[herculix]

Hi there,
My recently purchased 1960's property has a number of cracked sub-floor joists (perhaps 50% look to be damage-free). A pre-inspection builders report didn't mention them, and a subsequent visit by same builder says the cracks are normal for New Zealand rimu timber and it's not a problem. I'm not so sure. The damaged joists typically look like the one in the picture below, some are worse. The bearers are steel I-beams on concrete foundations. They look fine. The joists are 9x2", length approx 12ft, spacing 18". They are herringbone-braced twice per span.

The arrow indicates a gap above the joist between it and the partition wall above, which is essentially being supported only at its ends. I'd appreciate any comments.
Thanks.

 

[Half-fast eddie]

Looks normal for large timbers on this side of the world. If the gap under the wall bothers you, drive in a shim.

 

[Nealtw]

That would normal here, but it would fail as our garages have to sealed from the house with drywall.

 

[herculix]

Thanks for the posts so far. Here are a few more examples of my cracked joists. I'm trying to figure out if there's an underlying problem given that so many of these are cracked or is it just due to the wood drying out and they are fine to leave? There's potential for moisture in the garage. Could that be contributing?
Joist1

Joist4

Joist5

Joist6

Joist7

Joist10

Joist12

 

[Half-fast eddie]

Normal shrinkage cracks for large wood members.
The last picture seems to show a lot of water damage on the end of the joist.

 

[herculix]

The wood that sits on top of the I-beam bearers seems to be covered with something. Joist6 and joist12 show it quite clearly. At first I thought it was concrete, but could it be lime?

 

[That Guy]

Put tape over the cracks to see if their moving

 

[herculix]

Put tape over the cracks to see if their moving

Sounds like a good idea. What sort of tape would be optimal?

 

[huesmann]

Probably easier to fill them with solid filler; if you see more cracks after a while, you know they're moving.

 

[udraft]

String line the joists. If there is no sag, they have not moved.