Bruce Coldham's notes on working with Durisol

July 2001

I visited David’s house in Lancaster, MA this evening to learn as much as I could about their experience in using the Durisol material for the construction of their house. It is a large 2-family building, Durisol running from footing to roof.

The building has quite a number of angled walls. David is acting as General Contractor, using a crew of masons experienced in commercial work using concrete masonry.

David made the following observations:

1. The masons have come to like and enjoy working with the Durisol material. They are basically positively disposed towards it. They like the fact that the drystack blocks go up quickly. (They are using 3-core blocks with only 1.5 inches of mineral wool insulation insert)
2. The masons found that the "biscuit" groove (a recent Dursiol innovation) is virtually useless, because it controls the block alignments too greatly and resists shimming and shifting to maintain alignment.
3. They have found that the use of dabs of "liquid nailer" on each of the four corners of the block is most useful for alignment.
4. Every four courses they snap lines to check horizontal alignment, and use chainsaws or belt sanders to cut down any high spots.
5. David's experience is that drilling and doweling wall reinforcing steel into the footing is better than casting them in the first instance. (They cast the dowels in and regretted it because the alignments were unsatisfactory.)
6. Perhaps the most important lesson they've learned to date is that the "cores rule" - i.e. that however the blocks are cut and dry stacked, the most important criteria is to maintain the continuity of the block cores - and therefore maintain the structural integrity of the wall system.
7. The material from the Idaho-based architectural firm that specializes in using Durisol has been invaluable to their process. In addition, the continued technical support offered by this firm has also been invaluable. I saw the two sheets of standard details that were provided by this firm and they appeared to be intelligent and practical. In some instances, their details deviated slightly from ours, including the following:

   · A double LVL ledger below the joist, which apparently eliminates the conflict of joist hangers and ledger attachment bolts.
   · Alignment of the top of the 2" concrete topping slab with the top of a block course - the upper 2" of the inside wall form wythe was cut down to allow the slab to extend in and lock in to the wall core.
   · 2x4 window sill nailer cast into the block core
   · A detail to attach interior partitions to the exterior Durisol wall.
   · A lintel detail using twin angles in a T-configuration, with the upward projecting angle legs extending into the center core of the block. Note that the blocks require shaving to compensate for the thickness of the lintel angle flange.
   

8. David has found chainsaws the most effective tool for cutting blocks. He uses a standard chainsaw blade with which he cuts approximately 100 blocks before sharpening is necessary.
   
9. Carpenters would, he feels, be better at this activity than masons. David's experience is that ...

Click here to download the entire document.

What is Durisol?

Field Notes on Durisol

Durisol and Rastra

Durisol and Vapor Barriers