Cutting Stairs Made Easy!

0:03 welcome ultimate DIYs today we're going to talk about carpentry and we're going to talk about one of the things that I get asked the most is how do you cut stairs so we're going to actually try to go through the math I'll show you some video of a small staircase that I'm actually actually it's only a couple of steps going up into a house but the technique is the same actually the truth be known the small ones are probably a little harder than the larger ones but we're going to go through some basic terms and help you try to understand how it works foreign [Music] [Applause] [Music]

0:55 okay starting on the actual terms some of the things that you do need to understand first of all which I see people have problems with all the time especially if you're not in the construction world is the horizontal versus Plum horizontal is going to be a horizontal like a weighing position and you do is a level and you'd have a little Gage and the center with two lines and a bubble the bubble needs to be in the center of the two lines that is going to be if I lay it set it down that means that that is going to be a very level surface if I can see that bubble which this one is the other is the plum the plum is going to be like trying to find out if a stud is plum or straight anything that is going on the vertical so I would take

1:41 the same level put it on the vertical but instead of reading this gauge I read the one up higher and that bubble still needs to break the two lines be right in the center very simple but a lot of people do not understand Plum verses going to be level they do not get that concept very important now in construction especially if carpentry construction you have a lot of triangles and if you were in school you remember the Pythagoras Theorem which how it basically Works through triangles and you'll have a squared times b equals c squared that type thing but we're going to try to simplify that and make it easier for you so we'll go into that

2:26 the math part in a minute but let's go ahead and go through the rest of the terms so that you kind of understand the terms so one of the most important terms when you're building stairs you need to know is what is a Stringer a Stringer is the piece of wood that actually if you're going to cut and cut your triangles into which will hold your steps as you go I've got a small one here a simple one just a couple of what we call Treads which is going to be one of your next terms to learn but this is what a Stringer is and you'll usually cut this from a two by ten or two by twelve most of the time it's a two by twelve you'll have a straight edge of your wood and then you are going to lay it and cut the angles now these angles

3:11 I made this little demonstration here for you to actually show you how these angles work and let's go over a couple more of the terms and I'll show you how it fits onto the string the next term that you need to really know is going to be your unit run which is down here at the bottom this is the same triangle just strong so it's my unit run unit run is also your tread and you can remember tread by don't tread on me don't walk on me it's where you walk so on my staircase my unit run is where I'm going to place my foot my next next term I need to know is the rise up to the next unit run which is this here so you have unit run unit rise and then

3:57 you'll have a stair slope which will be from the top of the unit rise to the very beginning of your unit run and it is your slope that is your triangle so when I actually place this on a step I have a big for Bottom t for top those are my truths I place it on there and now I have my unit run my unit rise and then my stair slope which will actually be from this point to this point these are very long Treads made for a special purpose as normal utreads are not quite that long we'll go over some of the basic sizes that we get to doing the measurements so the next thing that you need to know which is probably one of the most important parts of figuring out your

4:43 stairs and doing the math is the overall rise now overall rise if you look at this say this is a full set of stairs you're going to go from the bottom of the stairs to the top of the stairs and you'll take a measurement from this point right here all the way down and then that measurement let's say it's 80 inches that is your overall rise now one thing to keep in mind here on an overall rise especially at the top if you've already got your finished floor down at the bottom that's great or you can actually put your finished floor around your staircase but you have to keep in mind that that's going to change this Dimension here of your rise

5:31 but the big thing to keep in mind is it has to be from Finish floor to finish floor is what you really want okay so now that we've kind of got over a little bit of the terms that you're going to need to know and you have a basic understanding of that we're going to talk about some of the basic tools that you need just for layout there are going to be tools that you will use that are different when it comes to constructing a staircase but just for layout some of the basic tools you're going to need is obviously going to be a good tape measure good pencil now you can use the square flat carpenter pencil you can use the round pencil that's used a little bit more in cabinet making which may be a little more precise that's up to you I generally will stick with this one the other thing that you were is a framing square like this one not to

6:18 be confused with a speed square speed square is great it has its place it's very good when it comes to building roofs but you need the flat Carpenter square and if you're not familiar with a carpenter Square you have two parts you have a body and you have the tongue I always think of the body as the part that I'm going to walk on so if I put it on my little diagram my unit Run part is going to be the thicker my rise is going to be the tongue now what helps you speed this process up is you are going to take your word so this is a two by twelve you're going to lay it across it and make your marks like so and you'll keep making those and what'll speed that up is to use what's called a stair gauge now these little stair gauges will lock

7:04 into place and you will actually get them to the mark that you want as far as like if I'm going eight and a quarter I go up eight and a quarter put the gauge on then I'll come over to this one and say my tread is 10 inches I will come over here and I will put it on the tread now this was a two by twelve two by ten two by twelve I would actually place these like so and then I can make my marks and it would be longer of course and you could actually just follow it straight down that way it's a little awkward here on the but it just slides so I make my first tread and I'll slide down to the next one and I'll show you a little more depth of how we're going to do that but I'm going to show a simpler method to

7:50 that keeps you from having to buy these gauges that you can use it at home and all you need is a couple of clamps a couple of clamps and a straight board we would do basically the same technique so you would get where you you actually want it reading it at the bottom of the board and then you would clamp these in place like so and now I have my stairs I just slide this across the top saves you a little bit of money you'll understand that a little bit more when we get to the layout but I'm just trying to give you an idea some all you really need tape measures pencils a couple of clamps a good straight board and your framer square and one other

8:35 thing that you could use that will help you tremendously with the mat is a good construction calculator like this is the construction master they also have a version of this that works on your cell phone and I would highly recommend getting that if you don't already own a calculator like this one these work much better than a traditional calculator because they're set up for the imperial system and fractions work very easily on this so you can actually enter the full fraction instead of trying to turn it to a decimal so I'd highly recommend this so that really the basic tools that you need just to do a layout so what we're going to do now is we're going to try to get into the actual layout of a set of stairs so let's cover some basic math so the very first thing you're going to want to

9:21 find is your unit rise and an ideal rise is going to be seven inches you don't really want to go over eight and a quarter most of that's going to be determined by building code and it's done that way to make sure that you can comfortably climb the stairs so to find the unit rise though you're going to need to measure the overall rise of the staircase from finished floor to finish floor in our example it's going to be 90 inches or seven foot six inches so now we're going to take our example 90 inch overall rise and we're going to divide it by our 7 inch ideal height it's going to give you a total of 12.86 take that number and round it to your next whole number that's going to give you 13 steps

10:07 now divide 90 inch overall rise with your 13 steps and it's going to give you 6 and 7 8 of an inch so in our example we're going to have 13 steps each with a 6 and 7 8 of an inch rise [Music] so something else I need to bring up at this point is there's two basic ways to attach a Stringer the very first way is going to be to attach it even with your top floor just like in our example that's going to give you 13 Even steps the second way you would attach it would be to drop the Stringer down and use the header as your final riser in the finished floor is your final tread when you use this method it's going to reduce your steps by one so our example will be

10:53 reduced from 13 to 12. let's take a quick look at the Treads the ideal tread width is going to be 10 inches and you want to try not to go under 9 inches so if you want to know your overall length of your Stringer you're going to need to multiply your steps times your tread in our example we're going to go ahead and use an 11 inch tread if we use 11 inch tread we're going to take 13 times 11 and that's going to give us our total of 143 inches or 11 foot 11 inches that is going to be for like method number one if we attach our Stringer as in method number two it would be an even 11 foot so to be clear this is an instructional video that gives you the math behind building itself if you're going to actually build a set of stairs you still need to check with

11:39 your local building department and find out what codes that they use and what they're going to but do keep in mind most building inspectors are not going to require your stairs to be 100 accurate they usually give you about a 3 8 inch variance and how you find it is to find your smallest and greatest rise take the smaller and subtract it from the greater as long as you have a 3 8 of an inch difference or less you're golden okay I'm going to give you a quick demonstration of how you're going to lay out a staircase and how you're going to actually make a Stringer you'll make one Stringer get it perfect and then you'll use that to duplicate and make your other stringers so we're going to use our little diagram of unit run and unit

12:24 rise that we use all the time that I I showed you in the beginning and we'll use that as an example but you're going to start by laying your dimensional Lumber across say three or four saw horses and you start on the right hand side now the right hand side is going to be the bottom of your Stringer the part that goes into the first floor or the ground if it's a deck so remember that I always take and I write a big b on my Stringer so I know where the bottom is and if you look at this it makes perfect sense when you're laying it out because this is the way I've got it written with unit run and unit rise is exactly the way you would start and your unit run is the step so you know you're going to step step step so that being said we're

13:12 going to take our straight edge and we're going to lay out the framing square on it now we have our clips now the most common dimensions for your unit run are going to be between 10 and 12 and common unit Rises between generally seven and nine depending on the code that is being used and depending on your local building department you'll need to find that out before you lay your stairs out because that will actually determine how many steps you have and what you can do so let's take our example where you're going to take we have that backwards remember because the body is my thick part which is what I step on and I use the tongue for my rise just like so we're going to lay it on the board and

13:59 I'm going to take my 10 right here starting at one to ten and I'm going to put it at the edge of my board and then I'm going to clip that into place now I'm going to the other side for my rise and we want we're going to go with seven and a half seven and a half is a good number very typical so when I go to my seven and work it into the half and I'm going to clip that as well so now and adjust it make sure that it is dead on right there looks good that is off right there that's pretty good all right so now what we're going to do is we start with our first step going up the Stringer I place the board on the top and I will just

14:47 pick a spot you want you don't want to be at the very end of the lumber because you're going to have to do a couple markings at the bottom for your Landing but you'll do that you'll make your mark just like so so now there is my first tread and then this is my first stair rise then I'm going to slide it over to my next make sure that 10 is there in the seven and a half now one of the things I didn't do here which I should do and I'm going to do that real quick to show you you take your tape and double check these first two make sure because if you need to make an adjustment you can make it now before you go all the way up the board and by the way if you do mess up just get a little sander sand it off a little smooth start over or an

15:33 eraser but I use a sander it's quicker line it up at the edge I'm exactly 10 that's what I was looking for Edge seven and a half I'm dead on so we are perfect so we've already made our second we're going to slide up to the third we're going to go ahead and put a total we're gonna do one two three four we'll do five steps so here's that one one two three here's four and we're gonna Mark that now this is where it gets a little tricky when you get to your top step you're going to slide it down and line up that 10 with the top of your Mark again and you're going to make one more and you're going to stop you don't want to make this top one because you would go above your landing

16:19 at this point we don't need another Riser so we are going to stop right here we're going to unclip the square and we're going to turn it just like so and make sure that you are lined up on your line exactly and all the way to the edge and then you're going to take this Mark now and go the opposite direction this is the part that is going to ride on your framing member to hold the stairs so you'll stop right there and it'll look something like that and let me zoom in a little for you so that you can see that so now we're going to work on the bottom and where it actually hits the ground so

17:06 you will take your frame square instead of the normal way that we did it we're going to turn it upside down and we are going to figure out the last you line it up and you're going to figure out your last rise which we're going to fall down from the very corner uh it's right here in one perfect now we're going to go down to our seven and a half which is right here so we go down to the seven and a half and then we're going to turn it to 90 degrees just like the top was basically 90 degrees or not basically it is you'll line it up perfectly on the line and you will make this Mark backwards

17:53 this is the part that will actually hit the ground right here this is your first rise so your one rise up see that's your first step Second Step so this is one two and so on all the way down so the um the other thing you have to look at here though is what thickness is your Treads going to be that you're going to walk on so in my case we're going to say an inch and a half so at an inch and a half you can just take a inch and a half piece of dimensional Lumber if you're doing three quarter you do three quarter but you're going to mark that off here you're going to take it and put it at the bottom of the part that hits the ground get it on there perfectly one of the reasons I use the wood is if I'm using treated wood outside it's swollen so

18:39 it'll actually all be the same and when it shrinks up it shrinks up the same but you line it up on there perfectly and then you make your mark so now when I go to cut I am going to come through all the way let's do it again a little bit of dirt I think the lumber there we go just like so so when I cut everything out I'm going to cut this off at the very beginning where it hits the ground now what that happened what happens is when I take this same Lumber and put it on the top of each step with this gone this measurement is going to be the same throughout because now you've got rid of it off the first one and everything else will line up exactly the same

19:27 it's kind of you'll have to do one to understand what I'm talking about but take my word for you have to cut that out now the other thing that you could have a problem with here is if you were putting this down on an unfinished floor then you're going to have to take into account your finished board so say your finished floor is going to end up coming up here now and go all the way across now it has changed my measurement here so my first step is off and I'll show you a little diagram of how the variances that you can have it's most of them are 3 8 of an inch and I'll show you a diagram and go over that as well but that is the main issue now there is one issue at the top and I'm going to show you that real quick as well so I'm going to cover a couple of the basic problems most everybody can figure

20:13 out pretty quickly with the basic math how to lay out your your little triangles for your tread and your rise just like in the actual picture or template per se so if you know that and you're setting up there's a couple of error problems where people make errors they don't think about and one is the finished floor you need to take this into account not only at the Top If You're Building an interior stairwell but also the bottom and is your floor already down or are you placing your stairs on the actual subfloor so if you're placing on the subfloor down at the bottom you need to account for this inch and a half in other words now my

21:00 bottom tread is going to be in this case this is a three-quarter inch hardwood it's going to be three quarters of an inch short so my very first step is going to be out of a way out three quarters of an inch which means if an inspector comes and inspects it it's not going to pass it's it's well above the 3 8 of so how would you fix that so if you know that this is three quarters of an inch and you're going to place it you're going to lose that three quarters of an inch then that means I need to add three quarters of an inch to My overall measurement so that everything works out correctly at the very top if I have this already on I'm golden but

21:46 if I do not then I have to have I have to account for that three quarters of an inch at the top so when I actually install my stairs before the floor goes on it is going my stairs will be above actually it will be above so if you take this away I would actually have my stairs up three quarters of an inch higher than what it'll ultimately be now where this is kind of a trick is it depends a lot on your stair layout because you can take your Treads and you can stop so if it calls for six steps