Mick's New Deck - Queries

Hi guys,

Have been reading many of the posts, and all I can say is WOW!!!. - what a lot of information you guys have given.

Having scanned and searched and read, I am about to embark on a deck-building exercise. (after having some quotes to build the deck and they ranged from $20-25k)

I bought a copy of Staines, deck and pergola construction manual. (as the 2 libraries I checked both have had their copies stolen)!!!! and read it through 3 times. - I found it was OK, but it left a lot of questions unanswered, and often left me asking "why"?, as he often gives rules/guidelines, but does not explain the reasons behind these. My other issue with Staines is his tables. - He appears to give extremes in some areas, eg. -specifying the amount of concrete needed when the area supported per pole is 20 square meters. - Has anyone actually seen such a thing?

I have attached a copy of the rough plan. - An L shaped deck
Height varies between 1.8 metres above the ground. and 1.4 metres above the ground. So underneath is usable storage, for junk, but not really usable human space.
6.3 across the front (including stairs)
6.0 metres end to end.
TP subframe
TP posts into stirrups.
Decking - most probably merbau.
Am still working through the options on a pergola overhead, but most probably yes. I love the look of the A framed roof. - however may go for the conventional flat roof.
I am currently wrestling with designs of the subframe for the deck in particular the spacing of the bearers and, whether to have a joist span of 1.8 or 1.2. Have almost decided on 1.8 - as more bearers = more posts = more digging = more work. - I think I would rather just have increased sizes of timber.

Anyway, in all my reading I have managed to turn up a number of questions, and despite looking through the archives, have been unable to find answers. I would be grateful if some of the experts out there could lend me some of there wisdom....forever:

1) Regardless of which option, I choose (1.8 or 1.2 spans between bearers) If they both conform to the relevant standards, is one more advantageous than the other?.

1) Stairs. Staines advises that TP treads for stairs should be 50mm thick. (I assume this is due to the 900mm span). If I were to use 3x stringers, so the stair width is 900mm with another stringer running up the middle, could I use the decking boards as treads? As the max distance they are required to span is 450mm? The same as standard decking span? -

2) Posts: Was initially going to use steel, concreted into the ground, however upon reading countless forums,. - am of the opinion that TP in stirrups is easier to work with. - My one concern is deck height of 1.8 + roof 2.4 + = 4metre lengths…..I know that utemad has posted pics of posts greater than this, but still wrapping my head around it. However to go up that I, would need to use 125x 125 TP per the standard. Is this a commonly stocked sized timber?
Also, as only some of the posts would be going all the way up to support the roof, do I only need to make those out of 125x125 and get away with the rest out of 90x90 - or is that a bit dodgy?

3) Fastening joists to ledger. –
Staines advises to use either skew nailing or multi grips. –
What is the preference from you guys who have done this before?
What about skew-screwing (as opposed to nailing)?

4) Fastening joists to ledger -
Staines advises if fastening the joists above the ledger to leave a 12mm gap from the end of the joists to the house.. – However, if using joist hangers, no gap is left. – What gives? What is the purpose of the gap? Movement I guess. but is there no movement when using a joist hanger?

5) F5 v F7
Reading through many of the old posts, the advice was given, that if your deck remains uncovered and F7 TP becomes wet, then structurally it becomes F5. – Can anyone confirm whether this is the case? – if so, what advantage is there in building an uncovered deck out of F7?

6) Timber length
I am planning on the deck being 6.3m across. – Is it possible to get Beams that length, or will I need to join 2 smaller lengths?

7) Post holes. -
Initially I had planned on digging the post holes with a shovel, however I was told by a mate to get myself a post hole digger, (one of those ones that acts like a big pair of tongs/scissors)…Just wondering what you guys reckon? Is it easier than a shovel?

8) Based upon the span tables, have worked out that my bearers should be F5 225x50 - (continuous span of 1800 with a load width of 1800) with joists at 450 centers of F5 125 x 50…Can someone just quickly confirm this?

9) a company called north shore timber, has their entire price list on line, and while being on the expensive side , it has give me a guide as to what common dimensions of timber is available. It appears that timber 50mm in width is not as common as 45mm and 38mm in width. Is this a correct assumption?

10) Staines often refers to "high wind stirrups". - has anyone used them? atre they more secure than normal stirrups?

that is all i have for now.....it is amazing how all consuming the planning becomes.

Thanks in advance for all the assitance already given through the historic posts.

Mick

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