Process for costing and building a deck

[Lionel_82]

Hi all,

We want to build a deck (read, get a deck built), we are cost conscious but at the same time don't want to sacrifice on quality and size, we want the deck to be usable at the end.

With this in mind I have some questions on the best process to follow, and the likely difference in price for different sizes.

About a year back we got a bunch of quotes which scared us off, but now we have some more money we are going to go ahead.

First question, we are looking at a size of 6000X4000, but, we would love to increase the size to 6000X5000. How much roughly would the price increase for the size increase? Surely it wouldn't be 25%?

Now the details:
1. Deck attached to the back of the house
2. Sliding door as big as we can fit (around 2.4m I think) off the dining room.
3. A fly-over roof (so it doesn't feel closed in).
4. Insulated roof.
5. Stair case down one side.
6. About 2m off the ground.
7. We want a concrete slab underneath, block is gradual slope so will require a very small retaining wall.
8. Below where the deck attaches to the house, the underneath of the house is currently stumps into dirt. We want scope to dig out in the future, remove stumps, replace with I-beams and concrete. This would mainly be a workspace.
9. We may close in underneath the deck with slats and a gate.
10. Preferably not too many stumps underneath (does this increase cost much?).

OK, so the other questions:

Knowing if the larger deck option is going to be viable for us plays a big role. What I'm wondering is what the best approach is towards organising a design, concreting and construction. Previous quotes have indicated that they put on a bit of a cost to organise a drafter (drafter or architect?), council approval and a concreter, so I'm thinking that if we organise this we may be able to save some money. But without knowing if the the bigger deck is viable cost wise, how can I get a design drafted suitable for council submission without knowing the exact size and without incurring costs of getting two designs drawn up.

I'm thinking if I have a concrete design with all my requirements written down I can get more comparable quotes than what I did last time.

What would be the process to organise a concreter and what sort of costs would be involved? I saw on this forum maybe around $70/sqm, but would it be a bit higher with footings? If required? And would the concreter need to make any special provisions?

With the insulated roof, it would be nice to have scope for a hot water system or solar panels, what would be required to achieve this and does it add a lot to the cost?

OK, I think that is it for now. I hope there isn't too much there to answer easily.

Thanks

Lionel.

[Master Splinter]

You really need to sit down with a draftsman to work out what the details are, otherwise there are too many 'it depends' to give any worthwhile answers.

For example, for costing the jump from 4000 to 5000...does it mean just one more meter of length in the bearer, at $12/meter, or does it mean going from four meters of $12/meter bearer to five meters of $19/meter bearer (and then there might be 200mm waste on a 4 meter span, but 400mm waste on a 5 meter span).

If you want to do things like dig out under the house, do this first, not when you have a headroom and manoeuvrability reducing structure in the way! (but if you are keen to dig out by hand, and manhandle steel sections into place.....)

Then again, depending on council regs it may be beneficial to tweak the size so that the structure does not have to be approved, and you can take a more hands-on approach to it.

But in any case, having a set of plans to shop around means you'll get more comparable quotes in the end!

[Lionel_82]

You really need to sit down with a draftsman to work out what the details are, otherwise there are too many 'it depends' to give any worthwhile answers.

But in any case, having a set of plans to shop around means you'll get more comparable quotes in the end!

Thanks Master Splinter, I thought as much. Seems to be a bit of a chicken and egg situation. Are the draftsmen qualified to know what size bearers etc. are required? And how would I go about finding one? I'm trying to avoid paying for two sets of plans is all.

[barney118]

Really work out what you want now and in the future. I built a deck off the back of my house (3m off ground) only to 90% demolish it, change from skillion roof to trusses and turn it into rooms a couple of years later. I went through planning approval twice @ $900 each time. I am converting under this to rooms as well but this was always the plan.
Given you want to span it 4-5m makes a big difference as you can span a 240 wide joist 4m but have to go up in size to get 5m span and or add an a bearer in the middle, more posts/stump/concrete. If you go down this path you may as well go 6mx6m deck. Depending on roof design consider the drop over this span too for head room.
I would excavate under whilst there is nothing there and pier down where you will need supports, concrete in one go, its a little more upfront but saving for the future. I used 450x450x 600 deep min concrete for the 350x350 brick piers I used. 2 days work for a brickie I supplied materials.

[Master Splinter]

A decent draftsman will know not only the sizes to use, but the sizes that are cheap to use as they are used by everyone in the region (no use spec'ing a size that's hard to find locally or expensive) as well as any particular quirks that the council has (a draftsman's plans are typically ready to submit to council for building approval). Check your local paper for ads, try the yellow pages under draftsmen or architectural draftsmen.

[Bloss]

Buy a copy of Alan Staines book as it'll help you ask the right questions too: e.g. The Australian Decks & Pergolas Manual by: Alan Staines - Buy Books (http://buybooksonline.com.au/the-australian-decks-pergolas-manual-p-48.html)