New Header Tied into Block Chimney
I’m installing a new header to carry a section of my kitchen ceiling so I can remove the wall below. I’ve worked out the correct sizing of the header – if you look at the attached drawing you’ll see my main area of concern. The new header will tie into the existing CMU chimney stack. Here is my concern:
1. As I understand it the header cannot rest directly on the concrete block, so what is an acceptable detail here to prevent any moisture wicking?
2. Does there need to be some type of mechanical fastening of the header to the block – or can it just rest on there? The existing ceiling joists just rest there but I know that doesn’t mean that it meets code now.
A couple of notes about the chimney stack — it has two separate flu’s in it, one for mechanicals and one for a fireplace in the kitchen below. The fireplace flu is on the far side of the chimney in the drawing – and there is at least 8″ between the exterior of the chimney block and each of the flu’s.
Feel free to raise any other concerns you might have with this detail. The bldg inspector will be seeing this so I might as well find out any potential problems now. Note that I have removed some of the ceiling joists in the drawing just for clarity – so you can see the area of concern better.
Thanks in advance for your comments.
Replies
I was under the impression that nothing can come in contact with the chimney. I thought that 2" of clearance was required.
Am I wrong?
Depending on your code, you might need more clearance between the wood and the chimney, or some type of insulating barrier between them.
Since that is now going to be a load beaing point, you might also consider grouting the block cells under the beam.
Dave
RobWes -- I went back and looked at the IRC and 2" is what they require. Do you think it is possible to argue that because the block steps back the way it does, that I need 2" clearance from the upper section which I think I could get, but that I am ok to use the lower portion as my bearing point? For the record Dave I have already filled the cells of the block to ready them for the load.Another exception where the code allows combustible materials to be in contact with a masonry chimney is when there is a chimney lining system in place -- the catch here is that I need to have the chimney lined before I can use it anyway but that is definitely not going to happen before that wall needs to come out. Something tells me the inspector is not going to let it slide though.I might just be thinking out loud here, but would love to get some honest assesments of my situation and some sound recommendations.Thanks
If you can get the 2" seperation and still have enough bearing for the beam end, I think the inspector will pass it.
Can you set a lally colum next to the chimney? If the block wall was built with a seperate or thickened slab footing under it, a colum would take the load directly to the footing. Maybe cutting the slab and adding a footing, then a post is an acceptable option?
Just thinking out loud. I don't know what your design restrictions are beneath the ne beam. If that is a first floor beam holding up the second floor, could be another bucket of bolts to sort out.
Dave
Dave
Oh yes, The third would be that the chimney and its footer is constructed so as to be structurally cabable of handling hte load this beam will place on it. Your comment on filled cores is what reminded me.I think i have read thaat one exception in the IRC is that wood can contact the masonry if there is a minimum of 12" of solid masonry between flame passage ( flue) and the point of contact with wood
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I could potentially post this beam -- I'd have to look a little closer when I get home to see what the condition under the first floor is, but I know it is darn close if not right on top of a section of foundation wall. It may require some amount of work but nothing ridiculous - and ultimately does not impact the kitchen design - just kills a little space.Piffin - this chimney has two flu's in it, one for the fireplace and one for my combustion mechanicals (furnace and hot water). I know I have about 30" from the closest part of fireplace flu and I think at least 12" from the closest part of the mechanicals flu -- I know its tough to say definitively, but you think I might be able to sneak this past the inspector?I don't suppose wrapping the portion of the header that is in contact with the chimney in fire retardent material would do me any good?
OLook - if it was me and mine, and if this is built as drawn, with the fire flue on the other side, I would have no qualms doing this.But I don't know your inspector.
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Typically you cannot use a chimney for this.
Three reasons. One is that of fire concerns. Code requires an inch if free cclear spoace between framing and the masonry. There are exceptions in some codes but they are so rarely used or complied with that most inspectors don't even know.
Another is that a chimney will heat and the thermal expansion can make them grow in length/height, so there is a apossibility that your header can rise and fall at that end.
Third - senior moment - I gotta go get another cup of coffee...
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Judging from the sketch it appears that this could be solved with a steel angle
4" x 6" x 3/8" punch holes 3" in from each end and then 12" centers. identify the cells your punched holes align with and fill them solid with a portland sand and cement mix. I recommend hilti st. st. rods with hilty hy 120 epoxy after the grout sets ( the next Day) Bolt your angle into the CMU and set the header on the angle 2" clear from CMU. Of course you should verify with the local building dept.
let me know if this helps
Around here if you are placing a point load on a chimney you have to show that it will handle the weight and that it's constructed in a way that won't cause a fire hazard. Typically that means you need an engineer's stamp for the city to approve the plans, and the hvac inspector has to look at the design and sign off on it. Sometimes the chimney can be used for all sorts of things if an incert is used.
Cheers
Beer was created so carpenters wouldn't rule the world.
"Sometimes the chimney can be used for all sorts of things if an incert is used"That seems strange.
You mean a wod stove/fireplace insert????An insert actually increases the odds of a chimney fire because free flow open fireplace rarely if ever builds any creosote, buit the controls choking down an insert and the fact it is a 6-8" exhaust usually going into a 12x12" fireplalce flue means far more creosote build up, and an insert usually makes it harder for a chimney sweep to clean...It is the chimney fire that is the main concern with connections like this. Normal burns will never hurt the wood there, but a cchimney fire can melt the mortar out of joints and catch surronding material aflame with the heat
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That seems strange.You mean a wod stove/fireplace insert????
We are talking about using the bricks for structural purposes. An insert reduces the temperatures the bricks are exposed to, making direct contact of the bricks to flamable materials more feasible.
In a lined chimney not properly maintained I don't know and don't really care if it increases the chance of fire in the liner.
Beer was created so carpenters wouldn't rule the world.
An insert increases the odds of a chimney fire for several reasons.it is not normal operation that makes a chimney hot enough to char attached wood. It is when there is a chimney fire that the wood is exposed to dangerously high temperatures.
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I keep re-reading this line and really can't understand it. You and I are on the same page most of the time, so maybe I am just not reading it right.
care to rephrase?An insert is still a solid fuel combustion appliance, subject to all the same rules for flues and venting as a fireplace is, but it seems like you are saying that you just don't care.Makes no sense. What am I missing?
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Paul, I have to appologize for being cranky and it is coming through in my reply. We're doing a last minute rush remodel on a new house purchase, where the client want's a refurbished home and custom kitchen in 3 weeks (in time to cook thanksgiving dinner) so we've been hiring subs right and left and working mega hours.
As for the chimney, at least locally, if we can fit an insert (gas or wood) and can line the chimney, it's more okay with the local building officals to have contact with the chimney exterior because the temps are lower. That doesn't automatically make it a good choice, as you know.
As you said, this isn't a cure all by any means, and I'm the first to say it's a shame to not keep a good traditional fireplace. I don't want to sound like a liner is something I'd think of as a good practice over a more robust structural design.
I'll pick up the coffee tab tonight. :-)
Good building.
Beer was created so carpenters wouldn't rule the world.
I see. A gas appliance is different for one thing. And adding a liner is yet another step. Most wood inserts do not use a liner. They use the original flue.I'm going to bed before I wake up cranky.;)
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I know this thread has dropped off a bit but the project has stalled a little and now I'm back onto it. If you take a look at the original drawing again -- what if I replace the 2x12 dimensional wood header with a steal i-beam sized appropriately? Then I would no longer have a combustible material in contact with the chimney. I'm sure the steel would cost a bit more, but not quite as much as posting this thing down two floors to a new footing. Is this code-compliant?One other related question if you don't mind, there are probably about 10 existing 2x6 joists tied into the chimney from the original house construction -- is it within the inspectors power to require me to correct that detail even if I'm not touching those areas? Did anyone else notice in the last issue the article about framing a cathedral that it looks very much to me like he is tying his framing into the chimney?Thanks in advance for your thoughts,
Sean
re the steel beam, yes tht would eliminate the combustible material in contact with chimney issue. As for cost, the last time I compared steel vs LVLs, the steel was considerably less for materials, but a bit more for labour. Since then steel has gone up in price coinsiderably. I don't know wjhat the comparison would be today. You might also need a saddle bracket made up to spread the load on tht masonry ledge.As for the others already in contact - they are grandfathered and aloowed to remain on that besis alone, except that most jurisdictions have a rule that at some defined point, once you open up things, you have to upgrade to whatever the current requirement is. They may define that point as five thousand dollars, or fifteen percent of the dwelling area, or ______. You'll have to check with your local AHJ
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I know you posted to Piffen, but I figured I would chime in here.
I think the steel idea is a good one. Removes the fire issue, still going to need to show strength. As far as the inspector making you upgrade everything, yup, have seen that happen. Whether they do is usually dependant on how much construction is being done. If it's a wholesale remodel, and if everything's already open, many of them seem to be of the mindset that it's only going to cost "a little more". Of course it's not their money. Seems to be a function of the individual and whether they had to sleep alone the night before.
As far as the last issue and the ceiling article, I guess you missed it. That article was torn apart to the point where the author finally asked the main opponent of the article to take it off line. There was a real question of the propriety of the structural revision to the building. Author tried to defend it by saying he "talked" to an engineer who said it was okay. Let's just say it wasn't considered "Fine Homebuilding" by some. I wouldn't use that one as strong support for your position.
Think you would be better off, especially with inspector, if you could pull out a stamped drawing from an engineer.
Don K.
EJG Homes Renovations - New Construction - Rentals
thanks for the replies guys -- like I said even if the steel is more expensive for the material, I think it is offset by what I would have needed to do to post this header down 2 stories. I'm the labor with a couple friends helping out, so out-of-pocket for the steel is only the material cost.I am leaving the ceiling intact, only removing what is necessary to get the new header in and tie in the existing joists, so hopefully the inspector won't take issue with the other wood joists that are tied into the chimney.DonK -- I wasn't only posting to Piffin so please feel free to chime in whenever you like. Unfortunately I did miss the backlash on that article - funny when I was sizing everything for my project I felt like it was way overkill and then I saw that article and something didn't look/feel right about it. I will give FineHomebuilding credit though -- seems most months I get the issue and there is an article that speaks almost directly to a project that I am involved in at the moment.Thanks again -- I'll try to post some photos of the progress on this once my permits are in hand and I get underway.
To follow up and expand on my last post, to prove the chimney can support the weight means the footer is adequate for the weight (figure that out if your engineer won't pass it based on simple drill holes in the basement slab) and that the construction is such as to allow the weight.
Better find an engineer used to remodeling or they will just stare at you like you're an idiot for even asking. *chuckle*
Beer was created so carpenters wouldn't rule the world.
"Feel free to raise any other concerns you might have with this detail. "
OK ... U can't do that.
no inspector I've ever been inspected by would let that pass ... even worked one job where someone else tried that trick. We were called in to make it right.
bad idea all the way around ... plus ... U can't do that.
drop the idea and start designbuilding a way to header off the header.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa