Guys,

Want to get an idea of you're preference when laying out footers.  Do you string the centerline of the footer or one of it's sides (left or rigth).  What about 45's?

Thanks,

Leonard

According to the concrete guy I talked too early on in my house project, neither!

I had the footer dimensioned on the outsides. He said redo the drawing and dimension the footers according to the outside of the wall, that the usual practice is to string out the outside of the walls. It makes it easier to be sure the footers end up under the walls like they're supposed too! My footer drawing has a phantom wall outline on it, with the dimensions shown to the phantom wall.

I'll find out soon if a second concrete guy, who I probably will use for the house, thinks the same.

First string the exterior wall (outside) for ICF wall layout (mark on Batter board), and then string the footer layout (outside). refer to post below.

Make sure to set batter boards away from footers.
The batter boards should be long enough to layout and mark both footers and ICF exterior wall layouts.
Make sure all layouts are square using the 3, 4, 5 measuring method.

I set the exterior walls of the ICF walls on the batter boards.
Make all measurements with a steel measuring tape (100 feet tape perferably).

Depends on the width of the footers and width of the walls.

Subtract the width of the the footer minus the width of the ICF wall.
This difference you divide by two for the result (add this to the exterior wall layout on batter board.
Example: 23 inch wide footer minus 11 ince wide ICF wall.
The difference is 12 inches, divide 12 inches by 2 and this result will equal 6 inches.
Then add the result to the exterior ICF wall layout to achieve footer layout.

Recheck all you measurements, check for squareness,  and work.

Check the specification of your ICF brand block. Width, Height, & Length.
Layout your stem wall on paper or CAD.
The result will be where your ICF blocks will join when cut and will help in creating a more consisting webbing overlap (web spacers). Try to make all web spacers of the next row of ICF block overlap on top of each other. Will help for the drywall and other items needing fastening to these ICF blocks.
Do the same for the 45 degree ICF blocks.
This will help on eliminating ICF block waste.

I bought a new 100' fiberglass tape a few weeks ago for my house project. I have an older steel 100' tape that is a bit of a pain to use. I looked and looked for info on how much tapes stretch in normal use, and how the accuracy of fiberglass tapes compares with steel. I came up totally empty  handed. My brother, who has done quite a bit of construction, said get the fiberglass tape. It's as good as steel and a whole lot easier to use and keep clean, especially when you're working in muddy conditions.

So, what's your experience with regard to how fiberglass compares to steel. Are they less accurate, at least enough to make a real difference? I'm sure you don't want to put a lot of tension on a fiberglass tape or it may stretch, like in pulling it straight across a 70' open space. But from a practical standpoint is there really much difference between steel and fiberglass?

The fiber glass tapes do stretch out and fatigue over time.

With steel, there is little stretching and fatiguing.

Usually standard tapes will cover 20 to 30 feet.

Use the next size of steel tape, anything over the use of a standard steel tape, with steel tape less chance of the tape stretching.

"A good layout starts at the foundation and a good start to a home " by Richard L. Garcia, Home Owner Builder in Espanola, New Mexico.

Use the burn a foot method for more accurate results.

When I layed out my  last home, 68 feet length by 40 feet widths, the diaginol measurements was off 1/16 of a inch.
Check the diagnol measurements, from opposite corners. This will check how close the measurements are to square. It will take some time.
The closer the overall measurements, the squarer the  layout and home.

Are you using a surveyor to stake your corners and excavation depth, per your plot plan? While they are staking your corners, why not just have the surveyors stake your footer too. I find they are willing to do this at no extra coin since they are already out there. Certainly no problems with square, angles, contours, etc.

Always layout using "outside face of wall"
Pins, Stakes, String lines, nails with ribbons, we also red chalk lines, directly on the dirt, florescent paint, whatever works for you.
We use a theodolite to maintain 90 deg corners. 3,4,5, diagonals equal, whatever.
Offset the outside of footing appropriately. Projection from "face of wall" 6 inch plus, or as required.
Working with the "outside face of wall" dimensions for the footings will allow faster layout for the actual walls, as the numbers will be familiar.
You might catch a drafting error earlier too .
Can't beat an open faced surveyors chain for accuracy, but when it comes down to it, fiberglass is just fine.lol

I've never heard that phrase before. I take it that means start the measurement with the one foot mark on the tape to avoid inaccuracies of the hook. If so, I've done that a lot with shorter measurements by starting at the 1" mark on a tape. Works great except for those moments when I suffer a brain fart and forget to adjust for the first inch!!

The burn an inch method works too.

Don't forget the layout for the rebar.

Every post is correct. Different methods with the same results.

Burn a foot definately works better. And that brain fart your talking about is refered to as "inch syndrome"

Dave

Personally I do not use outside wall dimensions for layout, as what is most important is interior space.
This is very convenient, as many times you start with prints that are for conventional construction.
ICF conversion prints are not always ready at the start, and it is always the outside dimensions that get
changed in conversion as everyone wants the same interior space, of course.

Also I render more complex projects in Sketchup, as I said in another thread. A screenie is below.
(this is going to mess up the thread)

This model is fully to scale, and I can rotate in 3D and take any measurement anywhere, so can ensure there are
no errors in the prints and can run this by the architect for approval. Then I take off my physical
layout directly from the model, and if any errors, not my fault. No thinking allowed, on-site.

To this model I will next build the ICF walls block-by-block, with rebar, and this will allow me to get the
precise amount of materials needed for this particular job. (including cubic-yards of concrete)
Very little waste.

Sketchup is definitely not for everyone though, as it takes weeks --full time-- to become proficient
enough to model.

Leonard,

From some one who has done many hundreds of foundations, always work from the outside dimensions of your building. It is the standard in the industry and any time you are talking to your designer, architect, engineer, sub contractors, and or the county they typically will refer to your outside building dimensions.

I know Eric and Dave are experienced installers and give good well thought out advice. Any time I am helping a client or contractor lay out footings we don't even get started without a final set of properly dimensioned plans from either the architect or the engineer. The reason is, if you are building a simple four cornered box it is not a big deal to work with a wood set of plans and dimension them on the fly but when you start to get into more complex buildings with complex roofs with girder trusses and beams, everything needs to line up.

So that being said I use steel tapes and Pythagoras' Theorem (a good construction calculator helps). I always use two points and only those two points and find the rest of my corners from those two points. The reason is if you have 24 corners in the building and are off a 1/16 on the first corner then use that corner to find the next and so on. At the end you could be off 1 1/2 inches. That is the method I prefer but I have many contractor friends and colleagues who use batter boards with great success, especially now since someone has invented the jiffy batters that work, according to the folks that have used them, awesome.

ICF Contractor

Yes I realize that using outside dimensions is the traditional way. Go ahead and use it, but you will have
interior area and volume errors with ICF in certain circumstances, Eric.

Maybe no one will notice.

Quantum, that is correct if your working off a stick print. There was a time when we had to sell ICF and most prints where stick
frame drawn. Now that we have created a market the prints are drawn in ICF which alleviates your concerns above.

ICF contractor: I agree with your methods, as a past ICF installer our methods where allot like yours. Steel tapes are the only way
to go, vinyl stretches to easy and fluctuates with temperatures. People learn certain ways to do things and they become common
place for them. Sometimes there reluctant to branch out to new methods and still believe in old tradition. Personally I believe
batter boards are a waste of time (mine).

Dave

I prepare my models in early days, and since they are 3D sometimes the conversion prints are based on my
model. But conversion is not the only case where you'll get area and volume errors using outside
measurements in ICF. I will limit what I say here because it's the same case as with you and ART.

But using outside dimensions comes from traditional string layout... you can't run a string through a wall.
I don't use this method, suffice it to say, OK? And please limit disclosure of other methods I've told you.

Q:
If a survey crew has gone ahead of us we are smiling.
 Standard for them is "outside face of wall" also, as the BLS ( building location survey) required by the money lenders
 is proof of compliance.
When we have a crew of 6 standing around waiting for layout, it gets costly fast.
We look at the block module and try to maintain "interlock" so we minimize vertical joints.
Eliminating "oddball" dimensions eases frustration levels onsite also.
I wish more ICF designers were efficient in their course matching vs floor elevations and wall dimensioning.
Most of the stuff we have done has been converted wood frame drawings, so there are always issues.
As you can see from the pics we use a fair bit of paint..this really aids quick review by others , like the GC, homeowner, or the soils techs,
 they immediately see where things will be, and can ask for remedial if necessary.


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