Manholes - Formcrete Fiberglass Products

Manholes - Round holes for Mortar Joints in Standard Premium

For holes not intended for installation of field installed rubber connectors.
Both through holes and partial indentation knock out formers available.
Partial Hole/Knockouts must be ordered with attachment so they can be held tight to jacket wall.
Hole form diameters do not represent specific inside pipe diameter applications.
Hole diameters shown below are measured at the face of the Hole Form or at the inside radius of the manhole.
Super Durable 5/16” overall fiberglass laminate thickness.
Smooth surface concrete resistant polyester white gel coat for easier extraction.
We can create a custom sized mold that is not currently listed in this table.

Manhole Table

Manhole ID WALL	48" x 5'	Wall Taper	60" x 6'	Wall Taper	60" x 8'	Wall Taper	72" x 7'	Wall Taper	72" x 8'	Wall Taper	84" x 8'	Wall Taper	96" x 9'	Wall Taper
4"	4485	5.4
5"
7"	7485	10.6
10"	10485	7.1	10606	7.1			10727	9.6
12"	12485	10.6	12606	10.3			12727	10.9					12969	10.4
14"	14485	8.5	14606	10.9			14727	10.6
15"	15485	8.5											15969	9.8
16"	16485	10.6	16606	10.0			16727	10.6
18"	18485	11.0	18606	9.2			18727	10.1
20"	20485	11.3	20606	10.6			20727	11.6
21"	21485	9.9
22"	22485	7.1	22606	10.3			22727	10.6			22848	10.8	22969	11.0
24"	24485	9.2	24608	7.8	24608		24727	8.9			24848	10.8
26"	26485	16.4	26606	22.1			26727	18.1			26848	10.4
27"					27608
28"	28485	14.0	28606	21.9			28727	18.1			28848	10.4
30"	30485	16.4	30606	18.4			30727	19.0
32"	32485	17.0	32606	18.4			32727	18.5			32848	11.3
34"	34485	16.7	34606	17.1			34727	19.9					34969	19.5
35"							35727	17.2
36"	36485	17.4	36606	20.6			36727	18.5	36728				36969	19.9
38"	38485	21.8	38606	18.4			38727	18.7
40"	40485	19.9	40606	23.4			40727	24.3
42"	42485	21.8	42606	21.1	42608		42727	17.4	42728				42969	20.0
44"	44485	22.4
45"			45606	20.6			45727	24.1			45848	10.6
48"		21.1	48606				48727	19.7	48728		48848	17.8	48969	19.9
52"			52606	19.2			52727	19.0
55"			55606	18.4			55727	19.9			55848	9.5
58"							58727	8.1			58848	9.5
62"							62727	21.4
64"							64727	14.3
72"											72848	10.0
74"
76"

Revised: 6/19/25