Spacing of Vertical Joints in Insitu Concrete Basement Walls
Spacing of Vertical Joints in Insitu Concrete Basement Walls
(OP)
I have always used a rule of thumb that vertical joints in poured insitu concrete basement walls should be spaced at a distance between 3 and 5 times the height of the wall.
For example when a basement retaining wall is 10 feet high we would locate vertical construction joints in walls at 30ft(10x3) to 50ft(10x5 spacing.
Does anyone know if there is guidance in a code or document that describes the maximum spacing of verticl joints in basement walls?
For example when a basement retaining wall is 10 feet high we would locate vertical construction joints in walls at 30ft(10x3) to 50ft(10x5 spacing.
Does anyone know if there is guidance in a code or document that describes the maximum spacing of verticl joints in basement walls?






RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
Check ACI 224 for controlling cracking in concrete.
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
From observation, cracks will form at about 10' centres if a wall is restrained by a previously poured footing. Whether or not these cracks are of concern, and whether or not they need to be controlled by more reinforcement, is a matter to be considered in each instance.
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I assume you mean cracks will form at 10 foot centres when there is little or no reinforcing in the wall.
For a rebar reinforced retaining basement wall I would have no problem with joints at 30 feet or more. Drying shrinkage is what I would be most concerned with. Once temperature is not an issue rebar reinforced walls (10 to 12" thick, 10' high) are regularly poured up to 50 feet in length in the UK and Ireland.
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
I understand now where you were coming from in relation to the restraint that the already poured footing provides and it's a good point.
Going back to my experience with basements I have not seen cracking at 10 foot spacing. General we would use 5/8in vertical bars and 3/8in horizontal bars in a 10in thick RC wall for heights up to 10 foot. Where I work there is generally a lot of moisture in the air and its rare for temperatures to rise above 60 degrees. I suppose this helps the curing process. We have no problems pouring walls 30 feet or more in length that have very little or no cracking.
I was more looking for a reference that recommended pour lengths for walls to reduce cracking. I was asked to look at another consulting engineers design for a basement wall that has cracked with the resut it is leaking water. I haven't yet found a comprehensive document on this in the British Codes. It is easy enough to design for crack widths of between 0.1 to 0.3 mm but there is little guidance on recomended wall pour lengths.
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
BS8007 doesn't give guidance on the max length of wall pours. I can't find a code reference for the length of wall pours. There are a few unofficial references that suggest wall pours should be 20 feet for a standard 10 inch thick wall 10 feet high.
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
In ACI 350, joint spacing is a function of horiz reinf area.
For 30 foot joint spacing using fy=60ksi steel, minimum horiz area = 0.004.
That is, (2) #5 bars per 12" vertical spacing for a 12" wide wall.
Various ACI commentaries note crack control for environmental structures is intended to limit cracking to 0.10mm (0.004").
Agree with previous comment that drying shrinkage is the primary problem when temperature swings are controlled.
I always define construction joint locations on the dwgs, and they are typically 40ft apart, keeping at least 4ft away from corners and Tees.
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
I need to get my hands on copies of ACI318 and 350. I use British Standards generally but I did use ACI318 some years ago for punching shear in a heavily loaded slab as it gives guidance on how to use structural steel beams in a concrete slab to resist shear over column heads.
RE: Spacing of Vertical Joints in Insitu Concrete Basement Walls
There are different views on how to pour Olympic pools. I worked on an Olympics pool 7 or 8 year ago and we used a chequer pattern for the floor of the pool with water stop at the joints. It worked ok but was a lot of work for the contractor.
Pouring a floor 50m by 25m in one hit is a 375m3 (490 cubic yards) pour which is quite big for a thin floor slab around a foot deep.
I think two pours on an Olympic pool makes sense.
Remember designing a small pool where tiles were laid over the construction joints which didn't work out very well.