# Interlocking plastic foundations



## GarethT (8 Jan 2015)

Hi Guys

I am starting to plan my workshop build (12x10) and am trying to decide on a foundation to put it on.

I don't want to go down the solid slab route so have been looking at more cost effective solutions (I've a limited budget for the base and the shed construction).

During my browsing I came across some plastic interlocking foundation systems, which according to one producer can hold 180 ton per square metre. Sounds impressive to me, but I don't have a clue. :? 

Or I could go down the breeze block pillar route.

Both of these will allow me to build a base on, the interlocking system would give a more solid foundation compared to the pillar setup.

Has anyone used this system and got any feedback on it or can you suggest an alternative?

Thanks in advance.


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## SlowSteve (8 Jan 2015)

Hi,

I don't know much about the plastic foundation route, but have you got some different quotes for the concrete foundation.

This summer I laid two concrete drives at my house. I found a big variation in the prices of the concrete guys, and found that the smaller companies, who do a "mix on site" service, so you can use smaller loads, are a lot cheaper. For a 6 inch deep slab for your foundations, from the company I ended up using, you would pay around £90 for the pour. Where as a very well known company would charge you around £280 for that same slab as you have to pay a part loading fee.

I am not sure how much you are looking at for the plastic system, but £90 may be within your budget.

However, depending on your soil type, going down the "pillar on breezeblock" route will be a lot cheaper, but it will end up needing more timber for the floor - this may or may not end up being more cost than the concrete slab depending on how sturdy you make it.

I would say, if you DO go this way, it's well worth spending a bit of extra time ( and money ) putting lot of noggins between the joists. It makes for a far stronger, more stable floor which lasts far longer.


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## blackrodd (8 Jan 2015)

GarethT":3anwfpl3 said:


> Hi Guys
> 
> I am starting to plan my workshop build (12x10) and am trying to decide on a foundation to put it on.
> 
> ...



Can you say who the maker or supplier of this plastic base foundation is?
I am interested as to how plastic could be more solid than a concrete foundation.
For a 10'x 12' base @4" thick would only be a little over 1 cubic metre, plus around 1 more cube for the foundation 10"wide which is quite a mass, at about 3 .5 ton.
Or are you meaning you are setting flooring joists out as a base for the shed and you are looking for a good alternative for these floor joists to sit on? Regards Rodders


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## Ollie78 (14 Jan 2015)

Do you mean the plastic grids that you fill with gravel ?

My mum has got a log cabin which is built on these. It came as a kit which we built in a few days (quite big 6m by 3m or so).

The grids were about 400 mm square and green plastic which seemed flimsy at first but we followed the instructions and once filled with the pea grit and tamped a bit they became incredibly solid. 

On top of these pads were steel plates with a large threaded bar welded on with nuts to allow levelling of the floor joists. 

This must have been built for 5 years now and I don`t think its moved an inch. 

Ollie


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## GarethT (14 Jan 2015)

Hi Guys,

Sorry I just remembered about this thread :S

I posted a link in my other thread, where I posted the start of my sketchup designs.

However this is what I was thinking of, there are cheaper alternatives available, which I will be looking at.

http://www.simplygardenbuildings.co.uk/probase-shed-base-foundation-569-offer-9222-p.asp

SlowSteve, the main put off is the amount of work involved, carting, all the materials about 45 meters from the front of the house to the very back is the main put off for me.

Ollie78, yep, those are the ones


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## blackrodd (14 Jan 2015)

GarethT":2uk7kl2i said:


> Hi Guys,
> 
> Sorry I just remembered about this thread :S
> 
> ...




Interesting video, 
It appears to me that as you will still have to excavate and prepare the ground to allow for the proposed finished floor level and carry the pea gravel 45 metres to the site area, which will still need whacking down etc. anyway.
The only saving, surely, is not buying 50% of the agregate and the cement to go with it, and the price of a mixer use and hiring some scaffold boards for shuttering. for conventional base.
As these tiles are about £23.00 a sguare metre x 11 square metres of base area,(3.6x 3.0) is £250 +vat and any delivery?
I don't see any saving personally, but it's certainly a fast system.
As many traditional bases have cracked in the past through ground heave, for instance, I don't see 40mm of pea gravel or any agregate equaling 100mm of concrete, en mass.

Please keep posting as a WIP because if you are right, then I'll certainly be giving it a go! 
Regards Rodders


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## Hemsby (14 Jan 2015)

Your post reminded me of seeing these grids used extensively in the South of France car parks, most of the areas are also used by coaches etc. I was fascinated first time I saw them thinking they were a good idea :idea: .

Presumably the designers of these parking areas were confident that they would stand up to the rigors of vehicles back and forth.

Other than them being non permanent, I wonder if they are cost effective compared to a conventional concrete base, also will the physical effort (hammer) required for the correct groundwork etc be much less than a good concrete installation.

Regards,
Keith


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## Higon (18 Jan 2015)

I put some of this type of thing (probably not these exact ones) down on some grass near a gate that was prone to turning to mud at the first sign of rain. just laid them on the grass and drove the 4x4 onto them... They've been down 6 months and have been very good. Only after all that rain did they start to sink into the ground. (which was what I was after). 

I can quite see them being strong enough to take the weight of a shed, I don't think they would work as well if the ground wasn't level... but that might not be an issue in your application. 

I seem to recall that the ones I got were less than 3 quids each.. there were 2 types, one like the ones linked to and another type like the bottom of a milk crate... no apparent difference in performance between them.


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## shipbadger (25 Jan 2015)

I have a friend who is having a shed built for his model railway in the next few weeks and is using the plastic grid system shown here https://dunsterhouse.co.uk/rapid-foundations . I haven't paid much attention so far, mainly as it's been dark when visiting but if something of interest comes up I'll post some details. Must admit it sounds almost to good to be true. My shed ended up with a ready mix lorry and a concrete pump to get the mix up the garden, and uphill all the way. The concrete pump came from thirty miles away as he was much cheaper than the local guy who probably thought he had the market all to himself. Incidentally we hired a self propelled barrow on rubber tracks for some of the work when digging out the area for the base as I didn't feel like doing an impression of a navvy.

Tony Comber


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