I take it that the floor joists are in the same direction as the beam and that you want clear space in the basement, no surports. The floor joists should be strong enough to support the floor without adding extra, all the extra beam will do, if these assumtions are correct, is make the floor stiffer. If the floor joists tied together with spacing pieces between, then you will not need the extra support. In the end you need to get the loading calculations for the floor correct to have the floor joists sized correctly.

If it makes it easier and ties 'em in nicely, and it's not too much work, or cost....do it.

We've all done jobs and though afterwards...

If I hadn't been in a rush, or such a cheapskate it would have been much better if only I'd.....

Thank you for the replies. Basically the beam under the load bearing wall would have been the only support for the floor which runs 25' X 25', two story house. I have re-thought the 2 X 12s to 2 X 8s or 6s I have enough head room but might be a little crowded for the 6'+ crowd. I'm thinking of the smaller beam(s) and posts for added support. The joists are cross tied but it is an old house(1918) and had the two wire ceramic insulator wiring so I'm thinking more support won't hurt.

You will Probably find that a laminated beam will be of a smaller dimension strength for strength than an old single timber beam and as you intend to support it as well there should not be a problem. Most good builders timber yards can give you advice on this. More support won't hurt but will stiffen the feel of the floor above which could be a good or bad thing, you still need to think of the loading. Check for a joint in the old beam that is where the support would go.

I've found that most structures built before a construction method could be analyzed on a computer are overbuilt or have fallen down. If there isn't any noticable sagging in the structure already then it's probably fine the way it is as long as you support the structure on the load bearing walls. Of course if your foundations settle then the whole house is going to move over time and there will be little you can do to stop it short of shoring up everything yet again.

If the existing floor joists meet standards for width and spacing then you're probably OK since the old lumber was probably better lumber than you can get today for a similar price.

Easier (and less expensive) to make sure you've got it right now.

I love keeping the old insulators and wires for ambiance, but I trust you've switched to modern wiring and practices?

You haven't given enough information in my mind to make a full evaluation. You haven't mentioned spans at all. If the span is 25 ft, reducing the 2 x 12s to anything smaller without a post midway would I think result in deflection down the road.

If you have existing floor joists from 1918, run a string from one end of the beam to the other and see if there is any deflection (sagging). If not, you're ok. If there is, and I would think it likely, additional support would stabilize the situation

It is always a good idea to have more bracing than just enough, the girder beam would aid in sub-floor support.

Kent in Carrollton,TX

Treated Mechanical Beams

Treated mechanical beams are constructed based on the required load and span and are composed of layers of Treated timbers or lumber held together by an ultra high quality glue and fastened with high-strength hardware. They are attractive, interesting, durable, and strong. Contact us online or call (866) 397-3038.

Good source.......and data........

50 + YEARS BUILDER

MR. GUY

Have you considered steel beams or you just want to use wood for nostalgia or because the basement will be a living space and you want the wood look for decorative purposes? Is cost an issue?

What purpose is the OSB between the "2 x" board layers? Sounds like if you need to use wood, the pre-made beams offer you the best solution, or do you just prefer "do-it-yourself"?

Both Georgia Pacific and Trus Joist have software to analyze floor loadings, deflections, and stress. Have your local lumber yard analyze this for you or, better yet, find a structural engineer to do it.

All things considered, I'd use 3 ea 2"x10" hemfir s with 7/16 OSB spacers. Id use 2 ea. 3" diameter steel lolly columns on new 2'x2'x2' concrete foundations at 8' on center along the length of the beam shim joists as needed .

The origonal foundation probably was a crawl space and the old center beam had at least 2 if not 3 supports between it's end supports ( totaling 4-5) You should be able to visually see where the wood is lighter in color and may still have some nails in it.

The old house has adjusted itself ( deflected) to whatever support it had. If you put in a new ( straight as an arrow) beam and jack it up into place, you may find plaster cracking in the walls above.

Another thought, If headroom is a problem, install two temporary beams/walls on either side of the old beam. Remove the old beam and cut the floor joists back to allow a new beam to be slid up into the floor system. Use joist hangers to attach the floor joists to the sides of the new beam. If you make the beam taller than the joists you can add additional joist support by attaching a ledger bord to the side of the beam and in contact with the bottom of the old joists.

Hire a licensed insured home improvement contractor.

Tim from MD.

OK. I'm confused. It sounds like you are considering the wall you are running the beam under to be load-bearing. But it also sounds like the floor joists are running parallel to it. How can this be? Is the wall carrying the upper stories? What is carrying the ground floor over the beam? If you have a 25' unsupported span of floor joists in the basement, then the cross-ties are supporting your house; and you should seriously think about running the new beam sideways to the way you intend to install it.

None of this can be so, because the thought of a beam in the basement that doesn't support anything is too outlandish. Please help me out here.

By the way, for a conventional 2-storey home, the three-ply beam you are proposing is minimal. I'd recommend a heavier ply...at least 4 to 6 pieces. But since the beam is going to be new, I'd even more strongly recommend a steel I-beam calculated for your load by the company who sells it to you with an on-site visit by their sales engineer.

Mark

Dear DYI,

I am concerned because all the discussion has been about the beam. Beams need to be supported by columns and columns need footings. I hope you do not intend to use the basement floor as your footing. You will likely get cracking of the concrete and possible failure.

I love "doing it yourself". I learn a lot. But please think this one out and do not rush ahead. I would echo the sentiment of someone who suggested hiring someone. You do have a lot of money invested in your house. Why cause it to fall?

On the other hand, if you are cautious, plan carefully, and analysis this appropriately, it could be worthwhile. Get the wife and kids out of the house before you do this:).

If you do this wrong, you may not get instantaneous failure, but you will see sag, creep, cracking, etc. Keep your eyes open for this stuff. As soon as you see it - fix it.

Respectfully Yours

Beams need to be supported by columns .

I think this may be a slight overstatement. Were it entirely true there would be no such thing as a load bearing beam?

As someone else said we don't know the span etc.

I interpreted the Q as meaning....he knows the beam is fine but as wondering about extra support for the joists in terms of ease of fitting them and extra rigidity.

I s#pose we need the Q worded more carefull or a sketch..

Alot of good thoughts for me. The load bearing runs 90* to the joists as it should. I'm just inclined to add more. The basement is all pour 'crete. I would be using 3" posts for the load bearing and most likely 2" for the other beam. I like doing the work myself and did a 2X12 3 layers with 2 layers 7/16th OSD screwed with deck screws and glued with a good construction adhesive rated for this. This beam went under the west wall which was not supported due to the basement extended about 6' past the wall. The house was moved onto this basement. There was a couple of 2" posts and a mediocre beam for this wall which I removed to build the layered beam. This beam is also anchored to the concrete walls with 1/4" thick angle brackets (they were free) and attached to the house proper. Yes there is some loading deflection in the floor (I keep my construction materials in the house, no garage. Which is why I'm thinking of adding additional beams. I have seen some homes just had posts added to floor joists but I'm more inclined to over build I guess.

Oh forgot I'll pour pillars/pads for the posts. And I like the idea of more layers so I'll most likely go 5 or 6 layers of 2X8s with OSB sandwiched in between and screwed and glued, with a board on top and bottom like I did for the first beam. Also the load bearing is right beside the stairs going into the basement, which I need to build after the beam so there will be a little more support. There used to be plaster and lathe which is gone so I can tidy up the levelness of the floors. I'm keeping the insulators and the two ceramic w/ pushbutton on/off light switches that were still in use before the house was moved. Interesting looking items.

5 or 6 layers of 2 X 8's screwed (alternate sides -if possible- all the way through...every 16" or so) and glued probably does not require any sandwich material, which could be more detrimental than useful in terms of bearing support, since it runs the full depth of the beams and would act as a weak interruption rather than an enclosed space. Sometimes more is not better. However, the wooden plates on top & bottom of the beam will multiply its strength, so that's a good idea. Ensure that the support columns themselves are also actually fastened (screwed, bolted, etc.) onto the underside of the beams where they meet so a beam can't easily fall off a column in a catastrophe. (Req'd by code, anyway.) In a case where the load bearing wall is beside the basement stairs, headroom up & down the stairway can become a problem. Don't go modifying any hanger joists in the stair opening to compensate without first strongly modifying the stair opening itself.

As far as support brackets for the beams are concerned, again I'm puzzled. In the case of a load-bearing structure, columns must be present. In the basement beam's case, the columns are the basement foundation walls, with steel plates for beam rests. Hooking the beams onto the walls with any device just doesn't give the appropriate support. So I assume (uh-oh ) you mean that after the beams were rested on the foundation walls, a supporting piece was added, kind of like a big joist hanger, outside of the rests.

The knob & tuble wiring is cute. But it comes with three major problems. There is no grounding available, which will necessitate at very least the installation of GFI outlets as appliance receptacles. The neutral is not clearly indicated. And the wire and insulation is old and brittle. Keep the push button switch, but as far as utilitarian wiring is concerned, put the wire and ceramic insulators on display in a glass museum box and replace them with 14-2 Romex (or 12-2 if they are going to support any toasters, microwaves, or other kitchen appliances or your toolshop; and supply your breaker box with a 20 amp breaker to carry the 12-2 line).

What are 2" columns? Are they making support columns out of nano tubes nowadays?

Mark

Ahh the wiring comment I did not understand. The beam I have already built rests on two 3" dia. steel posts factory rated at 46,000 lbs ea. Posts are bolted to the beam and the beam is also fastened to the poured(around 12" thick) walls by 3"X3"X1/4" angle brackets two per side of each end of the beam. The load bearing beam will run beside the up and coming stairwell and will not intersect it. So I'll use the other side of the stairwell to add one or more posts as added insurance provided they don't interfere with using the stairs. The other beams I'm looking to install are just added peace of mind for me. Everything I'm doing in the house is being screwed together using deck screws cause I hate bending nails with a hammer. And if I mess up I can unscrew my mistake and redo it. ;-}

Blimey this beam just keeps getting stronger and stronger ....suggest you build up 5 storeys and let out as offices!

Re the wiring comment.

"Knob & Tube" is the name given to your old fashioned two-wire system with ceramic insulators ("knobs") and ceramic tubes through the joists/studs ("tubes") to insulate the wire from rubbing against the wood.

It's an old fashioned style of wiring, and needs to be replaced with a substitue because

1. It's old. the wiring is brittle and can crack (sparks = fire) or break (repairs = $$$)

and

2. With knob & tube, there is rarely a ground wire. Ground wires are used to send the current to ground in case it's necessary to do so (eg Suppose the hot line shorts against the appliance/fixture it is supplying. then it's better to send the current to ground rather that through an unwitting shock-ee who has just become the grounding agent for your curent.

Replace it with 14-2 romex or 12-2 Romex and add a slightly larger fuse.

Mark

Old isn't always worse...

About 25 years ago we had our old house re-wired..the old rubber insulated stranded wiring was still supple. The modern solid core plastic insulated stuff is rubbish! The cores work harden if the get flexed too much during installation and the insulation goes rock hard over every light fitting due to the heat.

Del

Haw!! Who did your wiring for you? Actually flexing copper wire enough to work harden sufficiently for concern would be at the very least a long tiring process. I have personally removed or extended that plastic 'rubbish' installed more than 20 years ago, and it's still plenty flexible and in my own experience not any harder than it was when it went in. It can be pretty hard, though; but it's made that way. If you've cooked it over light fixtures, I can think of two reasons that might have occurred. First, and obviously, the fixtures might have too many watts cooking their upper surface. One of my clients complained about the same thing, but it wasn't the wiring he complained about. The cooking was happening to the fiberglass insulation over the fixture! The other possible explanation is too much exposed outer wire insulation over the fixture. Normally, the outer insulation gets peeled away and only the wire leads coming into the fixture have any contact with the heat. I don't recall any of the fixtures I've repaired/replaced having had any difficulty with that individual wire insulation cooking to hardness, though I can theoretically imagine it happening in the presence of direct, intense heat.

Around here, anyway, knob & tube wiring is only in the houses over 60 years old, and is definitely past its prime. We only replace it if it has to be disturbed, if new wiring is required to provide a ground, or if a renovation is taking place and the city makes us replace it as a part of the work. Even though the majority of modern appliances have two-prong plugs, I still make a fair buck replacing knob & tube-supplied duplex recepatcles with GFIs to allow for the third prong in the outlet. One has to handle that wire with gentle care to keep it from breaking due to years of evaporation resulting in brittleness.

All the best,

Mark