Has anybody built one?
We have just made an offer on a property and all is looking well. It has a huge garden but the property itself needs bulldozing.
We are going to most likely be getting a static caravan dropped on the site to live in. However the first job is to build my home office so that the build/renovation I can still do what i do in quiet while the kids destroy the caravan.
We have talked about building a underground room and then build a shed/cabin on top of it for quite a while now and looking at my local planning portal it still comes under permitted development. With a cabin on top it may end up being used as a a place for guests to stay instead of teh main house so they can sleep while the kids be kids.
I know building underground and close(ish) to the sea sets some challenges but houses have had basements for years and with the amount of technology about there hopefully is some solutions.
from my research, sump pumps and air circulation is important and obviously stopping damp walls.
Has anybody built something similar (@imago probably has) I am expecting it be quite costly but I think in teh long term it will be ok.
The only places underground rooms make sense financially is where property prices are extremely high, and there is no (or very restricted) room to build above ground. The costs are colossal per square metre, and where you are located you wouldn't even get close to adding the value it'd cost.
Just the excavations alone are a huge project. Site survey costs are crazy because you need to find the water table and use ground radar. You'd be working as cut and cover, so whatever volume the finished room was you'd need to excavate approximately 50% more by volume to access it. So a 4 x 5 metre room would need 75 cubic metres of soil shifting. Then add on the piling you'd need, along with pumps to keep the hole clear of water.
Basically, unless the property you're buying is in central London build above ground.