FAQs Archive - SWJ Consulting

Q: Do I need planning permission for a basement?

If it is a new basement where major works are involved to excavate for a basement that will provide accommodation, will affect the appearance of the existing house, or will have a light well you will more than likely need planning permission. It is best to contact your local planning authority before you start any work.

Q: Can I build a basement under an existing house?

Yes, it is possible to build a basement under an existing structure. You need to engage with a structural engineer at the earliest opportunity for them to complete a site visit to determine if it’s possible and the best method of construction. This will affect the budget of the project and therefore its feasibility.

Q: How does access affect my basement?

You can not assume that your neighbours will give you access for diggers and trucks to remove waste when you're digging a basement. If you are surrounded by trees and other buildings this will also hamper access. There are ways to overcome these issues, but you need to speak to a structural engineer and have a site survey completed to determine whether your basement is feasible and the best construction method.

Q: Do I need long term water monitoring for my basement?

BS8102 says you must design a basement assuming for a full head of water, i.e. up to ground level. Long-term groundwater monitoring can demonstrate that a lower level is appropriate saving you money. This is why SWJ recommend that long-term groundwater monitoring is undertaken as it allows them to design for the actual ground conditions and not the assumed worst case.

Q: What is heave due to removal of overburden pressure in basements?

Heave due to the removal of overburden pressure is a calculation Structural engineers need to make for a successful basement design. They have to ensure that the design is heavy enough to resist the ground underneath your basement from rising because the compacted soil, which had been there for millennia, has now been removed.

Q: What is 'heave to counter uplift' in a basement?

Uplift in basement design is where changes to the ground where you have dug your basement will push up ‘uplift’ your basement structure. Structural engineers complete site investigations to calculate what weight of structure (and how it is built) will be needed to counter movement caused by ground water (hydrostatic uplift) or by the removal of the soil to build the basement (Heave due to removal of overburden pressure).

Q: Do I need a topographical survey for a basement?

[fusion_builder_container type="flex" hundred_percent="no" equal_height_columns="no" menu_anchor="" hide_on_mobile="small-visibility,medium-visibility,large-visibility" class="" id="" background_color="" background_image="" background_position="center center" background_repeat="no-repeat" fade="no" background_parallax="none" parallax_speed="0.3" video_mp4="" video_webm="" video_ogv="" video_url="" video_aspect_ratio="16:9" video_loop="yes" video_mute="yes" overlay_color="" video_preview_image="" border_color="" border_style="solid" padding_top="" padding_bottom="" padding_left="" padding_right=""][fusion_builder_row][fusion_builder_column type="1_1" layout="1_1" background_position="left top" background_color="" border_color="" border_style="solid" border_position="all" spacing="yes" background_image="" background_repeat="no-repeat" padding_top="" padding_right="" padding_bottom="" padding_left="" margin_top="0px" margin_bottom="0px" class="" id="" animation_type="" animation_speed="0.3" animation_direction="left" hide_on_mobile="small-visibility,medium-visibility,large-visibility" center_content="no" last="true" min_height="" hover_type="none" link="" border_sizes_top="" border_sizes_bottom="" border_sizes_left="" border_sizes_right="" first="true"][fusion_text] Yes, a topographical survey provides information on existing natural and manmade structures including utilities and road furniture that could affect your development. You will also need a site investigation to determine ground conditions and water levels. Read our blog - What's the difference between a site investigation and a topographical survey. [/fusion_text][/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]