Posts, Poles and Split Levels

[Dion N]

:confused: The Chief Designer and I (well mostly the Chief Designer), have been tweaking house plans for our sloping block of land. To prevent a house that is perched a ridculous height off the ground at the back, we would like to have three levels stepping down the slope. A slab is out of the question (we could - but why pay the extra cost for excavation, retaining walls etc etc?). Therefore, the house will be elevated on some sort of posts or poles (which means plenty of space for a workshop underneath

It's my intention to do some of the building work myself. I have a few questions though about the design.

Firstly - I'm tossing up between a pole house (ie the poles go through the floor and hold up the rafters) or a conventionally framed house with steel posts and Hyspan floor bearers. From an owner builder perspective, steel posts seem alot easier to erect than poles (ie lightweight!). On the other hand, poles allow for easier roof framing as there are no load bearing walls and thus you can accommodate a variety of heights in the roof design without complicated trusses and hip/valley rafters.

Secondly, the house is a split level, so how do I change floor heights? With wooden poles, it seems relatively simple, you can have a row of poles along the line of the split and bolt two bearers to it at the two different floor heights. But with a steel post, can I drill a bolt hole halfway up the post to attach a lower bearer whilst the upper bearer sits in the stirrup?

[Bodgy]

I built a pole house a while back, and helped a mate with his. In so doing learnt a few lessons.

1. Pole house resale is stuffed. Seen as 'hippy' and inherently owner built. Bit like a concrete yacht.
2. Great method of construction, particularly on a sloping site.
3. When you begin framing, build your wall frames inside and seperate to the poles. Don't try and incorporate the poles into the walls.
3a. Do run your top plates etc off the poles.
4. Check if you have rock near the surface. If so, forget poles. Poles need around 2 metre holes. Drilling rock puts the $$ out of the question.
5. Yeah, its politically and greenie incorrect, but before you errect the poles, ensure no nasties or rot will get to the below ground CCA wood. I filled the holes with diesel, sump oil and 245D.
6. Be aware that you need a crane to stand the poles, I got 10 mates and 2 x slabs of XXXX but mine was only single storey
7. Do not even think about non CCA poles (ie Bush poles)
8. Buy a few dozen extra slabs of barbed wire bitter, construction is such fun!

Good luck

[Dion N]

Thanks Bodgy

Having read over your post, I can see that poles are going to be a bit trickier than I first thought. Some of the negatives I can see are:

Cost - Crane hire and hole dimensions (I am presuming that gal steel RHS postes require a much smaller footing). I suppose it depends on the soil type. Since the block does tend to have a few boulders, 2m deep holes might be a little costly...

Termite protection - I was thinking of using Red Ironbark or another Class 1 timber rather than CCA, but I suppose steel posts would be better again, presuming the hollow section is properly selaed off

Resale value - not really an issue as I don't intend to sell for a long time and in any case, the area, whilst not "hippy", could be considered a "tree-changers" location. There aren't many too many brick and tile boxes on Tamborine Mountain!

[silentC]

If you use the duragal flooring system, you can use the verandah plates to set up a split level floor arrangement. I've used them to accomodate different depths of joists at my place (not split level but switching from 90mm hyspan to 200mm hybeam).

Get onto your local OneSteel place or download the brochure on the web: http://www.onesteel.com/productspecs.asp?specID=170. It shows details of connections. Duragal is perfect for O/B because you don't need any special tools. Cut with an angle grinder or a metal cutting blade and tekscrew together.

[bitingmidge]

I can't agree with Bodgy, I think Pole construction is an absolute waste of timber.

think about it: Telegraph/ electricity poles have a finite lifespan, so does any timber in the ground, including timber poles. How the heck do you replace them?

So you bolt the poles to steel brackets mounted in big lumps of concrete, which defeats the bracing advantage that the poles give you.

Build a lightweight, well braced steel platform, and go from there!

cheers,

P

[journeyman Mick]

Dion,
also be aware that pole homes are a whole other ball game to conventional building. Theres quite a few built around here, but by specialists. I've known a few builders that have come unstuck and almost gone broke when they attempted a pole home. These were experienced tradesmen, not newbies. Not really the sort of thing you want to attemp as an OB.

Mick

[Dion N]

I'm now leaning more towards steel posts. The idea of excavating 2m holes makes me shudder knowing how much underlying rock there is....

Supposing I don't use the Duralgal flooring system, how would I change levels? Can I bolt the lower level bearers to the side of the post that carries the upper level bearers? Or do I need a double line of posts where the change in level occurs? And if I want to enclose the underfloor space (say for a workshop ) can I bolt the battens for my cladding to the perimeter posts without compromising their structural integrity?

Also, what size footings am I going to need (roughly) for steel posts? I know these depend on the soil and the wind rating. The soil is red volcanic clay and the next door neighbour said he had to build to the lowest of the two cyclone ratings. He reckoned he had to use 600 x 400 for his post footings.

[floydus]

I'd agree with Biting, platform building with steel posts is the easiest method , plus you can weld lugs on to accomodate diffrent heights if need be.