New floor pillars

[Richo Relaxo]

Background
I have recently purchased a house which as renovated 12-odd years ago. Part of this reno was the addition of a new wing to the house; an old original cottage with the addition of a large living area & full brick veneer.
After recent heavy rains I inspected the crawl space under the house to find that I have wooden pillars which are absorbing water (building inspector...yep I hired one prior to sale, but that is a different storey).
My question is....
What recommendations do you have for replacing new floor pillars (noting that I have about half a meter crawl space to work with & coming-in through the floor is a last option)?

See pic attached - you will note that there is evidence of water damage to the pillar in focus.

(side note: Im in the process of adding a new drain to minimise water entry at the high point of the house plus water proofing where I believe there is water entry at this point & adding new ventilation where, again as part of the reno, the driveway was resurface which blocked 3/4 of ventilation points on one side of the house).

What Im Thinking....
1. Dig & hole & create a cement base
2. Purchase steel braces (placed on cured cement base) that I can tighten to create new pillars (& ant-cap).


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[Richo Relaxo]

um...should I be here?

[Darren Miller]

I would assume you have some type of base (footing) under the existing columns now. If so, you can temporarily support the beam, remove the existing column and replace it with a new metal column. (the most important part here is to PROPERLY support the beam while the work is on-going).

In the picture, it almost looks like a block wall is running at grade below the beam. If so, you can build piers on top of that wall.

[Bruce Ramsey]

Yeah it is a tight space. Looks like 16 inches based on the concrete pier to the left.

Dig a hole in the dirt and pour a proper footing. At least 12 inches deep. Then install a pier on top of new footing.

[John Kogel]

Richo, you appear to be down under in Australia.
You do not have a concern for frost heaving, but you have some of the most voracious termites in the world. You definitely need a concrete footing, but it may not need to be deep. The critical thing IMO is to keep termites away from the posts. I'm sure there are accepted methods for accomplishing that. Talk to local builders.
Steel jack posts are usually considered to be temporary, so you should go for a permanent post design.

[Jerry Peck]

Additionally, not being able to see a relative spacing scale in the photo, or where the next supports are, you many well need to add additional supports as those "beams" do not look very large, maybe 3x4 or something similar (based on the size of the concrete block next to the far beam). Something that small would not have much of a span rating.

[Richo Relaxo]

G'day John,
Termites & white ant are the issue - lucky there is no evidence of these guys within the dwelling.
I have sourced a product which I beleive may do the job - "unipiers" unipier.com.au.
This will both serve as a permanent solution & resistant to termites, whiteant etc...
Thank you.

[Richo Relaxo]

Good day Jerry,
Im looking at 24" (60cm) headroom in which to do the work.
These are 2x3 which I assume were used to create the form (here in Oz we cave corro as the base to pour the cement), these beams are 24" apart. There is quite a bit of form work under there with a combo of brick & wood piers (could these wooden piers be temp as a result of the form work?).
Sundays job is to don some hard yakka clothing (keep spiders out if anything) & map the place out down there to see what needs replacing?

Question: What spacing of piers would one expect for a 14m x 12m extension?

(Helpful hints: looks like the floor has been formed, brick veneer exterior on cement base, I can visual brick piers but unknown distances etc).

[Jerry Peck]

These are 2x3 which I assume were used to create the form (here in Oz we cave corro as the base to pour the cement), these beams are 24" apart.

Wow, even smaller than I imagined (however, I was thinking 3x4 at the most, so I guess 2x3 would be the next size down).

2x3s are not going to have much load bearing capacity at much of any space, which would mean the piers would need to be quite closely spaced. The 24" spacing of those 2x3 "beams" (I hate to refer to a 2x3 as a "beam") would depend on what is laying on them and what that stuff can span.

Not much help in answering your question other than saying that 2x3 would need piers very closely spaced - unless that was some kind of very strong wood ... VERY strong wood.

[Rick Cantrell]

The floor looks like corrugated tin, if so I think that would make it a poured concrete floor. How does that effect span?

[Jerry Peck]

The floor looks like corrugated tin, if so I think that would make it a poured concrete floor. How does that effect span?

That's what it looks like to me to, and the span you are referring to is the span of the slab above or the 2x3?

If that is concrete, that would increase the weight on the 2x3 which would reduce their allowable span.

If you are referring to the concrete then its span will depend on the reinforcing used in it, which is unknown.

[Rick Cantrell]

I was thinking about the concrete.
I've seen these before, mostly for porches. The wood looks like it's only purpose was to hold up the concrete during the pour, not as permanent support.

[Richo Relaxo]

Good day Rick, good day Jerry,
Indeed this is a poured slab. I am seeing cracking inside where tiles have been laid & it has been deduced that this is where the 'old' cottage meets new.
Regarding reo, sorry I cant help here.