Pier Construction Question

[daz]

Work will be beginning on the obsy soon and I'm thinking about the pier construction.

My obsy shed does not have a floor at present, so I can construct a dwarf brick wall at whatever height I need, but I don't want to have to assemble the thing, measure the height of the pier, take down the shed, etc. etc.

So, I am thinking that, while I have the digger to flatten the garden area, use to dig out the necessary sized hole. Then when I come to pour the concrete, I am thinking:

Insert vertical rebar into the 'plug' where the pier will sit

Use a smaller diameter sonotube over the vertical rebar, pour 6 inches of concrete

Build the shed then

Use the planned diameter sonotube that sits over the 6 inches poured before, which can then be cut to the right height and filled with concrete over the vertical rebar

So, does this make sense? Any gotcha's that I've missed?? Is there a better way???

[MikeP]

It sound like a good plan, but if it were me, I'd build the whole pier and assemble the shed round it. If you do as you propose, won't it be a pain trying to concrete into the shed to fill the second tube eg a bucketful at a time? Those pier top things that you fasten the mount to seem to have tons of adjustment, so you would not need to get the height spot on.

Just my opinion - thousands will disagree.

Mike

[barkis]

I did it the way Mike suggests Daz. I built a wall for the shed to stand on with concrete blocks. These were cemented to a foundation of concrete, not free standing, but I suppose they could have been.

But, the shed was L bracketed to these blocks to hold it down in a hurricane. I assembled the shed, wiorked out the position for the pier, then dug a hole 2ft square and 1ft six inches deep. I then filled the hole with concrete. When it set, I built a wall using the pad as a base, about 2 foot high. When that had set, I placed the pier onto the pad having drilled 1" holes at several points in the pipe around the base to a height of 1ft. 6" to allow the concrete I filled the brick box with, to get through the holes.

I poured concrete into the pipe right to the top. Therefore the crete in the pipe, mixed and set with the crete in the brick box. Solid as a brick s********. The wooden floor of the shed was fitted around the brick wall the protruded above the floor level about 9" I think I use it as a shelf for putting bits and pieces on. The following picture is not all that clear in illustrating what I have been saying, but I can take more if you wish.

Ron.

(click to enlarge)

[daz]

Yes, that makes sense Ron. Did you assemble the shed, work out the pier position then disassemble the shed again? I was trying to avoid that but Mike is right, trying fill the pipe with a bucket is going to take forever!!

It looks like I'm going to have to at least partially assemble the shed to get a good indication of the height.

Stop trying to cut corners Daz!!

[barkis]

I did not dismantle the shed Daz. The weather at the time was persistent rain, so I put it up and screwed it down. I left the floor out until All the excavation, concreting, Pier insertion and filling had been completed. A framework was put around the brick shell to take the floor joists in order that there was no contact between the floor and pier. I left it all to set and cure for over a week before putting in the floor. 2" Drainage pipe ran under the floor into the base of the pier, up near the top, and out near the top below the pier head. A mouse was run through the pipe at a later time to draw the necessary cables through to the computer desk. The pipe I used was HP Water pipe with 30mm thick wall and 12" ID The concrete I poured in reaches to the top which was cut to the correct height prior to the pour. I put a 30mm thick Alloy plate 28" diameter on top of the pier, which allowed me to place the Meade wedge in the most optimum position atop the pier. This plate is fully adjustable for levelling purpose by four 3/8" thick support L Brackets spaced at 90 degrees around the pipe.

It is very solid indeed.

Ron.

(click to enlarge)

Ignore the the Mount atop the pier, that was an experiment I dispensed with.

The Meade H/Duty wedge in on there now.