self build waterproof basement formwork membrane concrete gallery
Link to the Supervision and Clerk of Works page.

Gallery with photos and explanations selected to help you.

  self build basement

I was the specialist sub contractor and built the basement beneath this new home. Like all the basements I built it never had a leak.

basement for a structural engineer

Two owners got permission to replace an old building with two new detached bungalows. I helped the other build his basement the year before. This owner then decided to use me as well.

basement in Enfield

waterproof basement in Cotswolds   I was the site engineer on commercial projects until I built this domestic basement in the Cotswolds during 2005.

It has a maid's flat at the far end with an outdoor staircase and this end is for functions.

The house is a timber frame structure on top.

I formed the maid's straight staircase in a stairwell and also this curved staircase and the patio area retaining walls.

Botley, Near Southampton.

waterproof basement finished bar

completed waterproof basement icf   completed waterproof basement render

I built this whole house with ICF. That was the last year I used it, in 2012.

The long walls had 3 regular vertical cracks and I had to take off a lot of polystyrene to find them.

They were very easy to repair and the basement has not leaked since.

The clients put in basic internal drainage themselves to this shallow sump we had cast in the basement floor slab. It is in the plant room floor. The pump is ready, but they know it won't ever see a drop of water because they lived with the bare basement concrete for long enough to be completely confident.

completed waterproof basement cracks   completed waterproof basement sump

I learned soon afterwards how to prevent the cracks but it persuaded me to always take the formwork off and inspect the concrete. So I have not used ICF since that year.

In fact, I take what is best about ICF and use that with timber. Timber is screwed to timber very easily, whereas you cannot screw much to polystyrene. So corners, shapes, tops, floors, everything is easier now I don't use ICF.

The basement contains a large area, about 9m square, for table tennis or gym or cinema or party (which is why in this photo they have the disco lights and the projector on). Also a guest bedroom with a double bed and bunks, and the plant room. I took a video about their alternative heating arrangements when I fixed the cracks and I went back again two years later to see how it had all worked out. Unfortunately they weren't saving any energy after all. I go into a lot more detail on my energy saving page.

completed waterproof basement cinema   completed waterproof basement bedroom

Also, toward the end of 2015, we have built or been involved with helping others to build, these basements.

Near Bury St Edmunds

basement Suffolk

This client decided to only wire his basement then paint all the walls white. A Saniflow pump pumps the water from the washing machine up to his drainage.

He has reported that without any heating or insulation his basement maintained a constant 14°C all winter.

And he has a lift.

basement Suffolk      lift in basement

Near Chelmsford

A carpenter built a new house to sell on. Because it was to be sold immediately he had to have internal drainage. Any new buyer's solicitor will want to see a 10 year guarantee with insurance backing, and internal drainage is the only way to get one.

FRP threaded rod formwork

Chelmsford basement internal drainage membrane

Chalfont St Peter

Piling down both sides first to support the neighbouring properties.

Party Wall Act

basement Bucks

This basement in Redhill was built during the Summer of 2015.

We were sub contractor to the client.

A rear addition was demolished and removed before the original rear wall was underpinned. The underpinning is about 3m deep. The engineer specified two storeys of underpinning, deliberately with a footing beneath the first storey that had to be gunned off before the basement walls could be formed.

Access is very tight.

A week or so later and the walls are ready to pour 1.8m high.

You can see a pile of pale green rods on the floor. These are fibre glass threaded rods.

In the far wall you can see ends of rods securing the two sides of the formwork.

Unlike virtually every other team doing this sort of work, we do not leave holes through otherwise waterproof concrete.

We cut these rods flush with the concrete when we have finished with them.

No repairs needed also means we could not miss any repairs.

This is just one of the many ways we have developed to be better at what we do.

basement underpinning blinding
  basement underpinning blinding

basement underpinning blinding


This basement, about 11m x 5m, is interesting in that the client is a structural engineer more used to designing timber frames.

He designed the upstand the other way round and specified that the sole plate for the timber frame that will continue up was cast into the concrete wall with the advantage that it is absolutely level, to within a mm, all round.

You can see his prototype of the timber frame that will be going on top, though the actual frame will be very much bigger and taller.

Above ground the house will extend left and right to be much bigger than the basement.

The timber frame will be made by Timberwright Ltd.

basement for a structural engineer  
We cast our threaded rods, made of fibre reinforced plastic, into the concrete

and trim them before we leave.

No holes.

No missed repairs.

FRP rod cut flush

No leaks.

Here are some other examples of work.

This new home in Witney will have a pool accessed from the ground floor, so it will be on a plinth in the basement.

pouring waterproof concrete basement with pool
  This is the largest basement our founder managed, in 2007. 25m x 25m, a pool in the basement and a second storey down wine cellar.

basement pool cellar

Years ago, construction quality mattered and all parties worked together to get the outcome the Client desired. But that changed 25 years ago with the coming of Design and Build and complex contracts - both used to increase profit at the expense of quality.

We have revived the old levels of care but with the most modern materials.

This was near Halstead in Essex.

waterproof concrete basement slab

  1. We scabble and clean every joint.

  2. We form walls without kickers and we don't use threaded rods that leave holes - the two most common causes of leaks.

  3. We pour the walls in two half heights so that all the concrete can be placed and compacted properly.

  4. We make sure that the slurry to line the concrete pump pipes never goes in the work.

  5. We make sure that every waterproof concrete pour is supervised.
Details that make all the difference.

waterproof concrete basement slurry

We try our best to persuade the design team to design out causes of failure and design in better practice.

An interesting comparison opportunity arose during July 2014.

On July 19th, Ockbrook in Derbyshire and the A52 alongside had a deluge so great the locals thought that 200mm of rain seemed to have fallen in about 90 minutes. All traffic came to a halt for an hour and roads were running like rivers.

This excavation had been left on the Friday with all the steel fixed and cleaned and the 300mm high formwork in place and checked. But in this photo taken on the Monday after the rain the formwork is floating and the water is more than 300mm deep.

waterproof concrete flood plain

Before choosing us, these self builders visited another basement we had helped build the year before, less than a mile away.

Both basements suffered the same 200mm of rain and this next basement had a river running down their drive right beside it. We took both these photos within an hour of each other.

waterproof concrete flood plain

No water showed itself on the inside anywhere.

We helped build both basements with concrete additive and FRP rods. Not only is the concrete proven to be waterproof in the worst possible conditions but neither did the joint leak.

This completed basement was the first time we used the resin rods. They were successful fixed into underpinning to make single sided formwork and in double sided formwork as well.

Some of this customer's comments at the time were: This is crackin', it's so strong, I'm delighted with this, you know I'm really excited I'm loving it.

The alternative was to use steel threaded bar that leaves holes through otherwise waterproof concrete, and hope they were all filled properly, which is plainly a cause for concern though still the norm for other contractors.

derby waterproof basement slab ready

  derby waterproof basement customer

  waterproof basement window

derby waterproof basement scaffold and steps

  derby waterproof basement wall form

  derby waterproof basement wall form second side

  derby waterproof basement front wall ready

  derby waterproof basement pokering concrete

Here you see the extension is finished. The basement is bigger than the extension extending under the small patio at this end.

derby waterproof basement finished
  In the large photo just above you see how the concrete was stepped around the window to create ledges for brickwork that would not let water past the window frame. Below you see the finished detail.

basement window well

This basement, near Witney in Oxon, was complete by Christmas 2013. This self builder doesn't just want zero energy bills, he wants to sell excess energy for profit. So this structure will be exceptionally well insulated and those PV panels, and others not in this photo, will go on the new roof.

This basement was built by one of our teams.

built waterproof basement

Redditch. A basement and house above all being built out of reinforced concrete by the same team that built the basement near Witney. The basement and flat roofs are waterproof concrete. The other walls above ground are plain structural concrete.

cotswolds basement slab

This time they hired in proprietary formwork for the walls, because it made sense using them 6 times to form all the walls up to the roof.

cotswolds basement slab

cotswolds basement slab

Streatley, north of Reading.

cotswolds basement slab

Here are some other photos of the Witney basement under construction.

cotswolds basement slab Mik

walls first pour
  This self builder is building his new home in the Oxfordshire Cotswolds. He bought his own machinery and hired a digger driver and muckaway lorry on dayworks. Due to hard ground lower down the excavation took a long time but all the sacks are filled with stone he quarried for his own house walls and to sell.

He intends the whole home to be energy cost neutral or better.

He is already selling solar electricity under the FIT scheme from two groups of panels. The panels will be transferred to the new structure.

He has glass foam insulating aggregate under the basement slab and he will have sprayed foam against the walls. Then blockwork outer leaf to support the wide stonework.

He visited us on 5 sites.

We agreed that he was to be the site supervisor on his site throughout, he will supervise the whole dwelling on a Value Engineered basis.

Willesden Green, London NW10.
This developer is extending as well renovating a house to be his own future home.

He adopted Value Engineering a long time ago, so his workforce is his regular gang. He pays them all fairly plus some bonus after developed properties are sold. They are loyal, turning down other work when he wants them.

The pool is beneath the backer board. The pool will be tiled and the backer board plastered.

waterproof concrete basement with pool
  Sun tubes and artificial grass.

waterproof concrete basement light tubes

swimming pool waterproof concrete

Some small leaks where they could not prevent mud falling inside the formwork gave us our first chance to use the resin injection leak repair kit.

waterproof concrete leak repair with resin PU injection
  Kingston Upon Thames in a private, gated community.

Like most customers, this customer visited us on a previous job and chatted with that client about how things had gone with our being involved.

The basement is about 24m x 20m maximum. It has a lift pit and foul waste pumping chamber deeper than the basement floor, a swimming pool at a higher level and two overhead concrete floors. One is the garage floor. This one will be the patio, the house above ground is not quite so big as the basement.

You can see that the outdoor patio deck is formed. The last stage is forming the upstand that will prevent water under the patio paving getting into the house or basement.

waterproof concrete basement deck over

This half-depth basement under part of the building is near Newmarket. It was poured during March 2015.

This couple built a new building in their garden as an art studio for practicing and teaching purposes.

They had one small leak that was their fault for not keeping the joint clean. They easily fixed it with advice from us and it has been dry since.

The basement floor slab, its walls and the remaining floor slab are waterproof concrete.   The one doing least is the client, obviously.
waterproof basement art studio 1   waterproof basement art studio 2

A building firm saw a self builder's basement. Studied these web pages then placed their order. I took this photo when I delivered the FRP threaded rods and nuts.

They have spaced the formwork with measured pieces of wood. These came out as they put in the threaded rods with thin nuts to control the width instead.

basement 3 weeks

3 weeks later I collected the steel waler plates they hired. This is the completed job.

basement 3 weeks later

A farmer in Somerset built his new farmhouse and the basement for his cheese storage was built with very old scaffold boards and new 6x2 timber plus a couple of days training from me in tying steel and the carpentry. It went perfectly well.

farmer built with my timber formwork

This small basement, top right, got a RC roof cast insitu because it might one day become a separate dwelling for the family's maid. the house above it will be much bigger and the solid concrete construction will pass building regulations for passage of sound and so on.

RC roof cast insitu

If your interest might be my keeping an eye on your team I can do that as supervisor or clerk of works.

Grenfell Tower has taught us all that very few builders ever get inspected and for various reasons they have got used to cutting corners and using cheaper materials. In 2019 i was paid too much to turn down just to inspect and report on what their sub contractor was doing. I found awful problems and got them put right. Read more on my Supervision and Clerk of Works page.

basement construction menu page   At the foot of every page you will find this image. Click it to go to our menu page where every page is listed.

Clicking the banner at the top will return you to the home page.

 Previous Page

basement rebar

 Next Page


 The Page After That

basement clerk of works