IRC Ledger Bolting Pattern

hello and welcome to building codes for building decks an educational program covering every international residential code provision that affects deck design and construction my name is Glenn Mathewson and I'll be taking you through this class ledger bolting patterns it's one class from the structural provisions one ledgers and lateral loads series so what's on deck for this class first we'll talk about what we did for ledger bolting patterns prior to the publishing of the o.9 international residential code then we'll talk about the new provisions that were published in that o.9 code next we'll talk about the changes to those provisions in the 2012 IRC and finally solutions to the 2012 IRC remember this class is only about the bolting pattern as the provisions in 2012 are quite cumbersome so first let's look at a 2 by 10 ledger and how we used to bolt them to the houses on on codes from 2006 and prior really deck builders did have a standard it was just not published we put a bolt high put a boat low put a bolt high stagger them down the length of the joist and it was usually one bolt every 16 inch on center 1 between every joist Bay some local or state jurisdictions may have written their own provisions but it would have only been regional the spacing between those was indeed governed by those local jurisdictions and again it was often just 16 inches on center then in the 2009 international residential code a table was provided that allowed us to see how to properly bolt a ledger to a wood frame structure and know that it was done to code a national standard was born under that code there's a 2-inch no zone no bolt zone 2 inches in from the end of every ledger piece that could be either at the end of the deck at the edge or the ledger ends or it may be between two ledger pieces if you have a wide deck running down the length of a house no bolts can be closer than two inches from the end there's also the 5 inch no past zone we're the first bolt placed must be no further than five inches from the end and this left us with a two inch to five inch area from the end of the ledger to place the first bolt that was likely already being done by most builders the first bolt right inside of that first in joist there was also a vertical control that was included in the 2009 stating that the bolt should be staggered high and low at a location two inches from the top and two inches from the bottom that's what these black lines represent so we would place our first bolt here followed by the next bolt and followed by the next bolt down the length of the ledger in accordance with the spacing we're not going to talk about the spacing as I said in this class as just the bolting patterns under 2012 we'll take the full 15 minutes where did the two inches come from it makes sense it came from joist spanning between two bearing locations under the international residential code the top two inches and bottom two inches of a joist cannot be drilled as these are the compression and tension cords that allow that joist to span anywhere in between you could drill your holes well similar to the hole for a ledger bolt this is what made it simple to put the two-inch provisions in for the 2009 IRC and then again your spacing comes from the table and we'll discuss that in a different class now we move to the 2012 IRC so the first thing that was done is the hard two inches down from the top and two inches from the bottom was eliminated and more of that no bolt zone was created simply saying the bolt didn't have to be right at that two inch mark but it couldn't be within the two inches however there was some changes to the bottom location that location dropped down to three-quarters of an inch for your no drill zone and that's due to the internal stresses that occur in the ledger let's talk about them here we have a ledger with our upper bolt in our lower bolt now the lower upper bolt being about two inches down from the top remember the ledger is loaded up with material patio furniture partygoers and just the weight of the deck itself this is pushing the ledger into the bolt and thus pushing the bolt back up against the internal material of the ledger if too close to the edge of the board it will split and it could even tear out the top edge of the ledger this is why the two inch distance there was retained however at the bottom the ledger is really just sitting on the bolt whereas at the top it's kind of like it's hanging from the bolt well when you're just resting on the bolt you don't risk tearing out any part of the ledger so the three-quarter inch was a lot was RIT was reduced to three-quarters so I've gone back to the graphic now and let's take another look we've shaded in the area in green where that first bolt is permitted to be located the red shows a no bolt zone the first vertical control is that of the distance between the Volt's the staggered bolts they cannot be less than one in five eight inches apart and not more than five inches apart so we have to raise our lower control in this example up to the five inch line based on that upper bolt location and let's raise our lower bolt as well now we look at the second vertical control and this one is from the top of the joist down to the lower bolt and these are minimum distances a 2x8 can be no less than five and a half inches from the top however there's an exception if it's a two by eight on a two by eight band joist it can be reduced to four and a half for a two by ten Leger six and a half and a two by twelve seven and a half so we'll add in another control line but this represents the highest that the bolt can go so we'll fill in the allowable bolt zone in green as we did before let's pull away the label and just move our six and a half inch max minimum distance from the top over to the side and we'll shade in the rest with red now everything we have here represents the distances with the top with the upper bolt being at the highest location and this looks pretty simple we look at it we're only about seven inches to the center of that bolt location and two and a half inches from the bottom now this really didn't change much from the o.9 code two inches from the top two inches from the bottom however there's a little more to it let's take those labels away and let's put that green back in there as indeed we can get that lower bolt down to that three-quarter inch from the bottom line but what it takes is lowering the upper bolt if we lower the upper bolt it can go as low as one and five-eighths above the lower bolts but this means we can now lower the lower bolt as well up to five inches less than the upper bolt lower than the upper bolt so there's a dual relationship the relationship of the bolts together as well as the lower bolt to the top of the ledger now we've established the entire acceptable bolting zone for this 2 by 10 ledger well pull away our labels and we'll color it in in red and make it simple now let's take a look at the next piece in 2012 concerns were also added to how we penetrate the band joist and where the bolts are located on the band joist this causes a significant problem right at the start we have to know the band joist to know how big it is to know where the ends of it are materials and so forth but this class reveals how simply the bolting pattern requirements are going to cause a condition where we have to visually verify that band joist where it ends how big is it first let's remember the band joist is fully supported along its bottom edge by the plate below the same two-inch rule applies to the ends no bolts 2 inches from the end of any band joist piece most homes are going to have a segmented band joist running along a long line of the house so you'll have to look at both sides of a joist to see if the grain changed if the marking material some some type of clue from one side of the joist to the other as the splice is at the end joist and from inside would not be visible alas determine where the ends of the joists are the band joist and state two inches away we also have the upper and lower limits for the tear out just as we did for the ledger but they are reversed the forces are different the ledger places forces on a bolt downward and that bolt then places those forces downward on the lawn the band joist on the ledger the bolt is pushing upward so here we see our three quarters of an inch moves to the top and our two inches moves to the bottom and now we've established the drill zone and the no drill zone for the band joist we'll take a look again at the at the ledger and now let's overlay the two to see the interrelation and find where the two allowable bolt locations overlap as these will be the only places the lag bolts can be placed I've dropped the ledger a quarter of an inch so that the decking is flushed to the top and here we can outline the area where the two acceptable bolting --zz overlap this is the bottom limit which is based on the band joist and this is the upper limit which is driven by the ledger you can see there's not much room in between so if we wanted to drop the deck down as many homes want a step outside their door we're going to find very quickly the upper and lower limits meet and we can only get a three-quarter inch step from the home down to the deck this may not be acceptable to many many homeowners especially in regions with snowfall so again a 2 by 10 band joist on a 2 by 10 ledger will not yield more than a 3/4 inch step according to the provisions in the IRC let's go to the chalk board and see how that affects numerous combinations of Ledger's and band joists here I've listed every combination of 2 by 8 ledger and two by 10:00 band joist some of them are even a negative distance thus there would be no way to structurally install the 2 by 8 2 by 10 ledger on the 2 by 8 band joist or below the 2 by 12 on a two by ten let's take a look at this bottom one the two by twelve ledger on the two by twelve band joist we get one and three-quarter inch step I'm going to show this to you in a different orientation this is looking at a section view of the rim joist ledger and you'll see the joist extending off to the right here's the no drill zone for the ledger and the no drill zone for the band joist here's where we'll place our upper bolt at the top at the highest it can go and we'll look at our first vertical control stating it with at the lower bolt must be no less than seven and a half inches from the top so this becomes a no bolt zone however there's another control which is no more than five inches from the bolt and here lies our first problem the minimum distance is lower than the maximum distance thus we cannot put that first bolt where it's located it would need to lower down so that the maximum from the bolt and the minimum from the top meet at the same line at this time we can now determine where that bolt can go however we would still like a step down from the deck so let's take a look the upper limit is here for the ledger and the lower limit is here for the band joist this leaves only one and three quarter inch in between if we lower the deck and lower the deck until the two limits meet we find that we have a maximum one and three-quarter inch step and we can go no further now let me try to provide a solution to this one idea would be to use a lower profile joist than the ledger installed this would be compliant to the international residential code in this example a two by eight joist is used with a two by twelve ledger and a two by ten twelve band joist and we can get a step up to five and three quarters of an inch this is the greatest step I could get to derive using the IRC provisions so we'll look at the final results on the chalkboard again here's what we had with the standard installation if we use two by six joist with two by eight Ledger's we can gain about two inches and get upwards of a five and three-quarter inch step with that lower combination if we use to buy eight joists with two by 12 and two by ten Ledger's you'll see here in red the amount of increase we can get in our step including the one at the bottom in the example we just gave the five and three-quarter inches there's one last suggestion I'll make and this is not code compliant but let's look at it realistically here's that condition again at the two by twelve and two by twelve band joist and ledger and the two inches you see at the bottom where the bolt can go no lower remember we were concerned that we may tear out the bottom of the band joist we have the force of the bolt pushing down on the band joist but the band joist is completely supported along its length by the plate below and the force of the house above is squishing those two together will we really tear out the bottom let's look at it this way here's our two inches and what if we lowered that to one inch not code compliant but perhaps worth exploring with the local building department with that being fully supported at the bottom this tear out is going to be pretty difficult with that plate supporting the bottom this is not code compliant but it is something worth considering to explore and see if structurally will work to get that step down from the door this class has been provided to you produced and narrated by Glen Mathewson I hope you enjoyed it and I hope you will continue to pay attention to the changes occurring in the code for the decking industry thank you

Channel: Glenn Mathewson

Views: 41,614

Rating: 4.8802395 out of 5

Keywords: code, decks, ledger, IRC, 2012, 2009, bolt, codes, engineering, building

Id: f4y5JT1XH4o

Length: 14min 59sec (899 seconds)

Published: Mon Apr 09 2012