Prior to launching into a full scale renovation or restoration of your school building you should evaluate the condition of the building. A full structural review should be performed by a licensed engineer to determine if the building has any deficiencies that should be addressed. You might notice that a floor is sloping or has soft spots when you walk over a certain area. This may be the result of the foundation moving, termite damage, or the result of water damage. Wood roof trusses have a tendency to sag over time, if your roof has a low slope or is flat (which was common construction practices in the early 1900's), the roof could be ponding water. Over time as the roof continues to sag as the ponding becomes more pronounced, the roof structure could collapse under the weight of the water. I have seen this condition occur, thankfully the roof did not collapse while school was in session, it occurred over a weekend.
The walls should be examined as well. The majority of the older buildings were constructed using the walls as 'load bearing'. This means the walls directly support the roof structure. Often times the walls can shift due to foundations moving. If the walls are leaning out of plane, this is a dangerous situation and must be corrected. Typically the exterior walls are load bearing as well as each side of the corridors. Caution must be taken when opening or cutting into these walls are desired to expand rooms or reconfigure spaces. Small openings for standard doors is usually not difficult to accomplish, each opening will require the head, or top of the opening, to be structurally reinforced.
All systems in the building should be evaluated including the electrical, mechanical, plumbing, roofing, and building envelope (walls, windows, etc). The cost of repairing/replacing these systems have a major impact on the project cost and should be carefully evaluated. A general rule of thumb is that if the cost of renovating exceeds 50% of the cost of a new building, you should consider building new. This of course does not take into account the historical value of the building to the community. This could far out weigh the cost implications.
Michael D. King AIA
Friday, June 21, 2013
Friday, June 7, 2013
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
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
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