Photos of Imperial Blades in Use - Aluminum Frame Insulated Glass Unit (IGU) Retrofit - Courtesy of Marlowe Restorations LLC

Initial inspection in 2013 of wood rot in 3 windows measuring 10'x15'6" on this commercial building c.1900

Scaffolding installed by others was comfortable and safe for the Tradesmen and the Public.

Here is a close-up view of the approx. 1/2" x 2" exterior applied stop which sits against the aluminum sash and on top of the sill. This relies on caulked joints without flashing and is prone to decay.

This before photo shows a window stop applied to the top of the sill. This slows down water flow and increases the chances for decay fungi to take hold.

Cut caulk lines, located nails with magnet, pulled nails and stop and often found more rot below.

The worst section of wood decay is in the S side of the EN window which is window #3 from left to right. There was a piece of plywood caulked over this fragile area plus the window stop placed on top of that.

Window #3 needed a section of the sill cut out. The damaged wood is on the center sill area with the bag containing moist decay. These items are generally saved for the interested parties to view so they can better understand the extent of damage.

After finally committing to this new extreme specification, I'm taking the plunge and cutting the outside of the aluminum bottom rail using an IBOAT330 Metal Blade on an oscillating tool. The base is a 3/4" Red Cedar clapboard capped with thin aluminum flashing. A noisy slow task.

The 90º blades were a life saver because they allowed me to cut away a blind aluminum rib from behind the existing bottom rails of three 10' long window rails and some shorter ones. Not sure how I would have been able to complete this detail of my specifications to keep water out if that blade was not available.

Project completed in 6 weeks

Final notes: there were challenges as is normally the case when wood repairs have been ignored or done poorly over many decades. The old wood had sustained decay in the past and the new generation of aluminum sash added to the problem with its lack of flashing and just cover over the rot approach.

The project took about 6 weeks. There are still more decay zones on these same three windows as well as other windows around the building. They will hopefully be addressed in future phase