Are gaps and cracked tile problems? Are gaps and cracked tile problems? (February 20, 2004)

Or, just normal, expected wear-and-tear in Eichlers?

by Lynn Comeskey

Q We moved into an Eichler home in Palo Alto that was built in the early 1950s. We have two concerns. The gaps between some of the ceiling boards are as large as 9/16" and we can see something black between the pieces of wood. Our second concern is about the cracked tile on the floor in our master bath, which was remodeled 11 years ago. In both cases the results don't look good, but more importantly, we are concerned there may be a structural problem. What can you tell us?

A The wood used to frame your house was what we call "green lumber." This is somewhat of a misnomer because it didn't come from a tree that had just been felled. The wood has been air-dried and, as a result, should have had a moisture content of just under 20 percent.

Interestingly enough, there are parts of the country where framing lumber has been kiln dried (and it is really dry). It is possible to purchase kiln-dried framing lumber here, but it is somewhat more expensive and most architects don't specify and most contractors don't use it. The thinking appears to be that using "green" lumber may create some problems, but the latter are sufficiently inconsequential to not justify the increased cost of using dry framing lumber.

Your house was built approximately 50 years ago. And, unless you and the house's previous owners have gone against the grain, the house has been heated for most of that time. This heated environment causes the framing lumber to dry. Wood shrinks across the grain as it dries. In your case, you are noticing that the 2 x 6 tongue-and-groove pine, redwood or Douglas fir (all three were used in Eichlers) ceiling decking has shrunk. Most of the shrinkage probably took place in the first five to 10 years of your house's existence. If you look around your house carefully, you will probably also notice that the 4 x 10 and 4 x 12 ceiling beams do not fit tightly against the surrounding wood trim where they enter the plywood walls.

The 9/16" gap you have seen is unusually wide. This probably results from the two adjacent pieces not being placed close together in the first place and/or possibly excessive shrinkage, but I don't think you have anything to worry about structurally. The black that you see is the underside of a piece of roofing felt or cap sheet that is a part of your tar-and-gravel roof. You could apply some paint or stain (depending on the finish on the decking) to cover the black and any unfinished portion of the tongue-and-groove wood that may now appear.

I talked with my roofing guru about the issue of shrinkage. The boards do move a little as they shrink and the few nails that hold the paper to the decking would also move with the wood decking. This could tear the felt in the process. Another, bigger problem he has encountered with Eichlers is that as a result of all the glass and the lack of rigidity, the houses move back and forth over time. This constant movement causes the roofing nails to work their way out, causing leaks. There is not much that one can do about it. If an Eichler were built today, it would be a much more rigid structure and wouldn't move around so much. With regard to your cracked tiles, the house slab is sitting on clay soil that expands and contracts with the amount of moisture in the soil. Although the 4" thick slab appears to be quite rigid, it really isn't and it will bend with the movement of the soil. The slab can crack with this movement and anything firmly attached such as tile will crack with the slab. Again, there is not much you can do about it. We try to install a "crack suppression membrane" between the slab and the tile and this helps to absorb the pressure exerted on the tile and seems to reduce the cracking.

Lynn Comeskey continues to work with Mac & Lou Construction Co. in Palo Alto. Readers can write Comeskey care of the Palo Alto Weekly, P.O. Box 1610, Palo Alto, CA 94301.

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