by aeyres »
Wed Aug 19, 2009 6:00 pm
Without knowing where the deck is in relation to your house, & the concrete quality, i will assume away from the house (as vertical walls can be used to fix to) & good quality concrete slab.
Essentially, what you need to do is make your sub deck perimeter frame timber to the size & shape you require without fixing it to anything. Place it in position (over your concrete) & using timber or plastic packers, level the sub frame out to the desired height (remember you will want a slight fall for the water to run off)
Depending on your frame timber size, Counter bore 25m holes around your deck frame (arrrox 1/3rd down) then drill remainder with 10mm hole to enable you to directly bolt fix through the timber & into the concrete. Use M10 x 150 Concrete fixings or anchor bolts. The concrete will need to be marked & drilled with (8mm masonry if using threaded concrete bolts) or 10mm masonry for anchor bolts. Remember to re-check everything is still to your desired level. Fix the frame securely bolting through timber into concrete at regular positions (ensure your fixing positions are adequately packed out)
Where you say there is a foot difference, this is slightly more tricky, as you will probably need vertical posts fixed to the deck frame. Here you will have to use some steel 'L' brackets at the foot of the posts to fix into the concrete. Standard nut, bolt & washer through the timber & concrete fix the base of the 'L' brackets to the floor as above.
Hope this gives you some ideas.
