Expert: Richard Taylor, AIA - 7/23/2009

Question
When I look at house plans, I always wonder if a house would still be stable if some of the walls are knocked down?  Is there a certain why I can tell which walls are essential for the entire structure?  It seems so easy and without consequential concern of ridding of walls on Home and Garden television shows.  Do these interior designers know which walls are important to keep and which are ok to rid of, or do they consult with architects behind the scene?

Answer
Judy - thanks for your question!

Let's hope they consult with someone who knows construction, as the results of inadvertanly removing a load-bearing wall would be disastrous!  Any TV program like that only shows you a very tiny part of all that goes on to get the results they present; there's a great deal of "behind the scenes".

Below is the text of an article of mine about load-bearing walls in your house:

Remodeling an older home often means turning several smaller rooms into a single larger one, or opening up an existing room to connect to a new addition.  Since our casual contemporary lifestyles are better suited for open spaces, remodeling and addition projects sometimes require the removal of walls.

“Bearing wall” is a shortened version of load-bearing wall.  A load-bearing wall carries some of the weight (load) of the structure above.  Removing or altering a bearing wall without properly supporting those loads can be dangerous, and can severely damage the house.

But not all the walls in a house are bearing - so how do you know which are and which aren’t?

In a finished home, plaster, drywall, paneling, or other surface materials hide the structural members from view.  Exposing the structure by removing the wall or ceiling surface is the best way to see what’s underneath, but with just a little detective work you can find clues to the layout of the structure and locate possible bearing walls without damaging the interior of your home.

You Have The Floor

A bearing wall has two distinct characteristics: it supports a load from above, and is in turn supported by structure below.  Home designers and builders generally try to make the structural layout of a house efficient, lining structural members up over top of each other and making it easy to trace the path of the loads through walls and floors.

Floor joists are the structural members that make up the floors of your home.  They’re hidden from above by the finish flooring material (carpeting, wood) and from below by the ceiling finish.  Floor joists are usually spaced 16 inches apart, and are supported on each end by walls or beams.

For various reasons, most floor joists span from the front of the house to the back, so right away we know that the front exterior wall and rear exterior wall are bearing walls – they carry the load of the floor joists above.  Walls between and parallel to the exterior load-bearing walls may also be bearing.  Measure between the parallel interior and exterior walls – if the distance is somewhere around 12 to 16 feet, or if it divides the space between the two exterior walls roughly in half, then it’s probably a bearing wall.

If your basement ceiling isn’t finished then you’re really in luck.  Now you don’t have to guess – you can see exactly what direction the first-floor joists span.  And the second-floor joists almost certainly span the same direction.

While you’re in the basement find the spot on the ceiling that corresponds to the location of our suspected bearing wall above.  Is there a steel or wood beam there?  Is there a masonry wall?  If so, bingo – you’ve found a bearing wall.  If not, the wall’s likely not carrying any significant loads.

Over Your Head

Because roof structures are more complex than floors, bearing walls that carry roof loads can be a little harder to identify.

Roof structures come in two varieties: stick-framed, and trussed.  Stick framing is just what it sounds like – the structure is made up of individual “sticks” working together to carry loads.  A stick-framed roof is made of rafters (the sloped members creating the shape of the roof on the outside) and ceiling joists (the horizontal members creating the ceiling on the inside).

Finding bearing walls below a stick-framed roof is similar to finding them below floors.  Find the exterior walls that the ceiling joists and rafters bear on, then locate parallel walls between them.  It’s easy to find the ceiling joists since they’re usually exposed to view in the attic.

Trusses are prefabricated structural members that combine rafters and ceiling joists.  Trusses usually span the entire distance between exterior bearing walls, so you probably don’t have any interior bearing walls under a trussed roof.

But be careful – trussed roofs and stick-framed roofs with complex shapes can be tricky to analyze.  If in doubt, contact a design or building professional for help.

Demolition And Construction

You’ve identified a bearing wall, how do you safely remove it?  Start by making sure that you have a proper replacement designed – a beam of some sort.  A structural engineer, Architect, or contractor can help with this; a new beam replacing a bearing wall will need to be supported at each end, which may mean adding structural members below.

Removing the wall requires first temporarily supporting the loads coming from either side.  This is usually done with temporary walls, one on either side of the wall to be removed.  They’ll hold the floor or ceiling in place while you take down the bearing wall.

Once the new beam is inserted and the temporary walls are removed, you’ll be ready to finish and enjoy your new open space.

Hope this helps!

Richard Taylor, AIA
www.rtastudio.com
www.rtastudio.blogspot.com