Cardboard-like substitute for wood

[thethrillfactor]

Trying to learn more about my 70s built house.

Recently learned that some cheaper builders used a cardboard-like substitute for wood in the walls. Not the joists of course, but between the tyvek and the drywall.

Anyone have any more info about this? How bad is that?

Any help is appreciated!

- J

[HayZee518]

Not really sure of what you are referring but two types are MASONITE and HOMOSOTE. Masonite is brown in color and comes 1/8, 1/4 and 3/8" in thickness. Homosote is like a gray compressed cardboard. You see it a lot in train boards. Neither of them has any "support" mechanisms. Masonite is used for drawer bottoms.

[thethrillfactor]

Homasote does sound exactly like what he described.

His characterization sounded somewhat structural, implying that it's use in our home was lateral spanning across the studs.

Would that type of use be of greater concern?

[HayZee518]

Homosote is used as sound proofing of walls. as I said before it is also used in model train boards. once cut it bends quite easily.

[Drywall DIY Guy]

Sheathing?

Sounds like a pressed board sheathing. We have that in ours 60's home. It is pretty weak, but I guess it was code at the time. OSB is better and used commonly now. Plywood is much better. Your drywall on the inside does a lot to stiffen the walls as well.