Today’s inspection on a 1961 single family. There was a wood burning fireplace insert and factory built chimney with a concrete base cantilevered around 4 feet without any supports. It appears they formed a stem wall and cantilever on one pour on the original foundation stem wall. There were some embedded brick remnants in the concrete below that made me feel there was originally a brick chimney, but its only a guess. In the crawlspace, I also observed a concrete (slab? deck?) cantilevered in the same fashion in the same spot underneath the fireplace appearing it was part of the same pour.
This does not look right to me and at a minimum should be supported by at least some post and piers but I’m no concrete engineer and want to make sure I don’t overreact on this one but it looks mighty sketchy. Can anyone provide me with some feedback on whether or not you feel this is acceptable or the reasoning behind this structure? Or am I justified to write hard…
That looks problematic to me, David. And with what I can see, I would refer it out to a structural engineer to verify structural integrity. Especially with the roof load on it, too.
It can be difficult to justify elevating things because they do not “look right”. There is certainly ways to make this cantilever structurally sound. The problem is you cannot see any of the embedded reinforcements.
However, I do see this rebar which is exposed and lacking cover. And a few cracks. That should do it.
So that is already in the report and I am recommending further evaluation by a foundation contractor on that repair. This is a seller pre-listing (almost all of mine are), cool clients, and they just bought the home a couple years ago but none of this was in the report they had done when they bought the home. I asked them if they had documentation about this repair as they bought the home after the foundation repair. They said no and the seller they bought from is deceased
More times than I can count on my fingers and toes (and all those of my family) I’ve sat looking at the underside of a concrete slab and wondered, “Are those form board imprints or structure members that failed?” “Is there rebar in there?” - This is the ultimate example of our job/purpose - Is it performing as intended??? When I’m skeptical of the design, I look for any (albeit slight) performance problem that I can “drag” in/reference to have it “further evaluated.” But, many times things just look wrong but have been that way (presumably) since 1965 and I’ll let it go without a write-up. At the end of the day, are there defects that you can actually cite/note? Just not understanding/able to completely see something isn’t enough for me to write-up.
I posted a picture of what appears to be a clean out hole on the outside cantilever under the fireplace. I think this open area underneath used to be a brick clean out chamber from circumstantial evidence as I mentioned but I just can’t tell and can’t tell if this double concrete cantilever is original to the 1961 home or created after the home was built. The exterior portion is not what concerns me too much, its the portion in the crawlspace that seems to have not purpose (not my lane) but no visible tie-in to any structural component. I’ve just never seen this and feel concerned about the cantilever since, like Brian mentioned, I can’t see interior structural components.
Thanks Matt, thats the type feedback I’m looking for. Some feel to refer out, and some not. Fortunately, I’m recommending a foundation contractor for the epoxy crack repair and a visibly somewhat minor cracked concrete footer under a stem wall.
I would have to say negative ghost rider…I meant to add a pic of the fireplace (and hearth) but couldn’t find it earlier. The hearth may be brick or a stamped brick material but not what you’re thinking, and I didn’t do the lick test
This house has been remodeled over the years, there might have been a substantial brick hearth at one time. That is a great point to mention for me to understand what may have been the original purpose of the concrete slab/deck. Thanks Brian!
The forming techniques for it were typical for the period, but I think it was done after the fact. The color and condition of the concrete tells me it’s newer but who is to say how new. It could only be a few years. Besides, there’s concrete on the wood framing to the left, so clearly that was existing when the cantilever was poured.
Did you notice the crack on the upper portion?
I recently inspected a 1920’s home with a brick fireplace and chimney essentially supported by four 4x4 wood posts in the crawlspace. So, I ran the calculations and was surprised to find out that whereas the (albeit) narrow chimney weighed a few thousand pounds, the combined posts were able to support almost 20,000 lbs. I also found out that this configuration was not uncommon during that era. So, I just called out the other much more pressing defects with the chimney, like the disintegrating mortar.
This situation looks like 8-inches, or so, of reinforced concrete supporting a manufactured fireplace and chimney (i.e. light, as you said). Even without running any calculations, I don’t think it is in any danger of collapsing, even with the crack.
Cantilevering is a well-known architectural / engineering design element. The equations are simple to use and understand. I would presume that the original architect did their due diligence.
That’s an unbalanced cantilevered slab. They do exist, but not like this. The footings required for these things have to resist overturning, and the stem wall has to resist bending. So relying on the existing stem wall and whatever footing it has is a big no-no.
The whole thing looks ad-hoc to me. I really doubt an architect was involved.
In addition, it looks pretty old. And this is a good lesson for home inspectors. There’s a bedrock concept in structural engineering that structures have to withstand the test of time. This assembly has not. There is a long crack near the point of highest moment that somebody tried to repair with epoxy. The crack is above grade and not anywhere near the cold joint along the top of the original foundation. Did the cantilever cause the crack? Unknown, but it’s located near the point of highest moment, at the outer fiber where you’d expect a crack. If it were me, I would be letting my client know that if he really wants the property, a repair is in order. Simplest thing to do is one or two piers.
Ii is my opinion that that added concrete partition, horizontal foundation crack injection repairs, and structural renovation work required a structural engineer at some point including municipal permits would require a structural engineer and plains.
I would refer this work to be reviewed by a licensed concrete forming contractor with inhouse structural engineer.
Just my 2 cents.
