Underground workspace

[sunbeamtigerv8ti]

Hi to all that might take the time to read this and advise.

I am considering building an underground workspace 25'x50'x12' as I have ample garden space. I am thinking of spanning the width with pre-stressed concrete lintels then either cover with Astor turf or maybe re-lay grass on top of lintels so the garden looks normal. Also strong enough to take some heavy weight on it without worry of collapsing.

Question is would it be better to build the walls with bricks,blocks or poured concrete with caged wire.

I like to have underfloor heating and have a dry workspace, what is the best way to ensure that no dampness works it way thru.

Also in the other area of the garden I am planning to have 1500mts of ground source heating pipes laid which will be used to heat the house and workspace.

So now I like to find any architect that might have designed something similar or someone who has had this done already ?

Plans, ideas or good suggestions are welcomed.

Many Thanks in advance of all replies.

[welsh brickie]

with building a room underground it needs to be a well drained area, and watertight.Excavate the area and install field drainage under the proposed room on well compacted balast,I would use reinforced concrete for the floors and the walls and also the roof,if you want to put weight on it its the best construction method.It will need to be painted with buitumin on the entire exterior and a damp proof membrane adhered to it.Also polysterene against that to protect the membrane,then backfilled with gravel to help drainage.