Pros and cons of Portabase for shed

[jon92]

Anyone know the good and bad of using a Portabase instead of a concrete base for a 8x6 shed? The basic idea is a frame of timber 'joists' that is attached to metal spikes driven into the ground. It means the air can circulate under the shed which I guess is a good thing but I'm wondering if the weight of a full shed would cause it to settle unevenly over time.
http://www.gardens4living.co.uk/cat...-shed-accessories/portabase-timber-shed-base.
I'd appreciate comments from anyone with knowledge or experience of these things.[/url]

 

[powerst]

Hi,

Don't use spikes, as you say it'll probably sink more where there's more weight in the shed.

4x4 posts set in postcrete and then attach the joists to those using coachbolts.

 

[jon92]

Thanks, you mean concrete posts? Presumably wooden ones would rot fairly quickly.

 

[powerst]

Hi,

No, use 4x4 presure treated timber posts set in to the postcrete. You need to dig the holes, compact the bottom and then fill about half (don't quote me on that) deep with water. Then set the post in and pour the postcrete in, level up the post and allow to set (which isn't long). Also. I used to place a couple of bricks at the bottom to firm it up.

Once all the posts are set you can attach the frame using coachbolts conneceting the two bits of timber.

Look up decking guides, it's the same idea, you're just not putting deckboards on top.

 

[powerst]

http://www.diy.com/diy/jsp/bq/templ...ised_garden_decking/raised_garden_decking.jsp

 

[jon92]

Thanks for taking the time to explain, I'll do as you suggest as it sounds fairly straightforward.

 

[powerst]

No probs, good luck!

 

[skotl]

This isn't advertising, I swear I work for a software company which is pretty much as far away from a plastic shed base company as you can get!

That said, I just put a 10x6 shed on top of this stuff; http://www.plasticshedbase.co.uk/

Bought a ton of aggregate, laid down and wacked about 3" deep, then put this plastic stuff on top, filled it with the rest of the aggregate, and wacked it again. Worked great!

 

[jon92]

Thanks, I had seen a couple of types of plastic base and was also considering that option. I wondered if they might tend to settle unevenly but I guess a layer of aggregate underneath would help prevent that.
My base would be partly above ground (due to slight slope) so I would need some way of containing the aggregate.