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ropeguru
Premium Member
join:2001-01-25
Mechanicsville, VA

ropeguru

Premium Member

Max span length for 2x8 or 2x10

I may be moving back to the old house I have in WV due to a job change. When I do, I am looking to pretty quickly remodel two rooms.

Ceilings in both rooms are 10'. For the downstairs room, two story house, I was to pull the plaster off the ceiling and expose the floor joists from above. When I do, I want to add in a second set of joists so I can ensure I have a level ceiling in the down stairs room and also want to add in some sound dampening. I want to go perpendicular to the original floor joist to also take out some of the bounce I get upstairs.

My question is, how would this be looked at for loading since the original joists will remain and be there to handle loading as before. I am looking at spans in the direction I want to go of 17 to 20 feet possibly.

I will be doing the same upstairs in the room right above the downstairs room, however for the upstairs room, I am probably not going to be pulling the plaster and will use the new space created for pulling updated electrical and additional insulation.

Ken
MVM
join:2003-06-16
Markle, IN

Ken

MVM

I really think you need to scrap the idea of going perpendicular. It's going to have it's own bounce, and more importantly it's going to be really hard to connect 2 floor systems together at dozens of intersecting points without a lot of squeaking and somehow make it come out flat.

Alternative 1:
Sister new 2x12's on to the side of each existing joist with construction adhesive and lot's of nails. If you push the 2x12 all the way up against the floor boards you will have an unlevel ceiling again and it will be hard to fit them in. Best way is to find the low point of the floor boards above and set the top of every 2x12 1" below that spot. So you'll have places where the 2x12 is 1" below the floor boards and in other spots it might be 1.5" or 2" below. The 2x12's will hang down below the existing joists by 2-4 inches depending on what size they are. You will have a nice level and flat ceiling, and the 2x12's will take a lot of the bounce out of the old joists. The problem is if you have a bunch of electrical or plumbing that is running perpendicular to the joists you won't be able to push joists up against the old ones. That takes us to...



Alternative 2:
Use a Glulam or several LVL's and put a beam perpendicular down the center of the room. You would have to open up the walls to support the beam though, and make sure that support continues down through the building. You could then use 2x6's or possibly 2x4's to make ceiling joists from the beam to the walls. They would only be there to support the ceiling. The beam would be against the lowest joist and you would have to shim all the rest. I didn't show the posts holding up the beam in the picture but they would be set inside the walls. This option it doesn't matter if you have pipes or wires and you have a lot more space to put in insulation for sound deadening.


ropeguru
Premium Member
join:2001-01-25
Mechanicsville, VA

ropeguru

Premium Member

Thanks for all the info and it made me realize I had left out some vital information.

The house construction is real masonry, double wythe brick from foundation to roof line of second floor. All current floor joists are pocketed into the brick through at least the inside wythe and some all the way to the outside in order to attach porch roofs.

At this point I do not know what is between the first floor ceiling and second floor, floor. My guess is that there will be no plate of any kind for the new beams to rest on like in your picture. That is one reason why I was thinking perpendicular joist and hanging a new ledger board anchored to the brick walls.

The current interior wall covering is plaster right on the bricks. I am looking to stud out the walls with at least 2x4's and insulate then sheet rock. Again, two reasons for the stud out of the walls is insulation and electrical.

Could the new studded walls be used to support the ends of the 2x12's , or whatever is used, for the sistering to the current floor joists?

cdru
Go Colts
MVM
join:2003-05-14
Fort Wayne, IN

cdru

MVM

said by ropeguru:

Could the new studded walls be used to support the ends of the 2x12's , or whatever is used, for the sistering to the current floor joists?

Should be able to.

Another idea, depending on how uneven the ceiling is and how stable the joists are is to sister a smaller joist next to the existing and not worry about supporting the ends. It doesn't add any load bearing capacity, but it would level out the ceiling. It's not as ideal as either of the above illustrated examples, but it still accomplishes what the main goals seem to be.

But since you're likely to put up new studded walls, I'd probably just frame up a room within a room so to speak as long as you don't mind losing 4" on each wall as well as however much is necessary for the ceiling.

sempergoofy
Premium Member
join:2001-07-06
Smyrna, GA

sempergoofy to ropeguru

Premium Member

to ropeguru
Given your descriptions, this probably won't work for you since you appear to be wanting/needing some structural changes. If all you were looking for was a level surface on the ceiling for drywall, then a modification to Ken's suggestion could be lighter-weight steel studs sistered to the existing ceiling joists. See what I did in this thread: »Another bedroom renovation nearly complete

The article I linked in that old thread has moved to this new URL: »www.finehomebuilding.com ··· ing.aspx
MaynardKrebs
We did it. We heaved Steve. Yipee.
Premium Member
join:2009-06-17

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MaynardKrebs to ropeguru

Premium Member

to ropeguru
said by ropeguru:

Could the new studded walls be used to support the ends of the 2x12's , or whatever is used, for the sistering to the current floor joists?

Yes. Align the studs of the new walls right under the ceiling joists to stiffen the ceiling joists as much as possible. Don't forget to 'block' the ceiling joists at least every 4' to further stiffen the ceiling

Also use a double top/bottom plate on the new walls. The double top plate stiffens the top chord for load bearing, and doubling both the top/bottom give you more nailing surface for crown moldings/baseboards.
H_T_R_N (banned)
join:2011-12-06
Valencia, PA

H_T_R_N (banned)

Member

said by MaynardKrebs:

said by ropeguru:

Could the new studded walls be used to support the ends of the 2x12's , or whatever is used, for the sistering to the current floor joists?

Yes. Align the studs of the new walls right under the ceiling joists to stiffen the ceiling joists as much as possible. Don't forget to 'block' the ceiling joists at least every 4' to further stiffen the ceiling

Also use a double top/bottom plate on the new walls. The double top plate stiffens the top chord for load bearing, and doubling both the top/bottom give you more nailing surface for crown moldings/baseboards.

I always double up on the top and bottom plates, where code allows it I will sometimes tripple up the bottom to aid in nailing up baseboard. When doing more then a 3 piece it makes it nice to not have to worry about where the stud is.

ropeguru
Premium Member
join:2001-01-25
Mechanicsville, VA

ropeguru

Premium Member

Good thoughts. I guess if you wanted the height and code did not allow for a true triple bottom plate, you could take the time and just make the third later blocks between the studs.
ropeguru

ropeguru

Premium Member

Thanks to everyone. My original thought with the perpendicular joists was that they would not have to be as beefy for the span length if they were secondary to the original.

I will take everyone's ideas and look at them once I get the remodel going and get the plaster ceiling pulled. I am doing these two rooms together because I also have to get a new gas line run from the basement to the attic in order to have a second heating and cooling zone upstairs. Plus, there is a fireplace that I will be opening back up in the down stairs living room and one being redone in the room above it. Both will be NG and setup to provide a extra heat to those rooms. Figured it is easier to have it all done while remodeling and have everything opened up.

Ken
MVM
join:2003-06-16
Markle, IN

Ken

MVM

You can use a 2x4 wall to carry the load from the new ceiling joists. However you are then transferring the load down on to the floor joist below. That might be to much load for those joists, so I wouldn't risk that option unless you either had an structural engineer look it over, or you planned to do the room below in the same manner.

Putting in a ledger board and using joist hangers for new floor joists would work just fine, but you have to be really careful drilling into old masonry walls. If the wall is sound and strong it's no problem but if chunks start breaking off and falling while drilling your wall might be to fragile for the ledger board option.
MaynardKrebs
We did it. We heaved Steve. Yipee.
Premium Member
join:2009-06-17

MaynardKrebs to ropeguru

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to ropeguru
If you have hydronic heating, you can run upto 40,000 Btu in a 1/2 PEX pipe to the upstairs for heat - no need to run a gas line for a 2nd heating appliance.

You could even install a 2 or 3 zone mini-split a/c - heat pump unit to handle the upstairs if your heatloss/gain calcs work out to 24,000 Btu or thereabouts.