Deck over concrete pad. Pile attachment?

[Dunning]

I am planning a deck with 2 of the 21 piles over a sloping concrete pad. The max height of the deck is to be 60 cm.

Part of the original 1980's deck has a stringer attached to the house and the piles just resting on the concrete pad. I am not (currently) planning on using a stringer attached to the house.

Can I have piles resting on the concrete or do I need to install a stainless steel footing for the pile?

Thoughts?

[jimO]

how good is the concrete? my builder son recently built a deck on my rental and he cut through the old concrete and dug holes for the piles

[Dunning]

Looking at the edge it's around 12 cm thick.

[AlFa]

Fancy one of these - http://www.miteknz.co.nz/Products/BO...ip-Galvanised/

[John the builder]

agree with AlFa but even s/s is OTT for a deck IMHO. Galvanized will likely outlive the deck and it could be replaced in the future anyway?

It is arguable whether a low deck even needs a foundation but all the better for it?

A deck supported on say two posts and a beam might be a different story but the loads spread over 21 piles will not be great.

what size is your deck ? 21 piles sounds excessive. Have you considered increasing bearer size and joist size to increase spans and the joist size This minimizes piles to save digging and concrete.....?

[Dunning]

deck is going to be 4.5 m x 8 m - 36 m2
3 bearers 100x100 mm(2 100 x 50 nailed together)running the 8 m length, piles 125x125 mm spaced each 1.25 m. Spaced 2 m apart with a cantilever on each side ~200 mm
Joists are 100x50 mm every 500 mm
Surface is 100x40 mm pine

Thoughts on the above?

[John the builder]

if you go 150x50 jpoists at 400 centres and cantilever 900 at each end then have two rows bearers the span in between is within 2.5m span for the jpists.

joists need to be single length (this also adds 10% to span allowance so some contingincy there)

bearers ; 2 rows 2x190x50 span up to 2000 5 piles in a row Total piles + 10no.


all from NZS3604 2011

[ChickenPie]

Given how many piles you have, bearing them on the 120mm concrete slab should definitely be fine.