Structural engineer in Hertfordshire

Structural engineering in Hertfordshire

Hertfordshire is our second busiest county after Surrey, with 42 projects since 2019. Nearly all of them are in the south of the county, in towns just over the boundary from Barnet, Harrow and Enfield. South Herts is a short drive from our office in London NW2, and it sits squarely within our core patch, which is London inside the M25 plus the counties around it.

Chorleywood, Borehamwood and Radlett have given us five projects each, and the Watford postcodes, including South Oxhey and Garston, account for fourteen more. We also work in Bushey, Potters Bar, Cheshunt, Kings Langley and the villages south of St Albans. Homeowners here mostly come to us for extensions, lofts and wall removals, while buyers and insurers ask us to look at cracking and movement.

Metroland villas, railway towns and post-war estates

The Metropolitan line brought Metroland to Rickmansworth and Chorleywood between the wars: detached and semi-detached houses with tile-hung gables, mock-Tudor timbering and long gardens, many extended more than once since. Watford has a Victorian and Edwardian core of terraces around the town centre, with interwar semis spreading out toward Garston and Oxhey.

Borehamwood grew quickly after the war as a London overspill town, so much of it is post-war estate housing, with flats and maisonettes as well as brick terraces. Radlett and parts of Bushey and Potters Bar have large detached houses on generous plots, often rebuilt or remodelled. Cheshunt mixes older terraces with newer estates.

Clay in the south, chalk toward the Chilterns

Borehamwood, Radlett, Bushey and Potters Bar sit mainly on London Clay, the same shrinkable clay found across north London. Shallow foundations here move with the seasons, and trees close to houses can dry the clay enough to cause cracking in a dry summer. Extension foundations near trees often need to be deeper, or designed as piles with a void beneath the ground beams.

North and west of Watford, toward Rickmansworth, Chorleywood and Kings Langley, chalk comes near the surface, usually capped by clay-with-flints. Chalk can contain solution features, natural hollows filled with looser material, so unexplained settlement deserves proper investigation. Along the Colne, Gade and Lea valleys, including around Cheshunt, river gravels and softer alluvium are common. A trial pit and foundation inspection report shows what is actually there.

Common structural work in Hertfordshire

Hertfordshire jobs tend to be larger than the average London house alteration: wide rear extensions on detached homes, first-floor side extensions, and remodels that take out several internal walls at once. Loft conversions are popular on Metroland semis, though hipped roofs and tall chimneys make them more involved. We also report on cracking, bay window movement and failed wall ties for buyers and owners.

• Single and two-storey extensions on detached houses
• Loft conversions in hipped Metroland roofs
• Taking out several walls for open-plan ground floors
• Foundations near trees on London Clay
• Pre-purchase structural inspections
• Investigating settlement on chalk

Towns we cover in Hertfordshire

Our Hertfordshire work runs in an arc just outside the London boundary, from Chorleywood and Rickmansworth in the west, through Watford, Bushey, Borehamwood and Radlett, to Potters Bar and the Cheshunt area in the east. We also go north to London Colney, St Albans and Kings Langley.

• Chorleywood and Rickmansworth (WD3)
• Watford (WD17, WD18, WD24, WD25)
• South Oxhey and Carpenders Park (WD19)
• Bushey (WD23)
• Borehamwood (WD6)
• Radlett (WD7)
• Potters Bar (EN6)
• Cheshunt and Goffs Oak (EN7, EN8)
• London Colney and Bricket Wood (AL2)
• Kings Langley (WD4)

Hertfordshire councils and the Green Belt

In Hertfordshire, planning and Building Control are run by the district and borough councils rather than the county. In our main area that means Three Rivers, Watford, Hertsmere, Broxbourne, St Albans and Dacorum. Almost all the open land between the towns is Green Belt, and Chorleywood, Rickmansworth and older parts of Radlett and Bushey have conservation areas, so speak to your council early.

Our calculations and drawings are sent to Building Control by us, and we handle the questions that come back. Our loft conversion guide covers hipped roof lofts.