0 Helpful?

What is the best way to build and insulate a bay window in new construction?

I have two bay windows to build and I want to keep the insulation levels consistent. I using 1 1/2 exterior rigid foam with lap siding on the exterior and 2x6 framing

Asked by Dan Easton
Posted Jan 30, 2013 8:33 PM ET
Edited Jan 31, 2013 6:17 AM ET

Tags:

1 Answer

Select your preferred way to display the comments and click "Save settings" to activate your changes.
1.

Dan,
A bay window needs structural support; if you understand the basics of framing, this shouldn't be a problem. Beyond that, a bay window should be treated just like any other ell on a building.

Pay attention to air sealing and to the continuity of your thermal barrier. If this is a projecting bay, the underside of the projection can be level or sloped. In either case, you want to design the bump-out so there is enough room for insulation -- below the window, at the sides of the window, and above the window.

It's fine to include insulation between the framing members if you want, just as you might include insulation between studs. However, the performance of this insulation will be degraded by thermal bridging. That's why multiple layers of continuous rigid foam on the exterior of the sheathing perform so much better than insulation between framing members.

Here is a GBA detail for retrofit insulation at a bay window:
http://www.greenbuildingadvisor.com/cad/detail/exterior-insulation-retro...

Answered by Martin Holladay
Posted Jan 31, 2013 6:25 AM ET
Edited Jan 31, 2013 6:39 AM ET.

Other Questions in GBA Pro help

Insulating Wall Between two Different Slab Elevations

In Green building techniques | Asked by Jonathan Lawrence CZ 4A New Jersey | May 24, 18

Difficulty finding a modulating multi-zone air-source heat pump

In Mechanicals | Asked by Jonathan Lawrence CZ 4A New Jersey | May 21, 18

Vaulted / Cathedral Ceiling -- Unvented

In Green building techniques | Asked by User-7075735 | May 23, 18

Should I insulate and/or heat my unfinished basement?

In General questions | Asked by J Greene | May 24, 18

How do we hire a green building advisor on an hourly basis?

In GBA Pro help | Asked by Joe Martin | May 24, 18
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!