Adjustable joist base options

[bolst3r]

Rather than laying a large slab as logistically it's tricky and costly, i'm thinking I can build my garden gym off a series of concrete pillars. I'm the past I've used a cowley to set the heights and have built directly off blocks but this time I would prefer the attached method, especially as it would mean I could adjust the height to get it near on perfect. In the past i've thought about this method but the adjustable posts were super expensive, now lots of people seem to do them at a much more reasonable price.

I've seen these on amazon which have the following spec:

1. 4 ton load
2. 50mm adjustment
3. Galvanised

Link: Adjustable post (amazon)

Does anybody see these as being an issue, or can recommend something similar that isn't super expensive?

 

[oldbutnotdead]

1 you don't usually put hardcore under foundations.
2 you'll need a fairly beefy substructure to your shed if it's only supported by a few points- gym equipment is heavy plus if you're jumping around in there you could get a fair bit of movement of the floor (and thus the whole building).

 

[bolst3r]

@oldbutnotdead

Thanks for the tips, usually I would prefer a solid slab but pouring this on my own, whilst ferrying stuff 60m to the end of the garden make this a no goer. Pillars like this are easier for me to do a few at a time... I usually put hardcore under a slab, so assumed the same was necessary under a pillar, is that not the case if going down to clay?

I was planning on putting mounts every 1.2m across the width (5m), and 1m front to back (3m) so a 4x2 substructure, maybe 6x4 should be sturdy enough.

 

[gonch69]

EasyPads - The easy-to-use foundation system for modular buildings

The EasyPAD foundation system is an easy-to-use foundation pad for a wide range of modular buildings. Get a quote for your project - call: 0333 577 1191.

easypads.co.uk

 

[oldbutnotdead]

4 x 2 to support a floor is deemed adequate with a span of 1800 (its actually a bit bouncy). Problem is your 4 x 2s are supporting not only the floor, occupants and equipment but also the rest of the shed. And you are wasting some of the height having a step up (though it will reduce any problems from damp)
If you've got good ground you could use council pavers as a shed base, if you've got a garden path you've got room to get a mixer and a barrow up there, hand-batching a 75mm base will be hard work but not impossible and (given the price of timber at the moment) likely cheaper.

 

[bolst3r]

EasyPads - The easy-to-use foundation system for modular buildings

The EasyPAD foundation system is an easy-to-use foundation pad for a wide range of modular buildings. Get a quote for your project - call: 0333 577 1191.

easypads.co.uk

Thanks, I had seen these but don't like the thought of them going directly on the ground, feel they could sink over time. Also quite expsnsive once you factor in their brackets (£45) a pillar, so figured what I was proposing was slightly cheaper but more robust.

 

[oldbutnotdead]

It's your money. £200 for fancy jacks, you'll be doing near enough half a cube of concrete (20 points 200 x 200 x 200) and a pile of timber- you could probably afford to pay someone younger and fitter to do a concrete base!

 

[bolst3r]

@oldbutnotdead

Yup, I'm trying to think what I used on my existing office, the floor is super firm and I currently do weights in it, it's just constrained by the 2.5m permitted development height rule. This new gym is going to be part of a planning application as I want it to be 2.9m high to account for the floor and warm deck, so loss of height shouldn't be a problem.

I'm on the fence for slab vs pillars. I would have to lug 5 ton bags, 50m to the end of my garden, trashing the lawn and breaking my back. Then knock it all up and lay it in batches which is less than ideal.

Once I've sorted my heights I could do one or two pillars at a time which I think is more manageable. I did consider shuttering it, getting a few barrows and 2-3 mates (not sure I have that many) and firing readymix in, but people aren't careful, and get tired, I think my garden will end up with a messy concrete paths down it.

I'm figuring as the max span is likely 1.2m, 6x2 is best (see pictures of my last build ten years ago)

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• bolst3r
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• bolst3r
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• bolst3r
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[oldbutnotdead]

6 x 2 will be a lot stiffer for sure. But have you checked timber prices recently?

 

[bolst3r]

It's your money. £200 for fancy jacks, you'll be doing near enough half a cube of concrete (20 points 200 x 200 x 200) and a pile of timber- you could probably afford to pay someone younger and fitter to do a concrete base!

I'm not shy of the physical side, two summers ago I shifted 10 tons of gravel down the end of the garden. Just know it's a lot of work and things will get destroyed in the process and mixing that volume of concrete by hand is a wedge.

I never really considered the cost of the extra timber for the base frame, and as you say that's not cheap at the moment, I would still need a floor plate but that can be a few lengths of 4x2...

You've given me something to think about now. Does it matter if i do a slightly wet mix to enable me longer to mix the muck for a slab myself?

Guess it's a day to move the ballast, and a day to mix and pour

I wish labour around these parts were cheap, around £200 per days in these parts

 

[bolst3r]

6 x 2 will be a lot stiffer for sure. But have you checked timber prices recently?

nope, i'm almost scared to look, I did build a chunky workshop in the height of covid and it was a shock at that point.

 

[oldbutnotdead]

If you can find a friend so one is mixing and the other is pouring, tamping etc it gets much easier. It's a shed base so doesn't have to be perfectly polished. Try and avoid the usual trap of making the base bigger than the shed- only leads to damage from rainsplash down the line

 

[bolst3r]

If you can find a friend so one is mixing and the other is pouring, tamping etc it gets much easier. It's a shed base so doesn't have to be perfectly polished. Try and avoid the usual trap of making the base bigger than the shed- only leads to damage from rainsplash down the line

very good point about the base, my floor plate will go to the edge, so by the time it's counter battened and clad there will be a nice 50mm overhang

I'll cost and weigh up a solid base. I used to dig down and whack 150mm of rubble in before pouring a base, that's my other concern as I don't have anything laying around, so i'll have to buy and put that in also. I figured a slab directly on bare earth was a bad thing?

 

[oldbutnotdead]

Depends on your ground. If it's good and firm then for a shed you'll get away with it. Don't forget to put DPM under the concrete- not so much for damp proofing, more so the concrete doesn't drag out too quickly (and not cure fully)