Framing a Crawl Space Underfloor | Paul Rea
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- Опубликовано: 9 июл 2024
- Paul Rea teaches how to frame a "crawl space" underfloor for a residential building using traditional 2x10 joists. He shows the components of the underfloor including the mudsill, vapor barrier, anchor bolts, joist hangers, and pony wall. He also discusses why pressure treated lumber is used for the mudsill and where to put the crawl space access to the underfloor. See actual video of mudsill installation, joist hangers installed, and the sheeting of the subfloor. The building is a Single Family Residence with an attached Accessory Dwelling Unit (ADU) located in Springfield, Oregon. Paul Rea is a Construction Technology professor in Oregon at Lane Community College.
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Excellent and very in depth video! You have a knack for teaching!
Paul is a good teacher. He is a college professor for the Construction Technology classes at Lane Community College in Eugene, Oregon.
Good stuff 👍
Thanks 👍
Over here in the Nordics, many houses in the 60s and 70s were built with pressure treated sills which begun smelling after a few years and nowadays regular wood is preferred. Perhaps other chemicals are used these days that won’t smell as bad.
We had built two other buildings in 2019-2020 with the same treated sill type. We haven't noticed any smelling. Thanks for the comment. :)
Very thorough
Thanks!!
Great teacher
Glad you think so! Thanks for watching.
Several things mentioned previously, and I ask the same.
Perhaps the structure has a height consideration and thats why floor joists are Not on Sill or mud plate.
A few others ask same and other points.
This is a good question. Here is Paul Rea's response:
I have been questioned a number of times why we place the top of the floor joists flush with the top of the mud sill and do not place the floor joists on the mudsill entirely. To answer this I will remind folks of what we are trying to achieve with a foundation and a subfloor at least in our application. The concrete must be a minimum of 6 inches above the backfill and the dirt must slope away from the building. I prefer to put foundation vents at the top of the stem wall and they are 8" tall. I don't like to build wells around the vents so basically the dirt comes to the bottom of those. This puts the mudsill around 10 inches off the backfill. If I place the joists on top of the mudsill this makes the distance to the finish floor around 20 inches (three steps) from the dirt. If I drop the joists inside, this knocks about 9 1/2 inches off of that total. I am required to have a minimum of 18 inches from the bottom of the floor joists to the ground in the underfloor area. My combination of 8 inch high footing and 24 inch high wall equals 32 inches. Add the mudsill and you are at 33 1/2. dropping back down the depth of the joists gets us to 24 inches of underfloor clearance. We could have poured a smaller footing and a shorter stem wall but this works out to be a comfortable combination. Thanks for the question.
Great stuff!
Glad you enjoyed it
Thank you
You're welcome.
Just a suggestion, Tim...try to balance the audio level, the commentary is quiet and the music is quite loud in comparison.
Audio level is a challenge to adjust any higher in parts. I can adjust the music lower in future videos. Thanks for the feedback.
Please let me know why you use hangers for the joist instead of putting the joists on top of the sill? Thanks. I’m just learning
If we put the joists on top of the foundation wall then the building would be a lot higher off the ground (would need to build steps to get to the front door). To get the same height, more excavation might be needed, or maybe a shorter foundation wall. Using hangers is a simple solution.
Nice work. What part of the country are you in?
We are in Springfield Oregon. Thanks for the positive comment.
i noticed the mudsills with the joist hangers were flush with the interior of the stem wall, but the mudsills that didn't have joist hangers were flush with the outside of the stem wall. and they also looked like they might have been a smaller dimension. am i seeing things right? what's the reason for these decisions?
Good question about the mudsill dimensions. Yes we did use different sizes. I believe we used 2x8 pressure treated lumber for the stem walls with the joist hangers and 2x6 for the end walls. We used 2x8 because the joist hangers needed to be flush with the interior wall and we wanted the mudsill to extend as close as possible to the outside of the stem wall. If you look closely, there is a gap between the 2x8 and the outer edge of the stem wall. Paul later cut long strips of pressure treated lumber to fill in those gaps. For the 2x6 end stem walls we just needed to be flush with the outside of the stem wall as it supports the sub floor and the 2x6 bottom plate of the wall, so really didn't need 2x8 material. The interior stem wall that runs parallel to the joists we used 2x4 pressure treated lumber. Two 2x4 firewalls are being built on top of it. We used 2x4 because we need an air gap in between the fire walls and because we are building 2x4 walls above. See our next video "Building Walls for a (Duplex) House" for more info. Hope that helps.
IRC 6”-9” for bolt??
What's wrong with actually bearing the joists on top of the foundation wall?
Nothing. However this solution can provide different benefits. Including reduce threshold height. Good for grandma.
@@samt5663 True enough:)
This method creates a direct path for foundation moisture and termites to the end grain of untreated floor joists.
@@theferallife8812 this is true,
@@theferallife8812 Termites don't care which way the grain runs. But if it was mine the beam ends would be soaked in creosote and that black (rubber?) layer under the hangers would drop all the way down past the beam ends.
Thanks for video is there any advantages to a engineered floor joist truss system in a crawl space home? Possibly doesn’t twist or bend at all limiting squeaks or things of that nature? Other than cost but would that be “overkill” in a raised foundation home vs the 2 x 10s? Thanks again!
Engineered floor joists can span longer distances. They may be easier to install. We had to use two 2x10's per row instead of just one floor joist per row. They are supposed to be less likely to split, shrink, twist, warp, or bow. The manufacturer may also provide a warranty which you won't get with the 2x10's.
@@buildinghouses thanks for the info! is this at all a common practice with a crawl space home? Or kind of unheard of in that realm?
And what might guy expect double triple or so the cost of dimensional? Thanks again
Another factor to consider is the cost of labor for installation of the joists. The engineered floor joists are easier and quicker to install so if you hire it out, the labor may be cheaper. Paul is a construction instructor at a community college and we were giving his college students hands-on training so labor and time were not a factor. Back in late 2021 early 2022 when we were constructing this building, the 2x10's were $1.40 a foot and engineered trusses were $3.80 a foot. We built another building in 2022/2023 and the engineered trusses were still at least two times more expensive. The 2x10's used to be the common practice before the engineered joists came along.
@@buildinghouses gotcha thank you. Is there a certain amount of days you want to wait before building on top of a raised foundation for the concrete to settle?
lmao i like the edginess of the builder
What kind of PT lumber is that with all the lines in it?
We used regular pressure treated lumber. The incisions in the wood help the preservatives to sink deeper into the lumber. Is that what you were asking?
👍 👍
Thanks!!
Hey! Are these Simpson strong tie hangers? What type? Thanks
They are Simpson hangers. They are top flange 2x10 hangers but I'm not sure what specific type we used.
One thing you didn't mention is that the engineered I-joists are a firemans nightmare. BTW I have never seen a floor system framed like the one I see here. joists have always been on top of the sill
First thing I noticed in the thumbnail…was wondering what all the hangers were nailed into.
Yep, we east coast guys start our framing on top of the foundation wall and the we use piers and girders in the crawlspace instead of a pony wall.
hmm pt can still grow mold i was told....... idk
What has been other folk's experience in the field with pressure treated lumber?? Does mold still grow??
Unfortunately my few years framing experience was mostly building on slabs but any joists or decking...where decking falls and fastened to middle of the 1 1/2" joists, how do you accomplish this with your staggered joist at center girder......sheet would fall short or long or is your distance to center an even 8,12,16, if not you'd need to notch out every 4x8 at this shift.The diy audience that this video is directed to would run into problems with this. The overlap at girder should give cantilever strength and lengthen the joists span but none of online span charts address this. I'm aware that engineering a build is smart but with so many tutorials online many who aren't required to pull permits aren't.
👍👍🌹🌹
Thanks!!!
Why are there no "noggins" or even steel strapping between the floor joists?. They stop the timber from twisting and spread loads more effectively than the floor boards
You didn’t add water proofing membrane under the mudsill.
No, we just put a plastic sill sealer under the mud sill.
@@buildinghouses oh cool okay
I like the information, But let's loss the music !!!
I will try to work on adding subtitles to the videos so that folks can watch in different ways.
lose
Omg don't do this folks. My lakefront home was built low to the ground like this and it is a nightmare working in such a short crawl space
Crawl space area is not too low because stem wall is nice and high. Pretty easy to move around while underneath. Of course you do have to crawl, but that is why it is called a “crawl space”. 😜
@@buildinghouses lol it should be called a back space because the only way I'm able to work on anything down there is on my back looking up and sliding around on my back.
I wouldn’t do this without putting a concrete pad on the floor and these us a mechanics sled to get around in the space
Sorry das macht für mich keinen Sinn. Man hätte die Balken einfach aufliegen lassen können. Randbohle fertig. Schlimmer ist die unterströmung mit kalter luft. Keine Isolation zwischen den Balken. So schafft ihr die energiewende aber nicht. Auch mit diesen dünnen aussenwänden. Wir sind bei tji trägern 356mm. Aussenwand mit zellulosedämmung!!😃😃😃
Just make your floor with concrete joists isolation and pressure layer with concrete. It wil never rot. This is Amarican way of building and the quality is bad
Concrete I-beams with load-bearing blocks between are super strong. But when you have more than enough lumbar why not use that instead?