Deck Footings

[Slimcatdaddy]

Hi - I'm sorry if this question has been asked before, but I couldn't find it in the search engine.

I'm laying some decking in a new build garden. The top soil is about a foot deep and very soft, below that the ground is rock solid. I'ts a ground level deck 4.7m by 3.6 m. I've seen plenty of references to bedding the frame onto gravel (which I have a tonne of) or paving slabs. Can anyone offer advice as to which method is best, and if paving slabs are recommended should I bed these in with concrete? And if so how much should I buy, I'm quite happy to use ready mixed.

Thank you to all replies.

 

[WabbitPoo]

1. Don't bed the frame on to gravel.
2. Only bed the frame onto slabs if they are exactly "level". I say "level" when I really mean all in a plane such that the deck will be level across and slightly sloping doen the boards away from the house - which is very unlikely and hard to achieve.

Much better to use posts concreted in or sitting on concrete blocks dropped into holes dug in the soil.

IMHO.

 

[Slimcatdaddy]

I thought it would be a bit too easy to just lay slabs, hence the question, when you say concrete blocks what are you suggesting, something like a breeze block or a proper deep footing?

 

[Thermo]

posts concreted in is by far the best and easiest way

 

[Slimcatdaddy]

I did plan on using posts but - it is only a small height i need to reach the level I'm after!

 

[Thermo]

cut them first!

cut them 6" higher than you need, then it is easy to get the frame exactly levelled up on the posts. once you fix it to the posts, then cut them flush.

 

[Slimcatdaddy]

Ok - I'll get back to the drawing board cheers fellas. I'm just a bit dubious about getting the posts all straight etc.

By the way Thermo I saw a pic of one of your decks in an earlier post very impressive!

 

[Thermo]

thanks. next deck i do ill do pics and then post a guide i think. funny how all the questions come in the summer!

anymore questions fire away!

 

[Slimcatdaddy]

Ok one last one - just to save me searching - what size hole for a post - i'm going to put 16 in (4.7 by 3.6m) so how many bags of concrete is that? Also the deck is sided by fences - how do I get my screws into the joist if I cant get to the sides?

 

[Thermo]

try to dig the hole as small as possible, to allow the post in and a few inches either side for the concrete. If you use postmix (the hanson stuff is good) its premixed and very easy to use. very good as well. one bag per hole more or less, well rammed in.

If you cant get to the ends to screw them in then you can skew nail/screw through the cross member into the frame. or you can use metal joist hangers.

 

[Slimcatdaddy]

Cheers Thermo - Your a Diamond!

 

[^woody^]

Probably a bit late on this, but surely it is better to lay a few slabs and span these with a horizontal timber, than to concrete posts in and have them rot in a few years?