[Strawbale] Cold rooms

[Rob Tom]

On Thu, 19 Apr 2007 07:13:21 -0400, kim thompson  
<shipharbour at ns.sympatico.ca> wrote:

> compacted earth floor in a
> large(about 1500 sq') unheated basement
>
> The client is looking at installation of :
> a leveling sand base on basically bedrock
> -> then a 6 ml poly vapouur barrier-> then about 3" of compacted clay  
> rich soil with some straw
>    fibre added. a finish clay/sand coat/ linseed oil.
>  a rain water cistern (covered swimming pool) in the space as well.

Dearest Kim;

Some thoughts from the Chicken Little/Nervous Ned corner...

But I suppose before that I should ask if the "unheated basement" is:

  	(i) going to be below grade
         	  and
	(ii) going to be isolated from the living space above, WRT air  
circulation ?

WRT (i):  Is the unheated basement really just an enclosed crawlspace  
built on top of exposed
            bedrock or is it a matter of digging down through some soil  
cover on top of the rock
	   and if the former, will there be some fill brought in to berms  
up/backfill around
	   the "basement" ?

If it's going to be a condition of the basement being below grade (as a  
result of either of the above) I wouldn't be comfortable with the sand  
layer beneath the poly/earthen floor and would prefer that washed stone be  
used instead and that stone within the footings provided with drainage  
tile (that is either drained to daylight or a dry well) to ensure that any  
water that gets in, gets out.

As I'm sure you're aware, sand can hold a lot of water and if not drained,  
it is entirely possible for sub-slab water to exert enough upwards  
pressure to find weaknesses in the moisture barrier and if that happens  
and the straw-reinforced earthen floor mix gets wet, Bad Stuff happens.

And as you're aware, earthen floor mixes take a long time to dry here in  
MooseLand and I would imagine moreso in a Maritime climate.  And I would  
imagine that a basement, which may not have as many doors and windows as  
above grade storeys, may present even greater challenges for timely drying  
(both of the earthen mix and later, the linseed oil sealer.  That too  
spells Trouble for the straw in the mix, I would think.

Bottom line (from the Nervous Ned perspective) is that it may be better to  
substitute compacted stone for the compacted earth/straw as well, and  
perhaps limit the earthen mix to just the optical finish layer ?  <<--  
Accent on the question mark.

I don't know what kind of stone you have in Nova Scotia but if it's  
limestone (as it is here in Ottawa) compacted limestone screenings does  
result in a concrete-like material as it sucks up CO2 from the atmosphere  
and turns back into a monolithic-like mass.

Okay. That's it for me.
The hockey game (Kanata (Ottawa) Senators vs. Pittsburgh Penguins) is  
proving to be too much of a aural distraction.

-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at   C h a f f Y a h o o  dot  C a  >
(winnow the chaff from my edress in your reply)