5.5x4m Log Cabin Concrete Base

snappyfish · 18 Jun 2017 at 14:35

Need some advice.

A local builder I have asked to quote for a log cabin base size 5.5x4m

His points.

Needs a concrete pump from just outside rear access as doesn't want to borrow in that much (fair enough)
Didn't mention using any hardcore stating will just dig out and see what's there but tamp it all down.
Said he would go 4" deep at first ( I said why not 5")
Will use reinforced mesh
Will use a DPM

£1200 tp £1300 (he quoted £500 to £700 on phone)

All this sound right? I presumed a compacted hardcore base is a must?

Thanks

Abyss · 18 Jun 2017 at 15:48

Pumping concrete for such a small base seems a bit overkill. Whether the builder does or doesn't want to do it isn't important at this stage.

I'd get quotes from local builders for both mixing on site and pumping to see which works out cheaper. The minimum charge for a visit to pump concrete in can be huge.

What type of soil / ground do you have? This was hugely vary the foundation design. I agree I'd want hardcore put down first before casting a 4" slab on top

thezappa · 18 Jun 2017 at 16:09

Hardcore yes, reinforce steel mesh no. Unless you're putting cars or motorbikes or something else very heavy a 150mm base of just concrete will be fine. Could probably argue hardcore might not be needed but you can get bags of that from gumtree - people giving it away (most of the time its broken bits of brick and rubble anyway.
To save costs from a builder you could dig it out yourself, thats about as easy as it gets then buy some 150mm timber for shuttering and screw it together jobs a goodun then your man can come in mix up the concrete and poor it in.

Steveocee · 18 Jun 2017 at 17:01

Pump does sound a bit overkill. 3 of us narrowed in my 6x3 base and it didn't feel like it took any time really. Probably actually cheaper hiring a couple of labourers than a pump.

MikeB · 18 Jun 2017 at 20:52

He is talking in metres, you lot in feet

snappyfish · 18 Jun 2017 at 21:18

MikeB said:
He is talking in metres, you lot in feet

Definitely Metres yes, 5.5m x 4m roughly 18ft x 13ft

BigBoy · 18 Jun 2017 at 21:53

Two days work for two people, 100mm hard core with 150mm cement no need to re enforce the concrete as there will be no movement across it.

Its a lot of concrete to mix by hand or stand mixer but it can be done (recently done 18sqm patio by myself)

Furton · 19 Jun 2017 at 08:11

I've recently had concrete delivered for a retaining wall trench and the minimum order was only £120, and that's barrowed and leveled in, well worth it.

snappyfish · 19 Jun 2017 at 12:22

Furton said:
I've recently had concrete delivered for a retaining wall trench and the minimum order was only £120, and that's barrowed and leveled in, well worth it.

So a local builder did it for you?

Steveocee · 20 Jun 2017 at 11:17

MikeB said:
He is talking in metres, you lot in feet

No. Metres.

snappyfish · 20 Jun 2017 at 12:07

Getting quotes of around £1100 all in, probably just going to go with that.

The cabin is due in July and running out of time, the guys quoted do a lot of this type of work in my area seen their fb page and website, so still not the cheapest, but coming in with small digger, all rubbish will be taken away. Less hassle for me and they seem to know exactly what's needed.

Thicker slab round edges compared to the centre where all weight sits. Will make sure it sits in right place just out of ground enough to stop rain splashing back onto the base form area around it. Will put some mesh in for sake of £40 and use dpm.

Cash job has lowered their quote quite a bit from £1600

I'm happy with that.

Furton · 20 Jun 2017 at 17:59

snappyfish said:
So a local builder did it for you?

No, excavated the trench myself, about 10m long, 400mm wide and 300mm deep then contacted a local concrete delivery company to fill it up

snappyfish · 28 Jun 2017 at 09:30

Quick question.

The base is started shuttering and hardcore in, I asked about DPM and they said "Id consider leaving one out, as the cabin sites on bearers and has a floor it's going to make no difference and will only take longer for concrete to dry out if wet"

Any thoughts?

Entai · 28 Jun 2017 at 09:48

For your application I wouldn't bother with a DPM at all. Finish the concrete level with your lawn, then rest the timber beams of the hut on plenty of blue engineering bricks rather than wooden bearers. These won't suck up moisture like bearers would, and pass it into the wooden frame of the shed, but will still allow a little airflow under the hut, again to keep moisture levels down.

A lot of times, a DPM is used under concrete slabs not to stop any moisture coming through it long term, but rather to slow down its curing when it's being laid, by stopping the ground sucking all the water out of it. This helps the concrete base to reach maximum strength, which for a shed base is hardly critical.

rexehuk · 28 Jun 2017 at 09:54

BigBoy said:
Two days work for two people, 100mm hard core with 150mm cement no need to re enforce the concrete as there will be no movement across it.

Its a lot of concrete to mix by hand or stand mixer but it can be done (recently done 18sqm patio by myself)

This. Framing up, peg it outside. Put hardcore in, get mixing! Could just rent a mixer which will make it a bit easier, mixing it all by hand on a board is back breaking but worth it.

A pump sounds.... expensive.

snappyfish · 28 Jun 2017 at 10:40

rexehuk said:
This. Framing up, peg it outside. Put hardcore in, get mixing! Could just rent a mixer which will make it a bit easier, mixing it all by hand on a board is back breaking but worth it.

A pump sounds.... expensive.

Job has started now, dont have time myself, this below is new question..

The base is started shuttering and hardcore in, I asked about DPM and they said "Id consider leaving one out, as the cabin sites on bearers and has a floor it's going to make no difference and will only take longer for concrete to dry out if wet"

Any thoughts?

snappyfish · 28 Jun 2017 at 10:40

Entai said:
For your application I wouldn't bother with a DPM at all. Finish the concrete level with your lawn, then rest the timber beams of the hut on plenty of blue engineering bricks rather than wooden bearers. These won't suck up moisture like bearers would, and pass it into the wooden frame of the shed, but will still allow a little airflow under the hut, again to keep moisture levels down.

A lot of times, a DPM is used under concrete slabs not to stop any moisture coming through it long term, but rather to slow down its curing when it's being laid, by stopping the ground sucking all the water out of it. This helps the concrete base to reach maximum strength, which for a shed base is hardly critical.

Job already started, will be an inch roughly above lawn... The dpm is only concern at the moment.

Entai · 28 Jun 2017 at 12:03

snappyfish said:
Job already started, will be an inch roughly above lawn... The dpm is only concern at the moment.

As I have said DPM should not be a concern it is pointless on a job like this.

I then just went on to explain why its pointless on a job like this, and what you should look at doing later to alleviate any concerns over damp.

snappyfish · 28 Jun 2017 at 12:06

Entai said:
As I have said DPM should not be a concern it is pointless on a job like this.

I then just went on to explain why its pointless on a job like this, and what you should look at doing later to alleviate any concerns over damp.

Sorry quoted in incorrectly. Thanks for input..

snappyfish · 29 Jun 2017 at 20:46

So someone else has mentioned dpm is needed if not for damp but to stop moisture being sucked out of concrete to quickly when curing?