Expert: Bruce E. Johnson - 8/21/2004

Question
Greetings Bruce,
 We had a home inspector say "Joist hangers or ledger strips need to be installed or floor joists that bear over foundation vents"

 The home is already complete.  Can theses elements be added after the fact.  What's the impact if we don't install the joist hangers.

 For what its worth, we live near Raleigh North Carolina.

Thanks,
Steve  

Answer
Hi Steve, without being able to see your particular situation all I can do is speculate. So here goes:  Perhaps your foundation vents have no structural "header" over them.  This is usually the case in stem wall foundations that have crawl spaces.  So what is happening is that all of your other joists have a support under them (the concrete or block wall).  But where your vent openings are there is no concrete above the vent for the floor joist to bear on.  Usually in construction such as this you have a "rim joist" that your joists are nailed into, usually a 2x12 but depends on the floor joist size.  Anyhow, if you can crawl up underneath to where the joist is over the vent you might be able to slip a joist hanger under the joist and nail it to the rim joist.  Basically, the inspector is worried that over time gravity will cause the unsupported joist to begin to sag and cause structural problems in the future. Hey, that's why we have inspectors and building codes.  To look out for things like this.  Remember that when you do this repair, to use special joist nails when nailing to the rim joist.  Joist nails need to be no longer than the thickness of the rim joist.  Otherwise they will poke out the other side and ruin whatever siding you have on the other side of the rim joist.  Because they are shorter, the joist nails have special "barbs" on the sides so they hold better, and they are "fatter" to give you good shear qualities.  Be sure and fill all the holes with nails.  If for some reason you can't get the joist hanger to slip under the joist you can get two piece or butterfly hangers and put one on each side of the joist.  I hope this information has been helpful, feel free to write again regarding this or other matters, sincerely bruce e johnson