Proper way to replace rotten floor...

[flyguy]

My wife & I bought a 1959 house with substantial damage to the kitchen and bathroom floor and underlying joists. Whatever the water didn't damage, the termites got. It also didn't help that someone cut the floor joist in order to install the plumbing for the tub.

Here's a picture of this beauty: http://www.vawaterfront.info/Public/rottenfloor.jpg

The joists are resting on a ledger board that is perpendicular (naturally). I will pull up the entire sub-floor, check (and replace if necessary) the ledger board and replace the joists with pressure-treated wood. The house has been thoroughly treated now for termites. I will replace the sub-floor (pressure-treated plywood?) and use a linoleum product for the floor covering.

I will also put down a 6 mil vapor barrier in the crawl space (where none existed before) and insulate between the joists.

My question: Is there anything else I've forgotten? Should I put down a sheet of plastic atop the joists before laying the subfloor down for an added layer of protection?

Any ideas would be most helpful.

[pushkins]

If your adding insulation between the floor joists it will need to be "faced" (paper on one side, paper side always faces the heated area), then you do not need to add anymore plastic as a moisture barrier on the house side, in fact adding a second layer would be very detrimental to the sub flooring by trapping moisture between the two, plastic should be laid in the craw space to stop ground mositure.
Make sure if your sistering the new floor joists to the existing (what's left of them anyway) that you bolt the joists together, I always use 1/2" bolts and stagger the holes one up, one down, one up...etc...etc.
There is really no need to use pressure treated lumber for the repair, as when fixed there is no more water to worry about, nor is it used in most new builds.
The cutting or notching of the floor joists for the tub drain, isn't all that surprising, it happens much more than you think, in an ideal world the joist should be cut completely and a header added across it from the floor joists on either side of it leaving enough space for plumbing.
Be very careful when using pressure treated lumber under vinyl flooring, many times it can an adverse reaction with the vinyl/glue, also it is very important to make sure it is very dry before adding any sort of covering over the top of it, most pressure treated material is very wet, your best solution would be a product called "Advantech" (Lowe's/Home depot sell it)it is specifically made for flooring and can handle reasonable amounts of water before any noticable failure. It is the most common used flooring product in new quality new builds and the only product I use for new or renovation/repair work.
I always use a bead of construction adhesive on the top of the floor joists before laying the new flooring and I always screw the flooring down, NEVER nail.

[flyguy]

Pushkins, That is GREAT advise that I will gladly follow!

Thanks!

~ Mitch

[Trishaj]

When you are talking about replacing joists and sistering in the new pieces should there be overlap on the old joist? Also, I have a manufactured home with extensive water damage to the sidewall floors and some rot on the sidewall joist, what would you recommend on replacing the sidewall joists and do i have to support the sidewall with a jack as i replace each section?

[llt2012]

rotten floor metal joists

i am looking for info on removing rotten and not partical board flooring to put 3/4" plywood joists are metal. do i need treated or not? also any other advice on how to get this crumbling part boards up faster would b great?!

[HayZee518]

joists?

are these metal joists or trusses? I've never seen metal joists

[llt2012]

Sorry joints.

are these metal joists or trusses? I've never seen metal joists

Maybe they are called joints. The support beams for the floor. They are metal.

[HayZee518]

hangers

those metal things are called JOIST HANGERS

[llt2012]

Hangers joints lol

those metal things are called JOIST HANGERS

My husband said no it being a remodeled modular home it has metal beams of support no wood. Do we need to add wood when we take up the partial board for plywood or can't it be attached like the partical board is only attached with a 2x4 under partical board that's attached to metal beam that's why this is hard the middle of our house is a modular we built on to and bricked and had a house roof put on. So it's the modular part we are tearing up that partical board and putting plywood to be sturdy and not rot through like this partical board is doing.

[pushkins]

Can you post a picture of what you have that would make life much easier?

However the modular part is framed is pretty well how you will have to redo it, I think what you have is the main beams are steel and on these sit Pine 2x4's and then the sub floor is screwed to the 2x4's. You will need to replace any of the 2x4's that are damaged they are usually held to the steel by little clips screwed to the steel and the 2x4's.
It is very wise to replace the damaged particle board with ply.