What's behind the wall???

[e-tek]

We are going to be renovating this spring and in order to remove a couple walls we'll need to run an engineered beam across the house. The problem I'm facing is that where the beam needs to rest on one end is over a huge bay window. How would an inspector (or me!) figure out if the header over and suurounding that window is sturdy enough to support the beam and roof?
What I'm asking is - short of ripping a couple of chunks of drywall off, is there any other way to determine what's behind a wall?

 

[RAMBIN]

good electronic stud finder???

 

[idoine in toronto]

You could look at window header span charts for your given window width and assume the smallest header size was used. From your description it sounds like you're wanting to replace a load bearing wall with a beam that needs end support over and existing window header. You'll probably need to upgrade the header.

 

[Bevis]

wood frame or CBS home?

 

[ddawg16]

I agree with Idoine.

Chances are that the header on that bay window is a 4x4 or 6x at best. To expect that beam to also support an engineered beam going across your room? NOPE.

Based on what I have been learning during the construction of my garage, the engineer is going to want at least a 4x6 stud under that beam...and that's straight down to the foundation.

You will basically have to rebuild that bay window or find another spot to land that side of the beam.

 

[bigdav160]

How would an inspector (or me!) figure out if the header over and suurounding that window is sturdy enough to support the beam and roof?

An exterior wall most likely has a header that runs from the top of the window to the upper plates. A tape measure will tell you it's size. Then, it would take some pencil work to figure out the weight of the materials (dead load), determine how much of that weight is transferred to the header and use the span tables to figure out if it is adequate.

As an example, I have a six foot wide, six foot tall bay window that has an perpendicular second story exterior wall resting on it. And it's (heavy) conventional stucco and tile roof construction. The header is a (2) 2x12 sandwich. It's been standing 40 years with no problem.

 

[rsanter]

that beam will meet the minimum requirements to pass for that span. I would assume that it will not carry that load
depending on the amount of load on the new beam you are installing, it may even require the beam over the window to be replaced with steel

bob

 

[charlie_nj]

Assuming wood frame construction, for determining what size header is above the window you could use a stud finder, or the nail in the drywall method. Since you are remodeling anyway, I'd probably just cut a square of drywall out above the window that way I can tell with 100 percent certainty what size the header is, both in depth and in thickness. Once I know this, in order to determine if it's big enough to support my beam, you have to figure out the load on the beam which is going to eventually bear on this header. This is difficult but doable with some good internet research and decent math skills. Here is a good tutorial:

http://www.umass.edu/bmatwt/publications/articles/calculating_loads_on_headers_and_beams.html

Once the load on the beam is determined, and the header span determined by measuring, the header can be sized using the sizing table for the particular type of header material you are going to use. Here's a decent tutorial on the sizing process:

http://www.umass.edu/bmatwt/publications/articles/sizing_engineered_beams_headers.html

It's definitely possible to have a beam bearing on a header, the header just has to be properly engineered. I think you can be pretty sure that what's there won't be nearly adequate and will have to be replaced. Not at all difficult. The only issue may be the amount of space between the top of the bay window and the top plate of your wall. If the deepest glulam you can sqeeze in there wouldn't be big enough, you could always go with steel if you have to.

Where I live, something like this would have to have drawings and an engineers stamp on it, although you could design and draw it yourself as long as a licensed engineer reviews and approves it. I did a lot of the design work to include beam sizing when I built my house, and I only had to pay the engineer to review and approve the plans. Saved me a ton of money.

 

[tfi racing]

I would suggest moving on to plan B.You will have to open that wall up to expose what is there,chances are it won't be enough,so start planning now.It might be best to leave that header over the bay window alone,and look into sistering a new lam beam in front of it to pick up the new perpendicular beam,and finishing it as a feature bulkhead detail.Not the end of the world to lose a few inches of space,a lot easier then rebuilding that old wall for the new beam.

 

[e-tek]

One option I'm (now) considering is moving the beam BESIDE the window. That would mean that the beam taking the place of the load-bearing wall would be "picked-up" - or suspended - from it's centre rather than at its end. Can you do this - perhaps with a steel beam - so the end not supported would not sag under it's load?

 

[charlie_nj]

If I read this right you're in effect creating a cantilevered beam. Yes, it would be possible, but would have to be adequately sized for the load and the unsupported length of the beam. More complicated, in my opinion, and more expensive. If you are able to locate the beam alongside the window, if it was me, I'd just open the wall at that point, and install an LSL post there to carry the end load on the beam.

 

[Mike in Ohio]

You probably will have to open the wall to put the beam in anyway. While you have things torn apart could you move the window over a little bit? Or replace it with 2 narrower ones, 1 on each side of the support column. You wouldn't be giving up that much light or view and it would solve your support problem. Would add to the cost of the project though. Good luck, Mike

 

[larry4406]

Normal wood framing (in my area) entails 2x walls with a double top plate with the second deck bearing on the double top plate. Most window headers are below the double top plate and have king studs beside the header's ends with jacks below the header (jacks support the header in bearing).

If you can shift your beam to miss the window and then add jacks under the new beam locations and ensure that the load posts down to the foundation (i.e., blocking in the first deck also), then probably your easiset route.

Another option, assuming this is your framing method, is to leave the window header alone, cut in a new header into the second deck framing band board area (new header vertically stacked above the existing window header, but deeper and wider as per your engineer) and then hanger the new beam you need (and possibly some of the existing floor joists) off the new header. You will have to add new jacks and king studs to support the new header as well as cripples in the first deck to post down to the sill.

 

[kbs2244]

Larry's second idea is the way to go.