Expert: Daniel Humphrey - 12/26/2007

Question
 ok heres the problem I have a large a frame house the entire upstairs is in the a frame I have wasted attic space I want remove the kicker wall but they were cut into the rafters now I have a center dividing wall for support on the ceiling but sense the kicker walls were cut into the rafters do you think I need any kind of extra support I just keep seeing the attic and the ceiling falling in were the cut outs were for the kicker wall mind you this is all thick native lumber what would be your suggestions

Answer
A spacious and well-glazed loft is a wonderful space.

Your intuition is correct that removing the kneewall framing would weaken the rafter system. The kicker wall you refer to reduces the span of the rafters and acts mechanically to link the rafter with the tie-beam joists, creating a truss. Just how much strength that wall provides is determined by the placement of the uprights (length, angle, how far up the rafter it connects, the size of notch, etc.).

Exactly how much weakening you could get away with depends on the size of your rafters and the kinds of roof loading your house experiences.

One way to compensate for the loss of the kneewall is to build a header there and put in supports periodically wherever there is a supporting wall beneath on the main floor. Follow the load path to make sure you can carry it all the way to the foundation. Another way is to sister up the existing rafters with full-length rafters of the same depth. Yet another way to strengthen the roof system is to put in collar ties as far down as possible. I would try to do all three things.

I'm unsure of where your center dividing wall is--on your ground floor or in the loft.

I would recommend that you hire a knowledgeable builder in your area to come over and do a on-site evaluation and discuss these options with you and make the engineering calculations to your satisfaction.