Old House Renovation Part 2!!

[jseklund]

Ok,
So, I have moved onto my next project in this old house renovation and have a big issue to take care of now. This apartment I am renovating is on a second story. The first story is where my grandmother lives currently.

The living room in the apt. has a 16 foot span between the exterior supporting wall and the interior wall. This is balloon framing - so not what we usually look at.

The big issue I have, is that the 16 foot span is carried by 2X6 joists. These are old, true 2X6 joists and many of them are actually closer to 6.5-6.75" tall. The floor bounces like a trampoline. This should be expected, since 2X12's would be preferred for a 16 foot span, and 2X10's appear to be the real minimum that most people desire.

My plan on this is to leave the joists that are there in place, tear up the sub floor above, and rebuild the floor system. Originally I was thinking of sistering joists, but since they're 2X6, I realize that will not be sufficient.

Once I have the floor off, I am thinking I should be able to take a 16 foot 2-by-whatever, slide it down onto the support wall, and then back to the second support wall, and nail and glue it to an existing joist or the opposite side of the stud that the current joist is on.

I would HAPPILY go to a 2X12 here, since the cost is probably only about $100 difference, but if I do that I will be raising the floor up about 4-5". This floor currently mates to the kitchen floor almost perfectly - so there would be a considerable and awkward step up. The door frames would also be reduced to about 72" tall from their current 78", and the plumbing pipes that come in for the heaters (retrofitted well after the house was built) would need to come up (which will be hard).

I REALLY need to keep the celing below in tact, or it would be easy to just drop the ceiling below by about 6" from it's current 8+ feet and I'd be happy...but I can't do that. I have to work from the top.

So, I thought of steel beams - but then I realized that 6 2X6 steel beams, 16 feet lont, will weigh about 1200 pounds, which will be quite the increase on the support members that the beams will be sitting on.

My next thought is that since the lumber in place is actually close to 6.5", maybe I can squeeze a 2X8 in there, at 12" OC intervals - which would still raise the floor, but not so much that it would be unbearable. My calculations using span calculators show that this may come close to the 15 foot span that I need, if I allow for extra deflection. I'm thinking that sistering the 2X8's and then blocking the joists in 3 seperate places will decrease the deflection....

So, my questions are:

1.has anyone come across a similar situation and how have you dealt with it???
2. What are your thoughts on the plans above?? I believe some of you may be structural engineers even...or not...who knows?
3. If I were to raise the floor, any ideas on how to deal with that? It's too short for a step, too tall for no step....

[Lonnie in Orlando]

jseklund

Our 1908 bungalow has baloon construction and also has true 2-by framing. Joists are undersize by today's standards. But we love its character, tall ceilings, and overall proportions. As you pointed out, any changes that you make in the floor height on the second floor will affect an untold number of other items both structural and aesthetic; and ultimately may lower the value of the house.

Just my suggestion - I think that would be worth the few hundred $$ fee to consult with an architect or structural engineer who is familiar with old houses and who respects them. It will be cheap money spent.

We used glue-lams to beef up and to rebuild some of the roof rafters on our house in the last remodel. (laminated veneer lumber - thanks toolguy1000, couldn't think of the official name).

- Lonnie

[cabinetman]

My suggestion would be to get advice from a local structural engineer, that is familiar with your building codes.

.

[toolguy1000]

My suggestion would be to get advice from a local structural engineer, that is familiar with your building codes.

.

+1 and ask about laminated veneer lumber (LVLs).

[LCHIEN]

you said you considered sistering additional 2x6 joists... is that not sufficient? Is a 4x6 equal to a 2x10 for span???

Since keeping the joist height the same and not lowering the downstairs ceiling or raising the upstairs floor is important, can three sistered 2x6 carry the load? You can level up the tops and bolt thru the original and two side joists.

[jseklund]

Guys, thanks for the responses -
The structural engineer advice is good in this case - and I had a non-formal discussion with one that I happened to meet the other day. He obviously didn't see it, but felt the span required 2X12's. He didn't seem to be that creative though...i.e. - not thinking of LVLs, etc.

He mentioned even doing a 2X10 on each side of the old joist, glued and bolted would be strong as **** - and may get it done. Even the 2X10 is a bit of a jump though.

I was thinking that I could squeeze 2X8's in there, since some of the beams are almost 7" as it is - put them every foot and sister them all. This would be approx. 26 joists between the new and the old over a 13 foot span.

Then I got to thinking - a 2X6X16 probably weighs about 60 pounds. 26 of these would be about 1,560 pounds!!! Considering that there's almost half of that weight on their right now....the steel beam option may actually turn out to be not much of a difference if I go with 18-24" spacings....

I'm going to see how much the structural engineer I spoke with would charge to take a look. This isn't a partition wall like the other thread - this is obviously a safety issue.

[conscience]

Think about structural aluminum I beams. A 7" beam should run between $12 - $15 a foot, depending on web thickness and weigh between 5 and 6 pounds per linear foot. I've used them in the past in the same situation, but it has been a couple of years so my pricing may be a bit off.

[chopnhack]

Conscience may have the best solution for you since with balloon framing weight bearing is going to be fairly critical. Those long continuous lengths from top to bottom can bow out under increased loads. Definitely worth a pro coming in to give you a real solution.

[cabinetman]

Definitely worth a pro coming in to give you a real solution.

That's very true. The "free" advice from forums is all well and good as for opinions. An engineer, or a "pro" as you stated will likely have opinions based on his/her knowledge specifically, as that is what they do. Being in the field may also mean that the "pro" might be able to save you some money with suggestions on materials and labor not privy to a DIY homeowner.

.

[jking]

And make sure the engineer you're talking to has some experience with residential construction. I've done some in the past & the 2x6 framing currently in there would be overstressed. 2x12 sound appropriate, but, LVL would be a good option due to the height constraints. Keep in mind aluminum weighs a third of steel but has only a third of steels stiffness. So the longer the span is, the advantage of aluminum's weight gets taken away by the lack of stiffness.

[jseklund]

Hi guys,
thanks for all of your advise, and I do realise that you get what you pay for on the internet! Still, you've all helped me come up with ideas that I could think through and maybe come up with a creative solution to.

I called a structural engineer who wanted $300 to look at the place and $1200-1500 to draft a solution. That didn't fly, so I passed. Then, it just so happened that I was doing some work for my real job (real estate) at guy's house. We got to talking and he told me he was a structural engineer. We actually discussed the problem at length and he was very helpful. I offered to pay him to come look at it, but he offered to help just to help....

What we decided on was that after I took up the floor and got a better look - the 2X6's were actually 2" X 6.5" in diameter, some as big as 6.75". They were spaced somewhat randomly between 14-18" on center.

I bought some 2X8" SPF beams, glued, screwed and nailed the new beams to the old, added 2-3 additional beams to approximate 1' spacing, and put 3 rows of blocking in. I am going to nail/glue plywood to the top of the old beams to bring them up level with the new beams. The new beams also run ledger to ledger.

Without the blocking in, and just the beam sistered, I could stand on the beam at center and get some movement - noticably twisting movement. With the blocking in the center, I can stand on the center of the beam on 1 foot and bounce up and down pretty good with really no visual movement at all. Putting the plywood down on the top of the old beam and then installing the T&G subfloor should make it even stronger.

I was very nervous about this situation, as I obviously don't want anyone getting hurt - but now I am confident. The old beams had a few very minor cracks but no signs of imminent failure. It's not really up to code per se - but it's definately strong enough and deflection has been limited. The floor will never take tile, but anything else will be good and you wouldn't tile a living room anyway. I think the deflection based on my own calculations, is probably around L/250 - L/320. Before, it was probably around L/90.

I wish I could have at least gotten a 2X10 in there, but this way was affordable, doable, and works. I know it's not perfect, but nothing in this house is and it will probably be the strongest floor in the place now....and at least a structural engineer agreed that it would be safe...

[pelligrini]

Glad it worked out and you got some knowledgable help. Sounded like a practical solution.

[iceman61]

Glad you got it worked out. I know Im a little late but in the past I have used 1/4" steel plate sandwiched in between two 2x-whatever (and all bolted together) with very good luck when adding extra height was a no-go. it's all case sensitive to each individual issue but it works like a charm.

[jseklund]

Never too late - thanks for the input guys.

The 1/4" steel would have been helpful. I have the floor half down. There is still a good amount of deflection, but it's not near what it was. My friend who was up there told me the first day we noticed, when I started bouncing he almost fell over. Now, with no floor down, he and I can both stand on 1-2 joists and I can bounce and you can feel it, but it's not disorienting. The joists each support 600+ pounds worth of people and there are 13 of them sistered plus a couple extra. With 2-3 of us standing on 1 joist, you feel deflection but it isn't bad unless we try to bounce and then it's WAY better.

A steel plate would have probably gone a long way - but I didn't really consider it. I was considering full steel beams, going 2X12, 2X10, etc - but I should have checked on the price of a 1/4" plate. Kind of kicking myself for missing the obvious on that. The engineer probably thought of it, but he knew I was most concerned with safety and not deflection, so he probably didn't go that route due to the additional cost.

Like I said, I'll never tile the floor, but it will be flat and suitable for hardwood or pergo, and no one will fall through the floor from the looks of it - so the mission was accomplished to a B level without getting into major reconstruction of the room below.

If I had unlimited funds, time, and resources, I would have either taken the ceiling down and removed all the old joists and put in steel beams 2' on center 6" tall, or built a header in the living room below mid point - but both these methods would have involved demolision in a living area of an 87 year old woman.

[JimD]

A piece of information you might find useful is the area moment of intertia. The deflection in a beam is inversely proportional to the area moment of inertia. For a rectangular beam (like a 2x12), the moment of intertia is the thickness times the height cubed divided by 12. So if we ignore the 12 for a minute we get 2136 inches to the fourth for a 2x12 (1.5 inches by 11.25 inches). If we then cube 6.5 inches and get 274.625 and divide that into 2136 we learn that a beam 8 inches by 6.5 inches would give equal deflection to a 2x12. With a 2x8 (assumed 7.25 height) I get 5.6 inches width required. Or in other words, 4 2x8s = 1 2x12. The fact that the height is cubed makes it very important, obviously.

When switching materials - like to a steel plate - it gets more complicated. The formula stays the same for a rectangle but the stiffness of the materials changes a lot. Pine has a modulus of elasticity of about 1.3 million lb/in2. Steel is about 29 million. So 1/4 inch of steel is about the same stiffness as 5.6 inches of wood. So if you put on a steel plate 1/4 by 7.25 inches you would have about the same stiffness as a 2x12.

These are the kind of calculations a structural engineer would do (or they would look it up in a table).

Jim