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Home Site Map - Steps - Basement Walls and Ceiling -

Access Holes


(The evaluation building is only single story so there are no concrete floors.)

Required holes

Here are some ideas for the holes you will need through the ICF walls and the concrete ceiling/floor above.  It is very hard to make holes through ICF walls after the concrete pour, so it is important to fully plan ahead.  In addition to the holes listed below you should add lots and lots of spare holes.  If in doubt, add a hole, or preferably two.  The list below is a bit random and could do with a cleanup, but that all helps stimulate the deep thought process.

Use 4" ABS pipe collars and then the actual pipes or electricals can be fitted later.

Main electric conduit from plot junction to come through back wall

Will come through the back wall in the service room that's mid way along the basement back wall.  Needs thick cable in schedule 40 conduit from the main junction panel that's to the north of the driveway.

Main water pipe from Well to come through back wall

Will come through the back wall in the service room that's mid way along the basement back wall.  The pipe must be well insulated (inside wall EPS sheeting), particularly as it comes through the drain rock backfill area so that cold air does not freeze it.

Implement toilet and sink drain pipes for Main Level above

These drain pipes need to be in the floor above, ie in the ceiling of this level.  This is because most things are either in an island (eg kitchen second sink) or are separated from the DWV stack by a doorway.  Typically each wet area will need a toilet ring in the floor plus one for the bidet plus a bath waste pipe in the floor plus a general one for the sink and anything else.

Provide floor drain in bathroom and utility areas (Basement ceiling)

Drains in bathroom floors are a good idea and would be hard to retrofit later through the concrete.  If nothing else they guard against someone accidentally letting the bath overflow.  During house construction they may also have a role in draining water off the flat roof.
Put a drain under the Main Level bathroom and one under the utility room. Also put one under the island in the kitchen.

Plumbing and electrical holes through ICF walls and floors

Don't forget there are 2 internal ICF walls that also need holes.  Make sure you have holes for all the plumbing and electricals that are on the house blueprints.

More holes and add plenty of spare holes to be safe.

Need a few electrical plugs on the outside wall for garden power.
Need water taps for the garden on outside walls.  Need ample external garden taps.

Need holes for broadband, gas, satellite coax etc.
Need ERV holes (ERV also needs to provide intake air to wood fire) (ERV ducting will be 4")
Need tumble dryer vents.
Need extractor fan vents for bathrooms and kitchen.  All bathrooms need extractor fans.  Ideally even the ones that have windows (although code does not require it).

Hot (and cold) water needs to go to the garden for a garden shower and for the swimming pool.

Need a pipe through back wall near each end in case a sump pump ever needs to be retrofitted.  A sump pump needs a way to get the water to a storm drain.

Need a pipe to and from the rain water storage tank (which will be buried outside).

Need fire sprinkler pipes.

Need trash shoots from Kitchen to basement.

Need fire ash shoot to basement from living room fire.

Need wall and floor holes as per drawings.  This includes wall alcoves eg up the stairway and for appliance garages.

Special provision is needed for the two bathrooms on the basement level (including the apartment bathroom). The toilets need to be mounted to the ICF wall using 5/8" threaded studs.  The baths are easier but even so need some planning.

Need a separate waste pipe to the outside from the kitchen garbage disposal unit. Waste pipe from garbage disposal will be separately routed out of the house so that it can either be routed to the septic or to a compositor.  The switch will be in the basement so it is just a pipe to an external composter.

Need access holes through the floors.  Lots are required.  They get services from the basement to the upper floors.  Used for lots of things such as sewer pipe, hot and cold water, radiant heating for upper floors, electricals, etc, etc.

Make sure right floor holes done to get all pipes and wires through

PEX pipes, DWV, ERV (ERV ducting will be 4"), radiant heating PEX, central vac, etc.
To do this it will be necessary to mark out where the various rooms on the Main Level will be so that holes in the floor are provided to get eg the PEX through under the fixture.
Sink drain pipes can be routed later, but if floor mounted toilets are used then their waste pipes need to come up through the concrete floor.

For central vac, need holes in the concrete floor.  The holes in the floor also serve as drainage if the fire sprinkler system goes off.

Floor plan drawings need to show floor holes.

Hole for a possible safe in internal ICF wall

Even if you are not thinking of having a safe (I'm not) it is still worth providing a hole for it.  Internal ICF walls are the best place.

Make sure right wall holes done to get all pipes and wires through

Outside wall lights etc.


Implementing the holes

The holes are implemented using 4" ABS pipe that is braced on both sides using 2-by lumber.  The ABS pipe is cut to a length of 16-1/4".

Hole bracing inside 


Hole bracing external 

(The pictures show bits of 2x4 to sometimes attach to the vertical bracing, but it is better to just always toenail them to the batons using 3" screws (in lots of places you need this anyway, so you may as well do it everywhere).  Drill angled screw holes 1-5/8" in from the edge so the holes come out about half way on the edge.)

Cut 4" holes in the 2-by lumber using a 4" ABS joining collar as a marking template.  The hole needs to form an interference fit with 4" ABS pipe.

Screw in place the bracing lumber on the inside of the wall.  Cut the ICF polystyrene around the hole and dig out the circular piece of polystyrene.  Be very careful not to let bits of polystyrene fall into the wall cavity.

Pipe bracing remove ICF EPS 

Use gentle hammering to fit the pipe after the braced holes have been made.

Utility pipe interference fit 


Utility pipe fitted through ICF 


Double utility hole


Utility holes on back wall 


Inspection and utility hole



Wall hung toilet mounting studs


Wall mount toilet studs 


ICF inspection holes

Under all the windows and in strategic places in the ICF walls it is necessary to implement inspection hole.  The functions are:

Let air out during the pour
Let you see the concrete level
Let you poke a concrete vibrator into the wet concrete to consolidate it.

A plug is fitted to the hole at the last minute as the concrete level rises.  It is held in place using wood screws.

After cutting the round hole with a jigsaw, keep the center piece and screw it to another piece of 2-by (at least 7" wide) to form the plug.  Glue (with EPS adhesive) a 4" circle of scrap ICF polystyrene wall to the round wood to complete the plug.

ICF inspection hole with plug 

Inspect, brace, and repair ICF EPS (Basement walls and ceiling)

Inspect the integrity of the ICF EPS in detail to find anywhere the concrete could leak out.  If necessary make and apply lumber to brace it.
Fill any holes with EPS glue or foam.


Cover top edges of top ICF

To protect the top Lego protrusions from concrete, cover the top with plenty of decent duct tape.

Duct tape Ace Professional 

(I tried using 2" scrap bottoms of ICF blocks, but the concrete sticks them in place so they are hard to get off.)

Thoroughly inspect all dimensions, window placement, etc

Inspection and double checking should have been done throughout the whole block placing process, but do a final inspection for plumb, level, true, etc as you won't be able to change things after the concrete pour.

Cut away Form-a-drain in southern corners

Want the concrete corner blocks to be right up against the polystyrene that is vertical against the footings. That polystyrene is 3.6" thick and separates the 72 degree house concrete from the 47 degree corner blocks.

Cap off the ends of the Form-a-drain, but not actually necessary because they will already be angled down away from the corners.

There is no requirement to put waterproofing round the concrete or to put gravel under it.