DIY Doctor

Decking membrane underlay holding water causing a leak under balcony deck

Postby borse2008 » Mon Jun 29, 2020 7:43 pm

Hello all,

Im looking for some advice and guidance on this situation.

I have a townhouse 3 floors, i have a lounge with a set of french doors onto some wood decking balcony below this is the kitchen on the ground level. Directly below the decking is the sitting area in the kitchen in the right hand corner of the area is a slow damp leak from standing water which i found today not being drained away underneath the decking.

Its sat on the membrane which is a patterned soft fabric matt which is red in colour, im not sure what it is, as such not sure what it is. Internally directly below is a slow leak which has been dropping though onto the ceiling and area around the hot water pipes where the combi boiler is running pipes and situated.

The decking is angled but water just sits in the area where the leak is but not angled enough to drain away.

I took up the decking board which are all rotted and not secure on the first floor to see the water in puddles.

Realistically the who deck never gets used and the boards are needing to be replaced would consider just doing the composite ones but want to seal the desk watertight not sure what to do?

Below are some photos
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DIY asbestos test kits

Postby stoneyboy » Tue Jun 30, 2020 10:26 pm

Hi borse2008
Suggest you remove all decking and structure, clean the tiled floor and check if the balcony drains when there is no decking in place. If it is apparent that the falls are insufficient and water is getting through the floor structure you could try using a 2 part epoxy sealer to form a DPM and then screed on top to give falls before you fit new decking.
This will all take months because the structure will need to dry before applying DPM.
Regards S
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