I agree with most that you say. It boils down to whether moisture is wicking up the bricks from the ground or there is a higher water pressure in the wall causing it to flow out of the masonry (bricks or mortar) onto the garage floor. My understanding from the original post was the garage floor was being saturated to the point of being wet.
Personally, I have never experienced moisture wicking up the bricks and forming a “puddle” inside but have experienced very damp walls (much as you describe on your rendered plinth). Where bricks are made damp by capillary action it stays in the bricks and may cause the garage floor to become damp (and typically ruins any porous finishes inside a house) but will not “saturate” it to the point it looks wet. Not to be confused with moisture condensing on a cold wall – sorry to throw that one in.
The first stage is to solve the problem of the higher water pressure in the brick whether due to drips, rain, water transferring from the build up of muck outside or water ponding on the concrete outside (if the outside concrete is at similar level to inside). Avoiding drips from the gutter and any build up of muck can be easily tackled but rain / build up of water on the outside surface are more difficult to manage. Reducing the level of concrete outside will help but also need to ensure the area can freely drain such that standing water cannot build up and come in contact with the wall.
I would agree that you don’t want to do anything to prevent drying out or trapping moisture in the wall but unless the route cause of higher pore pressure in the masonry is solved the cause is lost. Ideally the outside needs to be lower than the inside and the addition of fillets may solve the issue but wont necessarily cure the problem. They are a way of displacing standing water and may be easier to add than breaking out concrete. Fillets (like concrete) are not materials that easily allow for the passage of water but of course they may fail in time. A barrier (need only be an inch or so) such as black jack or similar may help but I agree it should not extend to the DPC (if one installed) but should allow some unsealed surface for drying. Also need to bear in mind that if the wall gets saturated from rain and you add an external barrier that moisture (when saturated) will then come out on the inside ! (which is a relevant point you have made).
Its a balance of what steps to take and demonstrates how important it is to get building details right in the first place to avoid problems occurring in the future. I hope that Anderson365 has progressed with his remedial works and our thoughts may now be theoretical but may allow others to get a perspective of the issues for their own problems.
My last comment regarding your bricks / plinth I expect was down to porous bricks used in the post war building boom. Similar issue on a 1950’s house. Nowadays there are requirements for more durable bricks below ground level. The issue was probably the bond between the rendered plinth and brick had failed, either due to poor workmanship or frost action, and ideally should have been replaced. I suspect the rendered plinth acted as a sacrificial element providing protection to the wet bricks.
Personally, I have never experienced moisture wicking up the bricks and forming a “puddle” inside but have experienced very damp walls (much as you describe on your rendered plinth). Where bricks are made damp by capillary action it stays in the bricks and may cause the garage floor to become damp (and typically ruins any porous finishes inside a house) but will not “saturate” it to the point it looks wet. Not to be confused with moisture condensing on a cold wall – sorry to throw that one in.
The first stage is to solve the problem of the higher water pressure in the brick whether due to drips, rain, water transferring from the build up of muck outside or water ponding on the concrete outside (if the outside concrete is at similar level to inside). Avoiding drips from the gutter and any build up of muck can be easily tackled but rain / build up of water on the outside surface are more difficult to manage. Reducing the level of concrete outside will help but also need to ensure the area can freely drain such that standing water cannot build up and come in contact with the wall.
I would agree that you don’t want to do anything to prevent drying out or trapping moisture in the wall but unless the route cause of higher pore pressure in the masonry is solved the cause is lost. Ideally the outside needs to be lower than the inside and the addition of fillets may solve the issue but wont necessarily cure the problem. They are a way of displacing standing water and may be easier to add than breaking out concrete. Fillets (like concrete) are not materials that easily allow for the passage of water but of course they may fail in time. A barrier (need only be an inch or so) such as black jack or similar may help but I agree it should not extend to the DPC (if one installed) but should allow some unsealed surface for drying. Also need to bear in mind that if the wall gets saturated from rain and you add an external barrier that moisture (when saturated) will then come out on the inside ! (which is a relevant point you have made).
Its a balance of what steps to take and demonstrates how important it is to get building details right in the first place to avoid problems occurring in the future. I hope that Anderson365 has progressed with his remedial works and our thoughts may now be theoretical but may allow others to get a perspective of the issues for their own problems.
My last comment regarding your bricks / plinth I expect was down to porous bricks used in the post war building boom. Similar issue on a 1950’s house. Nowadays there are requirements for more durable bricks below ground level. The issue was probably the bond between the rendered plinth and brick had failed, either due to poor workmanship or frost action, and ideally should have been replaced. I suspect the rendered plinth acted as a sacrificial element providing protection to the wet bricks.
