Decking on top on conrete...door threshold too low?

[m8rksimons]

Hello all,

This is my first post on this forum, however i've been gathering advice for a while. I've completed totally renovating the interior of my 1950's house now its time for the garden!

I'd like to lay a deck on top of the exisiting ugly and unlevel concrete patio / slab, however the door threshold is only 60mm above the concrete one end and 140mm (updated, i meant 140mm) the other. See pics.

do i have any other options beyond digging down into the concrete? ( i really don't want to have to do this is avoidable!)

Thanks in advance, Mark

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[Arthur2shedsJackson]

You don't have to dig up all the concrete.
Just pit a cutting disc through to cut a channel and then dig that out where you want the joists to sit, putting concrete into the bottom of the channels to support the joists.

 

[freddiemercurystwin]

Or just stick some thin joists (well battens really) down on top of the slabs. I've done this and the deck and battens are still good 10 year on. Gravity holds it down. People in this forum build decks to survive a third world war.

 

[Arthur2shedsJackson]

14mm Battens !!!

 

[freddiemercurystwin]

Ahh didn't see the 14mm bit.

40mm battens no problems but yea 14mm would give the screws too little depth to bite I'd grant you that.

 

[m8rksimons]

My error there , i did mean 140mm at the maximum depth end.

Thanks for the replies. For the end where it is 140mm would a 40mm batten be strong enough if i were to raise the deck with patio slabs ?

 

[Arthur2shedsJackson]

If you go the batten route, why don't you start at the 60mm end with whatever batten you can fit in ( Depending upon the thickness of your boards) and then adjust the batten/joist depth to suit,as the gap gets bigger.
Saves using slabs and should make it more solid.

 

[freddiemercurystwin]

Aye the battens need to get bigger as you go from one side to the other.

 

[m8rksimons]

Done!!

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[masona]

Didn't see your earlier post, not a good idea to have a decking plinth on the brickwork as it's above the dpc, ideally the decking should be 150mm below the dpc level then french drain for the higher garden area, however it's not the end of the world, if you do get any damp problem then treat the wall with Thompson wall sealer which is also available in spray then you should have no problem, I'm not trying to criticise, just to help you if you have any damp issues. Nice job