Hold down bolts question

[Forever Fendt]

Hi to all.
just wanted to know. Has anyone put up a building using. Chemfix anchors. Or threw bolts.
As I was going. To pour a large concrete slab raft First, with ring beam foundation Then use the anchors to fix the Stutions. Down. ?
building is. 40 feet. By 25 feet. 12 feet to the eves ,Hot rooled. Rsj frame. 7inc x4 inc.
Will be used as a tractor shed /work shop

Set bolts do it properly, we have put buildings up on customers flat slab and drilled them down before it takes ages and is very border line structurally, Probably blown it away here overnight

 

[Blue.]

Hi to all.
just wanted to know. Has anyone put up a building using. Chemfix anchors. Or threw bolts.
As I was going. To pour a large concrete slab raft First, with ring beam foundation Then use the anchors to fix the Stutions. Down. ?
building is. 40 feet. By 25 feet. 12 feet to the eves ,Hot rooled. Rsj frame. 7inc x4 inc.
Will be used as a tractor shed /work shop

Done all mine using resin and studs for the last 12 years,one is 35mX 60m.

 

[Hesston4860s]

I have used through bolts, fairly speeds up the base job, really slows down stanchion fitting. I would not use chemical anchors as they need time to set to usable strength. You must concrete over whatever fixing you use though.

I helped a mate put up a 60x30 few years ago and his structural engineer had him pour a slab 300mm thick and 500mm thick where the stantions are. It’s also 500mm thick down the Center of the slab as we poured it in 2 half’s and pinned together with rebar every 300mm the whole slab also has 2 layers of 10mm mesh in it.
He then chem fixed his 60x30x12 frame down on the top, to this day it still moves !. Dispite myself and two other mates telling him this was completely the wrong way of doing it he insisted that’s how we did it.
Theres 12 lorry load of concrete under that shed and some of those loads where 7 cube loads !.

 

[Sharpy]

I helped a mate put up a 60x30 few years ago and his structural engineer had him pour a slab 300mm thick and 500mm thick where the stantions are. It’s also 500mm thick down the Center of the slab as we poured it in 2 half’s and pinned together with rebar every 300mm the whole slab also has 2 layers of 10mm mesh in it.
He then chem fixed his 60x30x12 frame down on the top, to this day it still moves !. Dispite myself and two other mates telling him this was completely the wrong way of doing it he insisted that’s how we did it.
Theres 12 lorry load of concrete under that shed and some of those loads where 7 cube loads !.

Were the chem anchors incorrectly fitted (wet or dusty concrete /bad fill technique) or was the load applied before the chem reached strength?

 

[Hesston4860s]

Were the chem anchors incorrectly fitted (wet or dusty concrete /bad fill technique) or was the load applied before the chem reached strength?

Nothing wrong with the chem fixings, it’s just that its bolted to the top of the slab no concrete over base plates and fixings it’s literally just sat on the top. When we put the roof on it me and my mate could get to sway 3 feet just by moving about on it.

 

[Sharpy]

Nothing wrong with the chem fixings, it’s just that its bolted to the top of the slab no concrete over base plates and fixings it’s literally just sat on the top. When we put the roof on it me and my mate could get to sway 3 feet just by moving about on it.

If the bolts are tight and the base plates shimmed correctly it shouldn't do that surely?

 

[Forever Fendt]

If the bolts are tight and the base plates shimmed correctly it shouldn't do that surely?

Most new builds will have some degree of sway its particularly noticeable when walking about on the roof ,if they are grouted or caped with concrete over the bolts it stops this a lot,Just bolting the shed down and back filling bolts with earth or just stone is poor practice in my opinion after all you don't get much shed for less than £20k now why spoilt the job for a few £100s of concrete if the holes are very big when dug through fill material we have cut a 200l drum down and put around post and filled with concrete to cut the cost down

 

[Sharpy]

Nothing wrong with the chem fixings, it’s just that its bolted to the top of the slab no concrete over base plates and fixings it’s literally just sat on the top. When we put the roof on it me and my mate could get to sway 3 feet just by moving about on it.

If the bolts are tight and the base plates shimmed correctly it shouldn't do that surely?

Most new builds will have some degree of sway its particularly noticeable when walking about on the roof ,if they are grouted or caped with concrete over the bolts it stops this a lot,Just bolting the shed down and back filling bolts with earth or just stone is poor practice in my opinion after all you don't get much shed for less than £20k now why spoilt the job for a few £100s of concrete if the holes are very big when dug through fill material we have cut a 200l drum down and put around post and filled with concrete to cut the cost down

I agree, but 3ft of movement??

 

[Blue.]

Nothing wrong with the chem fixings, it’s just that its bolted to the top of the slab no concrete over base plates and fixings it’s literally just sat on the top. When we put the roof on it me and my mate could get to sway 3 feet just by moving about on it.

No wind braces?

 

[Forever Fendt]

Done all mine using resin and studs for the last 12 years,one is 35mX 60m.

If the bolts are tight and the base plates shimmed correctly it shouldn't do that surely?

I agree, but 3ft of movement??

yes forgot about that (3ft) I am talking a few inches of sway

 

[Forever Fendt]

Most new builds will have some degree of sway its particularly noticeable when walking about on the roof ,if they are grouted or caped with concrete over the bolts it stops this a lot,Just bolting the shed down and back filling bolts with earth or just stone is poor practice in my opinion after all you don't get much shed for less than £20k now why spoilt the job for a few £100s of concrete if the holes are very big when dug through fill material we have cut a 200l drum down and put around post and filled with concrete to cut the cost down

 

[Sharpy]

yes forgot about that (3ft) I am talking a few inches of sway

Yes, you get a wee bit of give, particularly side to side, not so much end to end, but 3 ft?

 

[Blue.]

I’ve a shed I acquired that swayed a fair bit once it was up,we fitted wind braces in one bay between the legs,it made a massive difference,now it’s got concrete panels down one side you don’t get any movement.

My main cowshed has 4 true cross type wind braces in the 1st bay,a lot of modern buildings just have diagonal braces a cross is far better in my opinion.

 

[Hesston4860s]

No wind braces?

Didn’t have then but it has now.
The main issue with it apart from it’s just bolted to the slab top is that’s its a cheap nasty frame that came out of Cambridge Machinery Sale. The base plates imo aren’t fit for purpose as they aren’t much wider than the leg and the bolts 2 per leg are on the ibeam faces instead of in the web.

 

[Sharpy]

Didn’t have then but it has now.
The main issue with it apart from it’s just bolted to the slab top is that’s its a cheap nasty frame that came out of Cambridge Machinery Sale. The base plates imo aren’t fit for purpose as they aren’t much wider than the leg and the bolts 2 per leg are on the ibeam faces instead of in the web.

So your friend has a wildly over the top base, with a very low spec shed perched on it? Genius

 

[Hesston4860s]

So your friend has a wildly over the top base, with a very low spec shed perched on it? Genius

Yep that’s pretty much it, 2 of us where asked specifically to go and put it up as we know what we’re doing but then he took no notice of what we said. We wanted to cut the base plates off lengthen the legs and do traditional foundations, it would have taken less time and saved a fortune in concrete but was having none of that the engineer was right and we where wrong apparently !

 

[Sharpy]

Yep that’s pretty much it, 2 of us where asked specifically to go and put it up as we know what we’re doing but then he took no notice of what we said. We wanted to cut the base plates off lengthen the legs and do traditional foundations, it would have taken less time and saved a fortune in concrete but was having none of that the engineer was right and we where wrong apparently !

The customer is always right, sometimes a Muppet, but always right.....

 

[Forever Fendt]

Yep that’s pretty much it, 2 of us where asked specifically to go and put it up as we know what we’re doing but then he took no notice of what we said. We wanted to cut the base plates off lengthen the legs and do traditional foundations, it would have taken less time and saved a fortune in concrete but was having none of that the engineer was right and we where wrong apparently !

Everything works on paper but not so in practice