Replies

1. GBA Editor
   Martin Holladay | Nov 30, 2017 03:20pm | #1

   Wenona,
   The best way to do it is with a window buck. If you plan to install pressure-treated 2x lumber as your window buck, the rough opening in the concrete needs to be at least 3 inches bigger (in both dimensions) than the rough opening would be without the buck.

   If your contractor doesn't know how to install windows in a weathertight and airtight manner, it's time to find a new contractor.

2. 
   user-6830721 | Nov 30, 2017 03:21pm | #2

   By the way....we will be using Roxul Comfortboard insulation.

3. GBA Editor
   Martin Holladay | Nov 30, 2017 03:22pm | #3

   Wenona,
   Two questions:

   1. Do you have a plan for how you will protect the above-grade portion of the foundation insulation from physical abuse?

   2. Does your project have an architect?

4. 
   user-6830721 | Nov 30, 2017 03:23pm | #4

   I think the contractor is thrown entirely by the exterior insulation. He doesn't know how to handle the whole situation. Usually the concrete guys would set the window directly into the concrete. Once we throw the insulation in, they all don't know what to do.

5. 
   user-6830721 | Nov 30, 2017 03:26pm | #5

   I had an architect draw up plans and told him what I planned to do and he did not address the question I have at all. He knows nothing about exterior basement insulation and was of pretty much no help!

6. 
   user-6830721 | Nov 30, 2017 03:28pm | #6

   I plan on spraying the Roxul with a protective coating. Martin, can you point me to an illustration on how to install the window bucks. Also, what kind of window do we need to get? I am also doing an egress window and am having trouble sourcing that. Can regular Windows be set into the bucks?

7. GBA Editor
   Martin Holladay | Nov 30, 2017 04:44pm | #7

   Wenona,
   Can you tell us the brand name of the spray-on product you will use to protect the Roxul?

   The window bucks should cantilever beyond the concrete, so that the exterior of the buck is co-planar with the exterior surface of the Roxul. You'll need to install sill pan flashing in the window buck, so that water drains beyond the insulation layer.

   Here are some links to GBA articles that discuss window bucks:

   https://www.greenbuildingadvisor.com/articles/dept/musings/installing-windows-foam-sheathed-wall

   https://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/flatrock-passive-framing-and-air-sealing

   https://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/103348/mounting-windows-concrete-block

   https://www.greenbuildingadvisor.com/blogs/dept/musings/innie-windows-or-outie-windows

8. 
   user-6830721 | Nov 30, 2017 04:52pm | #8

   I plan on using one of the Styro products. I don't have the exact name of the product in front if me but I don't think it is the one that was listed in the article about covering exterior insulation but one of thier other products that can supposedly be sprayed. I thought that it would work better to do a spray application on the Roxul. I plan on doing a test sample before applying to the building but I haven't gotten that far.....just got the Roxul in. Thank you for the links, I will check them out. So, you think it is better to do the whole buck in 2x lumber? I have seen pics where a 2x is set into the concrete and then a buck is made from thinner material and set into the opening.

9. 
   user-6830721 | Nov 30, 2017 04:53pm | #9

   Oh..again, can we use regular windows or are there special windows for this application?