Simple base (pillar, stud) for bike shed on bedrock

[flyglarm]

I am planning to build a simple bike shed on my property but can't get started because I don't know how to begin and need advice.
The foundation is packed gravel, about 30 cm, and then bedrock. I first tried with ground screws, but of course, that was a failure, so now I don't know what to do. It feels like overkill to drill deep into the bedrock to cast in pillars. On the other hand, I don't want to just let it stand loosely on the ground, propped up on some bricks, considering the autumn winds. Is there any simple solution for this modest project that you can suggest?

/Marcus

 

[ricebridge]

What does it look like around otherwise? Pictures?

 

[flyglarm]

There's not much around.

 

[ricebridge]

The question is how strong the autumn winds will be there? It seems to be sheltered on three sides.

 

[Viktor.J]

Casting 5 pillars (assuming 4 corners + 1 long side) against the rock isn't that complicated.
- Dig away 30 cm: 15 min
- Secure 2-3 rebar into the rock: 20 min
- Add a 160-200mm cardboard mold, level it: 15 min
- Cast with an adjustable post base: 10 min

Total 1h per hole. It will likely be faster if you do them all at once and get into a rhythm!

 

[flyglarm]

The question is how strong the autumn winds will be there? It seems to be sheltered on three sides.

Fascinatingly strong winds indeed, despite the shelter. So I'm not willing to leave it without being anchored in the ground.

 

[flyglarm]

Casting 5 plinths (assuming 4 corners + 1 long side) against the rock is not that remarkable.
- Dig away 30 cm: 15 min
- Dowel down 2-3 rebar into the rock: 20 min
- Place a 160-200mm cardboard casting mold, level: 15 min
- Cast with post shoe (adjustable): 10 min

Total 1h per hole. Surely faster if you do all at once and get into a rhythm!

Ok, that doesn't sound so extensive. But I am a complete newbie and don't understand how to dowel. Searching online but can't find a good explanation. Going to a hardware store and hoping for expert help is as unlikely as winning the lottery. Unfortunately, it is often no help at all or poor guesses.

 

[Viktor.J]

Ok it doesn't sound that extensive. But I'm a complete newbie and don't understand how to dub. Searching online but can't find a good explanation. Going to a hardware store and hoping for knowledgeable help is just as unlikely as winning the lottery. Unfortunately, it's usually no help at all or bad guesses.

I've done it a bit and can describe how I've done it. I can also provide pictures if needed.
1: Dig down to the bedrock. If you're going to use a 200mm pipe to cast in, maybe 300mm is sufficient.
2: Drill e.g. 16mm holes in the bedrock about 10-15 cm deep. Here you need a hammer drill, which can be rented for example.
3: Buy chemical anchors at Biltema
4: Follow the instructions for the chemical anchors. Generally, it's about blowing and brushing out the hole a few times, squeezing out the chemical anchor until it has mixed (usually 3-5 pumps). Press down the chemical anchor in the hole, insert 10 mm rebar while slowly rotating it.
5: Let it be for an hour or so (the chemical anchor cures quickly).

Now you have doweled the rebar into the bedrock. The chemical anchor can be replaced with expansion concrete fine as well, it's a bit cheaper but then you need larger holes which take longer to cure. But if, for example, you only have access to a 20mm drill, you can use 8mm rebar and expansion concrete. The principle is the same i.e., drill, clean out with brush and compressed air in cycles, fill up, insert the iron, let it cure.

 

[flyglarm]

I have done it a bit and can describe how I did it. Can provide pictures too if needed.
1: Dig down to the rock. If you're going to have a 200mm pipe to cast in, then maybe 300mm is enough.
2: Drill, for example, 16mm holes in the rock about 10-15 cm deep. Here you need a hammer drill, which you can rent, for example.
3: Buy chemical anchors at Biltema
4: Follow the instructions for the chemical anchors. Generally, it is to blow out and brush out the hole a couple of times, press out the chemical anchors until it is mixed (usually 3-5 pumps). Press the chemical anchor into the hole, insert a 10 mm rebar which you rotate slowly.
5: Leave it for a couple of hours (the chemical anchor hardens quickly)

Now you have anchored the rebar in the rock. The chemical anchor can be replaced with fine expanding concrete too. It's a bit cheaper but then you need larger holes which take longer to harden. But if you only have access to a 20mm drill, you can use 8mm rebar and expanding concrete. The principle is the same, i.e., drill, clean out with brush and compressed air in stages, fill, insert the rebar, allow it to harden.

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How kind of you!

And when I've inserted the rebar. Is that when I cast in the post shoes?

I have done it a bit and can describe how I did it. Can provide pictures too if needed.
1: Dig down to the rock. If you're going to have a 200mm pipe to cast in, then maybe 300mm is enough.
2: Drill, for example, 16mm holes in the rock about 10-15 cm deep. Here you need a hammer drill, which you can rent, for example.
3: Buy chemical anchors at Biltema
4: Follow the instructions for the chemical anchors. Generally, it is to blow out and brush out the hole a couple of times, press out the chemical anchors until it is mixed (usually 3-5 pumps). Press the chemical anchor into the hole, insert a 10 mm rebar which you rotate slowly.
5: Leave it for a couple of hours (the chemical anchor hardens quickly)

Now you have anchored the rebar in the rock. The chemical anchor can be replaced with fine expanding concrete too. It's a bit cheaper but then you need larger holes which take longer to harden. But if you only have access to a 20mm drill, you can use 8mm rebar and expanding concrete. The principle is the same, i.e., drill, clean out with brush and compressed air in stages, fill, insert the rebar, allow it to harden.

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How kind of you!
But do I cast the post shoe instead of the rebar, or do I cast the rebar with that cardboard casting form so I get a post shoe on top?

 

[fribygg]

God, so kind of you!

And when I'm placing the rebar. Is that when I cast in the post shoes?

God, so kind of you!
But do I cast the post shoe instead of the rebar, or do I cast in the rebar with that cardboard molding so I get a post shoe on top?

For a simpler shed, it's enough to drill holes in the rock and drive in the rebar or the post shoe, setting with lead, casting, or getting chemical anchors is overkill.

 

[Viktor.J]

God, that is so kind of you!

And when I put in rebar, that's when I cast in the post shoes.

God, that is so kind of you!
But do I cast the post shoe instead of the rebar, or do I cast in the rebar with that cardboard mold so I get a post shoe on top?

You place the cardboard tube over it so you cast the rebar into the tube. When you cast, you attach the post shoes so they are cast in place.