SDS drill through paving slabs

[DiamondBeezer]

Hi
This weekend I'll be fixing some timber bearers onto an existing patio area prior to building a 6' x 4' garden shed.
I'll be using 6mm DeWalt Hex Head Blue-Tip Concrete Screwbolts for the first time and these obviously need a pilot hole through the slabs first.

I read conflicting advice on whether using an SDS drill on the percussion setting will crack the slabs or not. I was hoping to use masonry bits and the hammer action, but does anyone warn against this?

Secondly, these 6mm DeWalt concrete screws from Screwfix seem to need a 6mm pilot hole rather than something smaller which seems a bit counter-intuitive. Can anyone confirm this?

Thanks in advance

Ian

 

[mrrusty]

Timber bearers direct to patio will likely rot fairly quickly. Why not just lay some concrete lintels across to raise off the patio, and then rest the shed bearers on there. Quite honestly, a 6x4 shed doesn't really need screwing down, unless it is either very light or you are expecting mega-severe weather...

It depends on the SDS - if I put my lump of a Titan SDS onto a patio slab, I wouldn't be surprised if it cracked. My smaller bosch, probably not. However, I think there is a risk those concrete screws will split the dense concrete of slabs - they are more for concrete blocks etc. - haven't tried using them like that, but my instinct says it is a risk.

 

[^woody^]

WTF?

Screwing a shed base down? Is this a council estate?

 

[Harry Bloomfield]

It depends on the SDS - if I put my lump of a Titan SDS onto a patio slab, I wouldn't be surprised if it cracked. My smaller bosch, probably not. However, I think there is a risk those concrete screws will split the dense concrete of slabs - they are more for concrete blocks etc. - haven't tried using them like that, but my instinct says it is a risk.

I agree and especially so near an edge of a slab. Drilling would have to be done gently and rather than an expanding anchor, resin anchors would be unlikely to split a slab.

 

[DiamondBeezer]

WTF?

Screwing a shed base down? Is this a council estate?

Haha - not quite, though quite close to the 'badlands' It's one of those little plastic Keter sheds, so I want to stop it blowing away!

Ian

 

[DiamondBeezer]

I agree and especially so near an edge of a slab. Drilling would have to be done gently and rather than an expanding anchor, resin anchors would be unlikely to split a slab.

My understanding is that these concrete screws work by cutting a thread into the concrete slab, and hence are meant to not burst the slab like an expanding anchor would do.

Cheers

Ian

 

[^woody^]

But presumably you will be putting stuff in it?

Anyway, either try the actual bit on non-hammer, or a small diameter bit on hammer, then the right sized bit on non-hammer.

Follow the drill size guide from the maker, the threads don't need to cut much into the material.

And consider not going mad with these, 2 fixings may well be enough to stop it sliding, it's not Kansas!

 

[mrrusty]

It's one of those little plastic Keter sheds

That's different then - If it does need tying down - and I agree it might - I think I would just gently drill some 8mm holes with a sharp mason bit and use screws and brown plugs - they won't go anywhere! - rather than risk splitting the slabs with concrete screws.

 

[Captain Nemesis]

Ive got a Keter shed - not a little one, cant remember but its in the 6x8 to 8x10 range. It just sits on paving slabs that sit directly on bare ground, and its never budged a fraction.

If youre worried, sit the shed on your patio and then cover the floor with a layer of basic concrete slabs. That will hold it down.

 

[phatboy]

Put a £3 slab or 2 inside the shed, job done

 

[DiamondBeezer]

Thanks for the paving slab on the shed floor suggestions - hadn't thought of that.
However the existing patio area has a bit of a slope on it so I'm shimming up the timber bearers to level things up.
So, I still need some advice on drilling through paving slabs with a 6mm masonry bit in an SDS. To hammer or not?
Cheers
Ian

 

[Harry Bloomfield]

So, I still need some advice on drilling through paving slabs with a 6mm masonry bit in an SDS. To hammer or not?

Hammer should be fine, with such a small drill bit, providing you keep 3" from an edge and the slab is well supported underneath.

 

[johnny2007]

Thanks for the paving slab on the shed floor suggestions - hadn't thought of that.
However the existing patio area has a bit of a slope on it so I'm shimming up the timber bearers to level things up.
So, I still need some advice on drilling through paving slabs with a 6mm masonry bit in an SDS. To hammer or not?
Cheers
Ian

Use a quality drill bit without hammer action and water while drilling so to avoid overheating.
I drilled mine with diamond bits of 10mm and used nylon plugs.
Been there 10 years and haven't moved.