portal shed foundations

[Hesston4860s]

so if it was out by 10 ft that means the line on a 1:1250 plan was 2.5 mm out of place did they make you apply again? if the house comes for sale it should make it less value should you want to buy it

No didn't have to re apply as they reported me for the straw stack before the shed issue was sorted and the reporting me for the roadway even before the shed was started, common sense on the councils part prevailed that my neighbors are w4nkers and they just said no problem carry on .
I don't wanna buy there poxy little old house my shed stands on 2.5ac in the corner of a 36ac woodland, I have room to build 1 of my own which I'll need to live in for security for my yard.

 

[wheresthedog]

Does anyone put nuts on the bolts first (then leg, then hold down nuts on top) to level the legs by adjusting the nuts underneath before tightening down?

Would that be better than shimming or is that a no-no?

 

[HatsOff]

Does anyone put nuts on the bolts first (then leg, then hold down nuts on top) to level the legs by adjusting the nuts underneath before tightening down?

Would that be better than shimming or is that a no-no?

Not very practical - getting to the underside nuts would be tricky and if all the weight ended up on one nut, you might end up stripping the thread. Better to have levelled shims in place and use the HD bolts for their intended purpose - locating the column and providing temporary stability.

In industrial buildings you shim them pour in non-shrink grout below the base plate before concreting the lot in.

 

[wheresthedog]

Not very practical - getting to the underside nuts would be tricky and if all the weight ended up on one nut, you might end up stripping the thread. Better to have levelled shims in place and use the HD bolts for their intended purpose - locating the column and providing temporary stability.

In industrial buildings you shim them pour in non-shrink grout below the base plate before concreting the lot in.

Thanks for that. Grout info says leave a 25mm gap under the column, what should I use for a shim - steel plate to make up the 25mm?

 

[jamj]

We put shim of about 12mm upward to 25mm. Depends how level your pads are. You don’t really want a post sitting on concrete pad.
Put shim at centre of post bottom plate. That will allow you to pull it on the bolts to get it plumb.
you can then put bund of cement round it to hold grout in, as it is quite runny.

 

[HatsOff]

Thanks for that. Grout info says leave a 25mm gap under the column, what should I use for a shim - steel plate to make up the 25mm?

Yeah pack up 25mm and then you can take out any level differences between concrete pads with thinner shims.

 

[LAF]

Is the grout doing anything structural or just to stop the gap under the edges of the pad (and the holes left by the cones) being a dirt trap ?

 

[HatsOff]

Is the grout doing anything structural or just to stop the gap under the edges of the pad (and the holes left by the cones) being a dirt trap ?

Both -

Structure role is to spreads the vertical loads from the base plate to the foundation. Grouting is done before the purlins, cladding, services etc etc are added so there is a real load transfer when completed.

Filling the gap is important because when the column base is all concreted in there'd be gap under the baseplate, ripe for water and corrosion. This is because concrete has 10-20mm aggregate and shrinks a bit, so would never get properly underneath the baseplate.

 

[LAF]

I can see there are very fine cement-based grouts, described as

The mix design consists of a blend of fine and ultra-fine cements, high quality graded sands and a set of synergistic admixtures. The mix design includes special shrinkage compensating components, which give a non-shrink grout in both the plastic and hardened states. Powerful plasticising agents produce a highly flowing grout at low water content.

and also 2-pack resin products out there, is one better than t'other for barns ?

Looking at the compressive and tensile strengths of the 2 materials it seems once finally cured concrete grout will have greater compressive strength, resin better tensile, but resin achieves final state faster, and I guess is less vulnerable to screw ups in mixing and curing, and is doubtless more expensive.

 

[HatsOff]

I'd go with cheaper!

 

[designanddetail]

Both -

Structure role is to spreads the vertical loads from the base plate to the foundation. Grouting is done before the purlins, cladding, services etc etc are added so there is a real load transfer when completed.

Filling the gap is important because when the column base is all concreted in there'd be gap under the baseplate, ripe for water and corrosion. This is because concrete has 10-20mm aggregate and shrinks a bit, so would never get properly underneath the baseplate.

Never grout your columns before you have erected all of the steelwork, including purlins. No way of getting it lined or levelled once it is grouted.

 

[HatsOff]

Never grout your columns before you have erected all of the steelwork, including purlins. No way of getting it lined or levelled once it is grouted.

Sure you could get away with that in an agricultural shed. Not sure I'd be too happy with that in a heavier steel frame building. It's like anything with construction... 'it depends...!'.

 

[designanddetail]

Our main line of work is industrial buildings, which is what I was referring to. Steelwork gets erected, lined and levelled by the steelwork contractors. Then handed over to the main contractor, they grout it and hand over to the cladding contractors as lined levelled and fixed.

 

[HatsOff]

Yeah that's alright - not much weight in the frame itself so the HD bolts can take the load. I was thinking residential multi-storey buildings with heavy steel columns and multiple floors. There have been cases where grout gets forgotten/not considered important, concrete starts getting poured and the base plate fails - fortunately never on one of mine. Not in that business any more though.