Home>Discussions>INTERIORS>Molding & Carpentry>Will this beam support this span?
5 posts / 0 new
Last post
Will this beam support this span?

This above picture is an overview of my situation. The french doors on the bottom floor--I want to replace them with a set of accordian doors so that when they are all open, almost the whole wall is open to the patio with no post in the middle. That leads me to my big question--can I take that 4x4 post out of the middle? There is a 4x12 header that goes across this whole wall--you can see it in this cutaway picture:

So this 4x12 beam needs to support the deck and the upstairs. The upstairs is cantilevered out about 4 feet over the 4x12 beam. The 2x10 joists in the deck go from the 4x8 beam over the deck posts back to the 4x12 beam above the doors. Here's a pic of the joists:

The 4x4 post doesn't seem to be very supportive. I pulled some of the siding and door casing away to check it out. The only thing that concerned me was that the post had one of those heavy duty brackets at the top securing it to the 4x12. I was expecting to see it toe nailed in or maybe with a couple of those thin metal Simpson straps since I thought it was there just to provide a place for the hinges on the French doors. Any insight will be greatly appreciated.

Re: Will this beam support this span?

There are some other factors to consider, but to start with what will the span of the 4x12 be when the new doors are installed?

Re: Will this beam support this span?

About 10 feet.

Re: Will this beam support this span?

Great to have pictures.

Curious ... when you say 4x12 ... are you meaning 2 2x12 ?

As for the 4x4 center post I suspect it will be providing some support being midspan. Not sure as to what bracket system for securing the 4x4 . Ideally it should be one like the attached. There is also the question how the bottom of the 4x4 is secured preventing kick-out.

There is a consideration of side loading of the header as the unsupported span increases. When a 2x12 is stood up there will be flexing side to side ... there may be a requirement to secure a 2x4 or 2x6 ( depending) along the top and bottom of the header creating an I beam. This will strengthen the header from the effects of the side flex.

It's also curious about the second level structure. The extension of the roof and second level loads come down around the center of the over hang where the cross blocking are. The joist configuration and spacing look unusual to me.

I'm thinking a professional should be consulted on this one.:)

Re: Will this beam support this span?

No, I'm pretty sure it is one 4x12 and not (2) 2x12's nailed together. I went down to city hall to see what the previous owner did and the plans call for a 4x12 and from what I've seen so far it is a 4x12. I haven't completely pulled the door frame apart to see though.

Yes, the bracket securing the 4x4 to the 4x12 is very similar to the picture you posted. I haven't checked how the bottom of the post is secured to prevent kickout--I'll look today.

The joists for the 2nd floor are 16" OC. The joists for the deck are also 16" OC but intertwined between the floor joists so it looks kind of like a maze in there. I'm not sure why the previous owner did that but most likely the deck was an add on after the upstairs addition.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.