1890 FLOOR JOISTS
1890 FLOOR JOISTS
(OP)
I am working on duplex units that were built in 1890 The floors are constructed out of 2x10 actual size floor joists but I can not tell what type of wood was used hence I do not know what allowable values to use. The joists span 21.5 feet and are randomly spaced anywhere between 16 to 24 inches on center. Does anyone know the today's equivalent of 1890 2x10's (actual size) floor joists.
The fun part is the roof is made of 2x6 joists directly over 2x8 (actual sizes) too spanning 21.5 feet. It's an interesting design to analyze. Any help will be appreciated as usual.
Merry Christmas and Happy Holidays!
The fun part is the roof is made of 2x6 joists directly over 2x8 (actual sizes) too spanning 21.5 feet. It's an interesting design to analyze. Any help will be appreciated as usual.
Merry Christmas and Happy Holidays!






RE: 1890 FLOOR JOISTS
RE: 1890 FLOOR JOISTS
Thank you very much!
RE: 1890 FLOOR JOISTS
Another thing you can do is to take some samples and test for their maximum tensile stress in a lab - using a beam break method and then associating the results with current NDS graded lumbers.
Or a load test on the floor if you really want to know what you got.
RE: 1890 FLOOR JOISTS
Thank you all
RE: 1890 FLOOR JOISTS
RE: 1890 FLOOR JOISTS
A Carnegie Companion I have from 1897 says conventional rectangular 2x spruce and pine beams had an allowable "extreme fibre stress" of 750 psi, oak 998 psi, southern yellow pine 1245 psi. (Please verify those numbers with your own research!) For the first two species these old allowables don't appear that far from modern values for the better grades.
Anyway, you can identify the species that you have by cutting a small sample and sending it for analysis by the USDA forest products lab. Believe there was a post about that process here a while ago, try a search in eng-tips.
Good luck.
RE: 1890 FLOOR JOISTS
Also, you should use a manual wood coring tool to core completely through the wood at several locations. This will allow you to look at the center of the wood as this is a location often susceptible to attack by "wood destroying organisms (WDO)". Further, it will give you sufficient sample to get a species identification done. You can probably get that from your local agricultural extension station affiliated with your state universities. Most of them have arborists/foresters on staff or accessible for such things.
RE: 1890 FLOOR JOISTS
An additional issue of renovation to consider was the joists are often notched from electrical and pluming upgrades.