wall types and avoiding odd dimensions

[jwilhelm]

Just curious how people are dealing with dimensioning issues releated to wall types, for example if I make my gyp bd 3/4" instead of 5/8" I dont end up with dimension strings with 1/8" dimensions, however this seems to go against the Revit concept, how are people handeling this? is it best to use real world dimensions thoughout?

[greg.mcdowell]

Don't change the thickness of the materials, move your walls. If you don't the contractor will do it for you. <grin>

[jarosa]

Don't change the thickness of the materials, move your walls. If you don't the contractor will do it for you. <grin>

Well, being a contractor I'll tell you my framers will try to build it to your dimensions and when the dimensions don't add up, they're going say unkind things.
Model it to the 1/8". If you need them to adjust placement of an element either place a ± at the least critical dimension or leave that dimension out and the remainder of the elements in the dimension string will be where you want them.

John

[dlpdi5b]

Dimension to the items that are present during that phase of construction. In other words, dimension to face of framing, don't dimension to something that won't be there for several weeks. the one exception is if you have a critical clearance, dimension it and note it as 'clear", or "finished" or face of ....

[sthedens]

Dimension to the items that are present during that phase of construction. In other words, dimension to face of framing, don't dimension to something that won't be there for several weeks. the one exception is if you have a critical clearance, dimension it and note it as 'clear", or "finished" or face of ....

Amen!, dlister, Amen!

[patricks]

This is why we always, ALWAYS dimension to edge of slab and CENTER of stud for stud walls. This pretty much avoids all fractional dimensions throughout. One of the few times it doesn't is when you have an exterior wall with something like 6" studs and brick, and it makes an inside corner near a door, and then you want a 3 5/8" stud wall on the inside to align at the inside face with the 6" exterior stud wall. But I usually don't dimension that interior wall and just say to align the interior faces.

For block/CMU walls, we dimension to one face of the block, and continue dimensioning to the same side of any subsequent block walls along that dimension string.

[cliff collins]

My advice from 20 yrs plus experience:

Set your dimension tolerance in Project Units to 1/256".

Then model the walls correctly, meaning placing them/moving them
where they fall to within either an 1/8" or 1/16" fraction of an inch--
or better yet with no fractions! ( which I know is sometimes impossible. )

Then, your dimensions will all show properly at 1/8 or 1/16 inch fractions--
not odd 1/128 or 1/256 fractions!

Your model will also work nicely with your structural engineer, who will also set up his model or cad at 1/256 tolerance.

Trust me--this method is industry standard ( and often gets overlooked by us Architects
who at first think "just get it within an 1/8 of an inch!" )

As for where the dimension lines should go--each firm has different standards--
however, logic says dimension to only one side of the stud--because the framer will be
snapping a blue chalkline on the floor for one side of his stud to align to. Spend a bit of time in the field and ask any framer and he'll probably agree. Otherwise you are trusting the framer to do all the math and account for the finish thicknesses--which can get complex with fire-rated walls, etc.

Only dimension to finish if you need a strict clearance for code/exiting/life safety, and be sure the finish will remain a constant thickness thruout the design cycle or you will have a potential mess on your hands.

cheers..............

[twiceroadsfool]

My advice from 20 yrs plus experience:

Set your dimension tolerance in Project Units to 1/256".

Then model the walls correctly, meaning placing them/moving them
where they fall to within either an 1/8" or 1/16" fraction of an inch--
or better yet with no fractions! ( which I know is sometimes impossible. )

Then, your dimensions will all show properly at 1/8 or 1/16 inch fractions--
not odd 1/128 or 1/256 fractions!

Your model will also work nicely with your structural engineer, who will also set up his model or cad at 1/256 tolerance.

Trust me--this method is industry standard ( and often gets overlooked by us Architects
who at first think "just get it within an 1/8 of an inch!" )

As for where the dimension lines should go--each firm has different standards--
however, logic says dimension to only one side of the stud--because the framer will be
snapping a blue chalkline on the floor for one side of his stud to align to. Spend a bit of time in the field and ask any framer and he'll probably agree. Otherwise you are trusting the framer to do all the math and account for the finish thicknesses--which can get complex with fire-rated walls, etc.

Only dimension to finish if you need a strict clearance for code/exiting/life safety, and be sure the finish will remain a constant thickness thruout the design cycle or you will have a potential mess on your hands.

cheers..............

Well said. I agree with this 100%. Model it correctly, and you still shouldnt have wacky dimensions. It doesnt take any longer to put it in accurately and correctly.

[btrusty]

our office policy is to do it right the first time

do exactly what cliff collins does.
and to change the walls so that we do not have any dimensions smaller than 1/4"

then, for whatever reason, if we have an existing building that has funky dimensions (not straight walls) we just put a note to the contractor to "verify all dimensions on site"