To seal concrete slab or not?

[Ed.]

Hi guys, just finished laying down a polished concrete slab for my shed I am about to build (approx 7.8 x 7.8 x 4m), and as there will be a some welding in there, I am after some collective wisdom on whether or not, to seal the concrete pad.

The last shed I built did not have any sealer on it and it was marked pretty bad with rust stains from all the grinding dust and BB's. I am just wondering if those hot bits of metal falling down on the sealed concrete surface are going to make a bigger mess than if I just leave the concrete surface raw.

Cheers
Ed.

Pic 2. The resident supervisors... keeping a watchful eye on the workers!

 

[brightspark]

leave it a month to completely dry out and give it a coat of sbr bonding agent to seal and waterproof it . it will harden the surface as well stop the dust

 

[Shox Dr]

I power floated my workshop slab, leaving it unsealed. Its been down 10+ yrs now. Oil and paint stained etc, hasn't affected the surface finish. No hot works on it though

 

[knighty]

my power floated floors are pretty impervious to anything - and they have blood/guts etc. on them :-)

 

[Onoff]

leave it a month to completely dry out and give it a coat of sbr bonding agent to seal and waterproof it . it will harden the surface as well stop the dust

+1 to SBR.

 

[Ed.]

Will the hot metal affect the sealed surface?

 

[frank horton]

I see u have a couple of Wallies inspecting the elf n safety.......

very nice spot....

wouldn't be allowed a shed facing such properties over the road....

 

[Ed.]

Thank you, the shed is sitting back 10m from the property edge plus another 3m from the curb, the local council doesn't have a problem with it where it is. The kangaroos use our property as a through fare to get to another property at the top of our block behind the house. They will get upset when I finally fence it off, at the moment there is a gap of about 60cm between the corner of the 2 property lines. We also get an ocean view from where the house is at the top of the block. Hopefully we will be able to move in about 8-10 weeks.

I was hoping to have the shed finished before then, but due to all the delays we have had that might not happen. So just need to decide now if I will seal off the concrete before I start welding up the shed. If the hot sparks don't damage the sealant then I will use it.

 

[arther dailey]

Thank you, the shed is sitting back 10m from the property edge plus another 3m from the curb, the local council doesn't have a problem with it where it is. The kangaroos use our property as a through fare to get to another property at the top of our block behind the house. They will get upset when I finally fence it off, at the moment there is a gap of about 60cm between the corner of the 2 property lines. We also get an ocean view from where the house is at the top of the block. Hopefully we will be able to move in about 8-10 weeks.

I was hoping to have the shed finished before then, but due to all the delays we have had that might not happen. So just need to decide now if I will seal off the concrete before I start welding up the shed. If the hot sparks don't damage the sealant then I will use it.

surely you could leave a gap in the fence to allow the fella s through ? lets face it they were using the ground way before any body else got there , I have the same thing here with roe deer , all neighbours have fenced of their traditional route , so I have left gaps where they cross through from one wooded area accross to tother .

 

[Onoff]

Surely you're made to include wildlife corridors there?

 

[clift_d]

Not sure about staining, but I'd probably put SBR down as well to stop the surface dusting.

 

[Ed.]

Just an update on this shed build, it is taking forever, we had an extremely crappy wet season here with the temps in the 32C+ in the shade and humidity in the 80%, almost daily drizzle, showers and rain for for more months than I care to remember. So end result is it is taking way longer to build than I anticipated that it would, and not to mention blowing 20kts daily.

So on the rare odd days that I could work I have managed to put in about 2-3 hours and by that time I am absolutely shagged with heat exhaustion considering I have to wear overalls in direct sunlight, at the end of the day I have barely enough energy to make it back up to the house and my brain is cooked.
All this has now changed with the dry winter season, temps are now in the 20-24C and humidity is down to about 40-50%, so I am putting in 7-8 hour days, Yay!.

I ended up sealing the concrete and it does protect the concrete a bit when grinding and welding above it, The concrete has a heap of cracks in it, don't know if it was poor workmanship or just the type of concrete, only place I could get it delivered was about 2 hours away so that probably didn't help. I only gave it one coat of sealer to just protect it a bit, I still have rust stains all over it but might give it a jet blast and then a final coloured coat after the shed is finished.
It is about 90% done now with the main longitudinal beams to go over the trusses for the colourbond sheets to get screwed down to. Two doors to be made and another horizontal beam welded on the back wall as the distance between sheet supports seems to be too far for my liking, So with all these changes I hope it passes inspection once complete.

Due to the length of time the steel has been out in the open I now have to power brush the white galv rust off the beams before painting them with Cold Galv paint so more time wasted. Had to make quite a few changes to the engineering drawings as the engineer didn't allow for the roller door track widths or the width of the electric motor to open it. Nor for room to weld 50mm on my back above the concrete pad for the bottom rails. But at least the end is in sight and about to order the roller doors and the sheet metal. With a lot of luck I should have it finished in about 6 weeks. I will give the frame a coat of paint before the sheets go on.

The Kangaroos are regular visitors to my place and 2 of them visited me and came within 2 meters of me this morning, then moved on as I don't think they liked the grinding noise, as for providing an access to neighboring properties, no problem, my wife and I watched them yesterday , they went up to the fence and from a standing position, jumped the 1.2m fence with room to spare.

 

[Morrisman]

Surely you're made to include wildlife corridors there?

I’ve made sure I have gaps under my fence to let the hedgehogs through.

 

[Ed.]

We don't get the same sort of wildlife over here that you have. The house to the left of our property doesn't even have a fence (yet,... but it is on my to do list) at the bottom of our street is a large bush wildlife area so plenty of room, but the main animals are the kangaroos and there are heaps of lawns around here that they are quite happy to munch on, since we have been here in the last 12 months our local mob has doubled in quantity so they are doing okay and they visit us about every 4-5 days, we open our bedroom curtains in the morning and there are about 3-5 kangaroos staring at us. A lot of the houses have 200mm square mesh wire fences so most small critters just walk through.

 

[Onoff]

we open our bedroom curtains in the morning and there are about 3-5 kangaroos staring at us

"What's UP Skippy?"

 

[Smallfry]

Small cracks are normally because it was allowed to become dry too quickly. Out there where its hot, especially in direct sun, did they cover the concrete after floating, and keep it wet after initial set for a couple of days ?

 

[Ed.]

No, they didn't cover it with plastic however I did hose it down multiple times a day for over a week, funnily enough the cracks started from the first time I started watering it down, temp was about 25C when they did the pour. The last shed which I had a slab put down was a 12m x 6m and I didn't even use the dirt on top of the base layer which again was clay, had much less steel in the form work and that one did not have a single crack after 20 years.