Browse Forums General Discussion 1 Jan 28, 2011 12:55 pm Is this doable? I've found lots of posts on building a deck over a concrete slab, but all the examples have been slabs in good condition... To give you some background, we purchased the property straight after it was subdivided in 2006 leaving us with the original house, backyard/courtyard of 15m x 5m, (90% concrete) and a pergola roof covering 10x3m of the yard. Going off original plans and the condition of the concrete, I'm assuming it was laid when the house was originally constructed in 1968. The concrete is in pretty poor condition, not even close to flat with a fair few cracks. That being said, I don't think it has moved much in the 5 years we have been there. I'm reluctant to rip up the concrete in order to build a deck bc the patio/pergola roof was built over the backyard concrete just before we bought it. The pergola posts are secured to the concrete, so i'm assuming that ripping up the concrete would mean taking down the pergola? In terms of the deck, i'm looking at covering the entire width of the pergola so 10x3m, with a height of around 60cm above the slab. If anyone has any opinions on this I'd be very much appreciative. Can post photos later tonight. Re: Building a deck over a cracked/un-level concrete slab 2Jan 28, 2011 1:00 pm You could rip up the concrete and just support the pergola with steel or timber posts in a different spot to the existing ones, then put new posts in and concrete them in. A bit of fiddling around but the problem you are going to have is getting anything flat on an uneven surface that exists. I think you 'll also find that you need to have 300mm clearance under your deck (even the joists/bearers) so really a lot of the decks people put over concrete slabs don't meet code Re: Building a deck over a cracked/un-level concrete slab 3Jan 28, 2011 1:21 pm Probably not recommended on an unstable slab because your deck levels should be within millimeters and if your slab moves, that would be a pain. Your option is to not necessarily rip up the old slab but instead cut out holes to where your supports would be and then dig your holes. That way you won't have to rip the whole slab up. Re: Building a deck over a cracked/un-level concrete slab 5Jan 28, 2011 2:24 pm I agree, great idea! but... there'll be a lot of holes to do... so which would be easier, rip up the whole slab? or create multiple holes for the stumps??? Pics would be great if you can post some? Re: Building a deck over a cracked/un-level concrete slab 6Feb 02, 2011 7:05 am ok so i've finally got my @rse into gear and taken some photos... although i couldn't remember my password or the linked email address so i've had to create a new account... also please don't mind the mess, eventually all the clutter will be gone! http://s1204.photobucket.com/albums/bb420/crunch8686/ Re: Building a deck over a cracked/un-level concrete slab 7Feb 02, 2011 8:26 am Dont forget any xtra weight on the slab ie a heavy timber deck may cause the slab to move even more.. Just a thought. I know it is easy to work out but I built a 7x5 deck and there were around 35 holes... Lots of work to cut through the slab. Re: Building a deck over a cracked/un-level concrete slab 8Feb 02, 2011 9:18 am Re: Building a deck over a cracked/un-level concrete slab 10Feb 02, 2011 11:28 am so my best bet would be to pull down the pergola, rip up concrete and start from scratch? on a positive note i'd probably prefer this option as it will mean i can build a much nicer pergola (to hell with the expense!) DIY, Home Maintenance & Repair Thanks. I was thinking of using either Extreme Joist or LOWDECK timbers for joists. Any idea what sets them apart and which… 2 12877 Thanks! I'm spoke to the builder I'm not sure if this is all true but basically went along the lines of they considered all options and if I was to compact and fill it… 2 6388 Plumbers 'can be' plumbers, made all the worse by self certification which the building surveyor invariably accepts as proof of compliance! The good thing is that you know know. 3 4843 |