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Form Footing - Inner EPS

Star Fill between the upper and lower inner Form-A-Drain with polystyrene.

Inner Form-a-drain filler strips

The 1.5" EPS is cut to 9-1/4" high for the inner Form-a-drain.  Fit the 9-1/4" strips of polystyrene sheet between the inner Form-a-drain.  Some trimming is needed when you have bulges due to Form-a-drain joins.

Inner Form-A-Drain Eps Installed 

Between the inner Form-a-drain it is necessary to prevent the backfill drain rock and the filler polystyrene from falling out ahead of having the footing lining done.  There are two ways of doing this dependent on the amount of space that there happens to be between the Form-A-Drain and the excavation soil.  Where there happens to be enough space then glue an 11" tall piece of 2" EPS behind the 9.25" 1.5" EPS, ie use the same method as with the outer Form-A-Drain.

Inner Form-A-Drain Eps Inside

It is best to cut the required sheet widths using a hotwire cutting bench.  Where you need to cut the length to fit or you need to trim then use a long thin craft knife.

Craft Knife 9mm

Eps Inner Form-A-Drain Pieces 

Sometimes where the excavation earth is tight you will not be able to pre-stick the sheets together and you will need to glue in place and use some creativity to get it to fit.  Where there is room, use 2" EPS for the backing piece, but use 1.5" or 1" in places where there is less room.

Creative Eps Form-A-Drain 

Where there is not sufficient space then it is necessary to fix some thin plastic sheet between the upper and lower inner Form-a-drain on the inside of the footing trench.  It should be a 1 foot wide strip cut from a 8'x4' sheet.  Suitable sheeting is about 0.060" thick PVC (available from Lowes).  Use self tapping screws on the top and bottom edges to attach the PVC sheet to the Form-a-drain.

Filler sheet between Form-a-drain 

It is necessary to remove any 2x4 spacer jigs that use U's on the lower Form-a-drain and replace them with straight bits of 2x4 that are 4'5" long.Eps Form-A-Drain Done Corners

(Typically the EPS between the outer Form-a-drain shown in the photo is added in a later step.)

Eps Form-A-Drain Done