Options for Fastening Deck Posts to Footings

[Music] so the post the footing connection is super-important for a couple of reasons this has to resist both lateral loads and uplift loads lateral loads of those that you can think of a riding lawnmower backing up into a post and if we weren't anchored down it could kick that post off and the deck could fall on up lift loads I would be like a high wind from a hurricane or even a heavy thunderstorm that could actually lift the deck up off of the concrete footing so by having a mechanical anchor to tie that down we're going to resist those loads and be able to keep the whole deck stable now they're a bunch of different options and we'll walk through each of those so you got see what your choices are starting with retrofits so if you already have a deck that has a six by six or a four by four posts down on top of a pier and you want to secure that down in place so it doesn't get moved you can take some of these retrofit post connectors they're going to just go right around the side of the post we get screwed in with some structural screws to the sides and then some structural concrete screws down into the concrete securing that post down now if you've got a big six by six you might put four of these on if you have a four by four which is a little smaller to is going to be more than adequate so one of the most robust connections you can make is a cast-in-place post base these are going to have an open hollow area at the bottom below a standoff that you're going to imbed down into the concrete by suspending this in the footing form before you pour the concrete preferably you can install them after you've poured the concrete but in that case you have to make sure you use a vibrator to get the concrete to flow evenly through and under that standoff now these are super heavy duty and they're tricky to install the way most contractors will install them to get the most accuracy is to actually frame the deck put the post in temporarily securing them in place with some temporary supports supporting the beam and then you attach this to the bottom of the post over the footing hole and then pour the concrete that way there's no mistake and where they're going to be located where I use this type of connector more frequently that other connectors is when on building a roof over a deck I've got additional uplift loads that have to be accounted for when you have a roof and that's going to be transferred through the post down to the frame of the deck then through the post down to the footing this type of connector gives us a lot more uplift capacity than some of the others I'm going to show you so probably the most common type of way to anchor into concrete footings is to use a anchor bolt or a J bolt these are cast in place when the concrete is being poured the nice thing about them is they're relatively inexpensive but they give us really good uplift capacity there's a bunch of different pieces of hardware we can make for the connection between the bolt and the footing to the post but each of those only gives us a little bit of lateral movement in and out or left and right and that's dictated by the slot so you still have to be really close when you're installing these in locations so that you can make sure that the post when it comes down is going to fit right in the socket of that anchor let's look at the bottom of a couple of these so you can see how that comes into play this one for instance has an l-shaped slot that's going to enable us to move in and out about an inch inch and a quarter or if we turn that 90 degrees is going to be an inch and an inch in corridor left or right so that gives us quite a bit of movement some of the others don't give us quite as much they're gonna have just a small slot so that might be something you take into consideration when you're looking to a piece of hardware in addition to some other features like the gauge of the metal how thick it is how much uplift capacity it has and how much lateral resistance capacity it has that's all going to be based on the height of your post or the exposure you have to high winds owns now all three of these have a standoff in the middle and these are important you can get connectors that will actually let the wood post sit right down on top of the concrete or very close to the concrete the trouble with those is that any water that settles on top of the pier or wicks up through the concrete can get sucked up by the end grain of the of the wood post and then increase the chance that you could get that post rotting out with that one-inch standoff that water's gonna tend to drain away it's also gonna dry a little bit quicker and you're not in direct contact with the concrete so the woods gonna last a lot longer longer lifespan on the deck for what you're spending the money on now these come in both 4x4 and 6x6 sizes one of the features on some of them where they have the upturn leg is they've got good height connection on the post and they'll come with some structural screws we can connect those others have an upturned leg that you get three sides that are already bent into position so when you set the post in you've got a way to slide that in and then you turn this final leg up and then dry fasteners in to secure it so there's a lot of different options with regard to the hardware let's take a look at some of the anchors that we can use to connect to these connectors to the concrete in the event we didn't cast a J bolt into the concrete when we initially did the footing so some of the anchors we can use that if in the event that we didn't put a J bolt or an anchor bolt cast down into the concrete or some structural hot-dip galvanized screws you're going to want to make sure that if you're going to use these you check with the manufacturer to make sure that these are compatible with both pressure treated lumber and the hardware you're going to be installing because some can be installed in exterior applications and some can't and some different ones are going to be a problem if you do actually will fall apart so what you need to do is bore a hole with a hammer drill into the concrete a little bit deeper than the depth of these screws and you're going to need to blow that hole out and then you can drive that screw right in the beauty of these is that they're simple to install and you can precisely locate that anchor underneath where the post is going to be you don't have to rely on doing that at the casting point when you're pouring the concrete way as you do with the J bolt another option is wedge anchors now these wedge anchors have a collar at the bottom which expands to grip the side of the concrete hole that you've drilled in the in the footing of the pier after you've installed it so you drilled the right size hole usually it's a half inch hole if you'd got a half inch bolt you drop that down and then as you crank down on the nut it will draw up the friction on the side of that hole will expand that wedge it'll secure this down remarkably these have a really good capacity for uplift more than I would have ever expected and all of the specifications for that are outlined in the manufacturer's guide so you can look to those to find out if you're trying to meet a certain uplift capacity what those would be with all of these fasteners as I'm going through them one important thing to note is the concrete itself you might be inclined to use these when you initially pour the concrete say a day or two later when you're ready to frame the deck but you don't want to do that you want to wait until that concrete is cured that may mean that you have to temporarily support that deck and wait 28 days till the concrete is cured before you use some of these systems so check with the manufacturer to see if there are any limits to the how old the concrete is to make sure it's not too green and tend to crack in the event that you use these before they're cured the last option is a chemical option these could be an epoxy adhesive and are acrylic adhesive and these have gonna Bowl tubes where there's actually two components inside of the the tube either with separate tubes or a uni tube and then once you put that nozzle on the front there are little convolutions in that tube as it exits out the front that are mixing the acrylic with the hardener or the epoxy with the hardener so that when you inject this into the hole it's going to be ready to set in probably a couple of hours depending on the temperature there are key installation details you want to check from the manufacturers installation instructions but some of the big ones are making sure the hole is clean before you actually install this that means brushing and blowing it out then after you insert the adhesive you just drop the threaded rod in and then you can start to set the anchor you just can't tighten up on the top of that nut after that's had enough time to cure [Music]

Channel: finehomebuilding

Views: 1,146,025

Rating: 4.9138474 out of 5

Keywords: Shop Class, deck framing, deck posts, footings, piers, posts

Id: 95_jg0Hms1s

Length: 8min 50sec (530 seconds)

Published: Thu May 30 2019