What Makes Structural Terra Cotta Structural?

[hausdok]

Hi Bill,

Got some questions - edumakate me!

Its an old 1922 8000 square foot structural terra-cotta mansion with flawless stucco. The only place the structure is visible is in the attic. No cracks or defects. The place appears to be in flawless condition. The main floor (above basement) is 11 inches of reinforced concrete, original Otis elevator. I'm wondering about windows. No arches, attic has timber lintels which would be too small on large lower windows. I beams? Were the webs filled with conc or slurry? Could you create a bond beam big enough for a lintel? Can you drill it without damaging the tile? How many wall thicknesses for a four story? etc.

Click to Enlarge

31.54 KB

Click to Enlarge

26.81 KB

Click to Enlarge

33.99 KB

Click to Enlarge

41.41 KB

Click to Enlarge

24.03 KB

Click to Enlarge

24.37 KB

Click to Enlarge

35.26 KB

ONE TEAM - ONE FIGHT!!!

Mike

[Bill Kibbel]

I'm wondering about windows. No arches, attic has timber lintels which would be too small on large lower windows. I beams?

Steel I-beams would be common for low rise urban and large suburb/rural mansions. Another possibility, although not very common, was to span openings with specialty blocks formed into shapes to create a "flat arch". The illustration below shows 2 skewbacks, 4 fillers and the key-block.

Click to Enlarge

15.5 KB

Were the webs filled with conc or slurry? Could you create a bond beam big enough for a lintel?

Not that I've seen.

Can you drill it without damaging the tile?

There are three types of terra cotta blocks - dense, semi-porous and porous. Exterior walls are usually dense, thus are the most brittle. Semi-porous are usually made with the clay mixed with coal dust. These were typically made for fireproofing, not structural purposes. Porous blocks were made with sawdust that burned off when firing. These were typically used for interior, non-load partitions. Occasionally, porous blocks were strategically placed in exterior wall assemblies, where nailing on applied details or trim. Wood "plugging" was also used for nailing points.

How many wall thicknesses for a four story? etc.

If you're talking "wythes", that's not the case with structural terra cotta. At least not in my experience.

The standard thicknesses for exterior wall (dense) tile was 6", 8" or 12". 12" was the most common for 3 or 4 storeys. Over 4 storeys, I've always seen a steel structural skeleton, with the blocks used to fill in between.

The dense, structural blocks have tremendous strength and are incredibly light-weight as compared to any other masonry building material. The exterior wall blocks typically have shell walls 1" thick and the webs are 3/4" thick. The chart below shows some testing results, but this wasn't on strictly dense, load bearing blocks.

Click to Enlarge

81.2 KB

[Bain]

I think Bill deserves a salary, too . . .

[hausdok]

Too??

Hi Bill.

I wish I'd had the opportunity to see that house; it looks like a peach - the photos and questions were actually sent to me via e-mail by another inspector who doesn't feel real comfortable in this kind of environment. He asked me to thank you.

ONE TEAM - ONE FIGHT!!!

Mike

[Bain]

Too??

Hi Bill.

I wish I'd had the opportunity to see that house; it looks like a peach - the photos and questions were actually sent to me via e-mail by another inspector who doesn't feel real comfortable in this kind of environment. He asked me to thank you.

ONE TEAM - ONE FIGHT!!!

Mike

Bill has said more than once that we ought to pay Jim K. a salary.

[Terence McCann]

Most of the older homes in our area have STC foundations. I've only seen one that was badly damaged due to prolong moisture exposer (in fact I think I posted pictures and Bill responded).

Poured concrete and CMU are porous but STC seems to be a sponge. It really loves to transfer moisture.