Wet Garage Floor

[SamO]

I have recently moved into a house that was built in the 70’s. There is a garage in the garden that I plan on using as a gym and a workshop in the future but I am worried about this plan because there seems to be a significant amount of water on the floor after heavy rain. It doesn’t appear to be leaking from the roof because there is no sign of wetness on the ceiling, I have checked the guttering for blockages on my own garage and my neighbours garage roof, and I don’t think that it is flowing from the garage door because of the direction of the water flow, it appears to originate from the wall. The wall where the water seems to be coming from backs onto the neighbour’s garden so I have had a look around there and dug out some soil from their bed to make sure that the ground level is not higher that the foundations of our garage floor but this does not seem to have made any difference. There are a few trees growing directly next to the garage so it is possible that these could be causing some issues with the foundations. I think I need to get some specialist advice but I am not sure a general builder will be able to help. Can anyone suggest what my next step should be?

I have attached some photos:

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• SamO
• 26 Dec 2013
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• SamO
• 26 Dec 2013
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• SamO
• 26 Dec 2013
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• SamO
• 26 Dec 2013
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• SamO
• 26 Dec 2013
• 1

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• SamO
• 26 Dec 2013
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• SamO
• 26 Dec 2013
• 1

 

[cotswoldbuilders]

Might help to put a mortar fillet along the edges.

 

[footprints]

As above it may be lying on the concrete and seeping under through the mortar

 

[Blagard]

I don't think you will find there is any foundation except the slab itself sitting on hardcore. It is likely to be a simple raft foundation

It looks like a small fillet of mortar on the water butt elevation but that moss is like holding a sponge to the brickwork. In any situation where the slab is extending outside from the brickwork it will help to have the fillet mentioned above.

The garden with the paving slab nearby is still high so aim to get that area lower.

In the end I think you will always have a damp slab due to the absence of a DPM

All the same I am surprised at the apparent amount of water on the floor and wonder if there is simply a puddle of water forming during the rain outside at the places where it leaks the most. Make sure there is a route for water to run away from the slab edges and at all time keep the ground well below the edges..

If you really want the floor to be dry the only real option is to put a DMP down inside and turned up at the edges and ideally lapped onto the DPC in the wall. You would then have to protect it with a screed. The detailing at the garage doors would need to be carefully done to ensure you don't get water making ingress at those points.

In your case the main issue with trees may be an accumulation of dead leaves between the fence and garage walls. If you get that they will simply hold the water until it seeps away which could easily be through the brickwork.