I am looking to start building a low-level deck, some part covered and some part open deck (6550*5800) and need someone to help with my questions below. The deck meets the house on two sides, one being 130mm clearance and the other 140mm.
1. @MitchellMc can you please help with some basic drawings based on the above deck dimensions?
2. What kind of joists I need ? H4 90 x 45?
3. What kind of bearers I need same as joists above?
4. What will I do in non concrete area? Is Tuffblock a good idea? Any other suggestions pls.
5. What height I have to achieve? (130mm?)
6. I am doing a picture frame deck 140x19mm Merabu as a frame and in the middle portion. Then rest is 90x19 Merabu. Pls see Pic attached.
I have more questions to ask. But for a start please help with the above questions will be great.
Welcome to the Bunnings Workshop community @Ren101. It's sensational to have you join us and many thanks for your questions about building a low-level deck.
If you haven't already read through it I'd suggest checking out @Adam_W's article on How to build a low-level deck. There are also plenty of other projects submitted by our talented members which cover very similar questions. In fact, @ssjolly's topic Ekodeck on a concrete slab - Picture framing method is almost identical to your situation of 140mm available height.
All that needs to be added to your drawings are the joists spaced 450mm across the deck. These are run perpendicular to the decking boards. In order to do the picture framing around the outside, you'll need to double up your joists, so there is enough room to nail off the decking and the picture frame timber.
140mm isn't really enough height to do a traditional joist over bearer deck. You'd be looking at a single layer deck using H3 90 x 45mm timber elevated on L brackets and packed out underneath with shims.
Tuffblocks don't have any height adjustment to them, and as your joists with be elevated above the soil, I don't believe you'll be able to use them. You might like to consider adjustable pedestal feet instead. Your soil is going to be very close to the H3 timber, so you'll need to think about drainage and @Adam_W covers this in his article.
The height achieved is up to you. If you'd like the deck to finish flush with the sill, it would be 130mm, though you could have it lower if you wish.
That should cover most of your questions. Please have a read of the article and other similar posts and get back to me with the rest of your questions when you're ready.
Looking forward to seeing what you achieve.