I suggest you get an independent survey to pinpoint the problem before undertaking any remedial works.
Damp concrete garage floor.
How do you fix low spots in garage floor concrete.
Here are 6 ways to reduce concrete floor condensation.
Damp proof membranes for concrete.
Damp in concrete floors.
Due to concrete s porous nature it can then travel through it causing issues in the flooring above.
I believe a damp proof sheet was used under the concrete floor as indicated by the telltale black sheeting used before the concrete floor was poured.
Sometimes the issue can be bridging of the damp proof course by the concrete floor assuming is was timber prior as this often occurs.
But if these methods are non existent or if they have failed in some way here are some ideas to resolve and reseal your damp garage floor.
Use a de greaser to remove oil from the surface.
This can cause issues with mold and mildew especially if you have carpet or.
Dry out your warehouse and materials using air movement.
Therefore it s advisable to have a floor tested for moisture content prior to installing flooring or moisture barriers.
Damp from the ground can make its way into your concrete floor.
If your garage floor is constantly wet or damp you may have a water problem from either excessive ground water a breach in the moisture barrier or a leaking pipe.
After the construction was finished i painted the concrete floor in the new extension.
Changes in the surrounding environment can have a major impact on moisture levels within the concrete slab.
All seemed good and it dried well.
Use a wire brush or a grinder or an acid substitute to prepare the concrete.
Concrete slabs and floors can be excellent subfloor surfaces for tile and other floor coverings but too much moisture in the concrete can cause problems with flooring installations.
When damp proofing a concrete garage floor a plastic dimpled membrane is required if the floor is going to be boarded either with chipboard plywood or similar or if a concrete screed is going to be laid.
I m guessing that this sheeting is the vapour barrier you talk about.
In an ideal world damp proofing methods should be taken during the initial construction phase of the garage.
It could also be bridging by the internal plaster or a failure of the wall floor joint.
Floor membrane from property repair systems roll out and lay on either chipboard plywood mdf or screed.