My $5K fixer-upper is closing today at 4:00p.m. I have created a rehab list and the first item on that list involves going into the 'spacious 4ft. high' crawlspace and making some repairs to three (2x10x16) original floor joists.

In one bedroom only, the hardwood floor sags down (only when you walk on it) due to 3 floor joists being cracked or broken. My handyman took photos of them and showed them to me. My handyman and his apprentice will be coming back on Friday to scab-on to these joists will new lumber.

My handyman is well qualified to make these repairs,however, I am curious as to what you all think is the best way to do this.

1. should 2x10 pressure treated lumber be used?

2. How should the new lumber (sister joists) be attached to the original 2x10 joist? I have seen 3 inch decking screws, nails and sometimes galvanized steel bolts/nuts used in other similar type repairs. Most handymen will use whatever is available.

3. Once the sister joists are in place, should a 4x4x12 support beam on concrete blocks be added to give additional support underneath the repaired floor joists?

4. What would you expect to pay for this type of service? (No permits will be pulled)

Thanks NE! My handyman does not own a Paslode nailer and I am not going to buy him one either. I have used a Paslode nailer before in building a deck and they are nice.

Is it the Paslode gun that uses a CO2 cartridge? It has been 12 years since I last use one.

If you use PT lumber, be sure to use galvanized fastners. I think the current PT is next to useless but it WILL corrode through non galvanized nails/screws pretty quickly.

Floor joists are typically framed up with standard lumber so regular douglas fir should be fine. Just make sure there are no big knots near the edge of the boards and if there is a knot near the edge, put it up facing the floor.

Hammer,

Thanks for the tip on how PT lumber can corrode non-galvanized fasteners. I am will buying all of the building materials here at Lowes and I am now considering buying the standard lumber (non-PT) 2x10's. Something tells me that 3/4 inch thick steel bolts,washers, nuts need to be used approx. every 4ft. along the span.

Roy, just load the $%K gem on a trailer & send it to me & I'll pay the freight plus 7K for your trouble.(g)

DO NO use PT 2x10's for the sister joists. I presume that those in your area like most of them in the eastern 1/2 of the US are made from southern yellow pine which could easily handle the load & span. However the PT treatment will cause the lumber to shrink a 1/2" or more as it dries out.

I would use 2x10 KD secured to the old joist with some PL construction adhesive & some GRK structural screws. All of this should be readily available on Lowes, HD or a decent lumber yard.

Make sure they get at least 2" od bearing on the existing sills, jack the old joist up a little past straight if possible before you fasten the sister joist to them. Leave the jacking / bracing in place overnight to give the glue a chance to set up.

In my area I would charge my clients for 2 men for 1/2 day to do this.

Steve (MA)

Give me $15K for my gem and I will ship to you on flat-bed trailer. For $7K in chump change, I will go buy one my 'rejects' and ship it to you! :)

Southern Yellow Pine is the standard framing lumber here. However, sometimes we get framing lumber imported from Idaho and that is some nice knot free lumber too.

What are GRK structural screws? That is a new one on me.

Roy, for jacking up a house, you want 12 or 20 ton jacks. Space them out every 6-8 feet, put some concrete blocks under them.

You might be able to lift one corner of a tiny house with two 6-tons, but since the 12-20 tons only cost a few bucks extra you'll do better to get the higher capacity ones.

Lovely thing with GRK screws is they can go in with ordinary drill, no nailer needed. Roy, they are self-tapping, and drive crazy well, especially nice when screwing into old, tight grain lumber. I have bad hands, that's all I buy. I think Lowes carries a different brand, but same idea: self-tapping, T-25 head, threads down the length of the screw change to really pull two pieces together.

PT lumber is only necessary when you have wood in contact with ground/wetness...so although nothing wrong with PT lumber I would use standard lumber.

As others have said, the critical part of this IMO is to ensure the new wood is supported by the original members at both ends. In other words, it should sit on the main beam on one end and the sill plate on the other.

Roy Google GRK screws. You'll find that make a huge variety that can be used from fastening trim & cabinets up to structural fasteners for all sorts of load bearing applications. Their structural screws go in easy especially with an impact gun, pull things together better than nails & have much more shear strength than nails.

From your description of 3 joists cracked / sagging, I doubt that you will need much of a jack. If I understand you correctly all you're trying to do is fix the sag not raise the whole house.

Do an experiment

1. Take a piece of scrap 2x4 lumber at least long enough you can hold it well.

Drive (drill) a sheet rock screw (or the other kind mentioned here) and a 16d nail head flush through the 2x4. Then take a hammer and hit to bend the pointed end of the nail and screw over so it lays flat onto the 2x4. You will find the nail will bend over and lay flay but you find 8 times out of 10 that the screw will break off.

Screws are like files. A file is hard enough to smooth or file down other metal but if you hit it flat wise it will break.

2. Take two boards and put a piece of corrugated cardboard between them so as to separate them by a little bit. Then put one screw through both of them. Or you could use several but one will demonstrate the principle here. You will find that the screws will most likely not bring or pull the two boards together. It (boards and screw) kind of act like a lock nut on a bolt. Now do the same thing useing nails. You will find the hammer blows will bring the boards together.

When I sister boards together I always use clamps to hold boards together until I get started for the reason you learn from above experiments.

Lots of good advice here. Please avoid screws and PT wood. Rent a nail gun if necessary. I typically add pocket screw holes to the top edge (floor contact) of the floor joist and use them to screw into the sub floor. Too much? probably.

Personally, I would add the 4x4 post, or a screw jack ($$) on a footer, somewhere toward the middle.

Use a piece of scrap 2x10 or cement block to support jacks.

Put a piece of 2x8 across the 3 cracked and sagging joists.

Jack the cross piece until the 3 cracked joists are in place.

Using a 2x10 about 2 feet longer than the cracked area (4 foot minimum) put it along each cracked joist. One on each side of each joust is better. Use the pl400.

Nail or use lag bolts in pairs about every foot to 16 inches.

Once all three are fixed, put a 2x8 across the there plus one more on each side of possible. Nail this to the bottom of all 5 studs.

Then make a pier under the middle. Use a 18x18 patio block and put comment blocks and shims up to the bottom of the cross piece. This should keep the floor from sagging again.

Richard (MI)

Since you seem to be an authority on this, just come on down here and I will be your assistant (for whatever that is worth). I know this is not rocket science but it does seem like a lot work,..especially in 4ft. crawlspace.

In other houses, with only a 12-18 inch crawlspace, I have had this same type of work done. Usually, the floor above was removed to get better access.

One question I would have is why did they crack in the first place. You need to look at the span of joists between supports (posts, beam, or sill plate) and how big the spacing is between joists. My bet is that the span is too long causing the failure.

Looking at the span tables says that for a 50 PSI live load with 16" joist spacing the maximum span should be 14 foot 8 inches for no 1 grade southern pine. Add roughly 2 feet if they are spaced at 12". Subtract 2 foot if you use number 2 grade lumber.

If the span is too long you need to add support to the middle of the joists with a beam or individual posts.

I was also wondering if it would be worth it to remove the floor above. Sure would make it a lot easier - and maybe a 5K house needs some floor work, anyway? Not like you would be destroying expensive italian marble, or beautiful carpet that you want to keep. Of course, if the subfloor was glued & installed well, maybe not as easy - but was it?

Work smarter, not harder.

DJ (VA)

One nice thing I like about this $5K house is the original hardwood floors and they are in good condition. I would not want to remove the hardwood floor in bedroom with the sagging floor. This will be a crawlspace job only.

Where I come from the term "lag- bolt or screw" are the same thing. Its a heavy duty screw with a hex head that is driven with a socket, or wrench.

There is no one way to sister a cracked beam. Some ways are stronger than others.

The ideal way is to sister in an entire new beam making the old broken one redundant. Often this is impractical. Plumbing, electrical, or framing are often in the way.

"scabbing" on a sister beam or patch is often done. The longer the better with additional "meat" to screw & glue will give the best support. Often a pier will be needed to support this repair, Especially when the span is long, the "Scab" is short, or there is a lot of damage and sag to take up.

Fasteners must be up to the task of supporting the loads, fighting corrosion, and handling the shear load. You can use LOTS of smaller fasteners like nails and screws, or fewer Larger fasteners like Lags, threaded bolts+washers.

no need for treated lumber

be sure you crown it, use ANY gun nail.

if you can't get the ends to sit on a plate you can add 4x4's at the ends to pick up the load most of which will be transferred to the existing plates by way of the sisters

a girder on a pier is also a great idea if you are space limited. a piece of 4x6 perpendicular to the sistered joists will be uber strong like bull