Removing a load bearing wall and replacing it with a beam is significantly different from removing interior non load bearing walls. Load bearing walls are structural elements, non load bearing walls are not.
If you take out the load bearing wall, you compromise the structural integrity of your house. If you remove a non load bearing wall, other factors come into play--how to dispose of the debris, how to fix the ceiling and floor, where to route vital services--but your house will not fall down.
Whether contemplating this project on a DIY basis or hiring a contractor for it, these are core issues you should first know:
1. You Are Probably Legally Allowed To Do It Yourself
While a majority of homeowners choose to hire a contractor for this heavy project, in most communities, permitting agencies will allow you to do this work. It is a matter of adhering to code and passing inspection, not possessing a contractor's license. Since all municipalities are different, check with your local permitting agency for guidance.
2. Permits Are Involved
It should come as no surprise that your permit agency wants to know if you are taking down a wall that affects the structural integrity of your home. You may even need to submit a detailed plan regarding an alternative support system.
3. What You Remove Must Be Replaced In Some Other Way
If you take something out, it must be replaced. To see how this works on a small scale, consider your home's windows.
Walls are the best way to hold up a house; cutting a hole in the wall can only compromise this. But window headers--basically small beams--serve to replace the removed-wall portion.
When you or a contractor remove a load bearing wall, it must be replaced with either:
- Beam Only: Horizontal beams of sufficient size. Other than the two ends, the beam has no vertical resting points.
- Beam + Post: Horizontal beams whose strength is augmented with one or more vertical posts between the two end resting points.
4. Order an LVL Beam for Better Support
You cannot pick a 4 x 4' off the shelf at Home Depot and use this as your sole carrying beam.
Instead, it is wiser to order a laminated veneer lumber (LVL) beam. LVLs pack greater strength into a smaller space than similarly sized dimensional lumber. Thus, a 4' x 6' LVL will be stronger than a single piece of 4' x 6' dimensional lumber.
One exception: build your own LVL. A common scenario is to build up your own beam out of three 2' x 10' sections of dimensional lumber, nails, and construction adhesive.
That said, you may be surprised that LVLs are not very expensive. Architectural LVLs are expensive, because the wood is meant to be viewed, not covered up with drywall. Non-architectural LVL are dramatically cheaper than architectural ones.
5. The Beam Might Protrude
The replacement beam may protrude lower then the height of the ceiling.
This is because you need to have a much larger beam to replace the walls that are being removed. It is difficult to completely hide the replacement beam because of the space issues.
Many homeowners view the exposed beam, though, as a necessary evil in order to achieve the greater good of opening up space into an open floor plan.
6. Vertical Posts Might Make the Project Cleaner
Intervening vertical posts (or columns) under a carrying beam admittedly do take away from that flawless open floor plan look.
However, any kind of vertical support you can add under a horizontal beam will give your beam assembly far greater strength.
Additionally, if you are having issues with the beam protruding too far below ceiling level, posts can allow you to reduce beam depth and get it back up to ceiling level.
7. Beam Construction Is Simple Work (But Not Physically Easy)
Once the replacement beam has been correctly sized, the actual work is simple, tools are few, and materials are cheap.
Even the LVL, the most expensive material in this project, is still relatively inexpensive.
One online retailer quotes a price of $8.85 per linear foot for 1 3/4" x 16" LVL, not including taxes and shipping.
8. Beam Sizing Is Difficult To Determine, So Get Help For This.
Span tables are hard for the layperson to read. If it were as simple as taking a few factors into account--distance spanned, one- or two-story house, type of house--we would all be structural engineers.
Span tables are readily available. But factors like deflection, shear, dead weight vs. live weight, and roof loads make beam sizing difficult for the amateur.
A structural engineer or contractor can consult with you on the proper size for the beam. Some structural engineers may agree to hire out on a per-hour basis.
9. With No Beam, Your House Will Fall Down Slowly, Not Right Away
Well-built structures are constructed with redundancy in mind.
Even when a major structural element such as an internal load bearing wall is removed, the rest of the house may stay more or less intact. You see this often after a tornado or earthquake, where two-story houses have entire exterior walls ripped off yet the building remains standing.
The reason: redundancy.
Even with the wall removed, a host of other interwoven elements, both structural and non-structural, pull together to keep the overall structure intact. When the wall comes out, flooring, sub-floor, underlayment, neighboring walls, joists, rafters, and many other elements, come into play to hold the structure intact.
However, gravity will slowly take over and the house will begin to sag and slump.
This should not be construed as an encouragement to remove load bearing walls without a beam replacement; quite the opposite.
It is a reminder that you should not be lulled by the power of structural redundancy.
Gravity will win. It is just a matter of how fast this happens.