Adding posts to 2nd floor baloon framing

[Lev]

Good morning all,

I've had remarkable help here in the past.
I'm working on a bedroom on the 2nd floor in a balloon framed 100 y/o house.
Under this bedroom on the first floor there is also a bedroom.

I worked on this bedroom in the past, stopped in order to do a more urgent project in the back of the house, now back to this.

After having completely stripped this room and an adjacent small room, I learned that there are 2x7 (actual) x 20' pieces that make up the 2nd floor support, leaning on a ledger board at +20" on a center.

There's a load bearing wall below this floor at the ~14' mark, but the floor has sagged around that load bearing wall. I'm not that surprised.

The ledger board started curling inwards a little, especially under the window in the picture. Below the window on the first floor there is also a window with the same dimensions, so there's not really a stud that the ledger board is resting on under the window.

After consulting with various people, I've come up with the idea to get 4x4 posts, cut them so that they are 3.5x2.75 (actual) to fit comfortably behind the ledger board, and place a bunch of 2x8x20 (cut to fit) to the span of the house, so that I have floor support that does not lean on the ledger board but on these new posts.

I've drilled at the bottom of the bays in the basement in order to clean the bays, so that the posts can sit directly on the beam that rests on the foundation.


I intend to cut the posts to reach from the foundation up to 1" below the ledger board.

To anchor the post at the top, I'm going to use a 2x4 that will lay on top of the post and connect the studs to its right and left. That will both hold the post in place from the top, and also create a surface for the joists that will rest on the post. (I only intend to put joists directly above the post, for load transfer). Hope that made sense - please ask me if this is not clear, I'm not that eloquent with construction vocabulary.

I was thinking that in order to anchor the posts at the bottom I should cut big enough a hole at the bottom of the bay, to insert 2x4 (again cut to size) pieces to prevent the post from ever moving, and nail however I can if I can.
I was thinking that in case of an earthquake or something I better tie the posts at the bottom as well.

Also, I was thinking that when I'm done with posts and joists around the window (shown in the picture), I'll cut the existing joist that's under the window (properly tying/supporting it first), put some metal brackets on the new or reinforced adjacent joists and put a double 2x8 along the wall. Then put a bracket on that double 2x8 and let the existing joist rest on it instead, maybe even add more brackets on it and add more joists.

I'm looking for your advice:

1. Your thoughts on this solution in general - is there a better way? Are there downsides to this solution? I don't mind the labor, I'm doing this myself and don't mind a good, creative overkill.

2. Your suggestions on anchoring the posts at the bottom.

3. Your thoughts/suggestions on my plan for support around the window.

The attached pictures show:

1. Bay with a post (not nailed or height adjusted yet)


2. Bays under window where the ledger board is slightly coming out of the stud. It's not a closeup or anything, nevertheless it's there.


3. Drilling at the bottom of the bay (might not be that interesting)


Would appreciate your thoughts and advice.
Thanks and have a good day.
Lev

 

[nealtw]

Nice detail in your explanation , but it is deep so excuse me if I ask questions that you have already dealt with.
Is the room downstairs also stripped to the studs?
Have you thought about making the wall thicker to allow for more insulation?
2x8s 14 ft long may be okay for the span but they will sag more than the old lumber, anythought of increasing to 2x10s @ 16" OC?

 

[beachguy005]

It's interesting how they built them back then. I can't see much in the way of fire blocking, I hope you plan on adding it.

 

[Lev]

Nice detail in your explanation , but it is deep so excuse me if I ask questions that you have already dealt with.
Is the room downstairs also stripped to the studs?
Have you thought about making the wall thicker to allow for more insulation?
2x8s 14 ft long may be okay for the span but they will sag more than the old lumber, anythought of increasing to 2x10s @ 16" OC?

Thanks Neal, and please feel free to ask any question anytime.

The room downstairs is finished and also occupied by another party.
I wish I could have access to the entire length of the bay all the way to the bottom. In a couple of the bays I had to move some wiring to the side to clear the way for the posts.

This space I'm working on was (and will be) divided into 2 rooms - 13'x14' and 13'x6'.
I have not thought of making the walls thicker - this bedroom is the biggest bedroom in the apartment, and I'm not sure of wanting to take any more space away if that makes sense. Also since the room below is fully finished, any extension to the wall on the second floor would rest on the joists/floor.

I'm adding 2x8x20' joists that will basically lay on posts all the way from left end to right end of the house. On the 14' mark they will rest on this load bearing wall. I plan on adding either double joists or triple joists connected with carriage bolts. I also am going to double or triple sister the existing joists. If I added 2x10 the floor would be too high compared to the rest of the house. Since the below room is finished, I can't go below the existing joists either. So I'm a bit limited unfortunately.

Since the existing joists are 2x7 actual, in some cases I'll have to cut my 2x8 (which is 1.5x7.25 actual) to be level with the rest.

I hope that answers your questions and gives a bit more information - sorry if I'm repeating stuff that you already know, it's more so that if you see that I'm completely off on something you can set me straight.

Beachguy thanks, I'm looking forward to getting to the stage of adding fire blocks... need to finish these posts and support first. Let me know if you have any thoughts on that.

 

[beachguy005]

Given that balloon frame construction is no longer used and such a specialty form of construction, I think a restoration contractor or architect might be a better way to go for info on your plans.

 

[nealtw]

OK then your plan is fine but as Beachguy said , fire stopping, is important so when you put your 2x4 on top of your posts make sure they completely close the space and then close those same spaces in the crawlspace. That slows the fire down to 30min. to breakthru from one floor to another.
A couple points, if the wall at 14 ft is load bearing all the wall to the foundation, you can overlap your joists there so you don't have to deal with a full 20 ft.
Like I said, 2x8s will still sag and may not improve your floor a whole lot and with that in mind there are subfloors available to span 20 inches and 24 inches OC

 

[Lev]

Thanks Neal, are you saying that 2x8 will sag no matter what I do? So even if I add enough joists for them to be 12" OC and double/ triple the joists it won't make a difference?

 

[nealtw]

Yes your better bet in my thinking would be to attach new lumber to the old 7"with crown up. It would be unlikely that the old lumber will sag anymore, then use a sub floor rated for 20" span
I am not sure but you could check 13/16 span, but I can't find any info this morning

 

[GBR]

"There's a load bearing wall below this floor at the ~14' mark, but the floor has sagged around that load bearing wall. I'm not that surprised."---------- is the wall settling or the floor joists sagging at the fasteners? Big difference... Typical balloon framing has the 1x4 (or 3) let-in to the edge of the studs, supporting the floor joist- usually also side nailed to the stud, double bearing in most cases. This is plenty strong enough for floor loads, and possibly adding sister joists for same load rating but longer span/less deflection when existing joists are over-spanned. Though quality of earlier lumber is far superior to today's product, unless special ordered.

Why are you adding joists? Too much deflection? Too great a span by today's standards? Or sagging subfloor when a better grade of plywood would solve? As mentioned... Why 4x4 posts when the ledger is sufficient? Solid 2x blocking- bottom installed 1/4" below top of ledger (both fire-stop and 1-1/4" bearing for joist) and another on top of joist face-nailed through studs for maximum shear power. IMHO, just sister the 2x6 or 2x8, ripped, right alongside existing, nail as a header-per code, forget the 4x4 posts as the studs are continuous to the sill beam anyway.

Sistering 2- 2x6 #2 Douglas Fir at 1500#fb gives close to same max. load as one 2x8 at 14' span = 64 vs, 67#sq.ft.

Sistering 2- 2x8 gives 111# sq.ft.- figure in your dead load, this at l/360 deflection for floors.

So adding a 2x6 to your 2x8 would figure somewhere between the two ratings, plenty for the span/loads, especially as "sleeping rooms" are now rated at 30# plus a "safety factor"; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_5_sec002_par017.htm

Gary

 

[Lev]

Thanks again Neal.
And thanks Gary for the detailed and well-founded and cited thought.

The lowest point in the whole space does seem to be around the load bearing wall and away from the side wall.
But the sagging of the joists seems to start from the ~3-4' mark. Worse in the center of the room where the window is.

I once rebuilt the floor in my kitchen (14'Lx16'W) a few years ago and double and triple-sistered the existing joists, and added more 2x6 double joists to make it a ~10-11" span. The floor still moves slightly when my dog jumps there. So the dead weight is one thing, but the experience of walking around or running or being active is what I'm thinking of improving. At the time I was working with an architect who advised to stay away from the ledger board and put weight on the studs directly as much as possible. He said 2x6 should be sufficient (at the time). The floor is now a stone floor (with all the cement board and other weight that comes with it. It has not sagged yet - still very level and stable. it's been 5 years now. Don't know if that is telling or not.

I don't mind an overkill - I would like to make the floor sturdier, even if it is just the bedroom.
I don't mind adding the 4x4, already got them and ripped to size (as seen in the picture). Just looking for ideas to attach them at the bottom.

As for the joists, I'm looking at the table you cited. I ordered 2X8X22 and the order says "#2+BTR KD SPF/HF/DF BDF".
I do plan on making it a span closer to 12" and double/triple sistering joists. But I don't know which "species and grade" the wood I actually received corresponds to. If SPF = Spruce Pine Fir and HF = Hem Fir and DF = Douglas Fir, I guess I should call and ask which wood exactly out of those I was supplied.

 

[nealtw]

In my book the DF, #2 or better is what you would wand and it should be stamped on the lumber about 18 inches from one end on a flat side.

If you have access to the bottom of the posts in the crawl space, 2 or 3 screws or nails and then you should fill the rest of the space for firestopping which would help hold them in place.

 

[GBR]

Any local wood is fine for sistering, when used as floor joist alone, the fiber bending rating comes into play for the load/span rating given as well as on-center spacing which is figured by the load per square foot... rambling now, goodnight.

Gary

 

[Lev]

Thanks both.
After some more thought and checking, I'm thinking of adding a post in the basement to support the wall that's bearing at the 14' mark of the space, before I proceed.

The beam in the basement that supports that wall looks like a 6x6 (actual), that has been heavily notched into in order to support floor joists from both sides.
There is a 13' section of it, right under the load bearing wall, without a post. I plan to jack up the beam in the middle (~1/8" a day?) until it's close to level, which is about 1-1.5" maybe.

The concrete underneath seems to be 5-6" thick, with only dirt under it.
I'm thinking that I'll first add a post at the 6.5' mark, and later after the project is done take care of the post at the 13' mark.

I'm going to pour some high strength concrete first.
I've broken through the concrete a hole 12" diameter. Now I'm digging with a shovel through the dirt. I've gotten to 1.5' deep. I read on some site that I should calculate for depth 12" + 1" for every 3" of the post. Then I was thinking that it's going to be bearing load for 2-3 floors. But digging so deep through a 12" diameter hole does not seem so effective, especially with a shovel. Any suggestions? Any additional thoughts?

 

[nealtw]

When we put posts in new houses the footings are anywhere from 24 to 36 inch square, It's more about spreading the load on a bigger foot print and the type of soil has as much to do about it as the load.
Concrete spreads the load out at 45* so idealy, you would have a cube but the footing is usaull onloy 10" deep and to help spread the load they call for a 5/8 rebar grid, 3 or 4 bars each way.

 

[Lev]

Thanks, that gives me a perspective.

Funny but I can't find a 5/8" rebar in the local stores - neither Home Depot nor Lowes. Online I get rebars with different designations, like #5 or grade 60.

Home Depot seems to have a 1/2" rebar, 12" long, or they come in 4' pieces.

I found a steel supply company that can get me a bunch of 2' long 5/8 pieces.

 

[Lev]

I think I misread what you wrote! Your footing would be at most 6" on a side... My 12" diameter hole would be closer to 12" on a side... Which is 144square inch... Oops. Now I have to cut those 2' 5/8 rebars into 1'....

 

[nealtw]

With out breaking any more concrete I would try to enlarge the foot print under the floor, go for 24 x 24 roughly. When you put in rebar it wants to be all inside the concrete by 2", so a 12 inch hole it would be 8" hardly worth the bother.

 

[Lev]

When you do 24-36 inch squared footings, how long of rebars do you use?

I can do 12" rebar 16" hole. The dirt is hard to dig up, I need to break the concrete. Fortunately I have a jack hammer, so it's not a big deal to break.

 

[nealtw]

That sounds a lot better than a 12" hole. 3 bars each way.

 

[Lev]

I ended up digging 28x28. So 4 rebars each way? In all 45* directions? |/-\?