I just received this inquiry from old friend and fellow remodeling professional Janver Holly in California:

Dear Mason,

I have an 1860’s house on a wood foundation. Over time the wood around the perimeter has rotted. I suppose this is because the outside of the building gets wet from weather and irrigation. The floor and floor supports are fine, just the lower part where it touches the dirt is gone. Underneath the house it is bone dry and the wood supports are perfectly preserved. The net effect is that over time the outside walls have drooped a couple of inches while the core of the house has remained where it started. My question is: If a new foundation is installed will the house go back to its original flat floors or will the house remain a slight cone because it has been that way for decades?

Thanks,

Janver

Thanks, Janver, for your question. Figures you’d throw me the toughest, most complex sort of thing. To understand what we’re dealing with, would you answer a few questions?

{just the lower part where it touches the dirt is gone} so I take it that some timber is actually in contact with the ground - like a big perimeter carrying beam below the floor joists - there is presently no concrete, stone or masonry foundation?

{while the core of the house has remained where it started} so there is some similar form of support, like a timber king beam or beam on piers or sitting on the soil in the core of the house, which has not rotted, as it has not been exposed to weathering? The entire house above the floor level is all-frame construction, yes?

Are there bearing loads on the interior of the house? Breaks in the floor framing, such as between floor joists or timber joists and internal beams?

Do you have lots of insurance?

Mason

Dear Dr. Hearn,

The original house is a rectangle 28’ wide by 52’ long. There was a 3x8 piece of redwood laid flat around the perimeter and one down the middle of the house. The perimeter is rotted away and is resting on the ends of slowly rotting cripple studs and siding. The center sill is perfectly preserved and remains dry year round. The entire house is constructed of tight grained, old growth redwood. Parts of it appear to be salvaged as different rafters show different square cut nails while the actual construction was with round nails.  On top of the mud sill is a 24” high cripple wall with a double top plate, this includes the center of the building.  The floor joists rest on this top plate. There is a wall down the entire center of the house. The exterior walls are studs, the interior walls are a double layer of 1 x 12 rough cut redwood boards with cheese cloth nailed on beneath many layers of wallpaper and paint. The center plate bears floor joists, a wall, ceiling joists and roof load. The joists and rafters are all overlapped at the center bearing point.

The soil is sandy and no masonry of any kind was used between the ground and lumber.

We have plenty of good insurance. The insurance company is trying to find the heirs of the original builders as the laws here in CA are so consumer oriented that warranties apparently extend for a millennium.

Thanks for your help on this one.

Janver

Janver,

OK, OK, I have the complete mental picture!

Most deteriorating conditions such as that you describe present a couple of remedial options: 1) stop the deterioration, and stabilize the condition / structure or 2) remedy the effect by returning to the pre-existing condition. Your specific inquiry is regarding the latter, which typically presents a host of other concerns, such as “what will the effect be on the structure and finishes?”

Naturally, there is some potential endangerment to the wall finishes, joinery etc that have settled into present condition, when those sometimes inflexible materials are jacked and twisted back to the form you desire. Any re-alignment, such as you may achieve by jacking the outside sills and cripple walls (thus, everything connected to it) must be done in extremely small increments as you monitor the effect of the same.

I would expect that most of the curvature of the floor over any set of clear joist spans would remain, as the floor joists have certainly “formed” into their present shape. . . especially since the deformation has occurred over a very long period of time. I would expect that it is possible for the load-bearing line down the center of the house to stay in place, as the joints at that location might act as a “hinge” (depending on the amount of joist lap and fasteners thereon, as well as the amount of load on the joint). You might encourage this by replacing whatever series of fasteners there might be at any joint, with a single through-bolt during the jacking process.

Naturally, you will need to do remedial work and foundation repairs following jacking, if you decide to go that route.

Vertical grain all-heart redwood is one of the most decay-resistant of woods. We won’t see much of it harvested for building use unless the Bush administration declares open season for commerce in Sequoia National Park. Even so, it is obviously no match for direct soil contact and water for 140+ years.

Mason

ps: I am vexed by your reference to “round nails” as the primary fastener in a c. 1860 house. It is my understanding that round shank (wire) nails appeared shortly after the turn of the 20th century. One would think that the original nails in such a period structure would be primarily cut (tapered rectangular shank) nails.