Not all jobs are going to be the same! When assessing any structural support repair, all we can do as contractors is estimate what needs to done after a thorough examination. More often than not, there are a few “stepping stones” that hide just beneath the surface, waiting to be discovered.
On a recent typical repair of a 6 family dwelling in Massachusetts, the removal of eleven 180 year old supporting columns, that were fashioned from tree trunks, was underway. Often the original supports were either placed on flat pieces of slate to make a base support for the columns or they might have been set right the standard supporting practices were in place and the digging into the dirt.
After temporarily supporting the entire structure, the standard practice of digging new holes for concrete pads that will support the new lally columns, which in turn, will support the building structure. This of course is always a bit of a laborious task since many basement floors are covered with concrete and/or hard-packed gravel. So, running into a few rocks along the way is par for the course.
Just grin and bear it!
However, every once in a while, the original contractor of the structure like to surprise us. What was full expected to be flat field stones under each of the original columns, turned out to be one to two hundred pound boulders. Time to get to work! With large bars and some good old fashion muscle, the rocks are removed making way for the new concrete pads that will be placed. Unfortunately, this building was slated for sale soon and not only all of the extra dirt needed to be removed from the basement…so did those boulders!
With all of the large rocks now removed, 5000 psi concrete is mixed and placed into the holes. Steel reinforcing rebar is added inside the concrete as the hole are filled to create even more base support. The concrete needs time to set before any weight is placed onto it. With eleven holes dug, placed and setting, no better time than the present to start breaking up those big boulders that need to go.
The following day, after the concrete has cured a little…and a general cleanup was preformed, it was time to set the new supports. The new lally columns are set in place with special steel plates and secured to both the above carrying support beam as well as anchoring to the concrete.
With eleven newly installed support columns replaced along with 18 feet of sill plate, this 180 year old multi-family home is ready for another two hundred years of much welcomed support!