Underground workshop help needed.

[Mickyas]

Hi all, I'll try my best to give a detailed overview...
My house lies on a hill and 15yrs ago I cut into the bankside to make an 'underground' workshop (not fully underground, imagine the side view of a rectangle and the ground going from one bottom corner to top opposite corner). The top of which is street level and measures approx 4m x 8m(I use it to park the car on ). The entrance is via a garage door at one end (as the other end is underground ). When constructed it was built using 7kn concrete blocks, laid on edge (interior walls) then another wall of them laid flat with an outer skin (showing above ground) of bricks. The ceiling/floor was built using block and beam, sealed with cement slurry, a dpm (tied into a surrounding damp proofing/tanking), with approx 6" of reinforced concrete on top and a polymer concrete drainage channel where it meets the pavement. It has been great for years, but then the council replaced the pavement and badly damaged the dpm and now I get water running through the ceiling when it rains and condensation droplets forming all over the ceiling.
I'm thinking of removing the top, right back to the brick/block work the beams are on (inc the block & beams). Any suggestions on how best to reconstruct to prevent water ingress and condensation?
I was thinking of installing a timber ceiling, filling with kingspan, setting the block & beam back in place, laying the dpm so that it drops DOWN to the outer brick skin, brick back up (incorporating weepholes all round) then finishing with reinforced concrete again, but I'm still concerned about condensation on the workshop ceiling and water getting in at the drainage channel.
Any help would be much appreciated.
Thanks
Mick

 

[Deluks]

Surely if the council damaged your damp proofing then the onus is on them to repair it?

Were you actually allowed to build your workshop underneath council owned land?

I'm struggling to imagine the side view of a rectangle.

 

[noseall]

Hi all, I'll try my best to give a detailed overview...
My house lies on a hill and 15yrs ago I cut into the bankside to make an 'underground' workshop (not fully underground, imagine the side view of a rectangle and the ground going from one bottom corner to top opposite corner). The top of which is street level and measures approx 4m x 8m(I use it to park the car on ). The entrance is via a garage door at one end (as the other end is underground ). When constructed it was built using 7kn concrete blocks, laid on edge (interior walls) then another wall of them laid flat with an outer skin (showing above ground) of bricks. The ceiling/floor was built using block and beam, sealed with cement slurry, a dpm (tied into a surrounding damp proofing/tanking), with approx 6" of reinforced concrete on top and a polymer concrete drainage channel where it meets the pavement. It has been great for years, but then the council replaced the pavement and badly damaged the dpm and now I get water running through the ceiling when it rains and condensation droplets forming all over the ceiling.
I'm thinking of removing the top, right back to the brick/block work the beams are on (inc the block & beams). Any suggestions on how best to reconstruct to prevent water ingress and condensation?
I was thinking of installing a timber ceiling, filling with kingspan, setting the block & beam back in place, laying the dpm so that it drops DOWN to the outer brick skin, brick back up (incorporating weepholes all round) then finishing with reinforced concrete again, but I'm still concerned about condensation on the workshop ceiling and water getting in at the drainage channel.
Any help would be much appreciated.
Thanks
Mick

Why don't you fit a flat roof system (3 ply felt, rubber, GRP etc) to the roof?

 

[Mickyas]

Surely if the council damaged your damp proofing then the onus is on them to repair it?

Were you actually allowed to build your workshop underneath council owned land?

I'm struggling to imagine the side view of a rectangle.

I've asked the council to send out an engineer, waiting to hear back.
Its not build under council land, it is my land it just butt's up to the pavement.
Ok, imagine a rectangle, then draw a line from the bottom left corner to the top right corner, the right hand section is the part underground, the top right being the part level with the pavement.

 

[Mickyas]

Why don't you fit a flat roof system (3 ply felt, rubber, GRP etc) to the roof?

Eh and how do I park my car on it?? It'd last about a month. It wouldn't deal with the issue of water ingress from the pavement edge, where the council done the damage.

 

[Ivor Windybottom]

It will be a botch to try and seal it from the inside, doubt you'll ever achieve anything.

Think you need to give a diagram, everyone's confused. It sounds like you've been counting on a membrane on the outside keeping everything out, which was very vulnerable as you've found out.

 

[noseall]

Eh and how do I park my car on it??

Asphalt?

 

[Mickyas]

It will be a botch to try and seal it from the inside, doubt you'll ever achieve anything.

Think you need to give a diagram, everyone's confused. It sounds like you've been counting on a membrane on the outside keeping everything out, which was very vulnerable as you've found out.

The membrane/tanking worked for 15 yrs....right up until the council dug up the pavement and cut through one entire edge.

 

[Mickyas]

Asphalt?

Asphalt is permeable, so no good at preventing water ingress. Thanks for the input though, much appreciated.

 

[ajstoneservices]

I think noseall is talking about mastic asphalt

 

[Mickyas]

I think noseall is talking about mastic asphalt

Wow, never knew about that, dread to think the cost though.