basement supports?

Question

I recently bought an old house in Northern N.H. It has an unfinished basement, the basement floor is just sand actully. My question is, under the kitchen (20' x 18') there is a 3 ply 2x10 beam supporting the 2x8 floor joists. The problem is the base of the metal columns holding up the beam are just dug into the sand about 1' and are not resting on concrete. I was wondering how big of a concrete pad I should try to put under the base of the columns?

Answer 1

The last house I built required 36x36x24 footers on shale for columns that didn't even support load bearing walls. While that is excessive in your case, based on the info you provided, 24x24x18 is most likely your best bet with some rebar/rewire thrown in unless you have really rotten soil conditions. If you have a usable adjustable lolly column you should also use it to make any fine adjustments to the level of your floor while you can. You don't want to jack them too much but you can tune them for a great finished product. A hydraulic jack with a sturdy support will take the stress off while you are working. Let the concrete set for a few days before you reload it.

Answer 2

I would suggest digging into the dirt deep enough to put a post extended to at least 7 1/2' on top of your concrete footing. This will allow you to dig out the basement (and finish it to a 7 1/2' ceiling) in the future and pour a concrete floor without having to mess with this footing again. Get 2 or 3 4X4 posts to hold up the kitchen and put them in close proximity to the post first. Put the 4X4's on a concrete block and then remove the metal post and dig away. You can shape your dig to be the form for the new poured footing and thus eliminate the need for wood forms around your slab. It also provides an "undisturbed base" for the concrete footing and thus eliminate settling of the slab. Good Luck!

Answer 3

Well if they are just on dirt, any concrete or even a block would be an improvement. It must have been built without any columns and they were added later to reduce sag. You should insert some boards tightly to hold it up before you remove them to add concrete. New homes here use a 30 inch diameter footing 8 inches thick under columns.

Answer 4

Ask your local builing inspector. No matter who tells you what on here it is your local authority having jurisdiction that will tell you whether the measurments you plan to use match the conditions in your area and local code requirements. If you don't use those guidelines it may come back to haunt you when you sell, or worse yet if an accident occurs and the party doing the repair ends up liable

Answer 5

I would go atleast 16" X 16" at the very least.Also i would buy new metal post and anchor them to the concrete. pour the concrete and insert anchor bolts when it begins the stiffen up a bit

Answer 6

just a pad wont do, if the floor is just sand as you say, the pad will just crack, it needs a footer under the posts at least 24 to 36 inches deep

Answer 7

10" is good