No Mud Sill - Rim & Joist directly on Conc. Foundation

GreenTrends

Hello List - I have a small historic cottage built in 1904 which was moved onto its current foundation in the 1950's. The original cottage size is ~15' x 30' with a small addition scabbed on the back which will not be retained. My focus is on restoring and maintaining the original structure.
The floor construction of the cottage is composed of 2 x 12 joists spaced 24" o.c. with a double rim joist. Both the rim joists and floor joist sit directly on the poured concrete foundation. In other words there is no mud sill. As I suspected there are no standard architectural details that show this type of construction that I can find. If the wood is ok, do I need to remedy this issue by jacking up the structure and adding a mud sill? Has anybody seen this before? What's keeping this building from blowing away like dorothy's house in the Wizard of Oz?
I've posted a picture that illustrates what I have found. The picture is taken of a window cut-out in the concrete foundation. I've checked behind the siding in other areas not above a window cut-out and there is no sign of a mud sill.

Thanks for taking a look.

Attached Thumbnails

 

Joe Carola

It's been there for 104 years, where's it going to go?

I have seen it before. I framed an addition last summer on a house with the exact same thing. Luckily I caught the mason because he would've put the foundation to high because he was allowing for double mudsill. That's why you always have to rip open both sides of a house where an addition is going.

__________________
Joe Carola

AtlanticWBConst.

My first thought when reading the post was:

Huh? ....why?


I had to re-read the post, to try and find out what the problem was....Either the OP forgot to list the issue, or I am not reading it.

The Rim joists serve as headers over that span. They are working. Why would you want to consider doing such major work on your home, when it is not needed? When there doesn't appear to be any problems?
No, it is not built by modern framing standards, but so are alot of other older homes that are still standing, and have not shown any signs of structural shifting.

Are you bored?

__________________
- Build Well -

Haveninc

My initial thought was the same as the first two replies...however I would like to point out that it looks as if the foundation was paraged. Your main concern should be whether moisture can absorb into the block and then eventually reach the joists. I recommend you waterproof the foundation extremely well. Don't just rely on the uncoated paraging as your water proofing as that is merely the first step towards a good seal. You need to follow up now with either a stucco application, oil based waterproofing or a dry lock paint to complete the job. Then I'm right on board with the other responses. Just another FYI....an inexpensive fix should this still concern you would to be to slide coil (metal flashing) between the foundation and joists.

GreenTrends

Thanks Haveninc. When waterproofing an existing foundation from the exterior, (to protect the untreated rim joist and floor joist from mositure that is absorbed and "wicked" up the wall and into the wood) how far below grade should I expect to go with this type of wall application? Ideally I could dig down to the footing, (I have a full basement,) but that seems cost prohibitive and messy.

Haveninc

The best case scenario would be to start at the footing but this of course would most probably be cost prohibitive. I'd recommend that you dig down at least a couple of feet and then just make sure you get good fall with your soil away from the house (Our rule is 6" in 10'). If you don't have overhangs that are at least 1' I'd also recommend adding gutters although I know this would probably not be historically correct. Be aware that you can use a foundation sealer below grade where no one can see it and then at grade start using a more attractive finish. If you use a tar based foundation sealer you could also apply a poly barrier (6 mil plastic) and turn it out away from the house at the bottom.

GreenTrends

Have you had success with this method? Do you left the wall slightly under the joist to get the flashing in place?

Haveninc

It depends on the project. What I see more of is that folks forget to use treated lumber in crawlspaces where there piers are and we've inserted coil with no problem. Sometimes you can just slide a piece of coil in,(I like coil because it's heavier than what most people think of when they think flashing) with the use of a nail puller or the slightest of jacking. Other times it's more difficult. This can snowball and get into the art or jacking a house also...a lot of things need to be taken into consideration. Jacking needs to be accomplished slowly and as evenly as possible. If you have plaster walls you could create interior issues. Overall if this were my house I'd try to see how easy it is to work in the coil with out jacking and definitely waterproof the foundation well.

GreenTrends

This is great information. So the coil in this application doesn't wrap over the edge of the foundation? I assume its only function is to keep water from wicking from the concrete into the wood and the coil could be flush with the exterior face of the rim as not to interfere with the sheathing.

GreenTrends

You are right, and hopefully there is no problem. I suppose unless we find a lot of rotten joist wood when the siding comes off there is no reason to think about jacking the house and all of the hassle that goes with it.