DIY Concrete Foundation for a Room Addition or ADU

[Music] hi david o'dell here with odell complete concrete this is actually our first day on the job site the homeowner here is a diy kind of guy really impressed me to be honest it's rare when you run into these kind of guys you just kind of do it all but anyway we got called in he's going to do all the plumbing he's doing the um all the underground he dug out these footings for the most part he tapped into the sewer line in the front of the yard and ran it through this side yard area we're going to be conquering the side yard as well but the main focus here is this foundation edition we're coming off the back of the house and the whole purpose of this is for the mother of the homeowner here she's uh almost handicapped so she's we're gonna do a roll in you know wheelchair accessible type handicap shower stall and that's the idea of this we're going to do a sunken shower here we're going to show you how to do that we're going to do a recessed area for a portion of this foundation where the actual shower stall will go and it even shows you the dimensions to get a wheelchair into there and all that kind of stuff little technical details right now we're running the 2 by 12 16 foot and then we've got actually a 2 by 10 on the back side because the grade was higher so i didn't need to go down as deep but those 16 footers right there 65 dollars a pop and then we got 2 by 10 on the back end so that was a little a little less money so i'm really seriously thinking about going with the plastic right now reusable two by twelve but you can see i've got my steel uprights at about three foot spacing then i have a kicker on every upright and the reason you put a kicker on the uprights because you only have to jump one stake really when you're screeding rather than just sporadic kickers here and there everything is kind of in one place right here we're laying out the stall for the recessed area that's why you see those string lines right there the entrance is on a 45 degree angle then you have your fixed walls or shower doors that's your actual entrance and that's 36 inch that little diagonal right there the plans called for 18 inch deep footing below grade and then of course we have the four inch slab above that so we're about two inches being two feet below top of slab right now that gives you four inches gravel underneath that slab four inches of concrete and this grain now right here what we're doing is doweling into the existing foundation and that's a 5 8 inch bit on the dewalt cordless a real powerhouse just blows the holes through i mean short order then what we're gonna do is uh we're gonna scrub the holes with a brush and then we're gonna vacuum out with the dewalt cordless vacuum then after all that's nice and clean the next step is using the uh epoxy that's recommended on the drawing which happened to be this simpson xp which is real typical you'll see that on simpson everything on all drawings really i mean i really haven't run into anything other than simpson here's your vacuum cleaning the hose vacuum brush vacuum you're pretty much good to go it's a clean hole now the epoxy we're using that's a two part you can see it here it actually mixes through the tip because it's in a corkscrew the tip displaces enough so you're not you know losing a lot of epoxy you're gonna lose a little on run out the reason they're drilled at an angle because the existing foundation is the same system we're doing here it's a four inch slab with the massive footing around the edge so what we're doing is angling from the top of slab into the footing and that's kind of crucial because a lot of times these older homes you know they're they were not poor to monolithic like we're gonna do here in other words they used to pour the footings they'd stab woodies into the slab hang their boards pour the slap so it doesn't work that well because it always separates now this in this case it's all monolithic poured there is no cold joints between the slab and the footing so it's never going to separate what we have as far as reinforcement goes we have half inch steel everywhere two half inch horizontal at top two half inch horizontal at bottom complete wrap around the perimeter top and bottom and you know i'm not going to even use adobe's on the bottom bars i'm just going to suspend it from this uh formwork that i've already got here going i'll suspend it with tie wire all this plumbing that you see right here the homeowner did all this he's got his bathroom fixture there he's got a shower stall he's got his vents on the back wall he's got everything wrapped in foam that's going through the concrete all the typical things that you'd see in a normal addition that high-rise three-inch is actually a clean-out that'll be cut down at some point flushed out when we do the wrap around with the concrete for the exit doors that wall in the back of the existing will be knocked out as well here's your gravel base right here this is just clean gravel and that's what they recommended on the drawing four inch lift of that over a six mil visquain there's your six this queen we're gonna ramp it up and in so you really can't get in there with the tractor at this point so what i'm gonna do i'm actually using the mini skid to go to the front scoop it then i dump into two wheelbarrows simultaneously to not lose any and then we just run them you can see it here now as far as the rebar grid goes on the slab itself we're going 18 inch on center both directions and then also every bar is going to have a turn down to the bottom bar in the footing because it's only a 16 by 14 8 inch i believe it was a drawing called for 15 feet but the existing actually showed 14 8. so you always match existing and you know the plan is not always perfect so you have to work with what you have existing so the rebar it's all full pieces there's no splices in this distance in other words even with your turndowns on the ends it's all custom bent we're just bending them on the field but we've got two turndowns on either end that just wrap over this horizontals in the footing and then tie into the bottom ones as well here's some dobies on the gravel because we are suspending a lot of weight we have 18 inch center half inch and then we got all those um horizontals right along the footing edge carrying a pretty good load for those tie wires to hold everything up so we put some dobies underneath the middle now we got a good support system to hit it with some concrete also we have a minor turn down against existing footing that that turned down on the existing footing just tops out at the existing footing which is below grade there and it's about 8 inch 10 inch something like that but as soon as we hit that we just stopped so the new slab will sit on top of the existing footing plus it's got two dowels top and bottom on the footings and then a dowel every 18 inch on the center along the back at in the four inch below grade so the homeowner also hung all the bolts because he's going to be building this entire unit by himself he's got the bolt set at two and a half inches and he's using all galvanized 12 inch long 5 8 inch diameter actually that's the new code here in california is galvanized apparently because regular still interacts with pressure treated lumber corrodes quicker so galvanized apparently doesn't so we're going with galvey basically now the reason it's two and a half inch even though it's a two two by four plate two by four walls the reason that it is um set in two and a half because the existing house didn't have a complete share wall around the perimeter with plywood they only did the four foot kick cross braces where they have the inside of the zoom level this will have a full blown you know four by eight sheets on top of the two by four creating a complete shear on this entire new structure so you have to inset your two by four studs in other words here's your pumper we got martin's pumping out here he's going to blow this concrete in here this is 2500 psi which is really nice because anything over 2500 we'd have to get a special inspection on something like this but since it's below 2500 we don't need one no special inspections are about 200 bucks minimal so this this little setup we have going in this wheelchair accessible shower stall it's three and a half inch drop down that'll get built back up with a mortar infill so you can slow the tile right exactly to the drain and you'll be flush rolling off of the top of slab all those bolts have to be pre-hung prior to inspection that's the reason for that you know in the old days you just wet set them and uh i mean it used to be half inch bolts which was was fine and dandy and now it's 5 8 and these are two foot centers it used to be six foot centers believe it or not you know 35 years ago six foot centers half inch walls now it's two foot centers five inch galvanized so it's changed a lot in 35 years there's the wood bowl float four foot width just knocking it down making it flat the more times you hit it with that the flatter it's going to get because every time you're hitting with that you're looking for holes voids in that span of that four foot distance and you're working it out you know making it flat so we're about hour and a half into it right now after placement and now these little templates have to come off it's plenty hard enough to support the bolt without sinking down at this point so now it's just a matter of because all these little plastic hangers are reusable so we're just gonna pull them off clean them up use them for the next job the nice thing about threading the nut back off of these templates that are holding the bolt that you have clean thread so when the framers come in here in this case it's the homeowner he won't have to uh worry about getting his nut back down on those bolts because they're clean because we've already pulled that off here's the funny trial going over this we got a really good mix here dried up really nice we got full sun just about see that stucco wall in the back well that's going to get knocked through after these walls go up and you can knock the chip you can knock the edges off to connect your new walls to that if you really want to maintain the main residence where people live in what you do is you chip off the edge connect your wall you can almost completely build this building and close it before you have to remove that stucco and drywall for the walkthrough in other words so that was the idea here you can take your time on this particular build and still maintain you know the living conditions on the interior now this concrete got really hard and we hit it really tight i mean when he was running this trial over the last time you could really hear the the trial screeching basically just about burned it black and the meaning behind that phrase burning it black means that you're you're trolling it so hard that the trowel is burning off the steel onto the concrete and it's actually changing the color of the concrete into a black tint that's why they say burning it black so if you ever tell anybody you want a smooth finish or you want to burn black they may know what you mean see the spacing on the bolts there on this entrance that's going to be just a passenger door right there so you can see how it was further apart on either side of your doors windows you're going to have a king stud of course and then you're going to have different bracket coming up on those studs rather than just holding the plate down you have brackets coming up along those studs that'll bolt in horizontal through the king studs that's about the only difference you need to know really on your i'm hold downs here's strip dab i believe this is uh two to three days after fortunately after i hung these forms um when the homeowner was doing the plumbing he also oiled up all my wood because i mean he had been watching my videos for a while i think that's why he was able to do everything that he did here for one reason so he already had everything prepped for me basically which turned out real nice and he saved a lot of money now this is a flat slab so you know water puddling at this point or not draining it's not a big issue because it's going to be completely enclosed but water curing is uh nice that's why i always put water on it after i strip just go ahead and flood it that helps a little bit but you know you should always water for about the first five days periodically nicely water cured out there's the side yard we did back there but we didn't really get a lot of that there's no good camera angles all right that about wraps it up now we're ready to start framing thanks for watching have a good day make sure you like share subscribe hit that notification button so you get notified when the next video comes up thank you

Channel: Odell Complete Concrete

Views: 2,069,937

Keywords: odell, odell concrete, odell complete concrete, concrete foundation, foundation, how to pour a concrete foundation, how to build a concrete foundation, room addition foundation, building forms for our concrete foundation, concrete foundation pour, garage foundation, concrete foundation for home, concrete foundation for house, concrete, how to build a room addition foundation, how to setup a garage foundation, how to pour a concrete room addition, how to build a foundation, slab, diy

Id: 2OYoDwNAA-Y

Length: 19min 41sec (1181 seconds)

Published: Thu Jun 17 2021