Build Your Own House

The ultimate website for owner builders & DIYers
It is currently Mon Oct 21, 2019 12:22 pm

All times are UTC + 10 hours




Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: Building on Clay in W.A.
PostPosted: Sun Apr 26, 2009 5:10 pm 
Offline

Joined: Thu Jan 10, 2008 12:11 pm
Posts: 2
Location: Perth
Greetings all.
We are going to owner build a rammed earth house in approximately 4 months. The property is situated on a clay belt. The building envelope is built up with sand approximately 1600m2 x 1.5 metres high (lots of sand).
This was done in stages starting 4 yrs ago with the last 2,000 ton brought onto the property 18 months ago. So this sand has had plenty of time to settle.
During the wet months the sand on the south side gets a shiny sheen around the base and remains that way 1 or 2 months after the rains have dissapeared.
I suspect that water isn't flowing through or away from the sand pad.
The southside of the sand pad has a 300mm limestone driveway running from the road front past the envelope.
Can this build up of water affect the home once it is built.


Top
 Profile  
 
PostPosted: Sun Apr 26, 2009 5:38 pm 
Offline

Joined: Fri Jun 10, 2005 11:43 am
Posts: 310
Location: Perth, Western Australia
john and sonia wrote:
The building envelope is built up with sand approximately 1600m2 x 1.5 metres high (lots of sand).
<snip>
During the wet months the sand on the south side gets a shiny sheen around the base and remains that way 1 or 2 months after the rains have dissapeared.
I suspect that water isn't flowing through or away from the sand pad.
The southside of the sand pad has a 300mm limestone driveway running from the road front past the envelope.
Can this build up of water affect the home once it is built.


First up, this is really a question for your engineer.

However...

Is the south side the low side? If so then the sand is doing the right thing - it is releasing the water. Even if it is holding water this isn't necessarily a problem - the reason you build on a sand pad is because it is stable whether wet or dry. Clay expands when it gets wet and shrinks in the dry, causing your slab and masonry to crack.

If you think the driveway is obstructing drainage then you could trench along the edge of it and fill with ag pipe + bluemetal, but personally I doubt that this is a problem. Probably the water is still seeping from the hill and through your pad and this is perfectly okay. If you are in the hills then there is a lot of pressure in the springs - the cut edge in the house I grew up in use to shoot 2m water spouts in winter until Dad built a retaining wall.

_________________
------------------------------
Bruce
Draftie


Top
 Profile  
 
PostPosted: Tue Apr 28, 2009 11:48 pm 
Offline

Joined: Thu Jan 10, 2008 12:11 pm
Posts: 2
Location: Perth
Bruce wrote:
john and sonia wrote:
The building envelope is built up with sand approximately 1600m2 x 1.5 metres high (lots of sand).
<snip>
During the wet months the sand on the south side gets a shiny sheen around the base and remains that way 1 or 2 months after the rains have dissapeared.
I suspect that water isn't flowing through or away from the sand pad.
The southside of the sand pad has a 300mm limestone driveway running from the road front past the envelope.
Can this build up of water affect the home once it is built.


First up, this is really a question for your engineer.

However...

Is the south side the low side? If so then the sand is doing the right thing - it is releasing the water. Even if it is holding water this isn't necessarily a problem - the reason you build on a sand pad is because it is stable whether wet or dry. Clay expands when it gets wet and shrinks in the dry, causing your slab and masonry to crack.

If you think the driveway is obstructing drainage then you could trench along the edge of it and fill with ag pipe + bluemetal, but personally I doubt that this is a problem. Probably the water is still seeping from the hill and through your pad and this is perfectly okay. If you are in the hills then there is a lot of pressure in the springs - the cut edge in the house I grew up in use to shoot 2m water spouts in winter until Dad built a retaining wall.



Thankyou for your input Bruce. Yep the southside is the low side. Building up the driveway with limestone has prevented the water from draining away. I was considering trenching, ag pipe and blue metaling 3 or 4 locations across the driveway. The reason I was concerned is I unwitiingly put the front wheel of a tractor off the side of the limestone onto the sand (same level) and it sank through the sand and got bogged. At the time it was humourous. But then I began to wonder about the stability of sand on clay and the effects water has on the two compounds. Best I get some advice from a proffessional.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group