[Greenbuilding] Thin High R-value insulation for exterior

JOHN SALMEN terrain at shaw.ca
Mon Nov 1 10:17:36 CDT 2010


I am surprised the eng. said it was out of his scope. I am also confused how
they would achieve a drain gap without either a ledge for thicker stone or
spacing system for thin facings. 

The big issue is supporting the stone and with a facing the manuf. would
have a recommended spacing for connectors for the lathing to whatever the
structure is. Normally this would be thru to a stud with a minimum 1"
penetration of a screw or nail. Most codes still require a max. of 16"
between rows (reflecting common stud spacing). Vertical spacing depends on
the product but 8-10" is common.

I don't know the holding strength of faswall compared to conventional studs
but I think it is designed to be comparable. So really the only problem here
is the connector and its bending strength. There are connectors on the
market designed with higher bending strengths. FastenMaster makes a number
of products with tested values - I've used them a lot. They have screws that
are equivalent to 3/8 or 1/2" lags with up to 2-3" of threaded area. They
can easily be designed to provide the support needed based on spacing and
depth of embedment. The foam will help but I would ignore it in working out
the connectors and spacing.

Simplest approach would probably be to use a 1x vertical spacer over a
weather resistant barrier over the foam and secure the spacer with the
structural screws and then fasten the lathing to that. Technically the
spacer is not thick enough for the lathing fasteners but it is done
commonly. This would give a drainage gap and something the masons are used
to working with for attaching lathing.

Another common approach is to use a vertical z strip (cold rolled) but that
involves cutting the foam into strips etc. - but that approach is just too
full of holes.

Exterior foam can be sprayed level with the use of battens (foam is spayed
between battens and then screeded/cut flat, battens removed and holes filled
- seems silly when you have flat sheets.


JOHN SALMEN ENVIRONMENTAL DESIGN
4465 UPHILL RD,. DUNCAN, B.C.  CANADA, V9L 6M7
PH 250 748 7672 FAX 250 748 7612 CELL 250 246 8541
terrain at shaw.ca


-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Lynelle
Hamilton
Sent: October 30, 2010 6:44 AM
To: Michael O'Brien
Cc: Greenbuilding
Subject: Re: [Greenbuilding] Thin High R-value insulation for exterior

Hi Mike:

They use screws at various points in the wall now to do this.  None 
wants to install a brick ledge, saying it won't work well for the stone.

Thanks!

Lynelle

On 30/10/2010 09:41, Michael O'Brien wrote:
> Hi, Lynelle--
>
> Hmmm...a brick veneer would normally sit on a ledge, like a metal bracket,
attached to the structure. Is there some way the stone could be supported
like that?
>
> Best,
>
> Mike O'Brien
>
> On Oct 30, 2010, at 6:28 AM, Lynelle Hamilton wrote:
>
>> Hi All:
>>
>> Again, I turn to this list for advice.
>>
>> My house is durisol block, but I want to add 12-15R insulation to the
exterior, in part to reduce heat loss from the webs of the block, and
partially because I want R40-R43 walls.
>>
>> I have reclaimed 3" SM Board (blue EPS)  to put on the outside of the
durisol.
>>
>> The facing is manufactured stone.  I have had 3 masons look at the
property.  One mason says no problem attaching the stone to the durisol
through the 3" EPS, the other two say well.,....can't you find something
else?   They point to the possibility that the screws needed will bend in
the EPS, allowing the block to sag.
>>
>> Both say spray on closed cell insulation provides too uneven a surface to
attach lath and stone.
>>
>> So, has anyone done what I'm doing? What was the result? Alternately,
does anyone know of anything with grater rigidity than the EPS, perhaps with
higher R-value per inch, that would work?
>>
>> Please don't point me to the engineer....he says this is out of his
scope.
>>
>> Many, many thanks!
>>
>> Lynelle
>> -- 
>> Effective immediately, please use the following e-mail address to reach
me: lynelle at lahamilton.com
>>
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>

-- 
Effective immediately, please use the following e-mail address to reach 
me: lynelle at lahamilton.com

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