# Cantilevered floor, plywood soffit



## Windows on Wash (Aug 30, 2011)

WRB shouldn't be wrapped under like that. That is why it rotted out.


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## jlhaslip (Dec 31, 2009)

Was the old soffit vented? Probably not.


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## Bud9051 (Nov 11, 2015)

Hi Strode and welcome to the forum.

If we assume your siding isn't leaking or has a condensation issue (probably not) then any moisture issues in that overhang are most likely coming from condensation. 

Let us know where you are, warm, cold, or wet climate.

When you replace that soffit be sure it is air sealed all the way around. Don't use a vapor barrier and IMO, add an air block to keep warm humid air from the basement from getting out there, something like a sealed piece of 2" rigid foam.

Assuming you are in a cold climate humidity from the basement is reaching that cold soffit right through the fiberglass insulation. 

Another approach would be to line the entire exposed surfaces, rim joist and soffit with the 2" foam to be sure all surfaces remain above the dew point. Use a plywood soffit to allow some drying to the outside through the wood.

Bud


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## carpdad (Oct 11, 2010)

1. vented vinyl soffit maybe the best choice but all the air moving in and around will cut the insulation value of entire insulation done there. Esp if the soffit insulation is for soffit only and ceiling bay is open. Extending to the upstairs wall and the floor may feel colder as well. Any plumbing there may freeze (including water heating and bath - back of the house if same kind of cantilever soffit). Any duct will lose. If soffit only, I would consider replacing all fiberglass with xps panels (combined thickness of 6") blocking the ceiling and interior joist bays. Seal all joints against air leaks. But read further on for problems with facia trim. You don't want leaks from outside.

2. The trim on the corner (facia) must have a drip edge and that drip edge must be sloped to drain. Some drip edges are carelessly installed with front edge bent up. Drip edge overlaps must overlap 6" and sealed with excellent caulk. They are aluminum and must not be over nailed. House wrap or flashing must overlap the drip edge. Windows must have header drip edge.

3. Any window flashing must not drain under the siding down to that soffit.

4. 2nd floor corner vinyl trims must drain over flashing or drip edge that drains to daylight and never give it a chance to drain under anything part of the building. 1st fl corner trims must be covered, esp on top.


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## joecaption (Nov 30, 2011)

What type siding is it?
Look at the top of that band board trim and see if there's a piece of Z molding.
If it's wood or Hardie Plank there also should have been kicker strip at the bottom of the siding so the water running down the wall will run past that trim board, not just lay on top of it.
https://www.google.com/search?q=z+b...AQIpQE&biw=1366&bih=638#imgrc=IFfvS8El5XzqRM:


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## Nealtw (Jun 22, 2017)

I haven't read it all so excuse me for repeating what others have said. Above the wall there should be solid blocking from the inside. Vented soffet with out that house wrap and I think Joe pointed out the missing Z flashing at the bottom of the siding.


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## Strode24 (Aug 27, 2017)

Thank you for all of the information. 

I know there are issues with the insulation, but I am pretty sure the water was entering from the gap between the bottom of the siding and band board. There was no z flashing present. 

Assuming I add z flashing and maybe aluminum or vinyl flashing, what is the preferred material for the soffit? There seems to be debate on vented versus solid soffit.


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## Nealtw (Jun 22, 2017)

Vented just like the attic you want air on the outside of insulation.
Vinyl because it is so easy to remove when you think you want to inspect something..

Is there solid blocking between the joists over the wall? There should be and the should be caulked. with insulation on edge on the other side of them


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## Strode24 (Aug 27, 2017)

There is wood blocking, so the pieces of yellow insulation in the picture are only about 2 ft. long. The blocking is not caulked and there is not expanding foam. I was planning on adding rigid foam pieces. I was going to install a vertical piece to block off from the rest of the floor and then a horizontal piece to go above the fiberglass insulation. I was also going to seal this with expansion foam or caulk.


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