Historic Renovations, Walls Part 2

Most older schools were built using brick for the exterior facades. As this material weathers over the years the face of the brick can become soiled with mold and mildew or stained as years of exposure to the elements leave deposits of dirt and dust.

When cleaning the exterior brick, previous common practice was to use a sand blasting method. This has proven to do more damage than good as the force of the sand on the brick could actually remove the facing of the brick itself and also damage the mortar joints. Current cleaning methods involve the use of solvents and low pressure water systems. It is imperative that the operator of the water spray unit have the nozzle set on a fan spray and not to apply the water in a stream. This will insure that the brick will be cleaned, but not damaged.

The exterior brick façade could also have deteriorated mortar joints. The joints at brick window sills are especially susceptible to weather as water can stand on the horizontal face of the brick and go through freezing and thaw cycles. The most common repair method is to remove the mortar between the brick to a depth of at least 1 inch and replace the mortar with new. This method is called "repointing the joints". If the mortar is significantly deteriorated, the entire building may need to be repointed.

Windows are the other major item in the building envelope wall façade. The majority of the existing windows will be either wood or steel materials. If the building has a historical plaque and is on the states historical register, the state historical commission will most likely want to see that the windows are replaced with a like material for continuity of the historical value of the building. The wood trim around the windows will need to be evaluated as to the amount of deterioration. If the wood is in favorable condition it is possible that it can be cleaned and repainted, if not, it should be replaced. If repainting the wood trim, be sure not to use scrapers or other tools that could damage the wood. This also includes no sand blasting to remove old paint. This method can severely damage older wood trim. There are chemical processes that can be used to remove the old paint and thereby not damaging the existing wood trim.

Diligent pre-planning can result in restoring an older school to its original splendor and not unknowingly or unnecessarily damage the wall systems in the process.

Michael D. King AIA