Does anyone know anything about gardening?

I'm not the only one then :)))

So far so good, only the Poinsettia from BnQ died. I guess 9/10 is ok.

Anyone have a recommendation for removing a concrete shed base and pouring a new one, SE London? It’s for a garden room and the garden room people have quoted a lot (£4.5k) excluding removal of the old. Trying to work out if getting removal and pouring done as one will be better value, and advice would be great

Obviously I don’t know size or access, but 4.5K seems a huge amount of money for a slab. Is it the same footprint as the old one? Should be a simple job if so.

For context, we just paid about £850 for a 2.5m x 3m concrete pad. In Bristol so slightly less daft pricing and went with some other work.

What are the dimensions and have you any idea how deep the slab is? 4.5 is a ripoff unless it's a huge area and a foot thick. I can tell you what it SHOULD cost.

I don't think I charged more than half that for the one I did for @stevo_com, and that was a fair old lump.

The room going on it is 4.8m X 3m - I don't know how thick it needs to be, but thinking about it it might need to be insulated?

I will ask some more questions and find out if there is a reason it is so much...

5 tons if you want to go 6" thick, 4" is almost certainly plenty unless you are storing woolly mammoths. Hard to make the job cost much more than £2k inclusive of a skip. I can't see insulation doing anything, surely any necessary insulation is within the building itself.

Presuming the access is OK and it isn't a 500m barrowing run!

Interesting, thanks - you think that would be about right with removal of the old slab too?

Yep, if the old slab isn't massively deep and/or reinforced.

Might be worth looking at a couple of the office/workshop build threads on here - think there’s a non-bike related current projects board for these.

Eg https://www.lfgss.com/conversations/333920/?offset=475#comment16493792

Thanks - yeah have seen a couple, although the more DIY ones seem daunting to me! Will have a look though

Thanks - really helpful. I'm asking for more details of what is needed but think they were suggesting insulation under the concrete (which I have googled and is apparently a thing); maybe that is what makes it more expensive but not sure how much benefit it gives? Anyway I should probably stop spamming this thread as this isn't plant-based enough....

@ColinTheBald Could you pour concrete around the old base and incorporate it into the new one or is that just a recipe for disaster? (Asking for myself for when I install a bigger shed.)

Personally I’d skip the middleman (I’m very much a do it yourself if you can person) and if expanding the footprint then use the existing footprint as a solid base for metpost brackets. You can then make a wooden base for a new structure floated a few inches above the existing pad. That it extends a bit outward is of no consequence. If you frame the floor out with 75mm tannelised post then it would be as rigid as a bishop in court.

Presuming a void between the base and the building it sounds a little snake oil to me, find out what insulation they specify, it's normally inexpensive.

The short answer is "yes" if the existing base is flat or very slightly sloping, at least 4" thick and hasn't cracked up.

Ragnar's suggestion would certainly work, but given the current cost of timber will almost certainly cost more and require some skills.

As a general point, tanalised timber ceased to exist years ago, the process was more than slightly toxic but had the benefit of working. What we get now is pressure treated, which rarely penetrates far into the timber and consequently doesn't work as well. Always treat the end grain of any timber of this type.

I think part of the point is to get around the void above the concrete as for a garden office, height is an issue - I think it will be a solid insulation layer under the concrete. But I am just repeating what I recall / have found on Google, until I speak to them later on.

Thank you for that - I didn’t know. I though ‘pressure treated’ was the current word for ‘tantalised’. Every day is a school day.

(Edit) I went off to educate myself further and found;

https://worcestertimberproducts.co.uk/tanalised-and-pressure-treated-timber/

Now I’m confused. If you have time (since you are presumably in the trade) could you explain further - perhaps it was different carrier chemicals?

Have they considered ground screws?
We had a random slab through the back of our garden, amongst other treats found by are @ColinTheBald...
The GR company just whacked in ground screws with some breaking where needed.
Seemed good, massive void space for insulation too.

Back then it was chromium and arsenic, now the treatment is copper based

Aha! Thank you.

Can anyone here recommend a company for a garden shed? There's tons of online companies and would prefer not to waste money on a flimsy crap shed.

Thanks for the advice!

So settled on Ace Sheds and their Thanet Summerhouse model.

https://www.lfgss.com/comments/16528260/