Door Widening

[CashRed]

Hi guys,

I am beginning my very first engineering job next week and I have a couple questions.

I was told that I will be working on a project where a home owner wishes to widen their door way in Ottawa, Canada. I will be visiting the site, inspecting the structure, then performing calculations and writing a report to offer suggestions to the client.

My question is: What calculations will likely be required for this project? What things in particular should I be keeping an eye out for on the site? And are there any other suggestions you can offer?

Thanks!!

 

[TDIengineer]

I would assume the residence is of wood construction? You will want to determine if the wall is load bearing and the ceiling joist direction. If it is a raised slab you need to be concerned about the new jamb stud locations and whether a floor joist is possibly compromised from a heavier post load. Be cautious of the redistribution of vertical load when you widen the doorway and possibly change in soil bearing pressures. Quite often in residential remodel no one pays attention to footing loads and you end up with differential settlement and a sloping floor. A new header will be needed and sized for the wider opening.

In terms of lateral resistance, usually interior wall isn't sheathed, or the home is relying on all the walls with gypsum sheathing and stucco on the exterior for lateral resistance. If they go crazy adding windows and widening doors, take a look at your loss in seismic/wind resistance.

 

[structSU10]

For a home, I'm guessing it is likely wood construction. There are a lot of things you would probably like to see, but won't be able to unless drywall has been removed. You want to get an understanding of the span of any joist being supported by the wall, if any, and how the load is transfered to the foundation, or other supporting elements.

Take a lot of pictures, and maybe try to key them into a plan sketch you make of the home. Take measurments of surrounding areas as needed. electrical and HVAC stuff running in the wall may be an issue you would also be worried about with relation to what your new structure may do.

There are many issues that are not strictly structural that you may encounter, especially if this is an exterior wall. You may inquire if a senior engineer could accompany you being your first field visit, so you can get a hands on view of what is important to observe.

 

[TDIengineer]

I meant a raised wood floor, not raised slab.. If slab on grade, a thickened slab may be a good idea at the new post locations.

 

[msquared48]

You might check too to see whether the walls to each side are shear walls with associated hold downs. Depending on the extent of the door widening, one or two of the hold downs, if present, may be eliminated necessitating their re-installation, and perhaps reinforcement of the associated shear walls.

Mike McCann
MMC Engineering

 

[SLTA]

It's mostly been covered, but I'd add: pay special attention to the new header connection to the studs, and follow that connection attention all the way down to the foundation. I've seen a few beautifully-designed headers come crashing down when no one remembers to connect the load path properly. And take overall pictures of the entire area you're working with, not just zoomed-in ones. It can help later when you're trying to remember crazy roof framing patterns, etc.

Get yourself a Simpson Strong-Tie catalog and get to know their products. I use their catalog almost daily. If you have questions, call their offices and ask for the engineering department. They're a big help with tricky connections, and sometimes there are uses for parts that they have tested but don't publish for whatever reason. New door openings can seem simple until you get deeper into it.

Welcome to Eng-Tips. I hope you find this site as helpful as I have. (As a side note: we're not all guys.)

 

[msquared48]

Really?

Mike McCann
MMC Engineering

 

[SLTA]

Oh hush up, Mike. just for you...

 

[dhengr]

CashRed:
Study some books on rough framing, and wood construction, how are door openings usually framed? So, you have some idea what is probably back there, if you can’t actually see it. How does that framing vary as the opening gets wider? What about the header’s make-up and how does that change? Where do ALL the loads on that header come from, and where do they go, all the way down to the ftgs. Any concentrated loads over the new opening? Do you need vertical grain blocking within floor framing depths to get the new jamb loads through the floor system, and maybe onto a center steel beam or a foundation wall? Or, should that jamb be a column member going all the way to the foundation? What’s the floor framing where the new jambs will be, and how do you rest on that or get around it?