Repairing notched bottom plate and floor joist
I am moving a cold air return before I insulate my home and as the title suggests, I’m looking for some advice “repairing” some of the notches.
The wall is an exterior wall, and there is a full 2×8 (rim joist; outermost) underneath the un-notched portion of the bottom plate. The home is balloon framed, and it appears the notched joist here is used half under the bottom plate and half for the sub flooring. Both joists rest on concrete; the foundation I assume. This is different than the other four walls (sides and rear), they rest on some 2x which sits on the foundation. There are buttress walls in the basement, and I recall while buying that the basement was added after the house was built or such.
Anyway, I don’t know that there is a structural concern here, given the setup, but confirmation would be nice. I’m thinking I can just cut out the rest of the bottom plate and nail in a piece cut to fit snug. The floor joist I don’t think is an issue notching wise, so I can also just block with 2×4 from the exterior face to enclose the cavity?
As well, there is a good 1.5″ gap or so between the rim joist and the next joist (this notched joist), at both the front and rear of the house. I have no good access to it except a notch like this. Should I pack insulation in here as well, or just worry about doing a good job on the interior in the basement? What about air seal concerns before I close it all up? I’m thinking there’s not much I can do there, except maybe dense pack it, and put a hole in the rears for the same.
Thanks in advance!
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Another perspective, viewing the joist, from inside the cavity along it's length.
(it won't let me attach another file for some reason)
http://oi61.tinypic.com/2r5yvio.jpg
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Nathan,
It's hard for me to visualize the notches from your description, so you might post a sketch showing your understanding of this notching situation. (You can just make a sketch on a piece of paper and take a photo of the paper.)
Some general principles:
1. There is no need to make modifications if the existing wood is sound.
2. If you have to remove part of a joist when you install your new cold air return, verify the structural path below the joist when you make your cut, and reinforce the area as required.
3. If there are undesired air pathways in the vicinity of your rim joist, the best way to seal these pathways is with closed-cell spray polyurethane foam. You may want to buy a two-component spray foam kit for this work.
Here are two sketches. One is how the framing used to be, before the notching for the cold air return (how the rest of the wall cavities are), and after the notching. Note, the notch in the 2x8 joist is 3 inches deep, and the notch in the 2x4 is just over half its width (only the thickness of a 2x remains).
The vertical brown framing are the wall studs. The purple horizontal framing is the bottom plate of the wall. The red and green horizontal framing (perpendicular to the bottom plate) are the rim joist (red) and the notched joist (green). The pink below is the foundation, perhaps with a sill plate buried in the concrete somehow (I can't see one on this wall). The blue background is the exterior sheathing.
My goal is simply to enclose the cavity like it was so I can dense pack it. If there's a structural concern, I want to deal with it properly. I'm thinking I can just replace the section of the bottom plate with a snug fitting cut, and "sister" 2x to enclose the floor joist, as it's probably not compromised with the notch (as it sits atop the foundation and is continuously supported).
There is another cold air return in the same wall, but two cavities wide adjacent to a corner. I plan to repair that the same way.
Nathan,
There are no structural concerns here. Feel free to patch in framing lumber to fill the notch.
If I were you, I would insulate all accessible voids with two-component spray foam -- unless you are worried that the wooden components in contact with the foundation wall are subject to wetting due to capillary action from soil moisture.
Thanks Martin. I think I'm going to close this in for now so I can complete the dense pack project. I believe I can foam the void after the fact by opening a bore (or multiple) in the joist. This will allow me to deal with any moisture concerns later as well, assuming that's not as large of a project as I think.
Help me understand the wetting concern (via capillary action):
I'm not sure how to determine if the framing is subject to wetting due to capillary action. As well, the only concern with wetting in regard to spray foaming is ensuring I deal with the wetting issue before I foam, correct? Even if I wasn't to foam (or insulate in general), I would still want to deal with this wetting issue, correct? Or perhaps the lack of insulation (and the structure "breathing" as it is), mitigates the wetting issue, and hence why it's a new concern when I insulate?
If adding insulation here means I need to deal with any wetting concern prior (due to the fact that the home now won't be able to breath and mitigate the existing wetting "issue"), I'm going to need to research this before I go much further, as it may be a larger project than I'm imagining. The front of the home (where this wall is) has a poured concrete patio, which varies in thickness, but is at least ~ 1 foot deep where it meets the foundation. The exterior is brick facade on bottom ~ 3 feet of this wall (the rest of the house is steel sided).
Nathan,
Old buildings generally lack a capillary break between the top of the foundation and the wooden sill. You can retrofit a capillary break if you want -- generally a rubber membrane or metal flashing -- by jacking up the house 1/2 inch and sliding the flashing in before lowering the house. The job is intimidating but not as hard as it sounds.
Is it worth it? It's a judgment call.
If your sill is solid now, it may be because it dries quickly in both directions. Adding spray foam or rigid foam on the interior side of the sill or rim joist reduces inward drying. That could eventually make a solid sill begin to rot.
Figuring out what to do is complicated. If the exterior of your house is unobstructed by bushes, and the lowest wooden components of the building are well above grade, and the lower portions of the walls all get sunshine -- that's good.
Not so good: high grade, bushes, shade, damp soil.
As I said -- a judgment call.
It sounds like I understand the concern then, which is what I wanted to ensure. I appreciate you breaking it down for me. It sounds like I can put this off and handle it after I dense pack, as I was hoping. One project at a time; :/.
I have a photo of the exterior of the house, of the wall in question if you wouldn't mind helping with the judgement. The areas to the left and right of the red front door are where these return vents were, and I'm sure that was helping to dry the space if there were is any existing wetting action (the notches open those cavities right up, and I can feel all of that outdoor cold air getting sucked into the return; ugh!).
http://oi62.tinypic.com/2w57j15.jpg
Looks not as good as it could be: little sun late in the day, with lots of leaves for shade in summer. It does look like this is above grade though, and the wood is not in direct contact with soil, and the foundation probably mates with more concrete (the poured porch). The porch has a crack in it, and I need to re-grade the soil along the house so the water runs away (not toward); but I think that's a different problem (though related: avoiding excess water in that area, which will also help).
Nathan,
It looks to me like someone has poured a concrete patio slab right up against the rim joist -- which is always a bad detail, since the concrete slab holds moisture against the building and inhibits drying to the exterior.
If the situation is as I describe, you might want to demolish that concrete patio.
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Martin,
Oh boy am I glad I brought this up then. Dealing with the concrete patio was a potential future project that could now be more involved. I will do some more investigation this evening to determine paths forward. I'm still feeling confident I can close up this cavity to finish the packing project and deal with the rim joist/sill plate/foundation/patio slab moisture concern in its entirety at a later date (as the bottom plate and joists won't need to come out, thus not opening the densely packed cavities).
Well, I think I need to replace the rim joist here.
In the single cavity return, there are what appear to be bricks below the joists. In the double cavity return, it looks like the joists used to rest on wood.
In the single cavity, an ant crawled over the brick while I was setting up the photo, and there were some dead ants in the "dirt.". It looked like dirt and smells like dirt, but I think it's just rotted/deteriorated wood?
The bottom of the rim joist in both returns come to a peak; they're pointed, trapezoidal if you could look on edge (or so it feels with my hands when I shove them under the joist...). The pan under the joists (the inside one and the one next from it, not the rim) for the duct in the corner return is full of something, feels like dirt.
I discovered a mess, I think. I should probably resolve this before insulating the walls then, no? I assume this will be easier/smarter, given that the bottom plate attaches to this joist.
Do I have any recourse here? Can insurance help? Do I just have to repair it (or not, hah!) and eat the costs, learning how to do better than the inspector I paid?
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Single cavity return photos (looking down between the two joists described, at what should be the sill plate in a modern construction):
http://oi58.tinypic.com/23w1loh.jpg
better view of rim joist (left half):
http://oi58.tinypic.com/rb9zdf.jpg
better view of rim joist (right half)
http://oi60.tinypic.com/r1hc2x.jpg
Double cavity return, adjacent to corner. Looks like an old sill plate deteriorated away:
http://oi58.tinypic.com/6rhf0y.jpg
Better view of rim joist (left half of left cavity):
http://oi62.tinypic.com/v4tmyt.jpg
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I fear this post describes my situation very well (the crack runs right down the middle of the entry, you can see it in the photo):
http://www.diychatroom.com/f15/questions-about-jacking-up-house-replace-rotted-rim-sill-67039/#post417044
There is also brick laid under the rotted rim joist on the double cavity return. I'm thinking there was a sill plate at some point in time, and it's either rotted away, or had before and some sort of repair happened once already. Is the brick the foundation, or could it have been placed to replace the rotted sill plate?
Now to check for sagging, I think.
Nathan,
This is hard to assess based on your photos; a full assessment requires a site visit. But based on your description, I think that you have some major repairs ahead. As far as I know, this type of repair is not covered by homeowner's insurance.
If you are unsure how to proceed, you need to consult an experienced contractor or engineer. Good luck.
Thanks for your help Martin. I'm going to borrow a borescope to get a better look, but I'm pretty sure this needs replaced.
I've been reading how to use a jack wall or bottle jacks to support (or lift) the house to replace this. Fortunately, it looks like I should be able to do it all from inside the unfinished basement, though that porch has to go eventually anyway it seems. I would have to block across the joists (perpendicular) in order to use the jack wall method; I'll have to do more research or hire someone to deal with it for me.
Well, I think I have more roommates than just the one, and I'm pretty sure the others decided my sill plate (and rim joist, and bottom plate) needed some love. If only they would help split the rent...
http://oi58.tinypic.com/v5jvrc.jpg -- found this guy headed to the kitchen; the fridge I'm guessing...
http://oi59.tinypic.com/dwt4kj.jpg -- rim joist after cutting out bottom plate
http://oi60.tinypic.com/jpk9k1.jpg -- edge of bottom plate
http://oi57.tinypic.com/2wgyvkz.jpg -- bottom of bottom plate
Martin, I'm so glad you brought up the moisture concern re: capillary break. I would have discovered this after I finished removing the joist pan ducting, but I'm glad I caught it now. I still haven't pulled out the pans in the corner, I bet I'm in for a nice surprise.