I have to replace all the floor joists in my house. There was too much moisture in the crawl space. I have 2x10 in it now but my thoughts are to replace them with a T beam made with a 2x8 and a 2x4 so that I can nail back up into the 1in sub floor? Will this give me the same load strength or more?

should be a little more

make sure you dry out that crawl space ,

Ventilate your crawl space and be sure you can keep it dry or the same thing will happen again. It may be healthier for your family too.

Whatever your replacement is I’d make sure it’s vertical measurement was slightly less than the existing joists so I could get them in easier. Once in place they can be shimmed up tight.
As to the replacements you should be able to get the load calculations from the maker. On center spacing comes into play plus the required dead/live load requirements in your area.
Nearly had the same issue here but caught it in time.

Osky

I am sawing my own lumber all true width. Unorganized township so no worries about inspections but it is built to standard. I put 4 8x16 vents in when I built it but didn't put a vapor barrier on the bottom my bad put in drain tile around footings as well. Now it's my job to repair my mistake. There are 30 30foot runs to replace on 12in center so it's a big job. It will be done write this time I am going to replace drain tile as well some time this summer. I only have 3 weeks off work know so my priority is to get the wood sawn and drying. Still snow on the ground here.

Osky I am going to replace the old 2x12 sill plates with treated lumber from the hardware store so it should give me a 1/4 inch wiggle room 2 story building so it is heavy. I over nailed everything when I built it. I have even thought about dismantling it and going to a one story but that would entail hiring a crain to lift the top off and replace it on the foundation when ready. To expensive for my wallet so I have to go this route.

Good luck

(30)x30ft overnailed 12" o/c working in a crawl space!!!

To be honest, it sounds impossible to me. That, even if you didn't have to deal with wires, pipes and ductwork.

Good luck. If you can do that, by yourself, in three weeks; you are a much better man than I ever was.

Maybe I am visualizing something worse than it actually is. I don't mean to discourage you, but I do think you need to be clear on your scope of work before investing too much.

I am making the assumption that 30' span is supported by at least one intermediate beam.

do you have to replace or can you sister them up , dry out the old , get a drylock type paint on them then pull the rim joist one side at a time and slide the new joists in and glue and nail them together?

you say no concern with building code enforcement

you said you are cutting to size , a section of beam you make with some blocks of wood nailed to it and a pair of jacks you can lift just enough to slide the new joist in along side the damaged one , nail then lower .

most structures with rim joist off you can lift a 1/4 inch to get clearance, especially since they are often sagging as the reason for replacement

Do not tear the old ones out, put new ones beside the old ones an screw them together. The old ones still have a lot of strength in them. And you will do a lot less damage to yo flors by leaving the old ones.

cutting out a rim joist with a sawzall and circular saw isn't that hard , but if all your sub flooring is glued and nailed or glued and screws to the floor joists that is going to be a mountain of work.

if they hold the weight today taking them out completely shouldn't be needed leave them in and leave the floor connected to them

if you have the room to work you could peobably just tip up new floor joists and shim the ends and not even take the rim joist off unless it is rotten

get a bunch of vents in

X2 Don't know how you floor is constructed , but if sitting on pilings with main beam running down the middle. Just use hurricane brackets and floor jack with blocks. Raise the old joist up slightly then measure attach bracket slide in joist, nail or screw in place lower jack . Repeat...........

• nail plywood under the existing joists
• support where necessary
• drill holes in floor above
• fill spaces between joists with concrete

On a more serious note: Sistering up your current joists makes a lot more sense, It will still be anywhere from difficult to impossible because of the 12" spacing/heat/elect/hvac.

Assuming it is realistic, and you already know this; it is a huge waste of time and money, if the moisture situation is not rectified.

Insure well.
Leave hot bucket of ashes/coals on a wood floor.
Build new house.

Vent it.

Yip. And dryed sufficiently, there may be enough strength in your existing joists to require nothing more.

Just curious, is there a mold issue related to this?