Thread: crawl space supports

I was inspecting a house with jack supports. I did not see any concrete footings below the jacks. Are concrete footings required?

I was also wondering about the piece of wood that sits on top of one of the jacks, is that allowed?

Also, is there a correct spacing procedure for placing these jacks.

Thanks,

Rich WhitmerphpGy6XbiPM.jpgphpc8TL9JPM.jpgphpmHxp7WPM.jpgphpoKF4gtPM.jpg

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Originally Posted by Richard Whitmer

I was inspecting a house with jack supports. I did not see any concrete footings below the jacks. Are concrete footings required?
I was also wondering about the piece of wood that sits on top of one of the jacks, is that allowed?
Also, is there a correct spacing procedure for placing these jacks.
Thanks,

Rich Whitmer

Rich,

Without piers/footings, the jacks are likely to just drive into the soil. They need some kind of support. Also, if the soil becomes damp, the metal will rust out.

The wood blocks are odd and make that connection somewhat tenuous. Could they have been put in to make up for jacks that are too short?

Post/jack spacing would typically be noted on the building plans. Without those, it is necessary to try to make an educated guess as to what kind of spacing is necessary. Is it a one or two story house? Is it supporting roof load? There are a bunch of things that we don't know.

Some questions from me...
What dimension are the joists? Are they continuous and large enough to span between the foundation stemwalls without a mid-span support? If so, then maybe the mid-span girder and jacks were put in to minimize bounce in the floor system. I have seen this done when the joists are near maximum span and someone decided the floor was just too bouncy for their taste.

Looks like visqueen on the soil. Was the soil damp/wet? Does water enter the foundation crawlspace area? Are you certain there were no footings under the jacks?

no to all questions--plus those supports are telescoping post--they should only be used for temporary supports and must be replaced by solid supports for final supports

cvf

It appears that the black columns are standard steel columns. The red "post jacks" are not rated for permanent support, even though in many cases they are strong enough.

There should definitely be footings below the columns. Regarding spacing, that is based upon the load on the beam, the strength of the beam, the rating of the column, and the size of the footing.

Placing wood on top of the column is generally acceptable. However, columns are more stable when installed with the adjusting screw at the bottom.

The guys are on the right track. A jack post is very strong and acceptable as permanent support in the jurisdictions I've known however they have to be installed properly. The one in the OP is upside down, among other things. Because by its nature the screw end creates a "point source" at the load it must be against the most solid surface, the concrete. Also, unless the concrete is poured around the screw to lock it in place, the threads must be peened or welded to prevent movement. A block between the beam like in the photo is asking for trouble. Hit the post hard enough at the screw end and it may well pivot out from under the main beam. Lastly, when the post is installed with the screw end down, the then top must be anchored to the support beam with welds or proper fasteners. Here is some good information at the Tiger Brand Jack Post web site. Adjustable Steel Columns, Tiger Brand Jack Post

Is the home in an earthquake zone? Is the CMU filled? If that is unfilled block and you're are in a seismic zone you will want to have an engineer look at it. It is more useful to concentrate on keeping the building on the perimeter than spending money on the joist supports. Point loads are of course a different matter.