Hey Guys,
Started laying out my deck today. I took the “John Carroll” approach. Installed the band, staked and clamped up side and end joists, marked and dug out footings. The Deck is 14’x14′. Once I had the perimeter joists in place on both sides (clamped to the band) I created two right triangles on each side using the Pyyhagrean Theorem and and attached braces the length of the hypotenuse. I then measured the distance between the two side joists to cut the end joist which was 167″. Now this is what has me confused, the ledger on the house is 165″ (plus the two side joists equals 168″) But the end joist plus the two side joists is 170″. A two inch difference. I pulled diagonals on each corner and both are dead on at 238.25″ plus the two braces are set at two right triangles. Is this normal that when you square something like this it changes the measurements as such? I assumed it would be the exact same measurements on each end, did I go wrong somewhere that I’m missing?
Replies
Did you use a tape measure with the black diamonds? What about using sheetrock screws for the braces?
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Not sure about the black diamonds but did use drywall screws to secure the braces
Ricky,
Maybe I'm missing something, but why is one end of your deck a different size than the other end? Or is this exactly what you are trying to figure out?
You can have even diagonals without having equal sides. However, you can't possibly have four 90 degree corners if your measurements are as you say. Not possible.
Not sure exactly how you squared up, but a 3-4-5 on a decent sized deck isn't as accurate as it may seem. Try a 9-12-15 or a 12-16-20 if you can.
Something ain't right.
Diesel'
Pretty much what i want to know if is it possible to have even diagonals and different measurements on the ledger and end joist and still be square? I'm attaching a quick diagram to maybe make it clearer. I right triangled the two corners at the ledger end. Pulled two even marks at 6', one on the ledger and one on the side joist (72"), then figured the hypoteneuse which is 101 13/16", cut a brace with mitered 45's and lined up the marks. (long point to long point). Did this on each side. Then measured the distance between the braced side joists to make the cut for the end joist which was 167" (2" different from the ledger). Cut it put it up , pulled the diagonals, and they both matched at 238.25". I "triple" checked all steps to see if I missed something and I couldn't find anything wrong with my layout other than the "mysterious" 2". What do you think?
Absolutely. If your 168 and your 170 are parallel, and the centers are lined up, then your diagonals will be equal, and you don't have a rectangle. Equal diagonals don't mean all the corners are 90 degrees. Unless the opposite sides are the same length, and in your case, they aren't. If this worked, see the attached.
The thing to do is to make your sides the right length, then square it up.
Couldn't make out your attachment Ten, but I get what your saying. Think I'll just recut the end joist to match the ledger measurement so I know all sides are cut at 14' and then just pull diagnols to square it up.
Like Jeff said, you need to start with the fundamentals.
No, you can't have 90 degree corners but different lengths. Thing is, the measurements that you're talking about would lead to the corners only being a degree or so out. The 3-4-5 method of squaring a corner works, but can be out of whack if your lumber is bowed, etc.
You're building a square, but one end of your "square" currently doesn't match the others. That's a lot easier to figure out than doing a bunch of math. Once you have 4 even sides, get 'em level and get matching diagonals. Then step back and make sure it looks ok.
As a friend of mine used to say: "You're not building a space shuttle". That doesn't mean shoddy workmanship, just means keep it simple.
Pete
Ricky,
If your drawing is somewhat to scale then I would guess that your diagonal braces are a little too short to accurately square your frame. You may very well be square within the area of your deck that is braced, however, your end or side joists may whip in somewhat resulting in your inconsistencies.
"is it possible to have even diagonals and different measurements on the ledger and end joist and still be square?"
Yes and no. It is possible to have even diagonals, and different measurements but your can't be square regarding the frame as a whole. Square means four 90 degree corners. Right now either your corners close to the house are accute and band joist corners are slighty obtuse, or as I stated above... you've got two 90's at the ledger and joists whipping in after the bracing.
Cut your band joist to the mathematically apporopriate size ( I frame my band to be ledger plus the 3" of end joists with the end joists "capping" the ledger and butting into the band joists). Nail or clamp together and then pull your diagonals and THEN brace it off.
Like I said, try longer braces.
Your right Diesel, something is off. I'll do a little re configuring in the AM. Thanks.
Ricky,
you should forget the higher math, it justs adds a chance for a mistake. Always use a 3X by 4X by 5X triangle. Easy math, fer'nstance, 3' side and 4' side = 5' hypotenuse; same as 9' side and 12' side = 15' H.
Try and use the longest hypotenuse you can for greater accuracy.
SamT
You seem to have built an isosceles trapezoid.
Thinking ya wanted a square ....
so why not cut the outter band and the inner ledger so they .... uh ... match?
Just like the sides ... the sides match, don't they?
btw .... the others are right ... if that sketch is anywhere near scale ... those diagonal braces are doing nothing but "maybe" squaring that little corner they are attached to.
JeffBuck Construction, llc Pittsburgh,PA
Artistry in Carpentry
Trapezoid. All night, watching the game, having a few, trying to remember that stupid word. Thanks Jeff.
You made a very symetrical trapezoid. The corners you measured square are exactly square to each other, and are symetrical to each other. They are just not "perfect" right angles. Instead they flare a fraction of a degree until the outside measurement is 2" more than the inside measurement. (It may be that the house is not a perfect "base" for the right angle, so that may have thrown the layout out of whack.)
Ok, how to get it right? Measure to your centerline on hte house side and the outside edge. Check that for square. Now, layout 84" (7') on either side of that. With the parallel-to-the-house sidesthe same length, then check the diagonals.Occupational hazard of my occupation not being around (sorry Bubba)
Check that the sides are all level.
All level Hack
The 'end joist' needs to be the same 165" as the house ledger, 'then' get 'equal' diagonals. (also, when using your pythagoran theorum, make sure you're measuring from 'inside to inside' or 'outside to outside').
Went outside to outside TR
I would drive a nail 3/4" in from the end of the ledger and 3/4"from the deck side(center of 1 1/2"ledger). Drive another nail 6' from the first on the center of the ledger.
Now grab two tape measures, hook the nails, pull one tape out 8' from the ledger and the other tape at 10'.
This will establish true square off of your ledger. It helps to have another person there to line up your string lines on your batter boards at this intersecting point.
Most of all have fun..........If you scratch your head too much you'll have a bald spot. "Rather be a hammer than a nail"
Bob
Tenpenny got it, Jeff backed it up.
You built a trapezoid.
Next time, just cut the pieces to length, end joists the same, ledger the same as the header or rim...nail it up...then measure the diagonals.
When the four sides are the same length, and the diagonals match, you have a square.
Then run the diagonal bracing.
To help you along, if the deck framing is indeed 14' on a side, the diagonal should be just a tad under 237-5/8". Don't have a calculator so I can't gnat's arse it down for you.
To help you along, if the deck framing is indeed 14' on a side, the diagonal should be just a tad under 237-5/8". Don't have a calculator so I can't gnat's arse it down for you.
Wow!
U did that in yer head ... that proves good beer does make us smarter ...
ok ... makes U smarter ...
JeffBuck Construction, llc Pittsburgh,PA
Artistry in Carpentry
oh man, with iron city.......you got a long row to hoe.Remodeling Contractor just outside the Glass City.
Quittin' Time
Yeah...the Corsendonk Cranium Calculator!
Sometimes it works, most times...it's just there.<g>
hey, 14 foot and 2 inches off?
Just put a true square on the corners and eyeball till tight. 2 inches on 14ft will show strong.
Whatta want, 64ths?
be a hack
don't have a calculater?
what the heck ya typeing on WEbtv?
accessories/calculater/standard..
or maybe it's a MAC..they probly don't have one <G>
View Image
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
what the heck ya typeing on WEbtv?
He just told ya ...
Corsendonk!
JeffBuck Construction, llc Pittsburgh,PA
Artistry in Carpentry
So much software right in front of me...and I'm oblivious to it all.<g>
Thanks for the calc link.
Looks like for a 14' square, the diagonal is about 237-19/32.
Gotta change beer, need to get rid of that errant sixteenth.
Your diagonal measurements should be about 237 1/2". Are you measuring frome the same relative point on each board?
Les, fixed her up and 237.5 is exactly what squared it . You were right on.
Ricky,
You have a deck that is a 14' x 14' square. If you use Pythagorean Theorem you will get 237.5879" or 237-9/16" as the diagonal. As Mongo said, just lay out your 14' x 14' deck and check the diagonals and then brace it up.
Whether you cut your ledger and outside box at 13' 9" and your two sides at 14' or vice versa all four side have to equal up to 14' and the diagonal has to be 237.5879".
Just make sure you pick out 4 nice straight beams with no bows in them and use them. It will make things a lot easier for measuring and bracing up. String a line on the side pieces to make sure that they're straight before you nail the brace in.
Another way to figure out the diagonal for any square is to multiply the length in inches x the the Square Root of 2 (1.414214).
Your 14' (168") deck.
168 x 1.414214 = 237 5879" or 237-9/16"
Using the 3-4-5, 6-8-10, or 9-12-15 method is fine but getting the exact diagonal for your square is a lot easier to work with. If someone can remember those methods, thern remembering Pythagorean Theorem or multiplying the length x 1.414214 shouldn't be a problem.
Joe Carola
Well written Framer, Thank you.
several things can throw you off
yes your ledger is on but is it stragint. Is the wall it is attached to got a wow in it , kicking th eledger out of a striaght line, youll get things square but you an get thrown and delayed by that too.
construction calculator, and they are getting cheaper these days
have one in every vehicle
first we make sure everything is nearly level.
14 feet at 6 inch out of level willthrow you off by nearly a 1/4 inch so level it as near as you can
we then pull the biggest square we can 3-4-5 and multiples of or if unobstructed stright line we go for the exact square, in your case 237 9/16 or 19'9 9/16
but no matter what the size we always find the exact the square using a constructon calculator
even if your deck is 23'8 5/8 by 17'3 inch. in a few punches on the calculator will give you the exact square (29'3 15/16, two more key strokes 351 15/16")
if your going to take the time to square it why not make it right on
the other thing we do, ,if we aqre using drawings then we calculate out the squares and write thme down on the plans before even getting to the job site ( like when putting together a meterlal list)