Can I replace masonry chimney at roofline?

gliptitude

The chimney that my boiler vents into is deteriorating and I am debating what to do.

There appears to be a few different factors working together to destroy this chimney, from the inside and from the outside. It is brick and it is integrated with the brick wall of the house. I presume it has a ceramic liner. There are at least two chambers and I don't think either is straight. There is also a small window in the middle of the chimney.

If money were no object and if I were confident this would be my own house forever, I would certainly abandon this chimney, demolish it at the roof line and replace the boiler with a new high efficiency one. Having that chimney gone would also make it much easier to build the roof out on that back side of the house the way I think it should be, (with an overhang like is on the front of the house).

My status being what it is though, I am considering fixing this chimney and trying to figure out what's practical. If this chimney is going to be used again next winter it will need one of those metal liners installed. I'm trying to figure out if that's doable, if it's something I can do or someone else can do and if it'd be worth it.

** I'm also trying to figure out if it is possible to transition from masonry to B-vent or something metal and engineered for the purpose. **

I think it would be a lot easier and cleaner job if I could demo the chimney down to the roofline. I'd be eliminating variables and going for a streamlined design, with fewer drainage/flashing/mortar/maintenance issues and also much easier access for installing the liner. And I'd be able to build the roof out more sensibly.

I'm not sure if it's to code, if a liner might make it to code, and how the transition should work. I don't plan on being inspected but I like to prepare for it and obviously I like it to be functional and safe, if not proper.

Can it be done?

Jamie Hall

Without seeing photographs of the chimney, and at least an elevation of its path up from the foundation, almost any suggestion I might have as to repair would count as a WAG (Wild A$$ Guess).

That said.

First, the chimney -- as it stands -- is an architectural feature of the structure. Is the structure historically significant? If so, removing the chimney would harm that and, quite possibly, reduce the value of the property.

Second, if the flues are not straight, slipping a metal liner in might be rather difficult, to put it mildly.

Your best bet would be to locate a really reputable chimney and masonry expert in your area -- they do exist (I might add that there are a greater number of disreputable ones, so be vigilant and do your research -- and NOT on Yelp or Angie's List or some other crowd sourced site). They will be able to evaluate the condition of the chimney, inside and out, and recommend the best procedure for repair and relining, if that is possible.

Your desire to make it functional and safe -- and to code -- is well thought out. You may or may not be inspected at the time of construction -- but you will be, if you ever try to sell the house, and if there is other damage related to the chimney or boiler venting at a later date, you can be sure the insurance people will be very interested in what was done, and how.

gliptitude

Thanks for the reply.

I know that the house is not a registered historic building and I know that it is not located within an historic district. The house already has another chimney that is abandoned and demolished to the roofline and roofed over. .. Selling this house soon is something I've looked into and would be a "rehab opportunity" "as-is" type sale and I know that almost any contractor around here would abandon this chimney and the whole hydronic system in favor of high efficiency forced air. But as the owner-occupant I am personally invested in the radiators and really couldn't even think of this place as my own without them. .. So this chimney failure is kind of a crossroads in the project and my ownership.

I was in a similar but less urgent situation years ago with my previous building and at that time actually did discuss it with the building inspector, although the work was never done and I never got confirmation that transitioning from masonry to metal was practical. As I remember he said that a consistent run of double-walled metal pipe, like B-vent, (all the way from the appliance in the basement, up through the roof and at or beyond a certain height beyond the highest peak of the roof structure), would be the most explicit and direct way to comply with building code. He indicated that this material cannot go through the existing chimney and would have to be conceled otherwise from the living space and framed to some specifications to avoid direct contact with wood or combustibles. .. He SEEMED to indicate that the existing chimney could be retained instead and transition to a metal pipe at the top, but that that would require some difficult internal modification to the entire length of the chimney, but he wasn't really clear on what that was, if it would be an engineered system of some kind or a specified material.

.. The second and third photos here are meant to show the difference in roof overhang in the back versus the front, which might help explain why I really want to remove the top of this chimney and improve the overall drainage of my roof and gutters. The fourth picture shows deteriorating plaster damage on the chimney inside the house, in a room that I have unfortunately quarantined and ventilated for this reason.

Jamie Hall

Well, of course you ca take the chimney down to the roof line. You have, however, a good deal more trouble than that: you have a lot of moisture seeping through the walls. I notice some attempts at patching -- perhaps with mortar? -- in other places on that end wall and around the corner, and a lot of deterioration of the brick.

I doubt that you will have much luck getting a liner into the chimney; there is at least one significant offset directly over that window.

What has happened is that for one reason or another -- and what is past is past -- the hard waterproof outer surface of the bricks has been damaged or lost.

What needs to happen -- regardless of what you do with the chimney -- is that any paint or other finish on the brick needs to be removed, as well as the patching material -- but do not, under any condition, use sandblasting or harsh abrasives or brushes. You will ruin what little waterproof outer layer is still on the brick (probably not much, but why push it?. Then you need to apply a known, penetrating waterproofing sealer to the entire wall surface -- top to bottom.

You will also need to be able to keep the interior of the house warm and keep the humidity at reasonable levels; ideally you would place a vapour barrier on the inside, but that's a big job.

lchmb

that is a really cool chimney..just sayin

Bob Harper

That chimney is a mess. Lots of code violations. You need to get a chimney pro in there to perform a level II inspection to determine if the chimney is salvageable. It will need a listed ss chimney liner at min. If you really want to chop off the top at the ridge you can do that then cover it with a stainless steel 'chase cover'. These can be powder coated as can a Class A listed chimney or type L vent and attending fittings and cap. I just did this at my house and I'm a chimney pro. Several liner mfrs. make a listed transition plate from liner to factory chimney. The chimney regardless needs to stick up 3 feet above the roof/ 2 ft. above any part within 10 feet horizontally. I"ll try to post some pics this weekend.
Please provide make, model, fuel, input BTU/hr. and appliance collar diameter, lateral offset from breaching and vent rise from top of appliance collar to breaching in wall (where the pipe goes in).

Fred

It's very difficult to tell what parts of that house are original and how many modifications have been made over the years. The soffit on the second story looks to me like an early modification that wasn't properly tied into the roof and may be allowing run-off to pool and run down the brick. That is a soft brick and it will absorb water and, in the winter moisture will freeze and burst the facing off of the brick. The fact that the window caps are partially covered with that soffit is a tell tale sign that something was modified there.
The facia boards on the rear, leading up to the chimney aren't correct either. I see there originally were two doors on the side that were taken out and replaced with windows and the lower portion bricked in. The brick infill was nicely done and it is an early modification but they left the limestone door sills and steps there.

That full size window over that fireplace is also suspect. I'm wondering if someone didn't cut into that wall/chimney to put that window in there. The wood trim cap on that window is also different from the others and the brick arched header is not flush with the brick wall, like the other windows.

I really think the modifications to that house created the problems you are having and I'm not sure how far you'd have to take it back to correct that problem.

gliptitude

Bob Harper said:

It will need a listed ss chimney liner at min. If you really want to chop off the top at the ridge you can do that then cover it with a stainless steel 'chase cover'. These can be powder coated as can a Class A listed chimney or type L vent and attending fittings and cap. I just did this at my house and I'm a chimney pro. Several liner mfrs. make a listed transition plate from liner to factory chimney. The chimney regardless needs to stick up 3 feet above the roof/ 2 ft. above any part within 10 feet horizontally. I"ll try to post some pics this weekend.

Thank you very much. This is the information I need to start planning.

If these engineered transitions exist and are code I fail to see why I should preserve the chimney above the roofline, where it will be a perpetual maintenance issue and immediately needs major work. The drama of demolishing a masonry chimney is minimal in my case because I have done it before, several times actually, and have a developed strategy, including safety precautions and because the circumstances of my ownership here leave me quite a bit of freedom. The advantages of having it out of the way are numerous, not the least of which is having easier access to the interior of the chimney to run the liner.

I was considering doubling duty on a sewer snake camera rental that I wanted for my main drain line, thinking that might go more easily through my chimney than a chimney sweep and obviously more easily than a chimney liner. .. Is that something that is done to survey the inside of a chimney?

Bob Harper said:

Please provide make, model, fuel, input BTU/hr. and appliance collar diameter, lateral offset from breaching and vent rise from top of appliance collar to breaching in wall (where the pipe goes in).

The appliance is a Dunkirk boiler, natural gas, 105,000 BTU/hr input, according to the label. I'm not sure I've got the other stuff right, perhaps these pictures help. The vent pipe coming out the top is 6" in diameter. When it enters the chimney it is slightly bigger, if that's possible. Horizontal distance from the face of the chimney to the center of the vent pipe at appliance is 4'4". Vertical difference between top of boiler to center of the hole in the chimney is 29".

I measured the chimney itself to be 33'8" from base of the stone foundation in the basement to the top of the masonry.

Fred said:

I really think the modifications to that house created the problems you are having

I agree and appreciate your narrative, but I don't think I can reasonably go back to how it originally was.

There are other similar ridiculous things about this house that cause me to speculate on the history and sequence of modifications. As a general rule and method, my strategy is to simplify and eliminate variables, and prioritize what I see as the engineering issues. I'm at liberty to do that because it is not a historic building and my ownership is pretty clean and un-encumbered, (no mortgage, no spouse, no building inspector, no official record of code violations).

The box gutters are a long term headache. I'm not averse to eliminating the historic features of them but I think there still needs to be an overhang (and an additional overhang on the back side of the house) and I'm not sure how to redesign it.

Fred

@gliptitude , if those box gutters are relatively solid (or any rot/damage is isolated enough to be repaired, you can get a rubber membrane to line the interior of them. I'm just not sure they are a part of the original design of the house. They are out of scale and not integrated into the roof edge like one would typically expect.

Also consider having that step flashing that goes up the roof line on the one story section of the house and lays against that back wall replaced. It was installed incorrectly and is a part of your water infiltration/ brick face problem. That step flashing should be installed so that each step (on the roof) lays directly under each shingle so as to prevent water from running under it. As it is installed (at least from what I can see in the pictures), it looks like the roof side of the flashing either lays on top of the shingle or maybe even an inch above the shingle, allowing run-off to flow under it and against the wall and probably down the inside of the one story section.

There are many, many mysteries with the construction and changes that have occurred on that house. From the look of the front porch and the short, out of scale second floor windows, it almost looks like that house started its life as a one story cottage or what we call a "shot gun" (long and narrow one story) and, at some point, had a second story added. During the timeframe of the construction of that house, it wasn't uncommon to build what was called a "half house" where, for financial reasons, they would build half of the house that was planned with the intent to later add the second half.

A chimney, like that is typical of a Federal style home but if it were, an identical chimney would typically be on the opposite end of the house. I'd love to know the history of that house!
Oh well, you didn't come here for a conversation on historic construction/design. Sorry.

Jamie Hall

As I noted in my earlier post, the chimney and its idiosyncracies and the gutters and theirs are among the least of your worries. You have real problems with all the brick, as I noted, and whatever you do you need to address those problems.

gliptitude

I have gotten to work on this recently and eradicated quite a bit of mystery. Today I finally found a complete path from the top to the bottom where the boiler connects. I am not entirely sure how I will proceed, aside from running a liner through and I could use some input.

I am documenting the process in detail partially for my own perspective and record, and I'm not sure it has anything to do with my remaining questions, but it might be interesting to others. This was pretty hellish work by my standards.

I demoed the chimney down to the roof line on the back face of the house and lower than that on the inside. I was hoping to preserve the base of the chimney so that it was just above the ridge in the center and left a platform for me to put a clay pot on top that I already have. But the brick was in such bad shape I really had to take it apart. Then on the inside I took it further down than otherwise necessary in order to be able to reach the debris...

















These pictures have shown the chimney and debris removal at the top. The chamber I was targeting to clear is on the left side, (left when facing it from the roof/attic where I was working from).

There are no clay liners in the upper section of the chimney (and I see no evidence of any throughout except for one small section at the very bottom going into the basement.). The chambers inside are seperated by precarious stacks of bricks on the right side, which explains where most of the debris came from.



After clearing this debris near the top I was able to drop a weighted string pretty far into the left chamber and approximate the location of the next clog. I pulled the wood paneling and found an old stove outlet nearby which I opened and reached into to poke around.





I drilled out a small section where I thought the clog was. I couldn't really tell where I needed to clear and started clearing to the left of the chamber which after I found the clay liner gave me a void to maneuver the relevant debris into. Now my string goes all the way to the boiler clean out in the basement and I am confident I can fit a liner through here..



.. I haven't looked closely into liners yet but I am imagining something that can interface with the existing square liner section at the bottom, rather than sealing directly with the flu pipe coming off the boiler. The clay liner is in good shape and it would be a pretty straightforward installation and assembly without doing any more demo, IF some sort of transition hardware exists.

At the top I am still leaning towards keeping a very short masonry chimney above the roof line to sit a clay pot on, but this will now require rebuilding since I had to demo lower than this.

I am also considering some engineered metal assembly like discussed in previous posts but I really prefer the simplicity in materials and methods that I already have experience with. Properly flashing a masonry chimney would be new to me but I think would at least be a clean and comprehensible job starting now from below the roofline.

Another factor continues to be how I will finish the roof/gutter structure overall. I still really think I should build out the back the way it is on the front of the house, to have an overhang. This might get awkward with a masonry chimney rebuilt, but still my preference.

I am also leaning towards keeping the structure of the box gutters in place, but roofing over them and putting regular aluminum gutters along the edge, just a simpler system and I can relocate drains for a better design, (current drain on one side is very hard to maintain because of proximity to power lines).

I'd appreciate advice on these plans, especially if it informs me on how to do it the way I want to do it.

ChrisJ

Does the window appear like it was part of the original design of the chimney?

Or was it put into the chimney later on?

gliptitude

I think it is possible the window was always there but more likely it was added when a fireplace was eliminated directly below it.

STEVEusaPA

I see no signs of a terra cotta liner.
Looks to me like the window was always there.
Just can't believe exhaust didn't leak into the living space and kill anyone.

gliptitude

It wasn't obvious to me that something was wrong with the chimney until late last winter, which would have been my third winter heating this house and it was only the deteriorating plaster that tipped me off. I quarantined that room and kept the windows open the rest of the winter.

I think it was mostly leaking into the attic space which has a few roof vents. I could also see it leaking outside through a crack.

ChrisJ

> @STEVEusaPA said:
> I see no signs of a terra cotta liner.
> Looks to me like the window was always there.
> Just can't believe exhaust didn't leak into the living space and kill anyone.

Aren't chimneys almost always negative pressure in the winter?

gliptitude

I am also reading about "poured liners" like Supaflu, where a mortar-like slurry is poured around an inflated tube form, said to be ideal in chimneys that have no previous liner at all.

This appeals because it is structurally integrated and seems like it would mitigate future deterioration of the brick chimney.

With multiple chambers and large areas where they merge maybe it would be worthwhile to run multiple new tube forms for multiple new liners for future use. I also wonder if the Supaflu liners could be oversized and then run an aluminum or steel flex liner inside.

STEVEusaPA

ChrisJ said:

> @STEVEusaPA said:

> I see no signs of a terra cotta liner.

> Looks to me like the window was always there.

> Just can't believe exhaust didn't leak into the living space and kill anyone.



Aren't chimneys almost always negative pressure in the winter?

Not damaged, oversized, unlined or incorrect ones.

salio

Personally, I think that chimney is an important architectural part of your house - but it's not too late! The idea of a poured flu liner makes good sense to me. It allows you to keep the original design as well as the original connections. You could rebuild the chimney from the roof line up, with the better materials and methods that are used today. This would be in conjunction with Superflu or something similar. There's no reason you can't build an overhang on that gable end with a rebuilt chimney there.

You would remove your roof shingles back a couple feet all along both sides of the gable (it's pretty steep so use brackets and a harness), locate the next rafter in from the end - or maybe go two rafters in if the first one is only a foot in, then cut your roof sheathing along that rafter. Then you're going to make purlins (beams running perpendicular to the rafters) which will attach flush to the top of your back set rafter (one that's at least 2' in from the edge), cut notches into the rafter(s) closer to the end of the wall that will allow the purlins to run through the notches, flush with the tops of the rafters, and out over the end wall - whatever length you're looking for; maybe match the overhang on the other end. Now you have the support you need to build an overhang that won't sag, and you just fit everything around the chimney. You still have the 'soft brick' issue everywhere, but it can be plastered. I've also used a penetrating silicon sealant with good success on porous brick chimneys that leak after several days of rain so that might be an option is some applications.

salio

But be careful with how the notches may weaken the rafters. They might just be full 2x6s on an older home like that. So you'd want to sister in 2x4s on each side, and use an oak 2x6 on the flat for your purlins so you have the strength you need but don't cut too deep into the rafters.

gliptitude

salio said:

Personally, I think that chimney is an important architectural part of your house - but it's not too late! The idea of a poured flu liner makes good sense to me. It allows you to keep the original design as well as the original connections. You could rebuild the chimney from the roof line up, with the better materials and methods that are used today. This would be in conjunction with Superflu or something similar. There's no reason you can't build an overhang on that gable end with a rebuilt chimney there.

You would remove your roof shingles back a couple feet all along both sides of the gable (it's pretty steep so use brackets and a harness), locate the next rafter in from the end - or maybe go two rafters in if the first one is only a foot in, then cut your roof sheathing along that rafter. Then you're going to make purlins (beams running perpendicular to the rafters) which will attach flush to the top of your back set rafter (one that's at least 2' in from the edge), cut notches into the rafter(s) closer to the end of the wall that will allow the purlins to run through the notches, flush with the tops of the rafters, and out over the end wall - whatever length you're looking for; maybe match the overhang on the other end. Now you have the support you need to build an overhang that won't sag, and you just fit everything around the chimney. You still have the 'soft brick' issue everywhere, but it can be plastered. I've also used a penetrating silicon sealant with good success on porous brick chimneys that leak after several days of rain so that might be an option is some applications.

Thanks for the input. I've been weighing all of this since you posted and still don't have a full response.

The brick concerns me longterm and I believe that getting the brick adequately painted is important too, after patching up and after addressing roof drainage issues.

The more I think about the chimney and the prospect of me doing the work or getting this done otherwise, I'm thinking the poured liner might be too much right now. One of my concerns is how vast the inside of the chimney is, (unlike the chimneys in the Supaflu demonstration videos I watched). I'm afraid this would make it a pretty difficult and expensive job and also introduce a couple of complicating variables. I'd be giving up a lot of chimney if I just poured around one single inflated form and that would be so much poured material I'd wonder if the chimney itself could hold it while it cures.

I haven't been back in the attic since my last post to check but I think the roof rafters might even be smaller than 2x6. I think they may just be 2x4's, (old 2x4's that are closer to 2" and 4"). So floating this possibility around with a few other people I was given the alternate idea of building a ladder-like construction in the shape and dimension of the desired roof extension and laminating this to the last rafter. Then cut the decking back a few rafters and replacing with continuous plywood sheet or new decking that spans the transition.

.. The carpentry advice reminds me of a tip I lost track of, that box gutters should be built out of a non-standard type of lumber that is more stable and resistant to heat fluctuations. I was wondering what this type of wood is and if this would also apply to the roof framing I'm trying to do? .. Or if maybe some composite framing material would be suitable?

.. I'm having some trouble with the heatinghelp website not running on my tablet that I do most of my computing on so I'm using a library computer now which is a bit disorienting. Even on this desktop iMac computer I had to try three different browsers before I could sign on.

salio

I'm guessing you need more than one flu in that entire chimney. If not now, you will at some point. Maybe you can figure out your own lining material (single wall pipe?) and pour it yourself, but pour only a few feet in height each day so you don't load the entire chimney with all that weight.
The ladder attached to the last rafter doesn't give you any cantilevered support, and just the roof deck won't give you much either. Present day carpenters build this way but it's a joke - quick and easy always wins. Get down into your attic and sister in whatever you need in rafter size to get back at least a couple feet to obtain the support you need.
It's difficult to assess just from photos what the condition of your brick is, and how well it will hold up long term. Might be good to talk to an older mason with a lot of experience on older homes and get his input.

MelanieButler

Oh man, that sounds like a really tough job actually. I mean, we really need some proper photos, or a plan of the house to understand the whole situation, not only from the outside. I would actually recommend you to call for some specialists, who would be able to help you and actually give you a proper advice. Moreover, you could actually call for the services of https://city2surfroofing.com.au/roof-repairs-sydney/ as they are one of the best companies that are offering roof repairs services, they will also help you a lot.

Jamie Hall

I may have made this suggestion before -- but find a really good chimney sweep/mason who can do historic restoration work. They do exist. They don't come cheap... but neither do problems with chimneys. Your State historical society may be able to help you find someone.

What I am seeing in the photos is restorable and possible to bring up to modern codes, but is going to take some ingenuity.