Decking over existing patio?

13 Feb 2006
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United Kingdom

The same question has been posted on this forum before but none quite answers my query.

I want to deck on top of my existing patio.

The decking will sit between the house and the walls around the patio.

The patio isn't level as it has sunk in places.

I want to keep the finished height of the deck to a minimum.

Can I lay say 2" thick tannalised bearers directly onto the patio?

Can I level the patio with chippings first?

Do the bearers need to be bolted down or will the weight of the finished deck hold it in place.

Any help appreciated, thanks in advance.

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I've done decking loads of times and here is what I would do. Lay a sub frame using 3" x 2" treated or treat yourself. Lay this on some damp proof membrane, then level the frame using large wedges. Place your decking boards on top. Use decking screws at the end of the boards (this allows some leverage if you ever need to rip them up) and nail everywhere else - it looks neater. Make your own wedges from your 3" x 2". The weight should keep it steady as will the fact it is enclosed within your existing patio walls.

Hope this helps you!
IMO i would not nail them all as these can come loose and can lift the boards in time. Screw them all down everytime.
Screwing down is easier no doubt and a bit more expensive. Its personal preference. Never had a nailed board come up yet, in fact, gone back to jobs to extend and had a tough time getting nailed boards back up. I only choose nails because I think it looks neater as you cannot see them. Having said that, the screws tarnish and blend in as well - again, its personal preference.
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On softwood decks i use a paslode nail gun with extra galvanised annular nails. They really dont move and are a lot more difficult to see. Personal choice though
Thanks, thats really usefull, I take it the deck frame doesn't need to be fixed to the walls then?

austin1 said:
I've done decking loads of times and here is what I would do. Lay a sub frame using 3" x 2" treated or treat yourself. Lay this on some damp proof membrane...

A question here, Austin - not trying to pick holes. If you lay the timber frame on a dpm, then, when it rains and the water gets thrugh the decking, won't the dpm hold the water in puddles so that the frame is sitting in it?
JonD - Thats right I guess, I have though about this one myself before, but I read this in a B&Q DIY manual (not that thats anything to adhere too) and that is what it recommends. I suppose in theory that it could make the problem worse if it allows the rain to well in parts. I don't think I'll bother doing the DPC thing in future - just following the advice in the B&Q book really. Maybe someone else reading this might like to have a say?


youd be better off fixing the framework to the walls as this will give a more secure fixing than simply laying it on the floor. Build the outside of the frame first securing it to the walls using anchor bolts or frame fixings. that should give you a level outer frame. You can now place the joists in the frame. Once thats done you can use indivdual posts resting on the patio secured to the framework to give the framework solid support that wont work. You could overlay the patio with weed suppresant fabric before constructing the framwork. Then just overlay it with boards. I always place a board along the edges of the framework where exposed as a fascia and this gives you a neat edge to lay the boards to.

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