Hold Up The Joists Ep.39

[Music] we're ready to start framing and the first thing you frame is the floor but the floor has to be held to your foundation and that's done with a mud sill a mud sill is a pressure treated board in this case a 2x8 that will sit squarely and perfectly straight on top of the stem wall now it's doing a couple things it's pressure treated so that the kiln dried or green or whatever type of ordinary framing material you put in contact with this board is separated from the concrete and a little further from the ground because it is the spores of fungus that are found in the soil and that are floating in the air and that love to generate where wood is in contact with moisture that degrade a structure pressure treating stops that and so this pressure treated mud sill keeps the structural members away from an environment with it where they will deteriorate over time the other thing perhaps a more obvious thing that a mud cell is doing it's creating a point to tie the structure to the concrete we've gone to a great deal of trouble to make this concrete strong you can see all the anchor bolts and the hold downs that will tie the structure down and the first part of that happens in bolting this mud sill to the top of the wall [Music] [Music] [Music] [Music] [Music] I'm marking the location of the anchor bolts and the hold-down bolts onto the mudsill I'm doing that directly i'm scribing the actual profile of the bolt onto the side of the board that takes out the guesswork of transferring tape-measure measurements and it takes out the time that it takes to reel your tape out roll it down the edge of the building write down the measurements and then transfer it to a board that maybe is on a set of sawhorses it's always faster describe if you can if it were just anchor bolts and no hold downs so they're all at about the same height I would just lay the plate on top of the anchor bolts and smack it with a little sledgehammer get a nice crisp mark on the bottom and drill it but with the hold downs in place and the different heights on these on these bolt tops there's no way to do that so we're doing sort of a hybrid between a production technique ie scribing and a more methodical accurate technique ie measuring to create the intersection at the center of the bolt these white rolls of foam that you see is putting in between the mudsill and stem wall are doing a couple of things I think primarily what they're doing is keeping the bugs out because there are little gaps here and there between the bottom of the mudsill on the top of the stem wall and the ants and the bugs would love to just kind of you know use that as their own little highway and so you put this foam in there and it compresses or it expands and it fills those spaces and it slows them up I don't know if it stops them but it slows them up the other thing it does is provide a bit of a vapor barrier so even though this this mud cell is pressure treated and even though it's good for a long time in ground contact I mean theoretically you can bury this in the ground for 25 years and it'll be fine so they say still it's not a bad idea to keep the moisture away from the bottom of even this material so this sill seal is making a tough on the bugs and making it nice on the lumber so just a little bit of a word about this pressure treated lumber it's a totally different animal than any other structural lumber that I'm going to use in this house or that really anybody uses to build anything pressure treated lumber is a little strange a lot of times it is made from a lower grade lumber to begin with now this particular unit is different this is good old Doug Fir and so the boards are pretty darn good even though it's not an exceptionally great grade of Douglas fir at least it's not the standard variety hem for white wood stock that pressure-treated lumber is most often made of now when you see or read or talk to someone about hem fir do not make the mistake of thinking that it is an actual species it's sort of a it's an invented name to describe a basket of three or four different woods be she's starting with hemlock and around here it includes white fur and grand fur and occasionally you'll even find a pine board in a unit all of those species are less valuable in Douglas fir they're less stable they're less straight they're less they're not as strong they are inferior in every way except ordinarily they cost a little less and they will all accept pressure treating pretty well the pressure treating process is you know it's it's kind of a messy thing it's it consists of in sizing or putting little slices in the surface of the board so that the pressure treating stew the mix the sauce call it what you will will go further into the board when the unit is slid into that VAT and pressurized in the presence of the rot reducing the preserving liquid whatever it contains I don't know how long they leave it in there I don't know what temperature they raise it up to although usually it is hot but when they bring it out that stuff has penetrated about a quarter of an inch into the sides and maybe as much as half an inch into the ends now what that means is when you cut a pressure-treated board the end of that board is unprotected so when you read the guarantee that this stuff is supposed to last up to 25 years in ground contact that's just not true if you've cut that board or if it's split because the inside of the board is not protected from rot at all installing the mudsill is really the last chance you've got to get your house square and true now make building it plumb will happen once you start building up vertically but once the mud cells are on or going on you ought to check them once or twice and try to reestablish square if the stem walls have varied a little bit in this case we were about 3/8 of an inch out in that what was a fifty two foot diagonal measurement or something that's not bad but we were able to correct it until you know I can look you in the eye and tell you that this floor is square I mean it's just plain square and that's a good thing we had to do a little shimmy because the top masonry course had just a couple of little wobbles in it up and down nothing egregious nothing that couldn't be fixed you'll see a little shimming here and there to counteract the additional thickness of the top flange hangers and Tico nails that are all around the inside and to sort of smooth out any of the little bumps or wobbles that inevitably you're gonna find when you actually start to build on a stem wall with the mudsill in place and bolted down it's not going anywhere I can put my layout on here for the floor joists the floor joists are going to hang I'm going to attach hanger so they will hang down inside the stem wall which seems enough on the face of it but there's two or three things that have to be sort of monitored and accommodated and sometimes played around with in order to make this work out right the first thing that you have to keep in mind is that this is not just a simple span that is they don't just bit they're not just hump held up on this end and held up on the other end with a nice clean smooth uninterrupted distance there are two intermediate bearing conditions that is those strip footings on the inside of the house are holding these one-piece joists up in two different places so all these things have to line up just about exactly right also the layout where the joist hang and where the studs happen in those pony walls have to be in line because I want these joist bearing directly down on top of the studs that are transferring a load down to the strip footing I don't want them hitting in between on the top plates if I can help it the other layout problem which has been a bit of a problem this morning is that I laid out some block outs some notches in the top of the stem wall for plumbing to go in later where the plumbing comes down from upstairs or from a sink or from a toilet and drops down through the floor with this sort of a floor system has to actually have fittings installed so that it makes a tight bend in the top of the stem wall that means I had to do some saw cutting I had to block out the grout and so the plumbing has to hit right there somehow I think because as I think about it the plumbing had no flexibility I got tangled up with my regular 16 inch layout on a couple of those block outs so I've had to fudge a little bit and create an under span right here I have an extra joist that's going to drop in right here and then right at this point we're gonna pick up with 16 inch layout and go let me explain what an under span is the center's the spacing on these joists is 16 inches that's a nice stiff tight floor an over span would be to have a span greater than 16 inches on Center an under span is a span less than 16 inches on center so in order to miss the plumbing on the other side of the building I've had to come in and create a 20 inch span that's a little too much might be fine but I'm gonna drop an extra joist in the middle of this span it'll give the plumbers room to get their work done it'll make sure that the edge of this floor is just as sturdy as the rest of it and it only cost me one joist I think I've got the board anyway the language is a little counterintuitive here with under spans and over spans if I say over span it sounds like somehow its superlative doesn't it or its exceeding a requirement actually it's a greater distance between two bearing members and it could create a weak spot in that diaphragm or in that wall system or whatever it is that you're building with an over span too far between centers and under span which sounds like somehow you're cutting a corner is actually to bring these bearing members closer together than the plan requires or the code requires or that the manufacturer requires creating an extra sturdy spot in the structure under span good over span not so good so to put this layout on and the typical layouts going to start right here I've put a nail in there on the on the far side of the layout I hang my tape on there and I just start marking 16 inches and go that means I'm marking the right hand side of the joist and putting an X on the left hand side of the mark it's 16 inches and go the alternative is I could mark 18 inches and back you see I can either mark the far side of the board or the near side of the board and when you're telling someone how to lay it out you say 16 and go or 16 and back so this nail with the joist to the left of it is exactly the same layout as on the other side of the building so if I hook that nail I can start putting marks at 16 and go by that I mean the joist itself happens on the far side of the layout you see that 16 and go 16 and go now if somebody says the layout is 16 and back or 24 and back or 48 and back or whatever the layout is and back that means that you would go to the layout mark but your your board would lay behind the layout mark if I was doing 16 and back I would mark this and put the X right there but my they lay out this morning is 16 and go I have a video describes this but on a Stan Lee tape the 16 inch layout is located with a little black arrow and a red rectangle around the the layout that is 16 inches on center it also is made inexplicably for left-handed carpenters even though you lefties are a minority of the market I don't know why working from right to left which is a direction a right-handed carpenter always works the numbers are upside down I don't like it but I still by Stan Lee tapes because I like the color of the layout so this floor system consists of TJ is that is engineered wooden I beams as the joist one piece spanning from outside wall to outside wall sitting in hangars so the layout is critical I mean I really want these joists to land on top of the studs in these walls these pony walls when they sit in the hangers on the stem walls so this is the plates bottom plates pressure-treated top plates Doug Fir that I'm gonna use to build these two Pony walls the pony walls sit on these strip footings they're holding up the mid span in two different places of these joists and if I get my layout right all of the studs and all the hangers and everything should line up so the joists will sit on here nice and straight now here's what I'm not doing I'm not trying to build these pony walls to the exact height of the bottom of the joist because I mean really how am I gonna do that I mean there's a little fluctuation in the height on the two sides there's a little fluctuation in the height on these strip footings so I'm gonna build these pony walls 1/2 an inch short maybe 5/8 of an inch short and then shim at each bearing point and glue and nail little shim packs down to get right up to exactly snug and no more against the bottom of the joists the layout is tricky remember I was fighting the spans that we just talked about on this joist layout I have to reflect that in both these walls exactly the same in the first part of the layout and then once I get to the standard 16 inch layout all the way down these plates it should just be standard 16 and go so I'm laying them all out at once I'm crossing my fingers and I hope that it works once I get it built so don't get bogged down in the carpentry lingo okay if you watch this video a couple of times or if you watch the whole series and then come back and pick up some of the intermediate points again it'll make a lot more sense than right now when I'm it sounds like maybe I'm speaking some sort of a redneck foreign language so just hang with me kind of we're trying to provide sort of a global a global perspective on how to put a floor system together on how to put a house together I'll give you some of the details and they'll make sense later and but in the meantime you can you can just watch the pictures if you want and make sense of it later [Music] these wood-framed Pony walls could very easily have been made from block just like the rest of the stem wall I mean the Masons were here and the mixer was going and the block could have been laid but doing so would have been more expensive and in some ways more inconvenient having them made from wood will make working in the crawl space easier for everyone whoever owns the house you can pass through these Pony walls easily anywhere and the subgrade underneath these strip footings was thoroughly compacted it is on good material I don't expect any settling or heaving issues under the stems and if they need to replace the heat pump or add a new drain line they will thank us because access for modification and repairs is just a lot easier now the term pony wall that's funny isn't it but it as with a lot of things in construction and harkens from the days of horse power where a pony is short and so any wall in a structure that is short you know often particularly when you're framing in the middle of your living space it refers to any wall that is shorter than the standard stud high standard stud length and these Pony walls in the crawl space are short they are not a full height wall no one would make the mistake of thinking this was a basement and so these interior bearing conditions are pony walls kiln-dried Douglas fir on a pressure treated bottom plate this black paper tarpaper 15-pound felt is stapled to the mudsill and is functioning as a vapor barrier you don't want moisture traveling from the stem walls into the end of the joists they need to stay permanently dry and just to be certain I'm fastening this tar paper between the block and the joists now it's not required the manufacturer specifies that these joists be set at least a quarter of an inch away from the block that's one way to do it and yes we are doing that we're not cutting this so that it fits tight up against the block it would be a structural mistake but it's easy for these joists to slip around during the process of decking and you know walking back and forth and blocking them and I would hate for a joist to get slid over accidentally and be in contact with the masonry while we are decking or at any other time and then not notice it and cover it up and have it wicking moistur for the people who live here later I'm not going to chance it I had this felt laying around I've had it since the last remodel that I did I don't remember exactly which one but this is a good use for a little bit of roofing paper that no one is ever gonna see again [Music] the only downside to installing these joists and hangers is the hangers themselves putting them in is tedious driving these Tico nails is a good way to blacken your fingernail and the thickness of the joist and the thickness of the head of the nails introduces a high spot on the edge of that mud sill that in our case bugs me and so you'll see me putting some shims some eighth inch door skin shims at the outside of the mud sill to compensate for the bump or the high spot that the top of the flange of the hanger creates on the inside of the mud sill is this a big deal I don't think so but seemed like the thing to do I had a little other Shin shimming to do for some of the highs and lows in the masonry not excessive just a little easy enough to take care of and you'll get a look at that in the next episode [Music] you [Music] Simpson hangers like these have become as important to residential home construction as screws and nails in fact they have sort of become so normal and so standard that it's really hard to find any sort of a construction project of any size it doesn't have quite a bit of Simpson Hardware in it they have an amazing assortment an amazing variety all carefully engineered with specifications and recommended nailing patterns and drawings and photographs of where to use them and they have and besides that how about this if you don't see something in their literature that tells you how to handle the hardware that you just bought they have a helpline you can call and talk to a real person with an engineering background and who is very familiar with their product so the downside to a Simpson Hardware attachment even though it's permanent even though it's you know you never have to really second-guess it if you install it perfectly it's going to do its job perfectly on a wide range of materials and applications but we've lost our freedom to improvise as we are building these houses because all of these special Hardware items and all of the engineered wood products and really everything now just has to be installed according to the manufacturer's specifications if you want the guarantee and the liability associated with selling something like this to remain with them and not to go with you so if you're an improviser you better learn to read those plans just a little more closely because you can get into a lot of trouble by making stuff up with these hangers [Music] [Music] now having said all that about improvising you see the screws that Nate is installing we clear we called our engineer Dave Thomas and said hey Dave those Tico nails that we installed on the top edge of that mud sill I mean there's kind of driven in what three-quarters of an inch from the edge to the board and they're holding the whole world and we don't want the edge of that board to split off over time and there's a hole on the vertical face of that hanger that would certainly accept a structural screw if it was run right back into the edge of that mud sill and not only would it be holding the hanger up but it would be holding the edge of the board on so we ran three inch gr case they are suitable for being installed in a pressure treated board they are structural they don't break and so we've held the edge of that board back right up tight against the Tico nails so to run down from the top and I think that these floor joists are not going to squeak that these hangers are never going to deteriorate and that the floor will be the last place these people are likely to have any problems for the years and years ahead that this house will be sheltering families now in many cases most cases the best way to hold up these floor joists would just be to set them right on the mudsill right on the stem wall with a rim joist around the boundary it's faster in many ways it's less monkeying around with hangers and they just go right in and gives you more space in the crawl space and you know a lot of times that's the way to do it and in fact you will see us do it that way on the second floor so you'll get a look at that sort of a process also later in the series but for us at the ground floor this option was not ideal because we needed the tall stem wall for the strength in the foundation and we needed the finished floor elevation to be right at grade coming out into the backyard and kind of keeping the house a little lower in appearance from the street if we would have put these floor joists directly on top of this down wall the house would have been you know a foot taller and it would have been two more steps down into the backyard and the space in the backyard would have seemed narrow and sunken because of the retaining wall on the west side and so it seemed the best choice to hang the joists down inside the stem wall inside the stem wall and then to backfill the yard behind the house to shorten and make more convenient the access with fewer steps from the outside [Music] [Music]

Channel: Essential Craftsman

Views: 366,228

Rating: 4.9394093 out of 5

Keywords: framing, stem wall, mud sill, anchor bolts, vapor barrier, pressure treated lumber, floor joists, over span, under span, Stanley Tapes, TJI, layout, pony walls, joist hangers, simpson hangers, crawl space, hammer tacker, I-Joists, teeco nails

Id: qw6GdjJ7VW0

Length: 30min 32sec (1832 seconds)

Published: Fri Aug 30 2019

Reddit Comments

[u/crazybehind]

The floor joist hangers don't seem like a very sound means for supporting the joists. Isn't there a way to have the joist sit directly atop the sill?