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Foundation Lining

Preparation

Check Form-a-drain height

It's worth checking again that the outer Form-a-drain is at the right height.  If any slight raising is necessary then use a prying bar and adjust the shims underneath.  At this stage of the game we are looking for exact levelness at the exact right height.

Remove wooden spacer lengths incrementally

Using 4'5" lengths of 2x4 are an added precaution against inward movement of the Form-a-drain and are fairly easy to remove as you work your way round doing the lining.

Spacer Wood In Footings As Needed 

Check footing trench soil

Check the soil below the footings is nice and smooth.  Remove any high spots and protruding rocks.  Fill with compacted non-organic soil any low spots caused by removed rocks.

Footing Soil Trench Smooth 

Sweep the trenches clean

Clean up the job site.  Get rid of rubbish and put away your tools.  The chances are that some of the crushed rock has fallen into the trenches.  Before putting down the membranes, make sure the soil in the trenches is free from sharp rocks and other debris.

Foundation design

Throughout the process of adding the different layers you will want to constantly refer to the Foundation design drawing.  (Click on image to see and download high resolution version)

Foundation Exterior

 Foundation Exterior (Cropped)

Here is the drawing version for the internal concrete walls...

Foundation Interior walls 

Foundation Interior Wall (Cropped) 

Don't bother to treat ground for termites

You can buy termite treatment from your local home center in the gardening department.  If you use it you would do it just before putting the polyethylene sheets on top so that evaporation is avoided and rain does not wash it away.

Note that termite soil treatment only lasts for about a year, and the house is designed to last for 500 years, so it really is of very little use to treat the soil for termites.  If you are in a high termite area then you might consider once a year blocking up the under slab drainage pipe at the house exit using an inflatable bladder and pouring termite treatment down the cleanout pipes and radon vent pipes.

My main defense against termites burrowing through the polystyrene will be the 6 mil polyethylene sheets and other membrane layers.  Also there is no wood used in the house structure so there is little to attract termites.  I decided not to bother with termite poison.  If I ever change my opinion then I will retrofit it using the drainage pipes under the building.

 

Install liners in footing trench

Put geo-fabric at bottom of trench

The geo-fabric provides a slight cushion against any rough edges in the soil.  Line the bottom of the complete footing.  It is best to use 5' wide geo-fabric.  With the trench being 4'5" wide this will give an extra 3.5" curl up at each side which is good.

Geofabric 4x250 DeWitt  Geofabric 

Geofabric In Trench On Soil 

Lay strip of Tough-Liner along bottom of trench

Tough-Liner is any suitable tough membrane and it provides just another protection membrane to keep out termites and other undesirables.

Grace TriFlex  Tough-Liner

In order to provide extra termite protection, lay a strip of Tough-Liner along the bottom of the footing trench.  The trench is 4'5" wide and typical Tough-Liner is only 4' wide.  You should position it on the outside of the trench (against the outer Form-A-Drain.  This leaves 5" on the inside of the trench not covered.

Tough Liner In Footing Bottom 

Attach Tough-Liner along outside

Use 2" wide double sided tape on the inside of the Form-a-drain (2"-4" pieces every 18") to hold it in position.  The Tough-Liner is typically 4' wide.  The top edge of the Tough-Liner comes to the top of the Form-a-drain.

Double Sided Tape On Outer Form-A-Drain

On the outside of the trench this will provide about a 4" overlap into the bottom of the footing trench.  The Tough-Liner on the side will overlap on top of the Tough-Liner in the bottom of the trench.

Attach Tough-Liner along inside

This lines the inside of the footing trench.  It is slightly different in that there is a filter sock over the inner upper Form-A-Drain and the vertical distance is less so there will be more overlap at the bottom.

Attach the Tough-Liner to the inner upper Form-a-drain with a 4" overlap above the top of the Form-a-drain.  Assuming 4' wide Tough-Liner there should be about 1'2" after the fold at the bottom.  This extra will cover the 5" of uncovered area at the bottom of the footing trench and also provide a 9" overlap with the Tough-Liner at the bottom of the trench.

On the inner upper Form-a-drain, the attaching is done using 2" - 4" lengths of double sided tape every 18" along the top of the sock covered Form-a-drain.  The Tough-Liner on the side will overlap on top of the Tough-Liner in the bottom of the trench.

ToughLiner On Sides Of Footings

Corner patches

Where there is a convex corner you will need to cut the horizontal edge of the vertical Tough-Liner .  This will expose some soil area.  Cover this area with a 2'x2' patch of Tough-Liner that you tuck round the corner.

Corner Patch ToughLiner On Soil 

Tough Liner In Footing Trench 

After installing the Tough-Liner if you expect heavy rain it can be a useful to put back the 4'5" spacer wood as a precaution against movement.

 

Cover slab area

Add a layer of geo-fabric over slab area

The crushed rock should be at a height of 1" below the top of the inner Form-a-drain and should be fairly well compacted and level.  The geo-fabric over the under-slab area is to help prevent the crushed rock from unduly puncturing the first 6 mil polyethylene sheet.  Geo-fabric is fairly inexpensive so you may as well use it.

Geofabric 4x250 DeWitt  Geofrabric 

Geofabric On Slab Areas 

Install 6 mil polyethylene sheet over slab area

The primary job of this 6 mil polyethylene sheet is to add to the protection for the first EPS sheet from termites.  It goes on top of the geo-fabric that is over the crushed rock.

6 Mil Polyethylene sheet  

The polyethylene sheet does not need to be sealed and may well get punctured by sharp pieces of rock.  Because it does not need to be sealed, there is no need to use a continuous big sheet as joins don't matter.  No need to tape joins.  It comes in 20' wide sheets so anyway you will probably find you don't need any joins.

Polyethylene Over Slab Areas 

Put 1" thick polystyrene sheet over slab area

The Expanded Polystyrene Sheet is a slightly compliant layer to protect the 6 mil polyethylene sheet above (the next layer).  I use 40psi EPS for the 1" sheets which means you are less likely to break them by walking on them.

Expanded Polystyrene Sheet 

The top of the EPS sheet should be level with the top of the inner top Form-a-drain.

When working on the EPS surface (and all future EPS surfaces) to avoid denting the surface use soft shoes and padded knee protectors.

Soft Shoes Green  Knee Pads

Use Foam Gap Filler between the sheet edges to stop the sheets of EPS from moving around.  While the foam is drying you can hold the edges in line using concrete paving slabs or blocks.

Glue Hold Down Eps Slab 

When the foam is dry, trim off the excess foam with a 9mm long blade craft knife to create a flat surface.

Eps First Glued Over Slab 

Site Ready For First Membrane 

 

Cut and glue footing EPS

It is good to try to minimize the time between lying the first polyethylene membrane and the second membrane.  Therefore it is good to have all your footing trench EPS assemblies pre-made and ready to go.  Make all the EPS assembles 8' long as you will be able to cut them to length later on the hotwire cutter bench when needed.

Eps Cut Piled 

For the outside of the footing you need a 3' 6-1/4" piece of 2" 15psi EPS with three pieces of 2" 15psi EPS that have been cut with a 45 degree angle on one edge.  See the foundation drawings for details.  These are glued together with foam adhesive and weighted down while they dry.  Use a 90 degree square to make sure that the sheets are properly aligned on the square top edge.

Eps Outer Gluing 

Make enough assemblies to go all the way round the outer footing and stack them up ready.

Eps Outer Pieces Piled 

For the inside of the footing trench there is a 2' 7-1/4" wide EPS sheet with a 45 degree cut on the top edge.  This goes with a piece that has 45 degree cuts at both ends.  From point to point these are 1'7".

Eps Interior Footing Outer Glued Piled

You can only pre-glue these for the the outer edge of the internal wall footings or else you will not be able to fit the EPS at the bottom of the footing trench.  For outside wall footings just cut the pieces and stack them up but do not glue them together.

Eps Double 45s Piled 

Make bracing pads

Once the EPS has been added to the footings you will use shorter lengths of lumber as a precaution against wet weather causing the footing trenches to contract.  You don't want the lumber pieces to damage the EPS so pads are used.  The pads are a 5"x5" square of 2-by with a 5.5"x5.5" piece of 2" 15psi EPS foam glued onto it.  It is good to have lots of these pads ready ahead of time.

Pads For Bracing 

Make EPS to outer Form-A-Drain clamps

To hold the outer footing EPS assemblies to the outer upper Form-A-Drain wood clamps are used.  Make these ahead of time so they are ready when you need them.

They are a 2x4 shaft that is 1' 0-5/8" long with a 2x4 across that is 11-1/2".  A rounded pieces that is 3.5" x 1.5" x 1.5" is screwed on at the other end.

Wood Clamps Outer Eps Form-A-Drain 

 

Install first polyethylene sheet in footing trench

Design and function

This is the first of the membranes that line the entire underground area.  It is primarily to stop termites getting to the main layer of polystyrene.

It is implemented such that any radon gas caught by it is prevented from seeping upwards while at the same time stopping termites from digging up through the bottom.

The membrane needs to be something tough enough to stop termites, and 6 mil polyethylene sheet is one step up from landscape fabric.  To catch radon gas, the polyethylene needs to be tightly sealed at all the high points, ie over the slab areas.  Holes in the membrane at the bottom of the footing trench are of less consequence, but I still try to avoid puncturing or ripping it.

Once the sheet is installed you will need to use a pump to remove rain water from the footings.

Obtain polyethylene sheeting

Even though not as critical as the official vapor/water membrane that gets added later, it is still good to avoid joins.  For the slab areas you want to try to get a good gas-tight seal.  See here for purchasing details of large polyethylene sheets.

Polyethylene sheet reinforced wide 

The first sheet needs to be cut to be long enough to go from the top of the outer upper Form-a-drain, then down the inside of the outer Form-a-drain, then along the bottom of the footing trench, then up the inner edge of the inner Form-a-drain, then across the first slab area, then down and up the inner wall footing, then across the middle slab area, then down and up the inner wall footing, then across the third slab area, then down and up the far footing to the top of the outer upper Form-a-drain.  It's worth also adding a couple of foot or so extra to be safe. 

Note that you will need to purchase two custom sheets as there are two polyethylene membranes used in the foundations.  You will want to have them shipped together to save shipping costs.

Install polyethylene sheet

To position it, select the two downhill sides of the building as your starting points.  In my case it is the west side and the south side.  Measure along the polyethylene sheet to find the center of the west side and align this mark with the middle of the west form-a-drain.  You can move it relative to this to put any excess on the uphill side of the building.  Use some double sided 2" tape on the top edge of the outer upper Form-A-Drain on the downhill side of the building as you position the sheet.  On the downhill side you only need about 4" beyond the top of the outer Form-a-drain.  Any excess will be used on the uphill side of the building.  Do the same on the south side.

Leave a bit of slack (say 2" either side of the footing and 2" at the bottom of the footing trench) in the 6 mil polyethylene sheet to allow for some settlement movement and to ensure the polyethylene is not stretched when you add the EPS.  Some creative crumpling and folding is needed at the corners.

We are not looking for neatness in the folding of the sheet.  The important thing is that it forms a continuous gas tight membrane (in the high areas).  We do NOT want to cut the sheet to achieve neat folds.  It's infinitely better to have crumpled up spare flaps rather than cutting to achieve neatness.

The spare round the edges can be laid over the sides of the outer upper Form-a-drain and rolled up out of the way.

Site First Membrane Being Installed 

Joins and seals (best avoided)

If you need to join polyethylene sheets (best avoided), use double sided tape, then single sided 2 inch tape, then single sided 4 inch tape on top of that.  This process is also repeated on the other side of the sheet join.  Using the belt and suspender approach helps keep the join gas tight even if one of the tapes fails with age.  Note that with the 2 foot overlap of the sheets, the double sided tape will be offset 1 foot one way and the single sided tape will be offset 1 foot the other way, then the opposite on the other side of the sheet.

If you have pipes coming through the slab (eg sewer or a radon vent) then you need to cut openings to allow the pipes to come through.  Cut a cross in the 6 mil polyethylene sheet at the carefully figured out place, but keep the cutting to an absolute minimum as we are aiming for a sealed membrane.  Gently forcing an under-sized cut cross over the pipes will nicely stretch the 6 mil polyethylene sheet to help form a good seal.  The flaps of the cut cross should face upwards around the pipe so they can be taped.  Leave a bit of extra slack in the polyethylene sheet between the pipes.

I decided that it is best for the sewer pipe to come through the basement wall just above slab height rather than come through the slab.  I also decided to route the radon vent pipes under the footing rather than through the slab.

We are aiming to have this sheet fully sealed in the under-slab areas so that no radon gas escapes upwards.  Tape it well all around the perforations due to the pipes that come up through the slab.  Use a couple of rings of double sided tape round the pipe and then single sided 2 inch tape on top, then single sided 4 inch tape on top of that.

Line footing trench with pre-made EPS assemblies

Line outside of footing trench

You may well need to trim the bottom edge of the EPS assembly to make sure it does not come up higher than the top of the outer upper Form-A-Drain.

Trim Eps Outer Bottom 

It is also good to round off the edge to help it sit better against the polyethylene sheet.

Bevel Trim Outer Eps Bottom 

You can make sure the EPS assembly is not sitting too high by using a bubble level off the top of the outer upper Form-A-Drain.

Eps Upper Right Height Level 

When fitting the EPS assembly, make sure there is something like 2" of slack in the polyethylene sheet so it is not accidentally stretched.  Note that the polyethylene sheet folding does not need to be folded neatly as it will all be flattened behind the EPS.

Slack In Membrain Before Eps Vertical 

Use the pre-made wood clamps at the top to attach to the outer upper Form-A-Drain.

Wood Clamps Eps Outer Form-A-Drain 

Attaching only at the top is ok because the horizontal EPS at the bottom of the trench will hold the bottom of the vertical EPS.

Initially just get the 8' lengths of EPS assemblies in place.  Don't initially worry about the corner pieces.

Site First Membrane With Some Eps

Squirt foam gap filler into the join between the edges of the EPS assemblies to hold everything together.  It does not need to be a water-tight join.

Line inside of footing trench

It should stick up 2" above the top of the upper inner Form-a-drain which means it will be level with the top of the first 2" EPS that will go over the slab area.  Use foam gap filler on the edges between the sheets.

Add bracing lumber with pads

The bracing wood spacers are pieces of scrap lumber cut to a length of 3'3".  With the 2 times 3.5" of the EPS+wood pads and an additional 2" of EPS, that makes a width of 4'.  At the bottom of the trench the designed width between EPS is 4'1", but half way up the trench it is ok to have half an inch of inwards bulge at each side which reduces the width to 4'.  The extra 2" pad of EPS is used at this stage because it takes the place of the extra 2" EPS piece on the inside of the trench which will be glued on later after the EPS at the bottom of the trench.

The EPS may be a bit curved and the trench may have contracted slightly so I find it useful to use a home-made hydraulic spreader tool to make it easier to fit the temporary wood spacers and their protective pads.

Tool Footing Spreader 

Do corners

Measure the dimensions needed for the various corner pieces and cut them to fit.  The cutting is done freehand on the hotwire cutter bench after first marking the flat side of an assembly piece with a permanent marker pen.

This piece is for a concave corner in the outer EPS assembly...

Cut Freehand Eps Outer Inside Corner 

...and this is for a convex corner...

Convex Corner Eps Freehand Cut 

Put the corner pieces in place to make sure they fit.

Fitted Cut Outer Eps Inside Corner 

Squirt foam gap filler into the join to glue the corner pieces in place.  You may need paving slabs (on protective pads) and/or wooden props to keep the corner pieces in place while the foam is setting.

Foam Gun Pressed Into Crack Paving Slab Holding 

Foamed Outer Eps Concave Corner 

Foam Glued Outer Eps Convex Corner 

After the foam has set, trim off the excess with a 9mm long blade craft knife.  Be careful not to accidentally cut the polyethylene sheet.

Footing Eps Glued Proped 

Site Outside Footing Eps Some Inner 

Also measure, cut, and fit the EPS for the corners on the inside of the footing trench.  It is good to make the corners somewhat rounded by using 45 degree cut infill pieces of 2" EPS at the corners.

In the case of internal wall footings you can use pre-glued assemblies on one side (the nominally outside edge) as it won't stop you adding the EPS at the bottom of the footing..

 

Cover slab area with a layer of 2" EPS

Get the right mix of 40psi and 15psi EPS

As described in Techniques - Building Science - Foundation and Wall Design in the section called "Distributing the load", it is important to use the right mix of psi rated polystyrene sheets in order to give the right distribution of load on the slab.

The first layer (the layer being described here) is mainly done using 4' wide sheets of 40psi EPS adjacent to the footings and then 15psi sheets for the rest of the slab to the center.  At the north and south ends of the slab areas I use 8' of the 40psi before switching to the 15psi.

Sponge off rain water from slab area

It is good to avoid trapping water under the EPS that goes over the slab.  After sponging off the rain water that will have collected on the polyethylene sheet, try to get the first layer of EPS over that particular slab area before it next rains.  If you are careful with the foam gap filler between the sheets then the EPS layer will be reasonably rain-proof.

Lay EPS sheets to overlap edge of Form-a-drain

The sheets go over (ie overlap) the upper inner Form-a-drain.  The edge of the polystyrene sheet is flush with the trench side edge of the Form-a-drain.  This corresponds with the edge of the vertical EPS trench lining.  Use foam gap filler on the sheet edges to join the sheets together at all the seams so they don't move around.  Use temporary packing tape and paving slabs to weigh the sheet down while the foam gap filler adhesive sets.

Packing Tape Scotch

Paving Slabs And Tape Eps Over Slab 

Eps First 2in Over Slab South Portico 

Corner Slab Eps Paving Slabs 

Paving Slab Weigh Down Eps Slab Foam 

First 2in Eps Slab West 

After the foam has dried and the paving slabs have been removed, go round with the foam gun to fill in any gaps in the join so that it becomes rain-proof.  Use a 9mm long blade craft knife to cut off the excess foam to create a nice flat surface.

Craft Knife 9mm

Site Started First Eps 2in Over Slab 

 

Cover slab area with second layer of 2" EPS

Get the right mix of 40psi and 15psi EPS

As described in Techniques - Building Science - Foundation and Wall Design in the section called "Distributing the load", it is important to use the right mix of psi rated polystyrene sheets in order to give the right distribution of load on the slab.

The second layer (the layer being described here) is done using mainly 2' wide sheets of 40psi adjacent to the footings and then 15psi sheets for the rest of the slab to the center.  At the north and south edges of the slab area I use 4' pieces of 40psi before switching to the 15psi.

The 8'x2' sheets round the outside are first cut on the hotwire bench with a 45 degree angle along one long edge.

Lay EPS sheets in a staggered joint pattern

You need to avoid there ever being a case where a join in the second EPS layer corresponds with a join in the first EPS layer.  The joint staggering is achieved because 40psi EPS on the outside of this layer is cut to be only half the size of the first layer.  Use a small amount of foam adhesive between the two EPS sheet layers.  Use foam gap filler between the sheet edges.  Use packing tape and paving slabs while the foam adhesive and foam gap filler is drying.  As needed, go back with the foam gun to fill in any joint gaps to make it rain-proof.

Gluing 2nd Layer Slab Eps 

Second 2in Eps Slab East 

After the foam is dry, use a 9mm long blade craft knife to cut off the excess foam to create a nice flat surface.

Site Second 2in Slab Eps Done East

Site 2nd Slab Layer Eps Almost Done

 

Prepare for under footing EPS and extra inner EPS

Minimize trapped rain water

You want to avoid trapping much rain water between the two polyethylene sheets so particularly in the rainy season it is good to minimize the time between pumping out the water and the second polyethylene sheet being fitted.  Having the EPS stacked ready for fitting helps minimize the time.

Site Last Foundation Eps Stacked Ready 

Suck out all water and debris

Realistically rain water will have landed in the footing and there will likely be leaves and other debris.  Use a submersible pump and then a wet/dry vacuum cleaner.

Wet Dry Vacuum Cleaner Lowes

Any water left will be trapped forever.  If you do have some water trapped between the sheets it is not actually too much of a problem because it will get pushed up the sides of the footing when you add the concrete.  The trapped water will have EPS insulation completely surrounding it.  It will not cause any thermal or structural problems.

Tarp site if it rains

You could decide to put a big tarp over the whole site in the event of rain, but in practice you will likely find that rain water still gets through.  It does however stop leaves from being blown in.

Tarp While Adding Footing Bottom Eps 

 

Fit footing EPS and extra inner EPS

Line bottom of footing trench

Under the footing there will be only one layer of 2" thick EPS (40psi).  This contrasts with the slab area that has two layers (some of which is only 15psi EPS).

Use 2" EPS (40psi) with a width of 4'.  Each sheet will do 8' of footing trench.  Fit it between the vertical side polystyrene at the bottom of the footing trench.  Position the 4' wide sheet on the outside of the footing trench.  Depending on how much space is left given that the footings have probably bulged inwards slightly, on the inside edge add a strip of 1" wide 2" 40psi EPS and force it into place.  You may have to do some trimming to get it to fit.  The EPS at the bottom of the footing trench will nicely hold the vertical pieces of EPS at the bottom.  It should by design need plenty of force to work the EPS into position at the bottom of the footing.  Having this tight is part of the strategy for holding back the force of the crushed rock.  Using a couple of pieces of thin slippery plastic sheet can be useful to get the EPS into place at the bottom of the trench.

Footing Bottom Eps Plastic To Fit 

Particularly at the edges you want the EPS to be tightly in contact with the ground at the bottom of the trench/  Use as many paving slabs as necessary to hold the edges tight down.  Squirt foam gap filler into all the EPS edges to securely glue down the EPS.

Footing Bottom Eps Paving Slabs 

You should aim to get the Foam gap filler to make a waterproof seal between the EPS sheet edges and to the EPS at the sides.

Footing Bottom Eps Foam Glued 

After putting the EPS at the bottom of the footing trench you will need to be careful walking on it with big boots.  Ideally wear smooth flat soled shoes.  Use a 9mm long blade craft knife to trim off the excess foam to make a clean flat surface.

Add extra inside polystyrene

Note that once the extra inside polystyrene has been added it will not be possible to add or remove the polystyrene at the bottom of the footing trench.

Add the pre-cut EPS pieces that have a 45 degree angle on both edges (1'7" from point to point).  Use the spacer bracing and packing tape to hold it in place while the foam adhesive is drying.

Extra Eps Inner Held While Gluing 

Finish the corners with a strip of 45 degree EPS to round off the corner.  Foam glue it on and then trim it with a 9mm long blade craft knife .

Corner Inner Extra Eps Rough 

Corner Inner Extra Eps Trimmed 

 

Fit official water barrier

Clean out all debris

Use a wet/dry vac to clean the trenches and over slab area thoroughly.

Wet Dry Vacuum Cleaner Lowes

Make absolutely certain there are no sharp bits of stone brought in on people's shoes.

Site Nearly Ready For Water Membrane

Best to use a continuous sheet

It is very time consuming trying to do good joins between polyethylene sheets and the joins may decide to leak.  It is far better to buy a custom made polyethylene sheet that is big enough to do the whole job without any joins.  See here for purchasing details.

Polyethylene sheet reinforced wide

Install polyethylene sheet

Even though there may be some later refining of the fitting of the membrane, it is worth getting the positioning of the sheet approximately correct.

This in the official impervious water/air/vapor membrane that lines the entire underground area.  It starts on the westward downhill side of the building with enough spare to go from 4-6 feet above grade, then down 2 feet to get to the Form-a-drain, then down the inside of the outer Form-a-drain, then along the bottom of the footing trench, then up the inner edge of the inner Form-a-drain, then across the first slab area, then down and up the inner wall footing, then across the middle slab area, then down and up the inner wall footing, then across the third slab area, then down and up the far footing, then up to 4 feet above grade.  It is held in place using the wooden clamps on the outer upper form-a-drain.

Any excess will be used on the uphill side of the building.  On the downhill side it is useful to mark with a marker pen 8' in from the sheet edge and align this with the top of the outer form-a-drain.

Don't forget to provide movement slack in case of slight subsidence.  Put 2" extra flap in any place that the you think might experience movement.  At minimum there must be about 2" of slack on the vertical outside of the footings.

Some creative folding and crumpling is needed at the corners.  We are not looking for neatness in the folding of the sheet.  The important thing is that it forms a continuous waterproof membrane.  We do NOT want to cut the sheet to achieve neat folds.  It's infinitely better to have crumpled up spare flaps rather than cutting to achieve neatness.

Seal openings for pipes (if needed)

If you have pipes through the slab (eg sewer or radon vent) then you need to cut openings to allow the pipes to come through.  Cut a cross in the polyethylene sheet at the carefully figured out place, but keep the cutting to an absolute minimum as we are aiming for a sealed membrane.  The flaps of the cut cross should face upwards around the pipe so they can be taped.  Leave a bit of extra slack in the polyethylene sheet between pipes if there are adjacent pipes.

It is fundamental to have this sheet fully sealed so that no water gets through.  Tape it well all around the perforations due to the pipes that come up through the slab.  Use a couple of rings of double sided tape round the pipe and then single sided 2 inch tape on top, then single sided 4 inch tape on top of that.

Ensure no holes in polyethylene sheet

It is important that the polyethylene sheet has not been damaged.  Thoroughly inspect it for holes.  If any holes are found then repair them with single sided 4 inch tape.

Polyethylene sheet hole mend 

Roll up spare polyethylene sheet

The spare round the edges can be laid over the sides of the upper outer Form-a-drain.  It will be rolled up over the previous membrane sheet to prevent water getting between the sheets.  The rolled up polyethylene sheet should be arranged so that it does not go further than 3 feet beyond the top of the form-a-drain.

There are now two pieces of 6 mil polyethylene sheet coming up round the outside of the footing trenches.  To avoid letting water get between the sheets, make sure the official polyethylene membrane completely covers the more tightly rolled up first polyethylene termite/radon membrane.

Site Water Membrane Initial Fitting 

 

Cover slab area with 1" polystyrene

Function and game plan

EPS (40psi) of 1" thickness is used to cover the polyethylene sheet membrane over the slab area.  It provides protection to stop the waterproof membrane being punctured during the concrete pour or by any sharp edges on the set concrete.

Cover slab area with polystyrene

Cut 1" polystyrene sheeting such that it completely covers the slab area up to the place where it starts to angle down at 45 degrees.  Using your hotwire cutter bench, chamfer the edge of the 1" EPS to continue the 45 degree slope.  Use foam gap filler on the edges of the sheets to join them together to stop them moving about. 

Eps Slab Protection Gluing

Leave a few paving slabs on the edge corners to make sure that high winds do not blow it off.

Protection Eps Over Membrane

Protection Eps Over Membrane Site

Site Starting Protection Eps

Site Gluing Eps Protection

Site Protection Eps 1in Done 

 

Line footing trench with Tough-Liner

Function

The aim of using this layer of Tough-Liner in the footing trench is to protect the polyethylene official waterproof membrane from being damaged by the concrete or the concrete vibrator during the pour process.  It is not practical to use 1" EPS in the footing for this protection as it's too hard to keep in place.

Implementation

Use strips of Tough-Liner that U into the trench.  The strips have enough length to provide good protection on both the outside and the inside.  You want 1' overlap onto the slab area and 3' beyond the outer edge of the outer upper form-a-drain.  The extra beyond the form-a-drain is used to keep sunlight UV off the rolled up polyethylene membrane.

For the perimeter footings I cut the Tough-Liner to a length of 15'6".  Put marker pen marks at one end 1 foot from the end.

Toughliner Protection 6in Mark 

Mark the other end at 3 foot.

Toughliner Protection 3ft Mark 

Provide about 4.5" of overlap between the strips.  Use a marker pen to indicate the line corresponding to the overlap.

For internal footings the length is 12 feet with markings 1 foot from each end.

It goes under the 1" EPS that is over the slab area so you need to lift up the EPS to fit the Tough-Liner.  Put a couple of line beads of foam gap filler on the Tough-Liner under the EPS and then weigh it down with paving slabs for the 15 minutes it takes to dry.  The foam holding the Tough-Liner is a little dependent on what you use as the Tough-Liner but typically synthetic roofing felt has a slip free surface which also makes it glue well on that side.

Paving Slabs Toughliner Foam Gluing 

Use a T square to get the strips properly square across the trench.

Toughliner Protection Getting Square 

Use the wood clamps to hold the form-a-drain end.  The 3 foot marks should be positioned to correspond with the outer edge of the Form-a-drain.  The wood clamps will stay in place until the concrete pour has reached up to about 6" from the top of the Form-a-drain.

Toughliner Protection Added 

Use a wet/dry vacuum cleaner to get dirt and the bulk of the water off the polyethylene sheet before putting the Tough-Liner over it.

Wet Dry Vacuum Cleaner Lowes

Use lengths of duct tape to form a continuous seam between the sheets.  It will not be a fully waterproof seam but it will be good enough to stop dirt getting under the Tough-Liner .

Duct tape Ace Professional

ToughLiner Protection Taped 

ToughLiner Protection Trench 

Site Starting Toughliner Protection

At corners it is more complicated.  On a convex corner you will need a north-south piece and an east-west piece, then a diagonal piece in from the corner...

Convex Footing Protection Lining

Site Bit More Protection Sheeting 

Site ToughLiner Protection Getting Done 

On the internal wall cross areas it takes even more creativity to patch together pieces of Tough-Liner ...

Internal Wall Footing Protection Lining 

Protection Lining From West 

Site Protection ToughLiner Done

Put back lumber bracing (if required)

Depending on how much earth backfilling has previously been done and the characteristics of your soil and how much rain is expected, you may feel that putting back the lumber bracing is a good safety feature.  These are the 3'3" lengths of scrap lumber that use pads at each end.

 

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