Using paving slabs for decking foundation - Decking foundations

[theoboeman]

Dear All,

Like many I've been messed around by cowboys and am now trying to finish off the project myself.

I was having some decking and paving layed, but after a week of nonsense I sent them on thier way.

I am having 2 areas of decking, one 12 foot by 10 foot the other 4 foot by 16 foot. The landscapers I had hired wanted to lay the frame straight on to the mud and hammer posts into it without any foundation. This was clearly going to rot! I've already lost 2 fence posts in this garden.

Can anyone offer advise on a good foundation for the decking, I thought using concrete paving slabs would be the best bet, I can only see posts in concrete rotting in a few years, but do I need to put anything underneath the slabs or can I lay 300 or 600mm slabs straight onto the mud?

Many thanks for your help!

Regards,

Joel

[henpecked]

Not really, if they're using composite posts

[lutonlagerlout]

joel
for decking <spit>
generally tanalised posts are concreted 600 mm in to the ground the frame is then built off these

ideally you would use galvanised steel posts but few want to pay for this extra expense
LLL

[GB_Groundworks]

in the states they use carbboard 300mm tubes that are then filled with concrete and the decking sits on these raised up from the ground

[dig dug dan]

last one i did, i set concrete blocks on concrete using the laser level, then laid black matting over the whole thing, then the deck frame ontop.
It was a better system as no need to cut through the matting to put a post in, which will rot in time
the method tony suggest is also fine, its just a matter of choice, but paving slabs would be too thin

[Mikey_C]

I use either a 7N concrete block laid flat or 4-6" of concrete, with a cut off sleeper upright to support my frame work.

[theoboeman]

Thanks for your advise!

The decking frame is only a few inches off the ground so sinking posts seems over kill. The 7N blocks seem like a good solution, would it be advised to put a layer of type 1 under these?

Thanks!

p.s. for those who disprove of decking the next part of the project is 22 sqm of Sandstone and I'll be asking a few questions when I get to that, unfortunately given the levels in my garden decking was the only practical solution for some of it and its a pain in the arse!

[dig dug dan]

Bed the blockson concrete and level each direction. Make sure each block is the same level as each other

[lutonlagerlout]

mostly i see decking where there is a huge fall ,so it works for that scenario
if the garden is pretty flat then a patio does the job
LLL

[theoboeman]

There is a big fall, I've dug half out level for the paved area and that was two full skips, going down further isn't practical for a number of reasons. I will have a question about the paving as I want it to come lever with the decking which I take it will mean that I will need to build a retaining wall for the hardcore along the side of the decking, but I'll put this in the paving forum.

Why do the blocks need to be bedded on concrete, if they are thick enough surely this makes no difference, its like using a thicker block? Unless the bedding is a wider area, but then why not just use a wider block, if the ground is compacted underneath I don't see how it will help.

Regarding laying all the blocks at the same level, shouldn't decking have a run off of around 100:1 like paving to prevent standing water?

Cheers,

Joel

[dig dug dan]

If you can dig the ground out under the blocks, and get each one to sit dead level and true, then you do not need concrete under them. Its just so you can bed them and tap them down to get them level