Termite Damage

[jlb446]

I'm working on renovations of many single-story, conventionally framed wood houses exhibiting varying degrees of termite damage. I need to develop guidelines for the contractors concerning acceptable and unacceptable levels of section loss and void penetration for various members (headers, studs, rafters, sills, top plates, etc.). Does anyone know of common guidelines for something like this? All I can think to do at the moment is to run analyses with typical loading conditions with varying member properties.

 

[mike20793]

The IBC has limits for notching and drilling through new wood construction. I bet you could go off that, but anything with a reduction in cross section will need to be analyzed for the reduced area; but if it's single story-single family, you may be able to stay within the conventional light framing prescriptive guidelines. But I'm not that familiar with the IEBC, so I'm not sure if there are even provisions or how they compare to the IBC.

 

[Teguci]

Are you using radar to detect the termites?

I'd think a procedure like:
- detect infested elements with radar and mark
- pick a section and probe around infested elements
- any penetration of 1/2" or more into element with probe requires replacement

How do you get an accurate amount of section loss for running numbers on?

 

[jlb446]

Interiors of buildings are stripped of all sheathing prior to construction (asbestos abatement subcontractor) so extent of termite damage is easily visible. Members will have to be probed and sounded to accurately determine actual section loss, but coming up with reasonable estimates should not be difficult. In some houses the damage is non-existent to superficial, while in others I'm amazed portions are still standing.

 

[MikeHalloran]

... extent of termite damage is easily visible. ...

Uh, respectfully, no.

Some of my house was sheathed with 'reverse board and batten' plywood siding. The intersection between walls and the underside of substantial overhangs had gaps from the substantial grooves in the siding. In an effort to control the interior insect population, I made and installed some softwood plugs in those holes, measuring maybe 1" x 1" x 5/16".

A couple of years later, I had occasion to inspect those softwood plugs.
All appeared intact, but weighed next to nothing.
Termites had hollowed them out almost completely, leaving an undisturbed skin nearing transparency on every face, with just a few tiny holes where the termites had entered and exited.

I've seen substantial wood beams where termites had substantially reduced the cross section.
... but the modified exterior surface does not define the limits of the possible destruction.
I don't know how effective 'radar' or thermography or whatever is.

The traditional detection method is plunging in an icepick with considerable vigor.

If I had to inspect a lot of houses for termite damage, I might consider trying a framing nailer as a mapping tool. I'd expect to find areas that looked just fine but didn't sound right as the nail went in, and other areas where the tool would propel a nail all the way through what looked like sound wood. Maybe you can work with the contractor on that; it sounds like rather fun.








Mike Halloran
Pembroke Pines, FL, USA