Replies

1. GBA Editor
   Martin Holladay | Sep 22, 2016 01:27pm | #1

   Barbara,
   What's a "rat guard"? Is that a California expression for what the rest of us call a rat slab?

   Is this a house with a post foundation, or a house with a conventional crawl space foundation (perimeter concrete walls)?

   If you are planning a conventional crawl space foundation with perimeter concrete walls, I think that an unvented crawl space makes more sense than a vented crawl space. For more information on crawl space details, see Building an Unvented Crawl Space.

2. 
   Jon_R | Sep 22, 2016 03:36pm | #2

   Why "locations" vs a single point fan, no ducts and numerous vents?

3. Expert Member
   MALCOLM TAYLOR | Sep 22, 2016 03:41pm | #3

   Rat Slab's Canadian equivalent is called a Scratch Coat. Our rats are much too polite to burrow into a crawlspace.

4. GBA Editor
   Martin Holladay | Sep 22, 2016 03:47pm | #4

   Malcolm,
   In my vocabulary, a scratch coat is for walls, not dirt floors.

   A stucco job consists of three coats: scratch coat, brown coat, finish coat.

5. 
   bchernusm | Sep 22, 2016 04:39pm | #5

   Thanks for the responses. It is a rodent guard slab. Yes, it is conventional crawl space foundation with perimeter concrete walls. In our county,if it is sealed then it must be mechanically ventilated at a minimum rate of continuously operated mechanical exhaust ventilation at a rate equal to 1 cubic foot per minute for each 50 square feet of crawlspace floor area, including an air pathway to the common area (such as a duct or transfer grille).

6. GBA Editor
   Martin Holladay | Sep 22, 2016 05:00pm | #6

   Barbara,
   The details you need to follow are explained in my article, Building an Unvented Crawl Space.

7. 
   bchernusm | Sep 22, 2016 05:01pm | #7

   Thanks Martin