Crawlspace ventilation help

[pmassie]

Hi

i have a question about crawlspace ventilation...

in the course i took last year, the ratio for crawlspace ventilation was 1:300 , but in the NACHI course it's 1:150..

can anyone pls direct me in the right direction?

thx

[Larry D. Kage]

Originally Posted by pmassie

Hi

i have a question about crawlspace ventilation...

in the course i took last year, the ratio for crawlspace ventilation was 1:300 , but in the NACHI course it's 1:150..

can anyone pls direct me in the right direction?

thx

I believe the 1:150 is the maximum and that can be reduced by region, vapor barrier installed, etc.

Check with your local AHJ/code.

[Joe Funderburk, CMI]

Even if it has a VB, I look for a lot of vents or note the potential for high moisture content in the wood.

[Claude Lawrenson]

Local conditions prevail.

Here's an example from OBC - Ontario Building Code

(2)

Where an unheated crawl space is ventilated by natural means, ventilation shall be provided to the outside air by not less than 0.1 m² of unobstructed vent area for every 50 m² of floor area.

(3)

Vents shall be,
(a) uniformly distributed on opposite sides of the building, and
(b) designed to prevent the entry of snow, rain and insects.

9.18.3.2. Ventilation of Heated Crawl Spaces

(1) Heated crawl spaces shall be ventilated in accordance with Section 9.32.

[Marcel Gratton]

I advise my clients not to ventilate the crawlspace.

Who would want humid air condensing on the cold floor / walls.

[pmassie]

Great infos guys!!

thx!

[Roy D. Cooke, Sr]

Originally Posted by mgratton

I advise my clients not to ventilate the crawlspace.

Who would want humid air condensing on the cold floor / walls.

Exactly I too advise my clients to not ventilate the Crawl space .
Here is some Info more if you need it

http://www.hgtvpro.com/hpro/bp_found...463221,00.html

http://www.buildingscience.com/docum...ce-insulation/

[pmassie]

Originally Posted by rcooke

Exactly I too advise my clients to not ventilate the Crawl space .
Here is some Info more if you need it

http://www.hgtvpro.com/hpro/bp_found...463221,00.html

http://www.buildingscience.com/docum...ce-insulation/

Thx Roy!! very helpful links indeed!

[Roy D. Cooke, Sr]

Originally Posted by pmassie

Thx Roy!! very helpful links indeed!

Glad to help any questions any time do not hesitate ..

[Claude Lawrenson]

Although we can see there is some mixed opinion here, several points need clarification.

1. Is it a "heated" crawlspace versus "unheated"?
2. What would the building "standard" be at the time of construction?

My point being does an engineers "opinion" trump "building code" as may be suggested; or perhaps be careful of how the inspector reports an opinion beyond the standards of practice.

[Roy D. Cooke, Sr]

Claude how about you give us your thoughts and answer your own questions .. Roy


I have seen too many damp from ventilation full of mould CS and cold rooms will give my thoughts and ideas to my client how to help have a healthier home .

[Claude Lawrenson]

Patrick posted the question. I simply reponded attempting to indicate what the code states in Canada, offering help.

Seems you take exception to my response - that is unfortunate!

How would I know if Patrick's question is related to a heated or unheated crawlspace? My point was simply there may be other "conditions" that equally make crawlspaces not as damp. This includes proper/adequate ventilation.

It goes back to simple logic of the intent of building code, and considering the conditions encountered by the inspector.

[Roy D. Cooke, Sr]

NO Claude I did not take exception to your post sorry if it came across that way .
("Seems you take exception to my response - that is unfortunate ") .
I and others are always looking on how to educate our selves and others .
If you have some information or thoughts I was just asking you to share them .
For you to not give facts or ideas is unfortunate for all.

[Marcel Gratton]

Originally Posted by clawrenson

Although we can see there is some mixed opinion here, several points need clarification.

1. Is it a "heated" crawlspace versus "unheated"?
2. What would the building "standard" be at the time of construction?

My point being does an engineers "opinion" trump "building code" as may be suggested; or perhaps be careful of how the inspector reports an opinion beyond the standards of practice.

Good point Claude!

I omitted to say that I also recommend that the perimeter walls be insulated, a sealed VB on ground and perimeter walls be installed and a source of heat provided being we are from the great white north.

Cheers,

[pmassie]

ok here is the situation :

surface : 30 feet x 24 feet
floor : dirt (irregular 2 to 8 feet of clearence)
VB : covers only half of the ground surface
Ventilation : 2 (on opposite walls) size 2 inches X 2 inches
Heat : one big a** electric heather (220) takes alot of energy to run
moisute : alot
insulation between joists (floor) : missing half of it
insulation on walls : none

Fix :
-insulate between joists
-VB everywhere (min 6 inch over laped...taped )
-insulate walls (fiberglass boards or spray foam + fire retardant)
-get rid of the big a** heater
-block the ventilation holes
-can't really add gravel over the VB because of the irregular ground
-insulation tubing over the copper pipes

i"m i on the right track? i would think yes , but if i"m missing something pls add it up!! lolll

thx