• Menu
  • Gallery
  • Soil Investigations
  • Information for Architects
  • Information for Engineers
  • Client FAQs
  • Our agreement with you
  • Guarantees
  • Floors over
  • Specialist products we use and supply to others
  • Home
  • Contact Us
  • Thinking of self building your basement?

Our founder was the site engineer on commercial projects until he built this domestic basement in the Cotswolds about 12 years ago. 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. He formed the maid's straight staircase in a stairwell and also this curved staircase and the patio area retaining walls.

Botley, Near Southampton. We built this whole house with ICF. That was the last time we used it, in 2012. The long walls had regular vertical cracks and we 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. We learned soon afterwards how to prevent the cracks but it persuaded us to always take the formwork off and inspect the concrete. So we have not used ICF since that year. In fact, we 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 we 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. We took a video about their alternative heating arrangements a couple of years ago. It is on Youtube here.

We were filmed building in Plaistow E13.

Near Bury St Edmunds

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.

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.

Chalfont St Peter Piling down both sides first to support the neighbouring properties.

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.

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.   We cast our threaded rods, made of fibre reinforced plastic, into the concrete and trim them before we leave. No holes. No missed repairs. 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.

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.

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.

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.

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

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.

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.

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

Sun tubes and artificial grass.

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.

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.