building an interior wall

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While applying for a permit last week, the building inspector was explaining something to me I didn't quite get.

He was describing how an interior wall should be supported with respect to the direction of the underlying floor joists. (I have a single floor house with crawl space).

I think he said that if the wall is perpendicular to the joists no problem but if it is parallel to the joists and it does not rest directly on top of a joist then I need to construct bracing underneith the floor consisting of blocking between the joists to hold a new (virtual?) joist (doubled up 2x8 he suggested) at the wall location.

Does this make sense or did I get it backward, mixed up or missing a detail. It seems to make sense this way. Seems like overkill for a non load bearing partition wall of less than 6 feet in length.

Thanks in advance for your insights

[Duane Bozarth]

May be overkill for a short wall, but certainly one could forestall a potential problem w/ some minimal additional effort beforehand. The subfloor material would influence my thinking some as well...if it's a stiff material such as ply it will handle the point load a lot more satisfactorily than the OSB's or similar materials that tend to sag more.

[Duane Bozarth]

...regarding support for interior walls running parallel to and between floor joints...

One additional thought...

I'd also not get particularly concerned unless the wall nearly centered between the two joists or the joists were on >16" spacing.

[tbasc]

respect to

consisting of

It's usual to place a double floor joist below a partition. If the partition to be supported contains vertical plumbing, joists may be separated and solid blocking mounted between them.

International Residential Code requires this kind of arrangement for bearing partitions. I call for it in all cases. TB

[Mike]

Your first step is to figure out if it is not resting on a floor joist, because if it is, then there is no problem. If it lays across joists, again no problem. If it is not either, then you have some extra work to do.

[Edwin Pawlowski]

Interior wall? Permit?