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SX Basement Construction London

SX Basement Construction London

5.0(37 reviews)See reviews ↓·London

What customers say

Based on genuine customer reviews

Basement construction, excavation and tanking work features repeatedly in accounts of this contractor's output, with reviewers describing conversions beneath Victorian terraces alongside full dig-outs and remedial waterproofing schemes. A recurring point is the handling of the statutory side, since party wall matters, structural calculations, drawings and council paperwork are said to be dealt with on the client's behalf, removing the need to coordinate several separate trades. Clients describe clear quotations and pricing they considered fair, with one recalling that costs stayed below the figure originally estimated.

Progress updates during the dig are mentioned often, and questions are answered without anyone having to chase a response. The standard of workmanship draws consistent praise, as does the finish matching what had been agreed, while the tidiness left behind and the design suggestions offered along the way also come up. No individual staff member is singled out in the feedback, but the workforce collectively is described as enjoyable to deal with. Excavation carried out safely and to a dependable standard remains the theme that recurs most.

ArchitectBuilding firmContractorEarth works companyConstruction CompanyGeneral Contractor

Reviews

Reviews are taken from publicly available sources.

KG
Korada Gouthami16 July 2026

been meaning to write this for a few weeks now. SX did our basement dig out and conversion and the whole thing was way less painful than i was expecting. we went in pretty blind, didnt really know what permissions we needed or how any of it worked, and they walked us through it from the start. paperwork, drawings, council stuff, all sorted by them which was the main reason we picked them over two other quotes. the build itself took longer than the original estimate but not by loads, and they were upfront when things slipped which i appreciated more than a fake timeline. site was kept reasonable, no shouting at 7am, no rubbish piling up on the pavement for weeks. finished basement is dry, properly lit, feels like part of the house not a damp box underneath it. price was fair for what it actually involved once you see the scope

AL
Alfie Leach26 May 2026

had a basement conversion done under our victorian terrace and these lot handled pretty much everything. planning docs, structural calcs, party wall stuff, the actual build. saved me from having to coordinate like five different people which was the main reason i picked them over other quotes i got around London. the dig took a while obviously but they kept me updated on where things were at and never had to chase them down for answers. waterproofing and drainage all sorted, new staircase put in, the space is basically a full extra floor now. ceiling height came out better than i expected tbh, thought it would feel cramped but its not. one thing worth mentioning is they dealt with thames water and building control directly so i didnt have to sit on hold with anyone. price wasnt cheap but basements never are and there were no surprise additions to the bill halfway through. been using the space as a home office since they finished and its comfortable year round

LT
Lami Theopilus28 April 2026

Our terraced property had practically zero storage and no room to extend outward, so going underground was really the only option we had left. The planning side of it was what worried us most because we'd heard horror stories about party wall agreements and structural surveys dragging on for months. SX Basement Construction sorted all of that out and kept things moving at a reasonable pace. They handled the permissions, lined up the structural engineer, and basically managed the paperwork so we didn't have to chase multiple people ourselves. The actual dig and build took a while, which we expected given the depth and the fact that neighbours were close on both sides, but there weren't any major hold-ups. What we ended up with is a full additional floor under the house - dry, bright with the lightwell they suggested, and properly finished. Went from having nowhere to put anything to having more usable space than the ground floor.

CD
Carley Davey26 March 2026

Had this ongoing damp issue in the basement for like 2 years maybe longer. Walls were literally crumbling in spots and nothing was fixing it properly. They came in figured it out. It was a waterproofing failure from the original build and redid the tanking system completely! Bone dry now even after all that rain last month which is wild!!! X

S
Shell21 January 2026

I would highly recommend SIX for their basement construction services. They managed the entire project from excavation to the final fit out with great efficiency and professionalism for us.

R
Ravi10 September 2025

Our basement construction project went perfectly. The team managed the job professionally and the finish is flawless.

FC
Freddie Carnell19 June 2025

Massive shout out to the team handling our basement excavation London. Fast,safe,and the results are incredible. Basement builder London legends-thank you!

Groundworks & excavation in London compared

Ordered by rating, weighted by the number of reviews — businesses with only a handful of reviews do not jump to the top automatically. 12 businesses in this category in London are compared.

RankProviderRatingReviewsOpen Sat.
1SX Basement Construction London (this page)★ 5,037Yes
2TARN Basement Excavation London★ 5,022No
3Evolve Groundworks London★ 5,08Yes
4BaseBuild Groundworks Construction★ 5,034No
5L&V Underpinning Services★ 5,011No
Contact
+447520637289londonbasementexcavation.co.uk92 Great Portland St, London W1W 5PN
Working hours
Monday08:00–21:00
Tuesday08:00–21:00
Wednesday08:00–21:00
Thursday08:00–21:00
Friday08:00–21:00
Saturday08:00–21:00
SundayClosed