) with a hole cut into it for the Class A to peek out? The oil burner chimney would be constructed the same way but obviously clearance to combustibles will only be a concern at the top. The radon vent should be simple enough to extend as it's all PVC pipe. I'll have a add a large enough access door aligned with the actual fan in the radon vent should it ever need to be changed. I'd be interested to hear some comments on this and also to see pictures of chases that other folks have constructed for ideas-thanks!

 

[Gooserider]

I think the slate will be overkill for the top - after all I doubt if many folks will be going up there to look at it from above... I'd probably just go with a sheetmetal cover instead. The rest of the ideas sound pretty reasonable to me, though I've heard some suggest that it can be a good idea to also insulate the inside of the chase.


Gooserider

 

[andybaker]

My chaise is sided with vinyl the same as my house, very easy. The top I had the pan made out of stainless steel so there will be no rust issues. The class A pipe just sticks out enough to cap it off. You don't see the pipe at all. Good luck with the stone look, sounds like a lot of work but should look nice when your done.

 

[DAKSY]

If you're going to finish the chases with cultured stone, you'll probably want to us Hardi-Backer
or Dura-Rock for your sheathing material. It's designed to support that type of finish.
Steel studs may allow you a little less clearance, but even with framing lumber
the required 2" clearance is pretty close.

 

[Badfish740]

If you're going to finish the chases with cultured stone, you'll probably want to us Hardi-Backer
or Dura-Rock for your sheathing material. It's designed to support that type of finish.
Steel studs may allow you a little less clearance, but even with framing lumber
the required 2" clearance is pretty close.

I was wondering if Durock was the better choice-is that what is usually used in new construction when a faux stone finish is applied to exterior wall of a house? It would also give more piece of mind if all materials used in the chase were non-combustible. Overkill probably, but it certainly can't hurt.

I think the slate will be overkill for the top - after all I doubt if many folks will be going up there to look at it from above... I'd probably just go with a sheetmetal cover instead. The rest of the ideas sound pretty reasonable to me, though I've heard some suggest that it can be a good idea to also insulate the inside of the chase.

Good to hear from ya Goose. Good point-for some reason it never occurred to me to use sheetmetal. I thought about insulating the chase but in all kinds of outside weather and temperature I've never once had a draft problem because the chimney is pretty tall. Even when the chimney is completely cold if I light a piece of newspaper and hold it near the outlet it will shoot right up the flue, so I don't think it's really necessary.

 

[Gooserider]

Insulating the chase is not only supposed to improve draft, but also cut down on any deposit buildups (which might not be a problem anyway) and do that much more to keep the heat you make inside the house instead of warming the outside world... In general, the advice that I see for all modern home construction seems to be to push the "thermal envelope" out to match the building envelope as much as possible.

Gooserider