Do I need Building Regulations approval for a basement fit out?

In most cases, yes—especially if you’re creating (or upgrading) a habitable room, adding a bathroom, altering stairs, insulation, ventilation or electrics. We can guide you through the process and coordinate sign-off with Building Control. See: Building Regulations .

Will I need planning permission?

Often not for internal-only works, but you may need permission if you’re adding/altering external openings (e.g., light wells), changing the building’s appearance, excavating, or if the property is listed/in a sensitive area. We’ll advise early and help with drawings and submissions where needed: planning permission support .

How do you deal with damp and waterproofing?

We start with a site assessment and design the right waterproofing approach for your basement, then detail insulation, ventilation and finishes to keep the space comfortable long-term. Where waterproofing is required, we follow recognised good practice (e.g., BS 8102 guidance) and build a maintainable system with clear access for servicing.

Do I need a Party Wall Agreement for basement works?

If the works affect a shared wall/structure or involve excavation close to a neighbour, you may need notices under the Party Wall etc. Act 1996. We can help you understand what’s required and support the process: Party Wall support .

What rooms can you create in a basement?

Common options include a home cinema, gym, office, guest bedroom with shower room, kids’ playroom, utility/laundry space, or a quiet snug. We’ll design lighting, heating, ventilation and acoustic performance so it feels like a natural extension of your home.

How much does a basement fit out cost?

Costs depend on the current condition (dry vs damp), ceiling height, access, whether a bathroom is included, and the finish level (joinery, AV, flooring, underfloor heating, etc.). We’ll survey, define scope clearly and provide a fixed-price quotation. Start here: get a quote .

Basement Fit Out & Finishing in Elmbridge, Surrey & SW London

Basement fit out and finishing in Elmbridge, Surrey

Basement fit outs that feel like part of the home

If you already have a basement or cellar, a professional fit out is one of the most effective ways to add valuable living space without extending the footprint of your home. HWP Design & Build delivers high-quality basement fit out and finishing across East Molesey, Elmbridge, Surrey and SW London— transforming cold, underused rooms into warm, dry, beautifully finished spaces.

We focus on the details that make a basement work day-to-day: comfort underfoot, robust moisture management, the right ventilation strategy, practical lighting design, acoustic control and durable finishes. Whether you’re creating a home office, cinema, gym, playroom, guest suite or utility space, our approach is the same—clear scope, tidy working practices and a finish that matches the rest of your property.

Basement home office fit out with lighting and insulation

Basement finishing with bespoke joinery, flooring and paintwork

What’s included in a basement fit out

Every property is different, so we start by understanding the existing condition of the basement and how you want to use the space. From there, we design the build-up and specification so the room performs properly—warm, dry, quiet and easy to maintain.

Survey & feasibility – head height, access, existing services and condition checks.
Moisture management – damp diagnosis, waterproofing approach where required, and maintainable detailing.
Insulation & thermal comfort – walls, floors and ceilings to suit the space and intended use.
Ventilation strategy – to control humidity and keep air quality high (especially in habitable rooms).
Heating & electrics – radiators/UFH options, lighting design, sockets, data and AV prep.
Plumbing & bathrooms – shower rooms, utility areas and drainage solutions where feasible.
Finishes – flooring, plastering, decorating, doors, skirting, storage and bespoke joinery.

Waterproofing, ventilation and compliance

Basements demand the right technical approach. Where waterproofing is required, the detailing should follow recognised good practice (such as BS 8102 guidance) and be designed with maintainability in mind—because access for inspection and servicing matters long-term. :contentReference[oaicite:3]{index=3}

For habitable basement rooms, Building Regulations commonly focus on areas like fire safety and means of escape, ventilation, thermal insulation, drainage and electrics. We can coordinate your project under our design & build service and help you navigate Building Regulations requirements so the finished space is safe, comfortable and compliant. :contentReference[oaicite:4]{index=4}

If your basement works are close to neighbouring structures (or affect shared walls), you may need formal notices under the Party Wall etc. Act 1996. We’ll flag risks early, help you plan sensibly and point you to our Party Wall support. :contentReference[oaicite:5]{index=5}

Our basement fit out process

1) Site visit & brief – we assess condition, access, head height and your goals.
2) Scope & specification – clear inclusions, finish level and performance requirements.
3) Design coordination – layout, lighting, services, ventilation and any waterproofing detailing.
4) Fixed-price quotation – transparent and itemised, with programme expectations.
5) Build & finishing – tidy site setup, careful sequencing, quality control throughout.
6) Sign-off & handover – commissioning (where needed), snagging and aftercare support.