Concrete floor thickness.

[greasedmonkey]

A friend of mine is having a detached garage built but I fear the builder may be somewhat of a cowboy.

The concrete floor is laid directly onto the ground, some of which is backfill. The floor itself is only about 1" thick. Is this enough? She says he made a trench about a foot deep for the foundation, then poured concrete into this and built walls onto that. I can't see a DPC in the wall and she tells me she did not see a membrane go in under the floor.

Now I am by no means an expert on such things, but I recently built a conservatory and advice I got was far from what he appears to have done. I was told foundations should be 1m deep with 150mm of hardcore, then 300mm concrete, then build up to just below ground with concrete blocks and finally build up to the DPC with engineers brick. For the floor, 100mm hardcore, 50mm sand, damp proof membrane, 50mm insulation, 100mm concrete and finally a layer of screed.

Did I waste a lot of time, effort and money? Or is she being ripped off? The ground in both cases is wet clay but quite firm.

 

[stuart45]

Or is she being ripped off

Without a doubt she is.

 

[tony1851]

A 1" thick concrete floor on backfill to support a car?? Forget it.

 

[freddiemercurystwin]

A 1" thick concrete floor on backfill to support a car?? Forget it.

Yea a bit of hardcore'll do the job!

 

[tony1851]

It won't take the point-load from a vehicle wheel. And as for jacking it up???

 

[KenGMac]

As the intervening post between this and yours OOO Yeas!

Tell your friend DO NOT pay this cowboy, If your description is even [sorry about this bit] remotely accurate. your description of work completed to date is a horror story.

Strongly suggest that the local Consumer Standards be called in as a matter of URGENCY !

Put the builder off by saying that his presence on site is not advised, a Bereavement, Illness, Anything to keep him OFF site before someone with something like a "Building Qualification" gets a look at what appears to be a rip off?

Hope this assists?

Lots of luck.

Ken

 

[leew2]

I highly doubt a 1 inch concrete floor laid onto earth will survive having a car driven onto it even once, and even if you don't put a car in it, it will almost certainly break up due to natual ground movement in a very short amount of time. A garage floor should be 100mm thick minimum, laid ontop of a DPM which is laid ontop of a sand blinding covering a minimum of 150mm of well compacted MOT hardcore.

 

[greasedmonkey]

Thanks for the replies. I thought as much, but as I said I am no expert.

Would this be something building control would be interested in? He is not due to return to the job until Friday so I will tell her to get some professional opinions in the mean time.

 

[tony1851]

If it's under 30 sq.m.. in floor area, building control won't be intereted as it will be exempt.

This is a job for Trading Standards, or 'Rogue Traders'.

 

[leew2]

Hello, Matt Allwright, BBC rogue traders.....

 

[greasedmonkey]

Quick update....

She has had a local builder out to give his opinion on the job. Apparently he dug some holes next to it (I assume to check the foundations) and his advice was to rip it down and start again. She said he sat down and explained to her exactly what should have been done and in what order. Anyway, he is returning tomorrow with an itemised quote to do the job properly.

Looks like the first builder is getting the sack.

 

[KenGMac]

As previous posts!

CALL IN TRADING STANDARDS.

Yes I know I am SHOUTING!

With all respect do you see where I am coming from?

In a previous post you noted that the "builder" will not return until later this week. "Suggest" that he is put off/ by explaining to him that you have a
Party or some such just to keep him at bay until you get other "Advice" as regards this fiasco!

Ken

 

[greasedmonkey]

I should have said, she has been in touch with trading standards. But she wanted the advice of a builder first as she did not want to go to trading standards and say "my mate who once did some DIY and some random people I don't know on the Internet say it's no good" as we figured a professional opinion would hold much more weight.

I'm sure you guys probably are very knowledgable, but she now has a written statement of everything that is wrong or just badly done, written by a professional who is prepared to be contacted by trading standards if needs be, this has got to be worth more than my own opinion as my trade is electronic design, hardly makes me qualified to give an opinion on such things.

 

[Johnmelad]

Unless this cowboy is already known to Trading Standards, they will do nothing. He will now be on their radar but without a bit of history he won't even be contacted.

 

[tony1851]

she did not want to go to trading standards and say "my mate who once did some DIY and some random people I don't know on the Internet say it's no good"

then why bother asking here in the first place?