Building and Construction - Framing Roof Joists for Addition when top Plate is not Level

Author

Framing Roof Joists for Addition when top Plate is not Level

tdmailbox@yahoo.com

2007-02-20, 5:25 pm

I am involved in a project where I am adding an additon to a ranch
house. House is about 25 feet wide about about 40 deep. Most of the
projects I work on are total gut jobs so I dont worry about saving
existing structure. However this house has a really good first with
new kitchens and baths so I want to keep from demoing the ceiling and
ceiling joists.

Joists go across house as expected. The top plate on the rght side of
house is about 1 inch lower then the left with a slight(1/2") pitch
toward the back.

I was wondering what methods others use to level the top plate before
adding a new floor in cases where the existing ceiling and ceiling
joists are to remain. In cases where I am am demoing the existing
celing joists and the slope isnt bad I sometimes shim under each
joist.

However for cases where I am leaving the existing ceiling joists (to
support exisiting drywall ceiling) and installing new joists I have
been doing is scribing and cutting the rim joist to follow the
contor. I like to install a rim joist because otherwise otherwise I
end up with a bunch of point loads which dont line up with the stud
wall(since the existing joists line up with the stud wall).

What I did in the past was a buy a engineered wood rim joist one size
over(assuming slope is less then 2 inches). I placed the enginnered
joist on the top plate temporally, shiming the low side until level.
I then ran a scribe down the outside of the building along the top
plate. This left me a line on the rim joist that followed the slope
of the top plate. I then trimmed it down with a circular saw so now
the contour of the rim joists makes the contor of the top plate.

This was time consuming but seems to work well. One thing that makes
it even mroe time consuming is the fact that the existing ceiling
joists in most cases extend flush to the edge of the top plate. This
causes me to have to cut these back 1 1/2 ". I then connect them to
the new rim joist with simpson angle brackets.

I was wondering how others do it when framing new floor joists in
parallel to existing when top plate isnt level.

M&S

2007-02-20, 8:25 pm

tdmailbox@yahoo.com wrote:
> I am involved in a project where I am adding an additon to a ranch
> house. House is about 25 feet wide about about 40 deep. Most of the
> projects I work on are total gut jobs so I dont worry about saving
> existing structure. However this house has a really good first with
> new kitchens and baths so I want to keep from demoing the ceiling and
> ceiling joists.
>
> Joists go across house as expected. The top plate on the rght side of
> house is about 1 inch lower then the left with a slight(1/2") pitch
> toward the back.
>
> I was wondering what methods others use to level the top plate before
> adding a new floor in cases where the existing ceiling and ceiling
> joists are to remain. In cases where I am am demoing the existing
> celing joists and the slope isnt bad I sometimes shim under each
> joist.
>
> However for cases where I am leaving the existing ceiling joists (to
> support exisiting drywall ceiling) and installing new joists I have
> been doing is scribing and cutting the rim joist to follow the
> contor. I like to install a rim joist because otherwise otherwise I
> end up with a bunch of point loads which dont line up with the stud
> wall(since the existing joists line up with the stud wall).
>
> What I did in the past was a buy a engineered wood rim joist one size
> over(assuming slope is less then 2 inches). I placed the enginnered
> joist on the top plate temporally, shiming the low side until level.
> I then ran a scribe down the outside of the building along the top
> plate. This left me a line on the rim joist that followed the slope
> of the top plate. I then trimmed it down with a circular saw so now
> the contour of the rim joists makes the contor of the top plate.
>
> This was time consuming but seems to work well. One thing that makes
> it even mroe time consuming is the fact that the existing ceiling
> joists in most cases extend flush to the edge of the top plate. This
> causes me to have to cut these back 1 1/2 ". I then connect them to
> the new rim joist with simpson angle brackets.
>
> I was wondering how others do it when framing new floor joists in
> parallel to existing when top plate isnt level.
>

What first comes to mind is, provided the structure below is sound (not
sinking/settling/rot/decay i.e. why is it out 1"?), why would you be
worrying about 1" in a remodel of a house where the structure below is
likely also out that same 1"?

An inch out of whack isnt much to deal with in construction but it also
isnt much for the homeowner to live with given the first floor is likely
the same. How do you deal with exterior details that will all now have
to be tapered or cheated to accommodate the leveling of the new
construction? The outside walls will be taller on one end than the other
and so on. Do you cheat the inch out in the siding? Taper your last
course? Will the correction show in the outside corners? Are the first
floor walls plumb? Leaning? As I said, an inch aint a biggie, but the
point is still the same. Its not to say it cant, or shouldnt, be done
just why and what are the repercussions of it.

Your first concern should be where did the inch come from? After that
would be why the need to level the second story in the first place given
the rest of the house is out an inch and seems to be acceptable enough
to the occupants that they want to save it. After that would be how will
you deal with the everything else affected should it be taken out.

I cant say we have ever done a second story addition over a first floor
which was out of level enough to be concerned with so I can only
speculate that in this case I would likely let the second floor mirror
the first. If it were out enough that the we, and the homeowner, were
concerned with it we would likely sister new joists/sleepers inbound of
the walls leveling the interior floor a bit but leaving the new second
floor exterior details parallel/in-line with the first. This would
result in a more level floor in the second story addition though it
would have to be taken out in the interior finish.

The way I look at it is, imagine you had a structurally sound home that
was leaning 6" out of plumb in 8'. When you add the second story do you
build it plumb in effect putting a "kink" in the house or do you carry
the second floor up matching the first so from the exterior it looks
good? This is only an inch but the principal is the same.

As for cutting back existing joists we find it is fastest with a
chainsaw. Snap a line, square down from that line, and do a nice job
cutting them back. If your no good with a chiansaw a sawzall is second
best but 1/10th as fast. I dont consider a chainsaw a great carpenters
tool but in some cases its handy and a real time saver as long as you
can cut a clean, straight line.

Mark

marson

2007-02-21, 9:25 am

I'm with mark on this one. I've always believed that once you have a
foundation, it is what it is after that. 1" out of level in 30 feet
is annoying, but it is within tolerance. I once framed shed roof
where the upper bearing point was level but the lower bearing was 1"
out of whack in 32 feet. I gnashed my teeth for quite a while before
we just framed it and it would take an experienced carpenter to notice
it when we were done. I would be more concerned that it be flat so
you don't get any whoop-de-doos in your eve or ridge.

tdmailbox@yahoo.com

2007-02-22, 1:25 pm

Very good points all around. The 1" isnt noticeable inside. You are
right, any changes I make to correct this issue will cause my side
wall/facade to need corrections to discount this inch. We are adding
a mansard roof on top of the existing structure so it could be really
tough to hide that inch.

On the lower floor there is a room that spans the 30 feet and it isnt
noticable there. On the addition floor there is a center hall and
rooms on each side that are around 13 feet wide. If I didnt notice it
in the large room breeak the 1" up into 2 rooms and a hall should
certainly hide it further.

On Feb 20, 7:49 pm, M&S <n...@no.com> wrote:
> tdmail...@yahoo.com wrote:
>
>
>
>
>
>
>
> What first comes to mind is, provided the structure below is sound (not
> sinking/settling/rot/decay i.e. why is it out 1"?), why would you be
> worrying about 1" in a remodel of a house where the structure below is
> likely also out that same 1"?
>
> An inch out of whack isnt much to deal with in construction but it also
> isnt much for the homeowner to live with given the first floor is likely
> the same. How do you deal with exterior details that will all now have
> to be tapered or cheated to accommodate the leveling of the new
> construction? The outside walls will be taller on one end than the other
> and so on. Do you cheat the inch out in the siding? Taper your last
> course? Will the correction show in the outside corners? Are the first
> floor walls plumb? Leaning? As I said, an inch aint a biggie, but the
> point is still the same. Its not to say it cant, or shouldnt, be done
> just why and what are the repercussions of it.
>
> Your first concern should be where did the inch come from? After that
> would be why the need to level the second story in the first place given
> the rest of the house is out an inch and seems to be acceptable enough
> to the occupants that they want to save it. After that would be how will
> you deal with the everything else affected should it be taken out.
>
> I cant say we have ever done a second story addition over a first floor
> which was out of level enough to be concerned with so I can only
> speculate that in this case I would likely let the second floor mirror
> the first. If it were out enough that the we, and the homeowner, were
> concerned with it we would likely sister new joists/sleepers inbound of
> the walls leveling the interior floor a bit but leaving the new second
> floor exterior details parallel/in-line with the first. This would
> result in a more level floor in the second story addition though it
> would have to be taken out in the interior finish.
>
> The way I look at it is, imagine you had a structurally sound home that
> was leaning 6" out of plumb in 8'. When you add the second story do you
> build it plumb in effect putting a "kink" in the house or do you carry
> the second floor up matching the first so from the exterior it looks
> good? This is only an inch but the principal is the same.
>
> As for cutting back existing joists we find it is fastest with a
> chainsaw. Snap a line, square down from that line, and do a nice job
> cutting them back. If your no good with a chiansaw a sawzall is second
> best but 1/10th as fast. I dont consider a chainsaw a great carpenters
> tool but in some cases its handy and a real time saver as long as you
> can cut a clean, straight line.
>
> Mark- Hide quoted text -
>
> - Show quoted text -

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