I'm building the 20x30 (with wraparound deck on two sides, ergo 30x40 total dimension).
It's on a slope that drops about 6' over the 30' distance. I could use some advice on how to center the holes for the piers.
I've put up some batter boards, approx 2'-3' off the edge of each corner, just square off the lines and ensure that I've sufficiently cleared the site. The batter boards are not nearly tall enough to level off the lines.
Short of renting and learning how to use the surveyor hardware, I imagine that I could get by with a string, string level, plumbob and a couple step ladders.
I'm open to alternatives or best practices.
Thanks!
My advice, Chateau Prideaux, would be to build your corner profiles all the same height. Once you have that right you can simply plumb down for intermediate set out for your stumps and such. This will give you a better chance of getting the building square. Just measure from corner to corner to get that square. You can hire a theodolite for levelling or use a simple water level like Jimmy did. A line level over that distance would not be reliable IMO, due to string sag. If siting is an issue you will need to establish distance from at least two boundary lines.
To make your corners square I've found a better way than measuring the diagonals across the building (and making them equal). Just use the 3-4-5 triangle thing you learned in high school geometry. Actually 6-8-10 is probably more accurate. Measure 6' along one line; mark it; measure 8' along the other line; mark it; measure the direct distance between the two "marks"; if it's 10' even you have exactly a 90 degree angle.
My building site has a 6' drop in 60' of length, so I know what you're going thru. My floor level is 4 feet above ground level at the shallow end; so at the deep end it's 10 feet above ground level. Yes, my batter boards are 10 feet up in the air (on the deep end).
Good luck
Thanks for the advice.
I used the 3-4-5 triangle method to approximate where to put the boards, with enough room for error. I figured I would come back later to get the true 900 angle. I guess I'll need to replace them on the low ends for much longer boards.
I'm assuming that I'll need to brace the 6' high boards to keep them secure.
Also, I imagine that you can remove the boards once the posts are plumbed, squared and secured/braced; coming back later with the water level to mark the level lines, cut them flat and place the beams on top.
When I was using the line level, I noticed the extreme sag, especially over the 40' distance. I had hoped that if the level is centered on the line it would read true, barring winds, high tides and lunar eclipses. ;)
Line levels ain't much 'count.
I'd think that inexpensive laser levels make better straight-edges than levels. Considering how much problem I've had with out-of-level vial levels.
But an ultra long straight edge, AKA inexpensive laser level (if you can see it far enough, you might have to work at night), may work best to line up your posts.
Laser is what I would use. There are sensors that see the laser in daytime too.
I broke my old one and bought a new one for about $500 the other day - complete outfit, but many places -even Costco have "will do" lasers as cheap as $39.00 - single lasers can even be much cheaper. You can check them for accuracy shooting along the edge of a good 4 foot level.
Jimmys water level is still a good idea as mentioned above.
Don't forget that you can cross square with a steel tape after you think things are near right and make final corrections.
Rent a lazer with a remote sensor unit to set your heights , cross measure for sqr. , with a steel tape like Glenn said , a cloth tape will let you measure about any number you want :othey stretch to much for accurate work.
If you've got a lot of slope it is a pain but set up tall batter boards to plump bob down from , makum out of a good straight 2x4 plumb it both ways , brace it firmly.
Keep in mind that , if I have what your doing right, the height is more important than post being sqr. to one another, your joist system MTL will be sitting on top of the beams you can sqr. that box sill up easier than sqr.ing those post perfectly.
Of course you could be doing a hung joist stystem where the beams are the outside corners like the other guy was talking about , the Alaska guy, your the french guy :-[my bad ;D
Don't make it harder than it is ;)
I agree with PEG. You don't have to have the pier-posts laid out "exactly" square as so much is correctable when the sill is built.
But if you can make it "near perfect" without too much effort... why not? The easiest and quickest way, especially on a slopiing site, is to use a surveyor's transit. I was lucky to buy an antique one from a retiring mining engineer years ago. But by the time you acquire the surveying equipment, and learn how to use it ..... well ....
Instead, there are easy trial and error methods that yield excellent results. I have worked with old-timers that could lay out a square building on the side of a hill never using transit or batter boards. Here's their method as I recall:
1. Using the steel tape already suggested, and the 3/4/5 triangles or the diagonals (already suggested) lay out and stake the corners as best you can. Dig generous size post-holes just on the inside/including the stakes. The holes will need to be a foot or larger in diameter ... unless you are really good (or lucky). Try to make the hole bottoms level.
2. Install temporary reference posts ("play-posts"). Very straight PT 4x4's work well. Two 2x4's nailed together will work. Add just enough soil to support posts. (The posts must be long enough to suit the sloping site.) Rotate the posts so they are roughly square with the proposed building.
3. Tamp the soil to support the posts vertically .... check plumb with bob or carpenters level. Using water level or whatever, chalk mark the posts to indicate a level plane. Later you want the building perfectly level ... but these chalk marks don't have to be that exact .. "close" is good enough. The lower you can make the marks, the easier things will work for you. Now measure from post-to-post at the chalk marks, including the diagonals, to see how close the posts are "to location". (NOTE: Some folks may prefer to use the inside surfaces and inside corners of the reference posts because the diagonals are easier to measure.) Making a sketch of current observations can help you make a wise decision of which post(s) to move.
4. Move the posts as required. By loosening the soil on one side and tamping on the other, you can move the posts quite easily while they are still in the post-hole. Until you run out of space in the hole ... then you may have to lift the post to enlarge the hole. Don't forget to re-check the chalk marks for level if this happens. Add more and more soil to holes as work nears completion.
5. Remeasure. Be sure to check all "wall lengths" as well as both "diagonal lengths" each time.
6. Repeat 4 and 5 until you're satisfied that the posts are near-perfect in square location and are near-perfect in plumbness. Now the playing is over, time to get serious ...
7. Using string and four steel rods (as stakes) at each post, make a "cross-hair" of stakes and string that exactly locates the outside (or inside, if you go that way) corner of the post. Be sure to have rod-stakes far enough away from posts so as not to be in way of later pier footing constuction. Drive the stakes deeply and mark/protect well so they will not be disturbed. This must be done well. Lift the stakes and re-install if they are not exact. Keeping a small (1/16" - 1/8") air gap between strings and posts works best. Be consistent in the direction that you wrap the string. (Digital camera?)
You can now remove the temporary posts as the steel stakes will "remember" the corner locations for you.
JRR, that's a great description! We'll give that a try.
Thanks!
Quote
7. Using string and four steel rods (as stakes) at each post, make a "cross-hair" of stakes and string that exactly locates the outside (or inside, if you go that way) corner of the post. Be sure to have rod-stakes far enough away from posts so as not to be in way of later pier footing constuction. Drive the stakes deeply and mark/protect well so they will not be disturbed. This must be done well. Lift the stakes and re-install if they are not exact. Keeping a small (1/16" - 1/8") air gap between strings and posts works best. Be consistent in the direction that you wrap the string. (Digital camera?)
You can now remove the temporary posts as the steel stakes will "remember" the corner locations for you.
So we tried it. I must admit we cheated early on and it bit us in the end, but here's some observations for those who'd follow this approach.
Rule #1 Drink lots of water
One of the first things that is impaired by high heat and thirst, is judgement.
Rule #2 Heavy machinery helps
I've borrowed a jackhammer to dig into the rock deep enough to set the posts. The first 2 when pretty well, but then the sun started hitting the high point and it was hard going. We're going to rent an auger (machine, not hand held) with a 16" bit for the final holes. I'd be dead by the time I dug and shoveled all the holes for the foundation.
Rule #3 No cheating
We placed the first post at the highest point and then pulled a level line to the next highest, this constitutes the uphill side. When we were pulling a straight line for the third post (south of Post 1), we used the 6-8-10 triangle and we got it to 9'3/4" and thought that was good enough and we could square it up later. (WARNING)
Rule #4 "Tamp it, tamp it good..."
We dropped in the third post. tamped it for plumb/level and 'mostly' square. This post was on the down hill side (about 8 foot tall post with 1 ft in the ground).
Now for the critical error....
On the fourth corner post, we measured off distance and square from the 2nd post. tamped it in and wanted to double check against post number 3. Guess what... we were about 2.5 inches off. In a heat inspired daze and having forgotten about the fudge in the first square, we decided to move post number 4.
Unfortunately, when we placed number 2, it wiggled off the line casting doubts as to it's distance. We still had the line from 1 to 2 there so we would hold it while trying to measure distance from 2 to 4. This doubt lead us to trust the other posts more.
We didn't realize the err of our ways until after a trip to HD to get some rebar to tie the two strings for each post. After we get back from the air conditioned bliss of the hardware store and truck, we checked the corner distances.... we were off about 3 inches along the diagonal from Post 2 and Post 3, we didn't bother checking number 4... we knew something was up.
As we sit in the shade pondering the gaps in our reasoning, realization sets in. That 1/2 in. on the first 6/8/10 translated (over 30'... 30'/6' * .5" = 2.5") to 2.5 inches out of square, which was the distance we had moved post #4.
At this point, in the several hours is took to get here, we'd manage to post up a pretty nice parallelogram.
We were out of time for the day, so we left it as is and we'll have to wait for another day. We'll be sure to get it right (goal is to get within about 1/2 inch in each direction for each post, as we expect that the post to pier brackets will have enough play to allow this amount of adjustment.
Rule #5 Pick two
For our site, each pair of posts is roughly at the same elevation. (1 and 2 are uphill, 3 and 4 are downhill approx 6' lower over 30')
This makes finding the level and distance pretty easy for each pair, but not easy between the pairs. Once you have 2 firmly planted, plumbed etc. (no wiggle at all) and a trusted distance, then work on the next two.
I'd recommened that you pick the down hill side for the first two. This seems counter intuitive, but here's why... The longer 4x4s are heavy and require deeper holes to hold them firm, while you are checking level, distance and tamping it down. They are difficult to keep in position and plumb during the tamping as well. These are much more difficult to adjust and true-up as ours need at least 2' to hold them steady enough to measure distance with steel tape and not pull it out of level while taking the slack out of the tape.
Once the down hill side posts are set, the uphill posts can be held steady, measured and checked for level and adjusted much much much more easily. Those holes are not nearly as deep and there is less complexity involved as you make your final adjustments. In the worst case, if you realized that you've blown it when you check the corner distances, you'll have a much easier time moving these.
I also think having more than one steel tape (one for corner and one for side), and a clamp (or awl) to hold it in place will help some of the frustration with trying to get accurate distances.
Excellent feed back, and congratulations on the progress. Some things are learned best by experience ... and it seems as you are really learning. You're right, its best to get the lower pair accurately in place to start with.
... Other tips: Try to measure without touching the posts. This requires two folks or course, step ladders, etc, etc. It takes some "arm power" and eyeball sighting, but it can be done fairly accurately. The person on the "dumb end" of the tape should "cut a foot" ... in other words, use the first foot of tape as a hand hold ... holding the "one foot mark" as though it were "zero". The person on the smart end knows to deduct the foot from observed measurements. Another way is to use a short piece of twine as a hand-hold in that little metal loop on the end of the tape.
You could use some stakes and 2X4 braces to stabalize the two long posts rather than just rely on the dirt at the base to hold them solid. Just a thought. You will use the braces for something else later anyway so they won't go to waste.
Good idea, Desdawg.
I've even wondered about using sack-concrete, on the lower poles, to stabilized them. Have to break it out later with a sledge hammer.
I sure would like to try one of these gadgets on something ... and this application might be very suited:
http://www.stanleytools.com/default.asp?CATEGORY=LASER+MEASURING&TYPE=PRODUCT&PARTNUMBER=77-910&SDesc=TLM+100+FatMax%26%23153%3B+Tru%2DLaser%26%23153%3B+Distance+Measurer.
Course, if you got the deep pockets (like a couple of folks around here, you know who), this would be the one to try:
http://www.stanleytools.com/default.asp?TYPE=PRODUCT&PARTNUMBER=77-930
Should give you some pretty good measurements without disturbing the poles.
We're starting a little shed for an earth oven. So we'll have something to do after the day's straw-clay gets put in.
With not so critical, but still there siting and sighting problems--it really is both.
May use the very inexpensive father's day gadget special laser level to sight along the posts.
If it will go far enough in the daylight. I think we (different we, though) did this last year and had no particular problems up to about 8 feet.
Looks like they improved the measuring tools, eh? JRR. I like the second one. :)
The old sonic ones were a joke.
Here's the laser I got - used it today - looks like 399 plus tax plus a few things extra I purchased -- not self leveling but a lot for the money. Includes sensor to use up to 400 feet away in daylight 800 foot diameter. .
Home Depot Item 263503 Can't get the link to go to the item so if interested in seeing more paste the number into the HD search box
http://www.homedepot.com/prel80/HDUS/EN_US/diy_main/pg_diy.jsp?CNTTYPE=PROD_META&CNTKEY=misc%2fsearchResults.jsp
(http://www.homedepot.com/cmc_upload/HDUS/EN_US/asset/images/eplus/644425572027_3.jpg)
The day after my failed attempt, I went down to Lowes to look at lasers. I found a couple that looked useful, but this isn't a full time job for me, so a $400 investment, while meeting the 'tool = cool' factor, it doesn't make sense financially. I'm trying to build this out of pocket, as we go, so I have to be very tight on the extravagances :(
I've been thinking (warning)... what about using a tripod, think cheapo / scrap old $20 telescope holding variety. If I secure a vertical line, using say, rebar to get the height, and hang a plumb-bob under. Use a couple of these to get the outside corners of the building. The rebar might be too flexible or I might have probs securing it to the tripod...
jus' thinkin'...
There were strings and cross squaring and trial and error before there were lasers. Things still got build and built well.
Even the laser won't help totally with the hillside project. I think you are on the right track. If you establish the bottom line first as you mentioned you can set the posts permanently with a string line for straight letting the tops run wild - extra high to nail a temporary board on at elevation. For more accurate squaring on a large scale then you can go 30/40/50 at the hillside - put the 40 on the established line on the projecting posts. I scribe a line in the dirt at the 30 and the 50 - where they cross is the square off of the established line as you already know I think. Then you should be close enough to fine tune it by cross squaring and tapping the frame around with a sledge hammer --- oversimplification I know. Sometimes you just have to be there to see all of the problems encountered.
Allow your flexibility on the uphill side as you mentioned -establish - secure, plumb the entire bottom line first so you have a positive line to work from. Just get them relatively in the right place so that you can live with the place the top comes out and adjust it to fit the bottom line. This way you can positively set the posts in line and in concrete on the bottom and fool around with the top where it is easier. It is then easy to run a steel tape from the established bottom line posts to get the top parallel line - scribe it in the dirt - set batter boards - set a string over it then measure and remeasure - adjusting the string until it is perfect -
Thanks for the idea Glenn.
The 30/40/50 is where we ended up recognizing the issue, we're taking the 20/30 and planning a 10' porch = 30/40/50 as you mention. So this was easy for us. Here's where a second steel tape would help. Setting the downhill posts at 40', measuring off from each 30' (building edge) and 50' (diagonal), where they meet is the outer corner.
I still think driving the 2 pairs of rods and tieing string is the way to go to 'permanently' mark the final outer edges of the corner posts. I'll let you know how it goes this weekend. :)
We figure that once we get the outers located, finding the other holes will be a cakewalk by comparison. Once they're all marked we'll get the auger and start diggin!
Batter boards are better than rods -- note that I use the rods sometimes too but they are easy to bump- fudge or not be plumb changing the line as it is raised or lowered or they get bumped -- batter boards will remain stable if installed past the end of the work area and done securely.
Not to mention take off and replace your strings when you need to work in the area where the strings are.
I've always hated them, but they do work. and they're easier than most of the alternatives a creative mind can come up with.
If you don't have rock-hard silt where you are building. Or just plain rock.
Amanda,
It's pretty much exposed rock... the first couple iches crumble some, but after about 6 inches its solid except for areas near trees where they've dropped enough material to make it almost look like soil, which means maybe 8 inches deep. :)
I've just posted under the projects, so you can look for pics over there, or go directly here
http://new.photos.yahoo.com/spriddy89/album/576460762312058174/photo/294928803055327545/1
Let me know if you have problems seeing the pics!
Pictures are fine at Yahoo--didn't try the other.
My first thought was--Wow! if you wanted to make a stone foundation or stemwall (for a strawbale house, for instance) all you'd have to do to get rock is to walk around and pick up rocks.
Yup, definately won't need to buy any prefab blocks for retaining walls/landscaping. Just a few days of gathering stones and a little mortar mix.
QuotePictures are fine at Yahoo--didn't try the other.
My first thought was--Wow! if you wanted to make a stone foundation or stemwall (for a strawbale house, for instance) all you'd have to do to get rock is to walk around and pick up rocks.
That's what my wife thinks, but when I try to do it, it just doesn't seem all tha easy. :-/
No kidding!
Of course you wouldn't run into the situation a friend did--she was out gathering rocks and urbanite--went into the highway department's lot, didn't think about when they might close, was locked in with her kids. No cell phone. Fortunately a worker had forgotten a thermos bottle or something, let them out when he came back to retrieve it.