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Basement conversion

Basement New Build

As specialists in basement conversions and basement building, we offer you a complete service from start to finish, from basement structure and waterproofing to decorating and kitchens.

Do you want a big home but have a limited amount of land?

With the high cost of land and numerous planning restrictions, our modern methods can help you obtain a prompt and economical solution. We propose a full service, usually being involved from the first design stage, right to completion of the structure.

Retrofit Basements

Retrofit basements are basements or cellar conversions that are built under your existing home or structure. Adding a new area in the basement to your home could provide much-needed space and add value to the house. The basement is also an excellent solution where extensions are restricted by size and planning issues.

We offer the structural design and construction of your basement together with waterproofing ensuring that it is ready for your design. Light-wells, windows, a separate entrance, stairs and even basement terrace areas can all be built to give much-needed space to your house.

Our waterproofing system is long-lasting and reliable; installed by our expertly trained team, we will ensure that our waterproof membrane is fitted correctly before starting to apply finishes to the walls.

The growing need for deeper and larger basements extending throughout the whole house and gardens can be satisfied with our piled retaining walls, reinforced concrete walls and other modern underpinning methods.

We are a business that prides itself on the level of help we offer and the specialist expertise that we use.

Structural Waterproofing

Our waterproofing team specialise in producing practical and efficient solutions for completely dry conditions using new products and techniques.

It is essential that the correct waterproofing system required is correctly identified and designed from the beginning. Because of our specialist knowledge, you can relax reassured that your basement waterproofing or cellar conversion has the waterproofing system it needs to meet requirements.

Drainage Channel

A drainage channel allows groundwater to flow to your pump below the floor. It decreases water pressure at the critical wall to floor junctions. The drainage channel system is placed at the floor to wall junction in a pre-formed slot around the perimeter of the basement.

Membrane Systems

Cavity drainage membranes are installed in most situations from very wet basements inclined to flood to damp walls and cellar conversion work. Cavity drain membranes are rated the no-risk method of waterproofing by most authorities and control water ingress in a maintainable way.

Pump Stations

We can supply and install a complete range of pump units for managing water from the basement and rainwater from light wells. We also provide pump stations for kitchens and toilets. From single pump stations to multi-pump stations including alarm systems, can be installed with a battery backup unit in case of power failure.

The Additional Costs to Count when Building or Turning a Basement

Many items need to be considered when preparing to build or convert a basement. Here we have posted most of the essential things that need to be considered. Some requirements might vary from place to place.

Planning permission - is required in most cases, and professional advice should be sought in the initial stages. In some boroughs, this can become a tedious and expensive process.

Party Wall Agreements - Unless you are rich and live in a detached house with no neighbours then party wall matters will need to be sorted out and agreed with neighbours on the left, right and sometimes at the back of your house as well. Surveyors costs need to be taken into account when budgeting.

Soil Condition - Groundwater levels and soil types that need to be excavated and removed can have a significant impact on costs.

Access - easy access to remove excavated soil and space to unload and store building materials will decrease costs and speed up the program. Parking bays will need to be suspended for skips and storage; however, this can be quite expensive and not always possible.

Renting - Retrofit projects are faster and cheaper when the house is empty, so renting costs also need to be considered.

Annual Maintenance - It is crucial to have an annual maintenance contract on all pumping stations.

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Do you want to convert your basement into One-of-a-Kind space?

If you're looking for a basement conversion to form a liveable space under your house, you are only one call away from having the perfect basement built by us.

As a basement conversion specialist, we will provide you with a complete design and build service. With very experienced design partners and an established construction and fit-out team, you can be sure that we are able to accommodate any type of basement build or conversion requirements.

We are offering inventive ideas and solutions right from the start of your basement project, and we work with our trusted architects and other teams of specialists to build the space that you desire.

100% Bespoke designs and planning to accommodate your every need

Innovative add-ons like skylights, sun pipes and light wells

Fixed prices with minimum disruption, maximum satisfaction

Full project management by our office-based professionals.

Ten-year warranty so you can be sure of our quality

Get in touch with us and we will answer promptly and can even visit the property the same day in an emergency.
We will make the best design for you


Q: Where do you provide your services?

We work across London, Surrey, and the South East.

Q: How long does it take to do a full house refurb?

On average a full refurb of a standard 2 bedroom property will take 6 -8 weeks.

Q: How much do house refurbs cost?

A standard two bedroom property will usually cost around £40k for mid spec finish. Using cheaper kitchens and bathrooms and other materials can bring this down as far as £30k and high spec finishes can be upwards of £100k.

Q: Can I tailor the service to my specific requirements and designs?

Yes, we will work with you every step of the way to make sure that your completed project is to your requirements. Although we complete many refurbs, no two are ever the same. We aim to help all of our customers add their own little bit of personality into their new home or investment.

Why choose us?

  • Professional Quotations
  • Up to 5 years Work Warranty
  • Own Designers
  • Specialists in High End and difficult projects
  • Member of Federation of Master Builders
  • Trustmark Member
  • Health & Safety compliant
  • We have decades of Experience
  • Friendly, reliable and clean Builders
  • We cover London and a 50 miles radius
  • Residential and Commercial Services
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feedback from our customers

We might want to express gratitude toward Red Builders for the Refurbishment they finished for us and the work done. We were intrigued by the professional approach of the entire staff, we have got endless commendations from all who see and use it. The team was obliging and set aside a significant effort to clarify all the information required from the design drawings, the advancement of the work to the completed venture. A point by point receipt was given for all the work and materials with no hidden cost. Words can't describe how cheerful we are with our new home. If we describe Red Builders, they are perfectionist professionals who caused us to feel secure, realizing the completed project would be accurate and neat, and it was. We have prescribed Red Builders to everybody searching for building work.

Leonn Berry

We are completely pleased with the change in our cellar, and we can't thank you enough for all your difficult work and your endeavors. We especially valued the counsel on a few changes Red Builders proposed which prompted considerably more productive utilization of room. We are very happy with your assistance, and we trust we get the chance to cooperate once more. The project manager and his group kept to the contract just as spending plan and consistently refreshed us on the turn of events and choices that we expected to make. The builders were respectful toour home, keeping the noise to the possible minimum, additionally keeping the spot perfect and clean. It was a wonderful experience, and we are very much satisfied. With the team's understanding and skills, everything was on schedule, they conveyed a phenomenal completion. We would recommend Red Builders to every one of our relatives and every house owner.

Claire Keating

Red Builders was to make some significant alterations and a loft extension to our home. We requested some critical changes during development, and the project manager was happy to give professional recommendations on every issue. From the underlying idea on to its fulfilment, we were surprised by their attention to detail approach and the priceless guidance he gave all through. The project manager arranged the breakdown of cost precisely, with straightforwardness, and trustworthiness. His group of builders were first-rate and did their best. I was so astonished by the work they accomplished every day to the point that the work was finished before the cutoff times. We are certain to recommend Red Builders Building Company to every single customer.

Joe Whaley

We applied to different companies for quotes and got what we viewed as a reasonable and realistic quote for a genuinely extensive renovation of our home from Red Builders. The project manager and his group worked admirably and exceeded our desires. They included us in the selection process for the property, way to deal with the work and specifications. They were truly flexible and effectively obliged our decisions for additional work. The work has been done to the most professional level in a friendly, considerate and ideal style. Red Builders entire staff was gathered outside of our home ten minutes before the start time. The things that surprised us more than anything was the way that the project manager recollects everything about the details and takes individual liability for ensuring that you, the customer, are totally happy with the work that you need to be done. I have worked with different building organizations on various under takings throughout the long term. Red Builders are most likely the best that I have worked with, and I have no hesitation in suggesting him. Catch him in case you can!

Bridget Snooks

I am writing to thank you for your expertise, knowledge, reliable attitude showed by yourself and Red Builders team to the fruitful outcome of this project. We asked Red Builders to redesign a little flat and, despite the fact that the flat is small, it was significantly difficult to renovate it as it required a detailed renovation. Red Builders performed brilliantly. The Red Builders staff we were in touch with were amazingly capable and pleasant. As in most of such cases with are design, little issues emerged during the remaking period. Red Builders had the option to manage these issues in the most effective and practical manner. The project came in on the financial plan and due to the schedule. They did a wonderful job, and we currently love our flat. When the activity was done, Red Builders kept on following up and disclose things to us about the flat and its equipment after we moved in. I would highly suggest Red Builders.

Kindly pass my gratitude to all engaged with this project.

Jonathan Gough

A little more than a year back, I planned my first renovation project. I had never done anything like this, and after the web research, I sourced 4-5 quotes. I chose to go for Red Builders since they were sensible and their quote was all around organized and detailed. The Job included a lower ground expansion and house redesign. I don't have anything but beneficial comments about capability. Their work was done to the highest level. Their tiling, carpentry and painting were remarkable, and the project was finished on schedule and due to the plan. They were negotiable about the inside plan changes and permitted me to be engaged with the cycle even to the point of helping me source-specific installations I needed for the house, keeping in topic with the style we had gone for. They gave me useful recommendations on specific components I had disregarded, for example, up-cycling the current wood planks, extra water siphons required and incorporating the outer bi-folds to make the augmentation even from the outside instead of inside. On-demand Red Builders made cabinetry around our chimney to match our new kitchen and truly, the craftsmanship and detailing makes them appear identical. When the undertaking was done, it was hard to accept that it was the same house.

George Elliot

When embarking on discovering an organization to plan and build our office, I had clear models at the top of the priority list. The organization must be lively, clever, solid, overflowing with thoughts and value for money. Red Builders beat the competition by a reasonable mile. Indeed, even before winning the project, the attention they paid to us was unmatched. When we began, the norms didn't drop. They committed an over the top measure of time to my venture and went far above what was required even to where it was evident it wasn't to their greatest advantage to do so. They were very supportive all through the process, continually delivering on our details and deadlines and totally adaptable toour tasteful changing preferences. They're similar to an extended family on building site. Without any doubt, the best I've worked with.

Ryan Woodcock

I have been suggested Red Builders through a friend of mine who had their kitchen wonderfully extended so we chose to reach them about a potential loft conversion and we couldn't be more grateful. The plans were delivered very fast, precisely, and I truly felt they accepted our interests and thoughts, parts that were not achievable were given different other options, and they truly set us straight during this process. We are happy with the outcomes from the start to the end. Strongly recommended. It was a pleasurable experience, and I wouldn't hesitate to use again.

David Walker

We are living abroad, and after a tenant had harmed our terraced house, we found that we need to set out on a top to toe restoration of our property. We got various quotes, and the Red Builders reaction was the most careful and thorough. Red Builders were incredibly useful in working through the selection and reacting quickly to each of our inquiries and concerns. Red Builders might not have been the cheapest reply we got, however, there was absolute clarity on what we were paying for and the nature of work we were getting. The project manager and his group at that point dealt with the venture, especially professionally - with regular and definite email and photograph refreshes, they exceeded all expectations in conveying a remarkable outcome for us. Our home presently looks spectacular - and each renting office that has seen it has remarked on the exceptionally high caliber of the work. In case we needed to do this once more, we wouldn't spare a moment to call Red Builders, and are very glad to prescribe them to anybody searching for top quality, productive, friendly or more all very professional and experienced building company.

Jennifer Smith

Red Builders changed over a mid-Victorian patio loft. It was done due to the deadlines confirmed at the beginning and the budget approved, with a magnificent quality completion. The group of manufacturers, builders, electricians and plumbers set up by Red Builders were unpretentious and extremely enterprising. When there were inquiries en route, they were replied, and the Red Builders group were consistently accessible on the mobile if necessary. Red Builders were flexible and responsive. I was not anticipating works in the house, but once they were in progress, I was incredibly satisfied with how they went. I would suggest Red Builders without a second thought and would use them again for a similar activity without hesitation.

Amelia Morrison