Building a single skin garage, some questions

[Danturboc]

I'm currently in talks with my mate whos going to be building me a garage.

I want the garage to be roughly 22ft x 12ft, if I have read it correctly then no planning persmission is needed so long as the walls are no higher than 2.5m which is fine.

I want it made from concrete blocks and then rendered on the outside. He is telling me that he cannot get hold of the right size blocks to do it single skin and so he needs to do it double skin with a cavity? I don't see why, is he right?

Also the concrete base/foundations, I think he said he would have to dig down 550 (mm?) and that hes had a quote for the concrete for around the £1000 mark. Does this sound about right?

Ive told him to just build me the shell for the garage and I will do the rest ie. doors and roof etc.. as I don't mind doing those bits myself.

Any info on this? He hasn't given me a full price yet and I'm not sure what its going to be.
Im in Manchester (HYDE) if that makes any differance

 

[^woody^]

Are you sure that your mate is a builder?

You can build the garage in a single 100mm block wall

There is a jolly northerner on here who can comment on the price.

 

[kazuya]

is there a block shortage where you are ?
around here, notts, £1000 will get you around 10 cubic meters of concrete, thats about 6x more than he needs for the footing
unless of course hes filling the trench to the top and casting the garage floor with it as well

 

[noseall]

If the concrete price includes a pump, then £1k sounds high end but ok. You will need aboot 5m³ for the trenches and you should be paying anywhere between £80 and £120 per cube.

 

[RonnyRaygun]

If you are planning to do 450mm wide by 225mm deep strip footings then you will only need about two cubic metres of concrete. If building 1/2 brick thick I wouldn't go any less thick than 225mm depth of concrete.

You can go as thin as 90mm blockwork for the walls but if less than 190mm wall thickness then you have to have piers at maximum 3 metre centres.

 

[^woody^]

You can go as thin as 90mm blockwork for the walls

Those must be the blocks that the OP's mate can't get.

 

[RonnyRaygun]

He's obviously not looking hard enough - Tarmac do them...

https://www.deepingsbuilding.co.uk/downloads/tarmac_building_blocks.pdf

Not saying that's what he should use...

 

[^woody^]

Blimey I've not seen anything less than 100mm for years. I can't think of any reason to actually make any that thin.

 

[RonnyRaygun]

I know someone who used 75mm blocks to save space on his extension...

 

[Danturboc]

I dont think hes an actual builder, he is just one of them that has done it all before and apparently knows what hes doing.

I do want the garage floor as concrete too so maybe the £1000 is including the concrete slab too. At least the price for concrete is about right. Hes meant to be giving me a full price in the next few days so will see.

 

[^woody^]

This could be fun.

 

[Danturboc]

Well he has been back on today with a price. He has said £3300 to build me a "shell" which is what I asked for. ie. the footings with steel mesh(not sure on the depth hes doing them), concrete pad too and a bare shell with double skin using 4" concrete blocks.

Now I didn't think this was too bad and was expecting that sort of money. But I have told him what you guys said about doing it single skin with pillars and hes gonna look into it. Might save me abit of money on blocks.

I haven't agreed anything yet. What do you lot think? I have thought about just getting the footings done and doing the rest myself but not sure.

 

[loply]

I'd say not that much point in having it double skin unless you're insulating the roof & door too, as there won't be any real thermal benefit. Just uses twice as many blocks and takes twice as long. Plus you loose about 20cm of space all around.