Fiberboard Sheathing

[joe1086]

I replacing a cantilevered bay door with new, slightly narrower patio doors myself. The house is 30 years old, no house wrap and sheathed with 1/2" fiberboard. Once I install the new door there will be gaps between it and the siding and the roof line of the old bay door. Eventually a new screened new porch will cover all that up. But I am concerned about the exposed fiberboard....it may be at least a couple months before the the new porch roof gets installed. The gaps will be about 8 inches on each side of the door and 18 inches above the new door. Looking for suggestions to keep the weather off the fiberboard. Or should I not worry about it?

[Snipe Hunter]

Kind of hard to picture what you are talking about. Can't yu cover the fiberboard with something until the re-do? Fiberboard is like a sponge.

[Cooler]

In the early 1970s fiberboard was an accepted sheathing.  There would always be one piece of plywood on each wall to keep the framing from racking. 

I joked at the time that I could shoot an arrow through both walls of a newly built home.  The arrow only had to pass through aluminum siding, a thick layer of cardboard (firberboard) and then sheet rock.  Probably "both walls" was a hyperbole, but certainly the arrow could penetrate one wall. 

By the late 1970s that type of construction was outlawed in New York.  I am surprised it appears in a house built in 1990. 

My best suggestion is take down the sheathing and install a proper one.  Flake board seems to be in vogue now, but I favor exterior grade plywood.  It sounds like just a couple of boards will do it. 

The alternative is to use house wrap and pray.

[joe1086]

Cooler that makes sense. I'll cut back the exposed fiberboard and replace it with 1/2" exterior plywood sheathing.

[Cooler]

While you are at it check the fiberglass for mold.  If there is black anywhere, replace it.

[Snipe Hunter]

It's not an approved sheathing (anymore) here either.

[crokett™]

I would cut the fiber board back. then install plywood sheathing, then house wrap that is as far back under the existing siding as you can get it. You don't say what kind of siding you have.

[joe1086]

I would cut the fiber board back. then install plywood sheathing, then house wrap that is as far back under the existing siding as you can get it.  You don't say what kind of siding you have.

Good idea. It's aluminum siding, so I should be able to get the wrap under the siding a little ways.