Draft AS2870 Residential Slabs and Footings Comment

Eric Frei · 22nd March 2010, 11:14 AM

I have attached the draft versions of AS2870

Comment can be made until 14 April 2010 here (you need to register):-

https://cas.hub.standards.org.au/cas...security_check

This topic is important as it concerns us with regard to trees and their proximity to houses, there's lots of detail and info in here that needs to be looked over and will become part of our job.

It appears where blocks are cleared on reactive clay soils and no measures undertaken to reinforce slabs likely means no vegetation is allowed to be planted, the block to remain vacant. It is pretty much accepted that people will plant lawns, shrubs and trees so why aren't slabs accomdating the future?

Have a read, make a comment on their website.

Pay attention to these areas.

Page 88 GUIDE TO DESIGN OF FOOTINGS FOR TREES

Page 150 APPENDIX CH GUIDE TO DESIGN OF FOOTINGS FOR TREES

Here's a snippet page 155

Quote:

Arboriculturists have found that the water up-take by trees is mainly related to:
• Tree species.
• Tree Health of the tree(s).
• Growth stage of the tree(s).
• Total leaf area.
• Height of the tree(s)
• Root and trunk mass.
• Soil type.
• Climate.
In their advanced growing stage trees require more water to construct their ‘frame’ than
they do in maintaining their frame after maturity.
Structural roots are concentrated nearer the trunk of trees, whereas ‘feeder’ roots extend
well beyond the drip-line (edge of the canopy) and follow the moisture gradient in soil or
continuous water paths such as leaky drains or aquifers. The fine, fibrous, feeder roots draw
most of the soil moisture and also store it together with the root and trunk mass. Reactive
soils extend this moisture gradient well beyond the extremity of the roots by the action of
soil suction, causing the ground to dry and shrink well beyond the end of the root system.
Calculation method for ‘tree effect distance’ (TED)

Page 158 states:-

Quote:

Engineering considerations
No design guidance is given for footings under the tree canopy (Area 1). The engineer
should use engineering principles for designs in this area and in some cases may consider
cantilevered floors.
The footings suggested for soil area 2 are suspended systems supported by drilled concrete
piers or timber or steel screw piles founded at minimum depth of 1.5 Hs or rock at P1 and
Hs or rock at P2. Excavated piers or deep continuous footings are not recommended in these
areas. The engineer may also design a concrete slab footing in area 2 by calculating a
design ‘yst’. For simplicity TD1and TD2 distances are considered equal.
In soil area 3 the range of ‘ys’ for design purpose is 1.5 − 1.0 ys.
The design engineer should determine any suitable treatments at the change of footing
systems. Wall articulation joints are recommended at these points.

So now is your chance to have a say.

glennak · 22nd March 2010, 12:26 PM

For putting this up, it's a lot to read.

Garry Brockley · 22nd March 2010, 07:02 PM

Thanks ekka, having a good read now might take a couple of run throughs but like you say we should be aware of these things and have a say on the future drafts.

22nd March 2010, 12:26 PM	#2
glennak Semi-mature vigorous tree Join Date: Mar 2010 Location: Melbourne Posts: 179	Re: Draft AS2879 Residential Slabs and Footings Comment For putting this up, it's a lot to read.

22nd March 2010, 07:02 PM	#3
Garry Brockley Bayside Tree Care Brisbane Join Date: Jun 2008 Location: Brisbane Aus Posts: 1,649	Re: Draft AS2879 Residential Slabs and Footings Comment Thanks ekka, having a good read now might take a couple of run throughs but like you say we should be aware of these things and have a say on the future drafts. __________________ My business:- Brisbane Bayside Tree Care

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
white oak slabs	corey	Firewood and Wood Working	4	31st December 2008 11:13 PM
Inner Circle of a Tree Website: Peer Comment	mdvaden	Non Tree Related chat	21	9th October 2008 02:11 PM
UK \| Mandatory tree inspections \| Draft regulation open for comment	Eric Frei	ANNOUNCEMENTS	9	5th July 2008 05:38 PM